Search

Herein, we explore, from a theoretical perspective, the nonradiative photoinduced processes (charge separation and energy transfer) within a family of donor–acceptor supramolecular complexes based on the electron-donor truxene-tetrathiafulvalene (truxTTF) derivative and a series of curved fullerene fragments (buckybowls) of different shapes and sizes (C30H12, C32H12, and C38H14) as electron acceptors that successfully combine with truxTTF via non-covalent interactions. The resulting supramolecular complexes (truxTTF·C30H12, truxTTF·C32H12, and truxTTF·C38H14) undergo charge-separation processes upon photoexcitation through charge-transfer states involving the donor and acceptor units. Despite the not so different size of the buckybowls, they present noticeable differences in the charge-separation efficiency owing to a complex decay post-photoexcitation mechanism involving several low-lying excited states of different natures (local and charge-transfer excitations), all closely spaced in energy. In this intricate scenario, we have adopted a theoretical approach combining electronic structure calculations at (time-dependent) density functional theory, a multistate multifragment diabatization method, the Marcus–Levitch–Jortner semiclassical rate expression, and a kinetic model to estimate the charge separation rate constants of the supramolecular heterodimers. Our outcomes highlight that the efficiency of the photoinduced charge-separation process increases with the extension of the buckybowl backbone. The supramolecular heterodimer with the largest buckybowl (truxTTF·C38H14) displays multiple and efficient electron-transfer pathways, providing a global photoinduced charge separation in the ultrafast time scale in line with the experimental findings. The study reported indicates that modifications in the shape and size of buckybowl systems can give rise to attractive novel acceptors for potential photovoltaic applications. [ABSTRACT FROM AUTHOR]

The plasmonic coupling between silver (Ag) and gold (Au) nanoparticles (NPs) under four polarization modes was examined: a longitudinal mode (L-mode), where the electric field of a linearly polarized incident light parallels the dimer axis, and three transverse modes (T-modes), where the electric field of the light is perpendicular to the dimer axis. The coupling was studied using the discrete dipole approximation followed by an in-house postprocessing code that determines the extinction (Qext), absorption (Qabs), and near-field (Qnf) spectra from the individual NPs as well as the whole system. In agreement with the literature results, the extinction/absorption spectra of the whole dimer have two peaks, one near the Ag localized surface plasmon resonance (LSPR) region and the other at the Au LSPR region, with the peak at Ag LSPR being reduced in all modes and the peak at Au LSPR being red-shifted and increased in the L-mode but not in the T-modes. It is further shown that the scattering at the Ag LSPR region is reduced and becomes less than the isolated Ag NPs, but the absorption at the Ag LSPR is increased and becomes greater than the isolated Ag NPs for the 50 nm Ag–Au heterodimer. This suggests that the scattering from Ag NPs is being reabsorbed by the neighboring Au NPs due to the interband electronic transition in Au at that wavelength range. The Qext from the individual NP in the heterodimer shows the presence of the Fano profile on the Au NP but not on the Ag NP. This phenomenon was further investigated by using a dielectric particle (DP) placed near the Ag or Au NPs. The Fano profile appears in the absorbing DP spectra placed near either Ag or Au NPs. However, the Fano profile is masked upon further increases in the refractive index value of the DP particle. This explains the absence of a Fano profile on the Ag NPs in the Ag–Au heterodimer. The large near-field enhancement on both Ag and Au NPs at the Au plasmonic wavelength in the L-mode for large NPs was investigated through a DP-Au system. The large enhancement was shown to arise from a large imaginary component of the DP refractive index and a small real component. Through examination of both the near- and far-field properties of the individual NPs as well as the whole system and examinations of DP-Ag and DP-Au systems, our study provides a new understanding of the couplings between Ag and Au NPs. [ABSTRACT FROM AUTHOR]

XYG3-type doubly hybrid (xDH) approximations have gained widespread recognition for their accuracy in describing a diverse range of chemical and physical interactions. However, a recent study [Song et al., J. Phys. Chem. Lett. 12, 800–807 (2021)] has highlighted the limitation of xDH methods in calculating the dissociation of NaCl molecules. This issue has been related to the density and orbitals used for evaluating the energy in xDH methods, which are obtained from lower-rung hybrid density functional approximations (DFAs) and display substantial density errors in the dissociation limit. In this work, we systematically investigate the influence of density on several challenging datasets and find that xDH methods are less sensitive to density errors compared to semi-local and hybrid DFAs. Furthermore, we demonstrate that the self-interaction corrected SCAN density approach offers superior accuracy compared to the self-consistent SCAN density and Hartree–Fock density approaches, as evidenced by performing charge analysis on the dissociation of heterodimers, such as NaCl and LiF. Building on these insights, we propose a five-parameter xDH method using the SCAN density and orbitals corrected by the PZ-SIC scheme. This new xDH@SCAN(SIC) method provides a balanced and accurate description across a wide range of challenging systems. [ABSTRACT FROM AUTHOR]

Macroautophagy is a catabolic process that maintains cellular homeostasis by recycling intracellular material through the use of double-membrane vesicles called autophagosomes. In turn, autophagosomes fuse with vacuoles (in yeast and plants) or lysosomes (in metazoans), where resident hydrolases degrade the cargo. Given the conservation of autophagy, Saccharomyces cerevisiae is a valuable model organism for deciphering molecular details that define macroautophagy pathways. In yeast, macroautophagic pathways fall into two subclasses: selective and nonselective (bulk) autophagy. Bulk autophagy is predominantly upregulated following TORC1 inhibition, triggered by nutrient stress, and degrades superfluous random cytosolic proteins and organelles. In contrast, selective autophagy pathways maintain cellular homeostasis when TORC1 is active by degrading damaged organelles and dysfunctional proteins. Here, selective autophagy receptors mediate cargo delivery to the vacuole. Now, two groups have discovered a new hybrid autophagy mechanism, coined cargo hitchhiking autophagy (CHA), that uses autophagic receptor proteins to deliver selected cargo to phagophores built in response to nutrient stress for the random destruction of cytosolic contents. In CHA, various autophagic receptors link their cargos to lipidated Atg8, located on growing phagophores. In addition, the sorting nexin heterodimer Snx4-Atg20 assists in the degradation of cargo during CHA, possibly by aiding the delivery of cytoplasmic cargos to phagophores and/or by delaying the closure of expanding phagophores. This review will outline this new mechanism, also known as Snx4-assisted autophagy, that degrades an assortment of cargos in yeast, including transcription factors, glycogen, and a subset of ribosomal proteins. [ABSTRACT FROM AUTHOR]

[Display omitted] • A universal "triadic" self-delivery system is proposed for mitigating multidrug resistance in lung cancer while enhancing efficiency. • Two GSH-responsive heterodimers, ERL-SS-CPT and CPT-SS-ERI, are utilized as both cargo and carrier materials. • Both ERL-SS-CPT NPs and CPT-SS-ERI NPs demonstrate well-defined spherical structures and excellent storage stability. • A computer-aided heterodimer-based carrier-free drug delivery platform comprising 40 variants is developed. Co-delivering multiple drugs or circumventing the drug efflux mechanism can significantly decrease multidrug resistance (MDR), a major cause of cancer treatment failure. In this study, we designed and fabricated a universal "three-in-one" self-delivery system for synergistic cancer therapy using a computer-aided strategy. First, we engineered two glutathione (GSH)-responsive heterodimers, ERL-SS-CPT (erlotinib [ERL] linked with camptothecin [CPT] via a disulfide bond [SS]) and CPT-SS-ERI (CPT conjugated with erianin [ERI]), which serve as both cargo and carrier material. Next, molecular dynamics simulations indicated that multiple noncovalent molecular forces, including π-π stacking, hydrogen bonds, hydrophobic interactions, and sulfur bonds, drive the self-assembly process of these heterodimers. We then explored the universality of the heterodimers and developed a "triadic" drug delivery platform comprising 40 variants. Subsequently, we conducted case studies on docetaxel (DTX)-loaded ERL-SS-CPT nanoparticles (denoted as DTX@ERL-SS-CPT NPs) and curcumin (CUR)-loaded ERL-SS-CPT NPs (identified as CUR@CPT-SS-ERI NPs) to comprehensively investigate their self-assembly mechanism, physicochemical properties, storage stability, GSH-responsive drug release, cellular uptake, apoptosis effects, biocompatibility, and cytotoxicity. Both NPs exhibited well-defined spherical structures, high drug loading rates, and excellent storage stability. DTX@ERL-SS-CPT NPs exhibited the strongest cytotoxicity in A549 cells, following the order of DTX@ERL-SS-CPT NPs > ERL-SS-CPT NPs > CPT > DTX > ERL. Conversely, DTX@ERL-SS-CPT NPs showed negligible cytotoxicity in normal human bronchial epithelium cell line (BEAS-2B), indicating good biocompatibility and safety. Similar observations were made for CUR@CPT-SS-ERI NPs regarding biocompatibility and cytotoxicity. Upon endocytosis and encountering intracellular overexpressed GSH, the disulfide-bond linker is cleaved, resulting in the release of the versatile NPs into three parts. The spherical NPs enhance water solubility, reduce the required dosage of free drugs, and increase cellular drug accumulation while suppressing P-glycoprotein (P-gp) expression, leading to apoptosis. This work provides a computer-aided universal strategy—a heterodimer-based "triadic" drug delivery platform—to enhance anticancer efficiency while reducing multidrug resistance. [ABSTRACT FROM AUTHOR]

Wnt/β-catenin signaling directs animal development and tissue renewal in a tightly controlled, cell- and tissue-specific manner. In the mammalian central nervous system, the atypical ligand Norrin controls angiogenesis and maintenance of the blood-brain barrier and blood-retina barrier through the Wnt/β-catenin pathway. Like Wnt, Norrin activates signaling by binding and heterodimerizing the receptors Frizzled (Fzd) and low-density lipoprotein receptor-related protein 5 or 6 (LRP5/6), leading to membrane recruitment of the intracellular transducer Dishevelled (Dvl) and ultimately stabilizing the transcriptional coactivator β-catenin. Unlike Wnt, the cystine knot ligand Norrin only signals through Fzd4 and additionally requires the co-receptor Tetraspanin12 (Tspan12); however, the mechanism underlying Tspan12-mediated signal enhancement is unclear. It has been proposed that Tspan12 integrates into the Norrin-Fzd4 complex to enhance Norrin-Fzd4 affinity or otherwise allosterically modulate Fzd4 signaling. Here, we measure direct, high-affinity binding between purified Norrin and Tspan12 in a lipid environment and use AlphaFold models to interrogate this interaction interface. We find that Tspan12 and Fzd4 can simultaneously bind Norrin and that a pre-formed Tspan12/Fzd4 heterodimer, as well as cells co-expressing Tspan12 and Fzd4, more efficiently capture low concentrations of Norrin than Fzd4 alone. We also show that Tspan12 competes with both heparan sulfate proteoglycans and LRP6 for Norrin binding and that Tspan12 does not impact Fzd4-Dvl affinity in the presence or absence of Norrin. Our findings suggest that Tspan12 does not allosterically enhance Fzd4 binding to Norrin or Dvl, but instead functions to directly capture Norrin upstream of signaling. [ABSTRACT FROM AUTHOR]

Extrinsic apoptotic network is driven by Death Ligand (DL)-mediated activation of procaspase-8. Recently, we have developed the first-in class small molecule, FLIPinB, which specifically targets the key regulator of extrinsic apoptosis, the protein c-FLIPL, in the caspase-8/c-FLIPL heterodimer. We have shown that FLIPinB enhances DL-induced caspase-8 activity and apoptosis. However, the effects of FLIPinB action in combination with other cell death inducers have only just begun to be elucidated. Here, we show that FLIPinB enhances the cell death in pancreatic cancer cells induced by combinatorial treatment with DL, gemcitabine and Mcl-1 inhibitor S63845. Further, we found that these effects are mediated via an increase in the complex II assembly. Collectively, our study shows that targeting the caspase-8/c-FLIPL heterodimer in combination with the other drugs in pancreatic cancer cells is a promising direction that may provide a basis for further therapeutic strategies. Targeting caspase-8/c-FLIPL heterodimer with small molecule FLIPinB in combination with death ligands, gemcitabine and Mcl-1 inhibitor efficiently eliminates pancreatic cancer cells via promoting complex II assembly [ABSTRACT FROM AUTHOR]

Summary Hereditary congenital erythrocytosis results from constitutive activation of the hypoxia pathway. This pathway is controlled by regulation of the α isoforms of the hypoxia‐inducible factor α/β heterodimer, notably via hydroxylation by prolyl hydroxylase domain 2 (PHD2). Mutations affecting PHD2 are involved in Type 3 erythrocytosis. We report an atypical family bearing two PHD2 mutations located in Cis (L195H and E225D) transmitted in a dominant feature, together with a phenotypic analysis, structural modelling and functional study. Mutations have a cumulative effect, with E255D playing the major role, and severely compromised PHD2 stability, probably explaining why the hypoxia pathway at the origin of the disease is activated. [ABSTRACT FROM AUTHOR]

Background: Platelet receptors ACKR3 and CXCR4 play a crucial role in a variety of cardiovascular diseases. Like most chemokine receptors, CXCR4 is a G protein coupled receptor that induces platelet activation. In contrast, the atypical chemokine receptor 3 (ACKR3) lacks the ability to activate heterotrimeric G proteins and its activation leads to platelet inhibition and attenuates thrombus formation. In nucleated cells, heterodimerization of ACKR3 with CXCR4 regulates CXCL12‐dependent signalling. The aim of our study was to investigate the formation of ACKR3/CXCR4 heterodimers in platelets and the subsequent consequences for platelet function. Methods and Results: Using a proximity ligation assay (PLA, Duolink®) to screen for CXCR4/ACKR3 heterodimerization inducing compounds, we found that ACKR3 agonism but not conventional platelet agonists or endogen ligands lead to heterodimer formation. To further characterize the formation of ACKR3/CXCR4 heterodimers, we studied the CXCL12‐dependent platelet activation via CXCR4. Both, CXCL12‐dependent platelet aggregation and collagen‐dependent ex vivo thrombus formation were significantly downregulated by ACKR3 agonism. Moreover, platelet intracellular calcium and Akt signalling were increased by CXCL12 and again suppressed by ACKR3‐specific agonists. Previously, CXCL12 was shown to decrease platelet cAMP levels via CXCR4. Treatment with a specific ACKR3 agonist counteracted this CXCL12/CXCR4‐dependent cAMP decrease. Conclusion: Our results reveal that the formation of platelet ACKR3/CXCR4 heterodimers is dependent on ACKR3 rather than CXCR4. Furthermore, ACKR3 agonism induced heterodimerization is associated with mitigating CXCL12/CXCR4‐dependent platelet activation possibly by modulating CXCR4‐dependent G protein signalling. Our results indicate possible ACKR3 agonist functions and reinforce the potential therapeutic applications of ACKR3 agonists. [ABSTRACT FROM AUTHOR]

Macrocycles that encapsulate two guests can self-sort those into homo- and heterodimers. We report here a family of self-sorting homobimetallic Pt(II) terpyridyl acetylide dimers secured together with a pair of Cucurbit[8]uril macrocycles (CB[8]). The rigid bridging unit between both Pt centers introduces varying "hinge" angles, resulting in disparities in Pt–Pt distances in the heterodimers, and leads to recognition motif mismatch. We found that the self-sorting process can be quantified using a simple model, in which each complex behaves as a simple harmonic oscillator, whose heteroassembly tends to minimize geometry distorsions through C(aryl)–C≡C–Pt axis deformation. [ABSTRACT FROM AUTHOR]

Decanuclear chiral gold(I) sulfido clusters (SSDP‐Au10 and RSDP‐Au10) have been assembled by taking advantage of the judiciously selected SDP ligands (SDP = 7,7′‐bis(diphenylphosphino)‐1,1′‐spirobiindane). Interestingly, an achiral heterodimer icosanuclear meso‐cluster (mesoSDP‐Au20) has been obtained by simply mixing SSDP‐Au10 and RSDP‐Au10 in a 1:1 ratio. These gold(I) complexes have been found to display intense near‐infrared (NIR) luminescence with an emission maximum at around 750 nm in the solid state. The photoluminescence quantum yield (PLQY) of mesoSDP‐Au20 in drop‐cast solid‐state thin film has been found to show a significant enhancement from 8 % in the SSDP‐Au10 and RSDP‐Au10 to 25 %. In addition, the dimerization process with heterochiral self‐discrimination has been found to be sensitive to the solvent polarity and configuration of the diphosphine ligand. This work has provided a platform for the investigation and mechanistic understanding of heterochiral self‐sorting and assembly processes. [ABSTRACT FROM AUTHOR]

Immuno-oncology has revolutionized cancer treatment, with NKG2A emerging as a novel target for immunotherapy. The blockade of NKG2A using the immune checkpoint inhibitor (ICI) monalizumab has been shown to enhance the responses of both NK cells and CD8+ T cells. However, monalizumab has demonstrated limited efficacy in in vitro cytotoxic assays and clinical trials. In our study, we discovered and characterized a novel anti-NKG2A antibody, BRY805, which exhibits high specificity for the human CD94/NKG2A heterodimer complex and does not bind to the activating NKG2C receptor. In vitro cytotoxicity assays demonstrated that BRY805 effectively activated NK92 cells and primary NK cells, thereby enhancing the cytotoxic activity of effector cells against cancer cells overexpressing HLA-E, with significantly greater efficacy compared to monalizumab. Furthermore, BRY805 exhibited synergistic antitumor activity when combined with PD-L1 monoclonal antibodies. In a mouse xenograft model, BRY805 showed superior tumor control relative to monalizumab and demonstrated a favorable safety profile in non-human primate studies. [ABSTRACT FROM AUTHOR]

Objective: Currently, 68Ga-labeled somatostatin analogs (SSAs) are the most commonly used imaging agents for patients with neuroendocrine tumors (NETs) in clinical practice, demonstrating good results in tumor diagnosis. For applications in peptide receptor radionuclide therapy (PRRT), targeted drugs should have high tumor uptake and prolonged tumor retention time. To enhance the uptake and retention of tracers in NETs, our goal is to design a 68Ga-labeled heterodimer for optimizing pharmacokinetics and assess whether this form is more efficacious than its monomeric equivalents. Methods: Using the somatostatin analog TATE and quinoline-based compound FAPI-46 as raw materials, we designed and synthesized 68Ga-labeled TATE-46. The labeling efficiency and stability were verified by Radio-HPLC. The receptor binding properties and tumor targeting were examined both in vitro and in vivo by using NCI-H727 (SSTR2/FAP, positive) and Mc38 (SSTR2/FAP, negative) cell lines and tumor-bearing mouse models. Preclinical evaluation was performed through cell uptake, pharmacokinetics, Micro PET, and biodistribution studies, and the results were compared with [68Ga]Ga-DOTA-TATE and [68Ga]Ga -FAPI-46. Immunohistochemistry and HE staining were performed on tumor tissues from tumor-bearing mice for further validation. Results: [68Ga]Ga-TATE-46 showed comparable SSTR2 and FAP targeting ability to monomeric TATE and FAPI-46 in cell uptake and PET imaging studies. [68Ga]Ga-TATE-46 exhibited significantly higher uptake in NCI-H727 (SSTR2/FAP, positive) tumors compared to [68Ga]Ga-DOTA-TATE (p < 0.001) and [68Ga]Ga-FAPI-46 (p < 0.001). No increased uptake of [68Ga]Ga-TATE-46 was observed in MC38 tumors (SSTR2/FAP, negative). Additionally, excess DOTA-TATE and/or unlabeled FAPI-46 significantly blocked the uptake of [68Ga]Ga-TATE-46 in NCI-H727 tumors (p < 0.001), confirming its dual-receptor targeting characteristics. The ex vivo biodistribution, immunofluorescence and immunohistochemistry results were in line with the in vivo imaging findings. Conclusion: Compared with 68Ga-labeled FAPI-46 and DOTA-TATE mono-specific tracers, the dual-target tracer [68Ga]Ga-TATE-46 improves tumor uptake, extends tumor retention, and enhances pharmacokinetics. It is an effective probe for non-invasive detection of tumors expressing FAP and SSTR2, and it is worth further studying its application in the expression of sstr2 and FAP-related tumors. [ABSTRACT FROM AUTHOR]

The article discusses the potential of the apelin receptor (APLNR) as a therapeutic target for cardiovascular diseases due to its positive effects on the cardiovascular system. Various small-molecule agonists have been developed, but challenges remain in mitigating adverse effects. Recent advancements in designing exclusively G-protein-biased APLNR agonists, such as WN561, show promise in reducing adverse effects and improving therapeutic outcomes. The research on APLNR serves as a model for precision drug design in G protein-coupled receptor (GPCR) therapeutics, offering insights into biased drug signaling and innovative strategies for future drug development targeting APLNR. [Extracted from the article]

Chalcogen bonds (ChBs) involving selenium have attracted substantial scholarly interest in past years owing to their fundamental roles in various chemical and biological fields. However, the effect of the valency state of the electron-deficient selenium atom on the characteristics of such ChBs remains unexplored. Herein, we comparatively studied the σ-hole-type Se∙∙∙O ChBs between SeF2/SeF4 and a series of oxygen-bearing Lewis bases, including water, methanol, dimethyl ether, ethylene oxide, formaldehyde, acetaldehyde, acetone, and formic acid, using ab initio computations. The interaction energies of these chalcogen-bonded heterodimers vary from −5.25 to −11.16 kcal/mol. SeF2 participates in a shorter and stronger ChB than SeF4 for all the examined heterodimers. Such Se∙∙∙O ChBs are closed-shell interactions, exhibiting some covalent character for all the examined heterodimers, except for SeF4∙∙∙water. Most of these chalcogen-bonded heterodimers are predominantly stabilized through orbital interactions between the lone pair of the O atom in Lewis bases and the σ*(Se–F) antibonding orbitals of Lewis acids. The back-transfer of charge from the lone pair of selenium into the σ* or π* antibonding orbitals of Lewis bases is also observed for all systems. Energy decomposition analysis reveals that the electrostatic component significantly stabilizes the targeted heterodimers, while the induction and dispersion contributions cannot be ignored. [ABSTRACT FROM AUTHOR]

The tanning hormone, Bursicon, is a neuropeptide secreted by the insect nervous system that functions as a heterodimer composed of Burs‐α and Burs‐β subunits. It plays a critical role in the processes of cuticle tanning and wing expansion in insects. In this study, we successfully identified the AcBurs‐α and AcBurs‐β genes in Aphis citricidus. The open reading frames of AcBurs‐α and AcBurs‐β were 480 and 417 bp in length, respectively. Both AcBurs‐α and AcBurs‐β exhibited 11 conserved cysteine residues. AcBurs‐α and AcBurs‐β were expressed during all developmental stages of A. citricidus and showed high expression levels in the winged aphids. To investigate the potential role of AcBurs‐α and AcBurs‐β in wing development, we employed RNA interference (RNAi) techniques. With the efficient silencing of AcBurs‐α (44.90%) and AcBurs‐β (52.31%), malformed wings were induced in aphids. The proportions of malformed wings were 22.50%, 25.84%, and 38.34% in dsAcBurs‐α‐, dsAcBur‐β‐, and dsAcBurs‐α + dsAcBur‐β‐treated groups, respectively. Moreover, feeding protein kinase A inhibitors (H‐89) also increased the proportion of malformed wings to 30.00%. Feeding both double‐stranded RNA and inhibitors (H‐89) significantly downregulated the wing development‐related genes nubbin, vestigial, notch and spalt major. Silence of vestigial through RNAi also led to malformed wings. Meanwhile, the exogenous application of 3 hormones that influence wing development did not affect the expression level of AcBursicon genes. These findings indicate that AcBursicon genes plays a crucial role in wing development in A. citricidus; therefore, it represents a potential molecular target for the control of this pest through RNAi‐based approaches. [ABSTRACT FROM AUTHOR]

An optimal HCV vaccine requires the induction of antibodies that neutralise the infectivity of many heterogenous viral isolates. In this study, we have focused on determining the optimal recombinant envelope glycoprotein component to elicit cross-neutralising antibodies against global HCV genotypes. We compared the immunoreactivity and antigenicity of the HCV genotype 1a strain H77C-derived envelope glycoprotein heterodimer gpE1/gpE2 with that of recombinant gpE2 alone. Characterisation of the envelope glycoproteins was accomplished by determining their ability to bind to a panel of broadly cross-neutralising monoclonal antibodies. Immunogenicity was determined by testing the ability of vaccine antisera to neutralise the infectivity in vitro of a panel of pseudotyped HCV particles in which gpE1/gpE2 derived from representative isolates of the major global HCV genotypes were displayed. gpE1/gpE2 binds to more diverse broadly cross-neutralising antibodies than gpE2 alone and elicits a broader profile of cross-neutralising antibodies in animals, especially against more heterologous, non-1a genotypes. While not all heterologous HCV strains can be potently inhibited in vitro by gpE1/gpE2 antisera derived from a single HCV strain, the breadth of heterologous cross-neutralisation is shown to be substantial. Our work supports the inclusion of gpE1/gpE2 in an HCV vaccine in order to maximise the cross-neutralisation of heterogenous HCV isolates. Our data also offers future directions in formulating a cocktail of gpE1/gpE2 antigens from a small selection of HCV genotypes to further enhance cross-neutralisation of global HCV strains and hopefully advance the development of a globally effective HCV vaccine. An HCV vaccine is urgently required to prevent the high global incidence of HCV infection and disease. Since HCV is a highly heterogeneous virus, it is desirable for a vaccine to elicit antibodies that neutralise the infectivity of most global strains. To this end, we have compared the immunoreactivity and antigenicity of recombinant H77C E1E2 heterodimer with that of H77C E2 alone and show that the former exhibits more cross-neutralising epitopes and demonstrates a broader cross-neutralisation profile in vitro. In addition, our data suggests a way to further broaden cross-neutralisation using a combination of E1E2 antigens derived from a few different HCV clades. Our work is relevant for the development of an effective global HCV vaccine. [Display omitted] • Glycoprotein-based HCV vaccines are immunogenic. • We compared the antigenicities of E1E2 and E2. • HCV E1E2-based vaccine induced a broader cross-neutralising profile. [ABSTRACT FROM AUTHOR]

The article compares two essential regulators of the ubiquitin proteasome system: the 26S proteasome LID and the COP9 signalosome. The LID and the CSN are paralog complexes with specific subunits that interact with cullin-RING ubiquitin ligases. The MPN+/MPN domain proteins in these complexes play a crucial role in deubiquitylation and deneddylation processes. The study explores the potential of the CSN as a regulator of the 20S enzyme and highlights the importance of understanding the interactions between these complexes for potential therapeutic targeting in various diseases. [Extracted from the article]

In order to determine the underpinnings of a dysfunctional NO-sGC signal pathway which occurs in pulmonary arterial hypertension (PAH), we investigated pulmonary arterial smooth muscle cells (PASMCs) derived from PAH patients. We found low expression of sGC, a poor sGCα1β1 heterodimer and this correlated with low expression of its facilitator chaperon, hsp90. Treating PASMCs overnight (16 h) with low micromolar doses of a slow release NO donor DETANONOate, reinstated the sGCα1β1 heterodimer and restored its NO-heme dependent activity. Transwell co-culture of HEK cells stably expressing eNOS with PAH PASMCs also restored the sGC heterodimer and its heme-dependent activity with sGC stimulator, BAY 41–2272. To determine whether the dysfunctionality in the NO-sGC pathway stems from a dysfunctional eNOS producing negligible NO, we did transwell co-cultures of pulmonary arterial endothelial cells (PAECs) with PASMCs. Our results indicated that PAECs from both control and PAH samples when activated for eNOS restored both sGC heterodimer and its heme-dependent sGC activity in the corresponding PASMCs, suggesting that PAECs from PAH can also generate NO. In line with these results expression of eNOS, its support chaperon hsp90, its specific kinase Akt, p-Akt or post-translational modifications (PTMs) like OGlcNAc or phospho-tyrosine were unchanged in PAH relative to controls. Additionally there was uniform expression of Hbα/β and Mb in PASMCs or PAECs in PAH or controls and these globins can effectively scavenge the eNOS generated NO, as there was evidence of strong eNOS-Hb/Mb interactions. Our studies suggest that factors such as globin NO scavenging along with vascular remodeling in PAH can cause hampered vasodilation which in the face of poor NO levels as occurs in PAH are additional impediments for effective vasodilation. However importantly our studies suggests that future therapies can use low doses of NO along with sGC stimulators as a potential drug for PAH subjects. [Display omitted] • Low expression of sGC and a poor sGCα1β1 heterodimer causes sGC dysfunction in PAH. • PASMCs derived from PAH were revived when treated with a low NO dose plus sGC stimulator BAY-41. • ENOS from PAH derived PAECs can be activated to cause sGC stimulation in the PASMCs. • PASMCs and PAECs express globins which scavenges the NO, but this was overcome by the low NO dose that activated sGC. [ABSTRACT FROM AUTHOR]

Eukaryotic cytochrome P450 enzymes, generally colocalizing with their redox partner cytochrome P450 reductase (CPR) on the cytoplasmic surface of organelle membranes, often perform poorly in prokaryotic cells, whether expressed with CPR as a tandem chimera or free-floating individuals, causing a low titer of heterologous chemicals. To improve their biosynthetic performance in Escherichia coli, here, we architecturally design self-assembled alternatives of eukaryotic P450 system using reconstructed P450 and CPR, and create a set of N-termini-bridged P450-CPR heterodimers as the counterparts of eukaryotic P450 system with N-terminus-guided colocalization. The covalent counterparts show superior and robust biosynthetic performance, and the N-termini-bridged architecture is validated to improve the biosynthetic performance of both plant and human P450 systems. Furthermore, the architectural configuration of protein assemblies has an inherent effect on the biosynthetic performance of N-termini-bridged P450-CPR heterodimers. The results suggest that spatial architecture-guided protein assembly could serve as an efficient strategy for improving the biosynthetic performance of protein complexes, particularly those related to eukaryotic membranes, in prokaryotic and even eukaryotic hosts. Cytochrome P450 enzymes (P450s) and their redox partner cytochrome P450 reductase (CPR) often perform poorly in bioproduction of natural products by engineered prokaryotic microbes. Here, the authors report spatial architecture-guided P450-CPR assembly for improving the biosynthetic performance of both plant and human P450s in E. coli. [ABSTRACT FROM AUTHOR]

Colorectal cancer (CRC) is one of the most common malignant tumors. Identification of new effective drug targets for CRC and exploration of bioactive small‐molecules are clinically urgent. The human dCTP pyrophosphatase 1 (DCTPP1) is a newly identified pyrophosphatase regulating the cellular nucleotide pool but remains unexplored as potential target for CRC treatment. Here, twelve unprecedented chemical architectures terpene‐nonadride heterodimers (1–12) and their monomers (13–20) were isolated from endophyte Bipolaris victoriae S27. Compounds 1–12 represented the first example of terpene‐nonadride heterodimers, in which nonadride monomers of 1 and 2 were also first example of 5/6 bicyclic nonadrides. A series of assays showed that 2 could repress proliferation and induce cell cycle arrest, apoptotic and autophagic CRC cell death in vitro and in vivo. Clinical cancer samples data revealed that DCTPP1 was a novel target associated with poor survival in CRC. DCTPP1 was also identified as a new target protein of 2. Mechanically, compound 2 bound to DCTPP1, inhibited its enzymatic activity, intervened with amino acid metabolic reprogramming, and exerted anti‐CRC activity. Our study demonstrates that DCTPP1 was a novel potential biomarker and therapeutic target for CRC, and 2 was the first natural anti‐CRC drug candidate targeting DCTPP1. [ABSTRACT FROM AUTHOR]

The active form of vitamin D, 1,25-dihydroxyvitamin D (1,25D), binds to the vitamin D receptor (VDR) with high affinity. The VDR then heterodimerizes with the retinoid X receptor (RXR) and associates with vitamin D response elements (VDREs) to regulate the transcription of target genes. Bexarotene (Bex) is an RXR ligand (rexinoid) developed to treat cutaneous T-cell lymphoma and is a putative therapeutic for other diseases. We postulate that VDR ligands (1,25D) and RXR ligands (Bex/analogs) can "synergize" to "super-activate" the VDR-RXR heterodimer. This "cross-talk" could allow disorders treated with high-dose Bex therapy (leading to significant adverse side effects) to instead be treated using both low-dose Bex and vitamin D. Thus, we designed experiments to examine the effect of both VDR and RXR ligands, alone and in combination, to activate VDR-RXR-mediated transcription. The goal was to determine if selected RXR-specific ligands can synergize with vitamin D to amplify RXR-VDR activity. The results demonstrate a synergistic effect with both Bex and 1,25D which could be further modulated by (1) the protein levels (or polymorphic version) of VDR present in the cell, (2) the concentration of the ligands, (3) the cellular "background" (e.g., brain cells versus kidney cells), (4) the nature of the VDRE platform, or (5) the type of rexinoid (Bex analogs). Our findings suggest that diseases that respond to treatment with either vitamin D, or with rexinoids, may be amenable to enhanced therapeutic potential by employing multi-ligand dosing via combinatorial therapy. [ABSTRACT FROM AUTHOR]

Seasonal polyphenism enables organisms to adapt to environmental challenges by increasing phenotypic diversity. Cacopsylla chinensis exhibits remarkable seasonal polyphenism, specifically in the form of summer-form and winter-form, which have distinct morphological phenotypes. Previous research has shown that low temperature and the temperature receptor CcTRPM regulate the transition from summer-form to winter-form in C. chinensis by impacting cuticle content and thickness. However, the underling neuroendocrine regulatory mechanism remains largely unknown. Bursicon, also known as the tanning hormone, is responsible for the hardening and darkening of the insect cuticle. In this study, we report for the first time on the novel function of Bursicon and its receptor in the transition from summer-form to winter-form in C. chinensis. Firstly, we identified CcBurs-a and CcBurs-ß as two typical subunits of Bursicon in C. chinensis, which were regulated by low temperature (10 °C) and CcTRPM. Subsequently, CcBurs-a and CcBurs-ß formed a heterodimer that mediated the transition from summer-form to winter-form by influencing the cuticle chitin contents and cuticle thickness. Furthermore, we demonstrated that CcBurs-R acts as the Bursicon receptor and plays a critical role in the up-stream signaling of the chitin biosynthesis pathway, regulating the transition from summer-form to winter-form. Finally, we discovered that miR-6012 directly targets CcBurs-R, contributing to the regulation of Bursicon signaling in the seasonal polyphenism of C. chinensis. In summary, these findings reveal the novel function of the neuroendocrine regulatory mechanism underlying seasonal polyphenism and provide critical insights into the insect Bursicon and its receptor. [ABSTRACT FROM AUTHOR]

Marine natural products offer a promising source in the development of new antibiotic drugs. Two previously undescribed compounds, including one sulfur-bearing alkaloid named quinosumycin (1) along with one chromone derivative namely chromycone (2), were discovered from an ethyl acetate (EtOAc) extract of marine Streptomyces diastaticus NBU2966 through a bioactivity-guided isolation prioritized for antimicrobial potential. The analysis of nuclear magnetic resonance spectroscopy (NMR), high resolution electrospray ionization mass spectroscopy (HRESIMS) data, and electronic circular dichroism (ECD) calculations enabled the elucidation of their structures and the determination of their absolute configurations. Quinosumycin (1) is the first heterodimer scaffold incorporating quinolinone and quinazolinone motifs coupled by a thioether bond. Interestingly, Compound 1 exhibited a relatively selective growth inhibition against methicillin-resistant Staphylococcus aureus (MRSA) with the minimal inhibitory concentration (MIC) value of 8 µg/mL. [ABSTRACT FROM AUTHOR]

The major histocompatibility complex (MHC) is central in adaptive immunity, with the highly polymorphic MHC genes encoding antigen-presenting molecules. Two MHC class II (MHC-II) loci, DA1 and DA2 , predate the radiation of extant birds and persist throughout much of the avian phylogeny. Within each locus, the MHC-II molecules are encoded by A -genes (DAA) and B -genes (DAB), which are arranged in A–B dyads. However, in passerines (order Passeriformes), the DA2 locus has been lost, and the ancestral A–B dyad at the DA1 locus has been replaced by a putatively single A -gene (DAA1) and an array of highly polymorphic B -genes (DAB1). In this study, we genotyped the DAA1 gene of 15 passerine species and confirmed that passerines possess just one copy of DAA1. We then compared selection patterns in DAA1 between passerines and nonpasserines and found that exon 2, which encodes the antigen-presenting domain, has been subject to weaker positive selection and stronger negative selection in passerines compared with nonpasserines. Additional comparisons showed that the patterns of selection in the passerine DAA1 gene are unlikely to be related to the loss of the DA2 locus. Instead, our findings suggest that the expansion of DAB1 (MHC-IIB) has imposed an evolutionary constraint on the passerine DAA1 (MHC-IIA) gene. We speculate that this constraint may be the result of each DAA1 chain forming heterodimers with many different DAB1 chains. [ABSTRACT FROM AUTHOR]

Context: The nature of double intermolecular proton transfer was studied with the ELF topological approach in two model dimers (the formic acid homodimer and the 1,2,3-triazole–guanidine heterodimer) under an oriented external electric field. It has been shown that each of the two dimers can have either a one-step (one transition state structure) or two-step (two transition state structures) reaction path, depending on the intensity and orientation of the external electric field. The presence of a singularly broad shoulder (plateau in the case of homodimer and plateau-like for heterodimer) around the formal transition state structure results from the strong asynchronicity of the reaction. A careful ELF topological analysis of the nature of protons, hydride (localized) or roaming (delocalized) proton, along the reaction path allowed us to unambiguously classify the one-step mechanisms governing the double-proton transfer reactions into three distinct classes: (1) concerted-synchronous, when two events (roaming proton regions) completely overlap, (2) concerted-asynchronous, when two events (roaming proton regions) partially overlap, and (3) two-stage one-step non-concerted, when two roaming proton regions are separated by a "hidden intermediate region". All the structures belonging to this separatrix region are of the zwitterion form. Methods: Geometry optimization of the stationary points on the potential energy surface was performed using density functional theory—wB97XD functional—in combination with the 6–311+ +G(2d, 2p) basis set for all the atoms. All first-principles calculations were performed using the Gaussian 09 quantum chemical packages. We also used the electron localization function (ELF) to reveal the nature of the proton along the reaction path: a bound proton (hydride) becomes a roaming proton (carrying a tiny negative charge ≈ 0.3 e) exchanging with two adjacent atoms via two attractors (topological critical points with (3, − 3) signature). The ELF analyses were performed using the TopMod package. [ABSTRACT FROM AUTHOR]

Context: The strength and nature of the two halogen bonds in the NCI···CH3I···−CN halogen-bonded ternary complex are studied in the gas phase via ab initio calculations. Different indicators of halogen bond strength were employed to examine the interactions including geometries, complexation energies, Natural Bond Order (NBO) Wiberg bond indices, and Atoms in Molecules (AIM)-based charge density topological properties. The results show that the halogen bond is strong and partly covalent in nature when CH3I donates the halogen bond, but weak and noncovalent in nature when CH3I accepts the halogen bond. Significant halogen bond cooperativity emerges in the ternary complex relative to the corresponding heterodimer complexes, NCI···CH3I and CH3I···−CN, respectively. For example, the CCSD(T) complexation energy of the ternary complex (-18.27 kcal/mol) is about twice the sum of the complexation energies of the component dimers (-9.54 kcal/mol). The halonium transfer reaction that converts the ternary complex into an equivalent one was also investigated. The electronic barrier for the halonium transfer was calculated to be 6.70 kcal/mol at the CCSD(T) level. Although the MP2 level underestimates and the MP3 overestimates the barrier, their calculated MP2.5 average barrier (6.44 kcal/mol) is close to that of the more robust CCSD(T) level. Insights on the halonium ion transfer reaction was obtained by examining the reaction energy and force profiles along the intrinsic reaction coordinate, IRC. The corresponding evolution of other properties such as bond lengths, Wiberg bond indices, and Mulliken charges provides specific insight on the extent of structural rearrangements and electronic redistribution throughout the entire IRC space. Methods: The MP2 method was used for geometry optimizations. Energy calculations were performed using the CCSD(T) method. The aug-cc-pVTZ basis set was employed for all atoms other than iodine for which the aug-cc-pVTZ-PP basis set was used instead. [ABSTRACT FROM AUTHOR]

Death receptor (DR) networks are controlled by the assembly of the Death-Inducing Signaling Complex (DISC) and complex II. The family of small molecules FLIPins (FLIP interactors) were developed to target the caspase-8/c-FLIPL heterodimer. FLIPin compounds were shown to promote apoptosis and caspase-8 activation at the DISC upon stimulation with death ligands (DLs) such as CD95L and TRAIL. To further investigate the role of FLIPin compounds in the DL-mediated cell death response, we analyzed their effects in combination with DLs and SMAC mimetics treatment. FLIPins were found to enhance cell viability loss and cell death induced by DL and SMAC mimetics in acute myeloid leukemia (AML), colon and pancreatic cancer cells. FLIPins enhanced both DL/BV6-induced apoptosis and DL/BV6/zVAD-fmk-induced necroptosis via an increase in complex II formation. Our results indicate that targeting the caspase-8/c-FLIPL heterodimer plays a prominent role in enhancing cell death induced by co-stimulation of DL/SMAC mimetics and opens new therapeutic strategies for targeting DR networks. [ABSTRACT FROM AUTHOR]

Death receptor (DR) networks are controlled by the assembly of the Death-Inducing Signaling Complex (DISC) and complex II. The family of small molecules FLIPins (FLIP interactors) were developed to target the caspase-8/c-FLIP L heterodimer. FLIPin compounds were shown to promote apoptosis and caspase-8 activation at the DISC upon stimulation with death ligands (DLs) such as CD95L and TRAIL. To further investigate the role of FLIPin compounds in the DL-mediated cell death response, we analyzed their effects in combination with DLs and SMAC mimetics treatment. FLIPins were found to enhance cell viability loss and cell death induced by DL and SMAC mimetics in acute myeloid leukemia (AML), colon and pancreatic cancer cells. FLIPins enhanced both DL/BV6-induced apoptosis and DL/BV6/zVAD-fmk-induced necroptosis via an increase in complex II formation. Our results indicate that targeting the caspase-8/c-FLIP L heterodimer plays a prominent role in enhancing cell death induced by co-stimulation of DL/SMAC mimetics and opens new therapeutic strategies for targeting DR networks [ABSTRACT FROM AUTHOR]

Nuclear receptors (NRs) are key regulators of multiple physiological functions and pathological changes in the liver in response to a variety of extracellular signaling changes. Retinoid X receptor (RXR) is a special member of the NRs, which not only responds to cellular signaling independently, but also regulates multiple signaling pathways by forming heterodimers with various other NR. Therefore, RXR is widely involved in hepatic glucose metabolism, lipid metabolism, cholesterol metabolism and bile acid homeostasis as well as hepatic fibrosis. Specific activation of particular dimers regulating physiological and pathological processes may serve as important pharmacological targets. So here we describe the basic information and structural features of the RXR protein and its heterodimers, focusing on the role of RXR heterodimers in a number of physiological processes and pathological imbalances in the liver, to provide a theoretical basis for RXR as a promising drug target. [ABSTRACT FROM AUTHOR]

Selective perturbation of protein interactions with chemical compounds enables dissection and control of developmental processes. Differentiation of stomata, cellular valves vital for plant growth and survival, is specified by the basic-helix-loop-helix (bHLH) heterodimers. Harnessing a new amination reaction, we here report a synthesis, derivatization, target identification, and mode of action of an atypical doubly-sulfonylated imidazolone, Stomidazolone, which triggers stomatal stem cell arrest. Our forward chemical genetics followed by biophysical analyses elucidates that Stomidazolone directly binds to the C-terminal ACT-Like (ACTL) domain of MUTE, a master regulator of stomatal differentiation, and perturbs its heterodimerization with a partner bHLH, SCREAM in vitro and in plant cells. On the other hand, Stomidazolone analogs that are biologically inactive do not bind to MUTE or disrupt the SCREAM-MUTE heterodimers. Guided by structural docking modeling, we rationally design MUTE with reduced Stomidazolone binding. These engineered MUTE proteins are fully functional and confer Stomidazolone resistance in vivo. Our study identifies doubly-sulfonylated imidazolone as a direct inhibitor of the stomatal master regulator, further expanding the chemical space for perturbing bHLH-ACTL proteins to manipulate plant development. This study reports Stomidazolone, a doubly-sulfonylated imidazolone that inhibits stomatal differentiation by binding to the ACT-Like domain of MUTE, disrupting its interaction with the bHLH partner SCREAM, which expands the chemical toolkit for manipulating bHLH-ACTL protein interactions, offering new avenues for controlling plant development. [ABSTRACT FROM AUTHOR]

During the embryonic developmental stage in vertebrates, internal organs are arranged along the left–right axis. Disruptions in this process can result in congenital diseases or laterality disorders. The molecular mechanisms of left–right asymmetry in vertebrate development remain largely unclear. Due to its straightforward structure, zebrafish has become a favoured model for studying early laterality events. Here, we demonstrate that growth and development factor 11 (Gdf11) is essential for left–right development via TGF‐β signalling. Morphological analysis showed that gdf11 morphants and mutants displayed clear heart and liver laterality disorders in a Nodal signal‐dependent manner. Additionally, we found that Kupffer's vesicle formation and ciliogenesis were impaired following gdf11 deletion. We also observed that Gdf11 may form a heterodimer with Spaw, which promotes Smad2/3 phosphorylation and activates TGF‐β signalling. Subsequently, Gdf11 promotes left–right laterality by stimulating Foxj1a and its target gene expression. In summary, we reveal a critical role of Gdf11 in left–right patterning, providing fundamental insights into the developmental process of left–right asymmetry. [ABSTRACT FROM AUTHOR]

Metabotropic glutamate (mGlu) receptor protomers can heterodimerize, leading to different pharmacology compared to their homodimeric counterparts. Here, we use complemented donor-acceptor resonance energy transfer (CODA-RET) technology that distinguishes signaling from defined mGlu heterodimers or homodimers, together with targeted mutagenesis of receptor protomers and computational docking, to elucidate the mechanism of activation and differential pharmacology in mGlu2/4 heteromers. We demonstrate that positive allosteric modulators (PAMs) that bind an upper allosteric pocket in the mGlu4 transmembrane domain are active at both mGlu4/4 homomers and mGlu2/4 heteromers, while those that bind a lower allosteric pocket within the same domain are efficacious in homomers but not heteromers. We further demonstrate that both protomers of mGlu2/4 heteromers are cis-activated by their orthosteric agonists, signaling independently with no trans-activation detected. Intriguingly, however, upper pocket mGlu4 PAMs enable trans-activation in mGlu2/4 heteromers from mGlu4 to the mGlu2 protomer and also enhance cis-activation of the mGlu2 protomer. While mGlu2 PAMs enhanced mGlu2 cis-activation in the heterodimer, we were unable to detect trans-activation in the opposite direction from mGlu2 to the mGlu4 protomer, suggesting an asymmetry of signaling. These insights into the molecular logic of this receptor heteromer are critical to building toward precision targeted therapies for multiple neuropsychiatric disorders. Metabotropic glutamate (mGlu) receptors form both homo- and heterodimers that respond to ligands differently. Here, the authors elucidate the mechanism of activation and differential pharmacology in mGlu2/4 heteromers, which may guide targeted therapy. [ABSTRACT FROM AUTHOR]

Eplet 52SK is unique in the HLA eplet registry as targeting the whole family of DQA1*01 alleles. It is proposed as an antibody‐verified eplet but has not been validated enough to deserve this label. Especially, confusion can occur with reactivity targeting the 52PQ eplet which is present on the DQB1*05 and DQB1*06 alleles families, as DQ molecule stability imposes DQA1*01 to selectively associate with these DQ‐β families only. Using two Luminex single antigen (LSA) assays from two vendors, beads bearing DR‐α/DQ6 heterodimers, a special build LSA panel of additional DQ beads, and an adsorption/elution strategy relying on cells from deceased donors or recombinant cells solely expressing one DQ antigen, we definitely established the antibody‐verified status of eplet 52SK using patients' sera reacting only against the DQ5 and DQ6 beads of the One Lambda LSA panel in routine patients' follow up. We also show that reactivity against this eplet is not a rare event among anti‐DQ1 immunisation. This study further strengthens the importance of considering the DQA1 locus in immunological studies of HLA and in organ allocation strategies. [ABSTRACT FROM AUTHOR]

As an essential intrinsic component of photosystem II (PSII) in all oxygenic photosynthetic organisms, heme-bridged heterodimer cytochrome b559 (Cyt b559) plays critical roles in the protection and assembly of PSII. However, the underlying mechanisms of Cyt b559 assembly are largely unclear. Here, we characterized the Arabidopsis (Arabidopsis thaliana) rph1 (resistance to Phytophthora1) mutant, which was previously shown to be susceptible to the oomycete pathogen Phytophthora brassicae. Loss of RPH1 leads to a drastic reduction in PSII accumulation, which can be primarily attributed to the defective formation of Cyt b559. Spectroscopic analyses showed that the heme level in PSII supercomplexes isolated from rph1 is significantly reduced, suggesting that RPH1 facilitates proper heme assembly in Cyt b559. Due to the loss of RPH1-mediated processes, a covalently bound PsbE–PsbF heterodimer is formed during the biogenesis of PSII. In addition, rph1 is highly photosensitive and accumulates elevated levels of reactive oxygen species under photoinhibitory-light conditions. RPH1 is a conserved intrinsic thylakoid protein present in green algae and terrestrial plants, but absent in Synechocystis, and it directly interacts with the subunits of Cyt b559. Thus, our data demonstrate that RPH1 represents a chloroplast acquisition specifically promoting the efficient assembly of Cyt b559, probably by mediating proper heme insertion into the apo-Cyt b559 during the initial phase of PSII biogenesis. A chloroplast thylakoid protein is involved in the formation of an essential multisubunit protein complex during the initial steps of photosystem II assembly. [ABSTRACT FROM AUTHOR]

The prothoracic gland (PG) is a major insect endocrine organ. It is the principal source of insect steroid hormones, and critical for key developmental events such as the molts, the establishment of critical weight (CW), pupation, and sexual maturation. However, little is known about the developmental processes that regulate PG morphology. In this study, we identified soul, which encodes a PG-specific basic helix-loop-helix (bHLH) transcription factor. We demonstrate that Tap, also a bHLH protein, dimerizes with Soul. Both are expressed in the developing PG. Interfering with either soul or tap function caused strikingly similar phenotypes, resulting in small and fragmented PGs, the abolishment of steroid hormone-producing gene expression, larval arrest, and a failure to undergo metamorphosis. Furthermore, both soul and tap showed expression peaks just prior to the CW checkpoint. Disrupting soul-or tap-function before, but not after, the CW checkpoint caused larval arrest, and perturbed highly similar gene cohorts, which were enriched for regulators and components of the steroid hormone biosynthesis pathway. Intriguingly, a chitin-based cuticle gene, Cpr49Ah, and a POU domain transcription factor gene, pdm3, are direct target genes of the Soul/Tap complex, and disruption of either phenocopied key aspects of soul/tap loss-of-function phenotypes. Taken together, our findings demonstrate that the Soul/Tap heterodimer resides at the top of a complex gene hierarchy that drives PG development, CW establishment, and steroid hormone production. [ABSTRACT FROM AUTHOR]

SUMMARY: Grain appearance and nutritional quality are critical traits for rice marketing. However, how to simultaneously improve grain appearance (slender grain and low chalkiness) and nutritional quality (improved protein and amino acid contents) in rice remains a major challenge. Here, we show that knocking out rice isopropylmalate synthase genes OsIPMS1 and OsIPMS2 can improve both grain appearance and nutritional quality. We find that OsIPMS1 directly interacts with OsIPMS2 to form heterodimers. Meanwhile, we observe that OsIPMS1 and OsIPMS2 influence the expression of genes previously reported to be involved in the determination of grain size and nutritional quality in the developing panicles and grains. Furthermore, we show that Osipms1/2 double mutants exhibit significantly improved grain appearance and nutritional quality in polished rice in both the japonica (Wuyungeng 23) and indica (Huanghuazhan) varieties. Our findings indicate that OsIPMS is a useful target gene for breeding of rice varieties appealing for marketing and with health‐benefiting properties. Significance Statement: It is challenged to simultaneously improve grain appearance and nutritional quality during rice breeding. Knocking out isopropylmalate synthase facilitates the development of rice varieties characterized by slender grains, low chalkiness, and high nutritional quality. [ABSTRACT FROM AUTHOR]

Modification of guanosine to N7-methylguanosine (m7G) in the variable loop region of tRNA is catalyzed by the METTL1/WDR4 heterodimer and stabilizes target tRNA. Here, we reveal essential functions of Mettl1 in Drosophila fertility. Knockout of Mettl1 (Mettl1-KO) causes no major effect on the development of non-gonadal tissues, but abolishes the production of elongated spermatids and mature sperm, which is fully rescued by expression of a Mettl1-transgene, but not a catalytic-dead Mettl1 transgene. This demonstrates that Mettl1-dependent m7G is required for spermatogenesis. Mettl1-KO results in a loss of m7G modification on a subset of tRNAs and decreased tRNA abundance. Ribosome profiling shows that Mettl1-KO led to ribosomes stalling at codons decoded by tRNAs that were reduced in abundance. Mettl1-KO also significantly reduces the translation efficiency of genes involved in elongated spermatid formation and sperm stability. Germ cell-specific expression of Mettl1 rescues disrupted m7G tRNA modification and tRNA abundance in Mettl1-KO testes but not in non-gonadal tissues. Ribosome stalling is much less detectable in non-gonadal tissues than in Mettl1-KO testes. These findings reveal a developmental role for m7G tRNA modification and indicate that m7G modification-dependent tRNA abundance differs among tissues. Here the authors reveal essential functions of Mettl1, catalyzing N7-guanosine methylation (m7G) of tRNAs, in Drosophila male fertility through a regulation of the steady-state level of tRNAs and the translational efficiency of genes essential for spermatogenesis. [ABSTRACT FROM AUTHOR]

Aberrant activation of IL-18 signaling regulates tumor immune evasion and progression. However, the underlying mechanism remains unclear. Here, we report that long-chain acyl-CoA synthase 6 (ACSL6) is highly expressed in liver cancer and correlated with poor prognosis. ACSL6 promotes tumor growth, metastasis, and immune evasion mediated by IL-18, independent of its metabolic enzyme activity. Mechanistically, upon IL-18 stimulation, ACSL6 is phosphorylated by ERK2 at S674 and recruits IL-18RAP to interact with IL-18R1, thereby reinforcing the IL-18R1-IL-18RAP heterodimer and triggering NF-κB-dependent gene expression to facilitate tumor development. Furthermore, the up-regulation of CXCL1 and CXCL5 by ACSL6 promotes tumor-associated neutrophil and tumor-associated macrophage recruitment, thereby inhibiting cytotoxic CD8+ T cell infiltration. Ablation or S674A mutation of ACSL6 potentiated anti-PD-1 therapeutic efficacy by increasing the effector activity of intertumoral CD8+ T cells. We revealed that ACSL6 is a potential adaptor that activates IL-18-NF-κB axis-mediated tumor immune evasion and provides valuable insights for developing effective immunotherapy strategies for cancer. [ABSTRACT FROM AUTHOR]

Faithful chromosome segregation requires biorientation, where the pair of kinetochores on the chromosome establish bipolar microtubule attachment. The integrity of the kinetochore, a macromolecular complex built on centromeric DNA, is required for biorientation, but components sufficient for biorientation remain unknown. Here, we show that tethering the outer kinetochore heterodimer NDC80-NUF2 to the surface of apolar microbeads establishes their biorientation-like state in mouse cells. NDC80-NUF2 microbeads align at the spindle equator and self-correct alignment errors. The alignment is associated with stable bipolar microtubule attachment and is independent of the outer kinetochore proteins SPC24-SPC25, KNL1, the Mis12 complex, inner kinetochore proteins, and Aurora. Larger microbeads align more rapidly, suggesting a size-dependent biorientation mechanism. This study demonstrates a biohybrid kinetochore design for synthetic biorientation of microscale particles in cells. [ABSTRACT FROM AUTHOR]

Spinal cord injury (SCI) triggers microglial/monocytes activation with distinct pro-inflammatory or inflammation-resolving phenotypes, which potentiate tissue damage or facilitate functional repair, respectively. The major integrin Mac-1 (CD11b/CD18), a heterodimer consisting of CD11b and CD18 chains, is expressed in multiple immune cells of the myeloid lineage. Here, we examined the effects of CD11b gene ablation in neuroinflammation and functional outcomes after SCI. qPCR analysis of C57BL/6 female mice showed upregulation of CD11b mRNA starting from 1 d after injury, which persisted up to 28 d. CD11b knockout (KO) mice and their wildtype littermates were subjected to moderate SCI. At 1 d post-injury, qPCR showed increased expression of genes involved with inflammation-resolving processes in CD11b KO mice. Flow cytometry analysis of CD45intLy6C−CX3CR1+ microglia, CD45hiLy6C+Ly6G− monocytes, and CD45hiLy6C+Ly6G+ neutrophils revealed significantly reduced cell counts as well as reactive oxygen species (ROS) production in CD11b KO mice at d3 post-injury. Further examination with NanoString and RNA-seq showed upregulation of pro-inflammatory genes, but downregulation of the ROS pathway. Importantly, CD11b KO mice exhibited significantly improved locomotor function, reduced cutaneous mechanical/thermal hypersensitivity, and limited tissue damage at 8 weeks post-injury. Collectively, our data suggest an important role for CD11b in regulating tissue inflammation and functional outcome following SCI. [ABSTRACT FROM AUTHOR]

Combination therapies are gaining interest, as they are expected to improve the pharmacological effects. However, current drug combination therapies involve the administration of individual drugs together, which results in differences in delivery efficiency to tumor tissues owing to differences in pharmacokinetics. In the present study, we developed heterodimeric nano-prodrugs (NPDs). We designed a heterodimer of podophyllotoxin and SN-38, from which an NPD with a particle size of approximately 50 nm and a high dispersion stability was fabricated. Our findings contribute to the development of next-generation drug delivery systems capable of co-delivering multiple anticancer agents. [ABSTRACT FROM AUTHOR]

The 5´–3´ exoribonuclease Rat1/Xrn2 is responsible for the termination of eukaryotic mRNA transcription by RNAPII. Rat1 forms a complex with its partner proteins, Rai1 and Rtt103, and acts as a "torpedo" to bind transcribing RNAPII and dissociate DNA/RNA from it. Here we report the cryo-electron microscopy structures of the Rat1-Rai1-Rtt103 complex and three Rat1-Rai1-associated RNAPII complexes (type-1, type-1b, and type-2) from the yeast, Komagataella phaffii. The Rat1-Rai1-Rtt103 structure revealed that Rat1 and Rai1 form a heterotetramer with a single Rtt103 bound between two Rai1 molecules. In the type-1 complex, Rat1-Rai1 forms a heterodimer and binds to the RNA exit site of RNAPII to extract RNA into the Rat1 exonuclease active site. This interaction changes the RNA path in favor of termination (the "pre-termination" state). The type-1b and type-2 complexes have no bound DNA/RNA, likely representing the "post-termination" states. These structures illustrate the termination mechanism of eukaryotic mRNA transcription. The Rat1 RNase helps terminate eukaryotic mRNA transcription. Here, the authors report the cryo-EM structures of the Rat1-Rai1-Rtt103 and the Rat1-Rai1-RNAPII complexes, illustrating the mechanism of mRNA transcription termination. [ABSTRACT FROM AUTHOR]

Recycling of 40S ribosomal subunits following translation termination, entailing release of deacylated tRNA and dissociation of the empty 40S from mRNA, involves yeast Tma20/Tma22 heterodimer and Tma64, counterparts of mammalian MCTS1/DENR and eIF2D. MCTS1/DENR enhance reinitiation (REI) at short upstream open reading frames (uORFs) harboring penultimate codons that confer heightened dependence on these factors in bulk 40S recycling. Tma factors, by contrast, inhibited REI at particular uORFs in extracts; however, their roles at regulatory uORFs in vivo were unknown. We examined effects of eliminating Tma proteins on REI at regulatory uORFs mediating translational control of GCN4 optimized for either promoting (uORF1) or preventing (uORF4) REI. We found that the Tma proteins generally impede REI at native uORF4 and its variants equipped with various penultimate codons regardless of their Tma-dependence in bulk recycling. The Tma factors have no effect on REI at native uORF1 and equipping it with Tma-hyperdependent penultimate codons generally did not confer Tma-dependent REI; nor did converting the uORFs to AUG-stop elements. Thus, effects of the Tma proteins vary depending on the REI potential of the uORF and penultimate codon, but unlike in mammals, are not principally dictated by the Tma-dependence of the codon in bulk 40S recycling. A study of ribosome recycling in the budding yeast shows that 40S subunit recycling factors influence translation reinitiation independently of their function in bulk recycling, which distinguishes them from their mammalian homologues [ABSTRACT FROM AUTHOR]

In this review, we address the oligomerization of G protein-coupled receptors (GPCRs), which significantly expands the functional capabilities of cells in living organisms by modulating intracellular signaling pathways. This provides a variety of physiological effects in both normal and pathological states. The structure and intracerebral localization of one of the most studied heterodimers, the D1-D2 receptor complex, and its signaling cascades, which correlate with the development of depressive disorders, are considered. Sex differences in the functioning of this heterodimer are analyzed, and the issue of the selectivity of bivalent synthetic ligands in triggering specific intracellular pathways is discussed, highlighting their potential as therapeutic targets for the targeted treatment of depressive disorders. The concluding part of the review is dedicated to the diversity of dopamine receptor heterodimers with other members of the GPCR family and their role in the pathophysiology of depression. [ABSTRACT FROM AUTHOR]

The assembly of two monomeric constructs spanning segments 1-199 (MPro1-199) and 10-306 (MPro10-306) of SARS-CoV-2 main protease (MPro) was examined to assess the existence of a transient heterodimer intermediate in the N-terminal autoprocessing pathway of MPro model precursor. Together, they form a heterodimer population accompanied by a 13-fold increase in catalytic activity. Addition of inhibitor GC373 to the proteins increases the activity further by ∼7-fold with a 1:1 complex and higher order assemblies approaching 1:2 and 2:2 molecules of MPro1-199 and MPro10-306 detectable by analytical ultracentrifugation and native mass estimation by light scattering. Assemblies larger than a heterodimer (1:1) are discussed in terms of alternate pathways of domain III association, either through switching the location of helix 201 to 214 onto a second helical domain of MPro10-306 and vice versa or direct interdomain III contacts like that of the native dimer, based on known structures and AlphaFold 3 prediction, respectively. At a constant concentration of MPro1-199 with molar excess of GC373, the rate of substrate hydrolysis displays first order dependency on the MPro10-306 concentration and vice versa. An equimolar composition of the two proteins with excess GC373 exhibits half-maximal activity at ∼6 μM MPro1-199. Catalytic activity arises primarily from MPro1-199 and is dependent on the interface interactions involving the N-finger residues 1 to 9 of MPro1-199 and E290 of MPro10-306. Importantly, our results confirm that a single N-finger region with its associated intersubunit contacts is sufficient to form a heterodimeric MPro intermediate with enhanced catalytic activity. [ABSTRACT FROM AUTHOR]

Eukaryotic TIR (Toll/interleukin‐1 receptor protein) domains signal via TIR–TIR interactions, either by self‐association or by interaction with other TIR domains. In mammals, TIR domains are found in Toll‐like receptors (TLRs) and cytoplasmic adaptor proteins involved in pro‐inflammatory signaling. Previous work revealed that the MAL TIR domain (MALTIR) nucleates the assembly of MyD88TIR into crystalline arrays in vitro. A microcrystal electron diffraction (MicroED) structure of the MyD88TIR assembly has previously been solved, revealing a two‐stranded higher‐order assembly of TIR domains. In this work, it is demonstrated that the TIR domain of TLR2, which is reported to signal as a heterodimer with either TLR1 or TLR6, induces the formation of crystalline higher‐order assemblies of MyD88TIRin vitro, whereas TLR1TIR and TLR6TIR do not. Using an improved data‐collection protocol, the MicroED structure of TLR2TIR‐induced MyD88TIR microcrystals was determined at a higher resolution (2.85 Å) and with higher completeness (89%) compared with the previous structure of the MALTIR‐induced MyD88TIR assembly. Both assemblies exhibit conformational differences in several areas that are important for signaling (for example the BB loop and CD loop) compared with their monomeric structures. These data suggest that TLR2TIR and MALTIR interact with MyD88 in an analogous manner during signaling, nucleating MyD88TIR assemblies unidirectionally. [ABSTRACT FROM AUTHOR]

TASK-5 (KCNK15) belongs to the acid-sensitive subfamily of two-pore domain potassium (K2P) channels, which includes TASK-1 and TASK-3. TASK-5 stands out as K2P channel for which there is no functional data available, since it was reported in 2001 as non-functional and thus "silent". Here we show that TASK-5 channels are indeed non-functional as homodimers, but are involved in the formation of functional channel complexes with TASK-1 and TASK-3. TASK-5 negatively modulates the surface expression of TASK channels, while the heteromeric TASK-5-containing channel complexes located at the plasma membrane are characterized by changes in single-channel conductance, Gq-coupled receptor-mediated channel inhibition, and sensitivity to TASK modulators. The unique pharmacology of TASK-1/TASK-5 heterodimers, affected by a common polymorphism in KCNK15, needs to be carefully considered in the future development of drugs targeting TASK channels. Our observations provide an access to study TASK-5 at the functional level, particularly in malignant cancers associated with KCNK15. The TASK-5 potassium channel is thought to be non-functional. Here, the authors show that it forms complexes with TASK family members, resulting in heteromeric channels with unique pharmacology and potential as therapeutic targets. [ABSTRACT FROM AUTHOR]