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Loss of cochlear hair cells (HCs) leads to permanent hearing loss in mammals, and regenerative medicine is regarded as an ideal strategy for hearing recovery. Limited genetic and pharmaceutical approaches for HC regeneration have been established, and the existing strategies cannot achieve recovery of auditory function. A promising target to promote HC regeneration is MEK/ERK signaling because dynamic shifts in its activity during the critical stages of inner ear development have been observed. Here, we first showed that MEK/ERK signaling is activated specifically in supporting cells (SCs) after aminoglycoside-induced HC injury. We then selected 4 MEK/ERK signaling inhibitors, and PD0325901 (PD03) was found to induce the transdifferentiation of functional supernumerary HCs from SCs in the neonatal mammalian cochlear epithelium. We next found that PD03 facilitated the generation of HCs in inner ear organoids. Through genome-wide high-throughput RNA sequencing and verification, we found that the Notch pathway is the downstream target of MEK/ERK signaling. Importantly, delivery of PD03 into the inner ear induced mild HC regeneration in vivo. Our study thus reveals the importance of MEK/ERK signaling in cell fate determination and suggests that PD03 might serve as a new approach for HC regeneration.Graphical Abstract

Background: The appropriateness of laparoscopic gastrectomy (LG) for super-geriatric patients with locally advanced gastric cancer (LAGC) is inconclusive, and the prognostic factors are also yet to be elucidated. Herein, we aimed to investigate the surgical and oncological outcomes of LG versus open gastrectomy (OG) for geriatric patients with LAGC who have outlived the average lifespan of the Chinese population (≥ 78 years). Methods: This is a monocentric, retrospective, comparative study. A 1:1 propensity score matching (PSM) was performed to minimize selection bias and ensure well-balanced characteristics. The primary endpoint of interest was 3-year overall survival, while secondary endpoints included procedure-related variables, postoperative recovery indices, and complications. Univariate and multivariate Cox proportional hazards regression analyses were performed to identify unfavorable prognostic factors. Results: Of 196 eligible individuals, 107 underwent LG and 89 underwent OG, with a median age (interquartile range [IQR]) of 82 [79, 84] years. PSM yielded 61 matched pairs, with comparable demographic and tumor characteristics. The LG group had a significantly lower overall complication rate than the OG group (31.1% vs. 49.2%, P= 0.042), as well as shorter duration of postoperative hospital stay [12 (11, 13) vs. 13 (12, 15.5) d, P < 0. 001], less intraoperative blood loss [95 (75, 150) vs. 230 (195, 290) mL, P< 0.001], but a longer operative time [228 (210, 255.5) vs. 196 (180, 219.5) min, P< 0.001]. The times to first aerofluxus, defecation, liquid diet, and half-liquid diet were comparable. Kaplan–Meier analyses revealed no significant difference in 3-year overall survival between the groups, either in the entire cohort or in subgroups with different TNM staging. Moreover, Age-adjusted Charlson Comorbidity Index scores of > 6 [hazard ratio (HR) 4.003; P= 0.021] and pathologic TNM stage III (HR 3.816, P= 0.023) were independent unfavorable prognostic factors for long-term survival. Conclusions: LG performed by experienced surgeons offers the benefits of comparable or better surgical and oncological safety profiles than OG for super-geriatric patients with LAGC. Graphical Abstract:

The involvement of low-molecular-weight thiols in the biosynthesis of natural products is rarely reported. During lincomycin A biosynthesis, ergothioneine (EGT) is incorporated in the S-glycosylation catalyzed by LmbT. In contrast to the widely reported glycosylation of nitrogen and oxygen atoms, the glycosylation of sulfur atoms is less studied. In particular, the crystal structure of enzymes that glycosylate thiols on small molecules rather than peptides has not been reported. Here, we report the crystal structures of LmbT in apoform and in complex with GDP and EGT S-conjugated lincosamine. We found that LmbT has a characteristic glycosyltransferase type B fold, which forms a symmetric homotetramer. The substrates are bound deeply in the catalytic cleft. Consistent with the substrate structure, LmbT does not have the large peptide binding groove of the previously reported S-glycosyltransferase. Combined with site-directed mutagenesis, we propose a catalytic mechanism for the unusual EGT-mediated S-glycosylation in natural product biosynthesis.

Cancer vaccine contributing to the success of the treatment and prevention of tumors has attracted a huge attention as a strategy for tumor immunotherapy in recent years. A major challenge of cancer vaccine is to target cytosols of dendritic cells (DCs) in the lymph nodes (LNs) to enhance efficiency of antigen cross-presentation, which elicits high levels of cytotoxic T-lymphocytes to destruct tumor cells. Here, we address this issue by conjugating ovalbumin (OVA) to PEG-PCL using disulfide bond (-ss-), and the degradable pH-responsive polymer-PEI-PCL as delivery carrier. In addition, the mol ratio of PEG-PCL to PEI-PCL in the mixed micelles was tailored to deliver the OVA to LNs. Subsequently, CpG ODN1826, a TLR-9 agonist, was further introduced into a mixed micelle of 30 nm or less as a unique tumor vaccine. Importantly, the results demonstrated the mixed micelles with 1:1 mol of PCL-PEG and PCL-PEI can effectively migrate to distal LNs where antigen were efficiently captured by DCs, meanwhile, OVA was modified to the surface of mixed micelles via disulfide bonds (-ss-) for promotion efficiency of antigen cross-presentation. More surprisingly, combination of tumor vaccine with anti-PD-1, the therapy of ectopic melanoma (B16-OVA) and lung metastasis melanoma (B16-OVA) is excellent therapeutic effect. Taken together, our works offers a novel strategy for the cytosol delivery of antigens to achieve potent cancer immunotherapy.

Mitomycins make up a class of natural molecules produced by Streptomyceswith strong antibacterial and antitumor activities. MitM is a key postmitosane modification enzyme involved in mitomycin biosynthesis in Streptomyces caespitosus. This protein was previously suggested to catalyze the aziridinium methylation of mitomycin A and the mitomycin intermediate 9a-demethyl-mitomycin A as an N-methyltransferase. The structural basis for MitM to recognize cofactor S-adenosyl-l-methionine (SAM) and substrate mitomycin A is unknown. Here, we determined the crystal structures of apo-MitM and MitM-mitomycin A-S-adenosylhomocysteine (SAH) ternary complexes with resolutions of 2.23 and 2.80 Å, respectively. We found that MitM adopts a class I SAM-dependent methyltransferase fold and forms a homodimer in solution. Conformational changes in a series of residues involved in the formation of active pockets assist MitM in binding SAH and mitomycin A. In particular, the 28ALGAASLGE36loop changes most significantly. When mitomycin A binds, the bending direction of this loop is reversed, changing the entrance of the active site from open to closed. This study provides structural insights into MitM’s involvement in the postmitosane stage of mitomycin biosynthesis and provides a template for the engineering of methyltransferases.

The inner ear is one of the most complicated structures that harbor organs for the perception of sound and balance, which is deep in the temporal bone and challenging to operate. Organoids serve as promising platforms for understanding developmental processes and pathological dysfunctions and discovering therapeutic drugs and gene therapy strategies for disorders in the inner ear. To better understand the origin and application value of organoids, we reviewed the developmental history and advancement of inner ear organoid research. We summarized the cell sources of organoids and the matrices supporting their formation. The history of the research on inner ear organoids derived from pluripotent stem cells (PSCs) and primary progenitor cells has been clarified in detail. We elaborated on the applications of organoids in inner ear development, hereditary deafness modeling, and hair cell (HC) regeneration strategy formulation. Finally, we mentioned limitations of the current culture methods and applications of inner ear organoids, and described several prospects for optimizing next-generation organoids of the inner ear for potential translational applications.

Cellular mechanotransduction plays an essential role in the development and differentiation of many cell types, but if and how mechanical cues from the extracellular matrix (ECM) influence the fate determination of inner ear progenitor cells (IEPCs) remains largely unknown. In the current study, we compared the biological behavior of IEPCs in Matrigel‐based suspension and encapsulated culture systems, and we found that the mechanical cues from the ECM promote the survival and expansion of IEPCs. Furthermore, we found that the mechanical cues from the ECM induced the accumulation of Ras homolog family member A (RhoA) and caused the polymerization of actin cytoskeleton in IEPCs. These changes in turn resulted in increased Yes‐associated protein (YAP) nuclear localization and enhanced expansion of IEPCs, at least partially through upregulating the canonical Wnt signaling pathway. We therefore provide the first demonstration that the RhoA‐YAP‐β‐catenin signaling axis senses and transduces mechanical cues from the ECM and plays crucial roles in promoting the expansion of IEPCs. The study demonstrates that the essential role of RhoA–YAP–β‐catenin signaling axis on inner ear progenitor cells expansion. The response of inner ear progenitor cells to mechanical cues from their microenvironment via RhoA‐mediated actin cytoskeleton contraction, which lead to nuclear Yes‐associated protein (YAP) accumulation. YAP as a mediator of mechanotransduction signaling to promote the expansion of inner ear progenitor cells through regulating β‐catenin activity.

The estrogen receptor alpha (ERα) has been proven to be one of the most important therapeutic targets in breast cancer over the last 30 years. Previous studies pointed out that a natural flavonoid, silibinin, induced apoptosis in human breast cancer MCF-7 cells. In the present study we report that exposure of MCF-7 cells to silibinin led to cell death through the down-regulation of ERα expression. Silibinin-induced apoptosis of MCF-7 cells through up-regulation of caspase 6 due to ERα signalling repression was further boosted by ERα antagonist. Moreover, up-regulation of autophagy induced by silibinin accounted for apoptotic exacerbation, being further enhanced by ERα inhibition. Upon ERα activation, series of downstream signalling pathways can be activated. We found that silibinin reduced the expressions of Akt/mTOR and extracellular-signal-related kinase (ERK), which respectively accounted for the induction of autophagy and apoptosis. These effects were further augmented by co-treatment with ERα inhibitor. We conclude that the treatment with silibinin of ERα-positive MCF-7 cells down-regulates the expression of ERα, and subsequently mTOR and ERK signaling pathways, ERα downstream, finally resulting in induction of autophagy and apoptosis.

Dracorhodin perchlorate inhibited proliferation of several tumor cell lines. The drug induced oligonucleosomal fragmentation of DNA in HeLa cells and increased caspase-3, -8, -9 activities followed by the degradation of caspase-3 substrates, inhibitor of caspase-dependent DNase, and poly-(ADP-ribose) polymerase. It also increased caspase-1 activity and a caspase-1 inhibitor, Ac-YVAD-cmk, and a caspase-10 inhibitor z-AEVD-fmk, also reduced dracorhodinperchlorate-induced HeLa cell death. Dracorhodin perchlorate decreased the expression of anti-apoptotic mitochondrial protein, Bcl-XL, but not Bcl-2; and it increased the expression of pro-apoptotic protein, Bax. Dracorhodin perchlorate induced a sustained generation of reactive oxygen species (ROS) in HeLa cells; caspase-1 inhibitor, Ac-YVAD-cmk, and caspase-3 inhibitor, z-DEVD-fmk, attenuated the generation of ROS. Taken together, our results indicate that dracorhodin perchlorate alters the intracellular redox status, changed the balance of Bcl-XLand Bax protein expression, and induces apoptosis through caspase pathways in HeLa cells.

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