Search

Angiogenesis is pivotal for osteogenesis during bone regeneration. A hydrogel that promotes both angiogenesis and osteogenesis is essential in bone tissue engineering. However, creating scaffolds with the ideal balance of biodegradability, osteogenic, and angiogenic properties poses a challenge. Thymosin beta 10 (TMSB10), known for its dual role in angiogenesis and osteogenesis differentiation, faces limitations due to protein activity preservation. To tackle this issue, ZIF-8 was engineered as a carrier for TMSB10 (TMSB10@ZIF-8), and subsequently integrated into the self-assembled sericin hydrogel. The efficacy of the composite hydrogel in bone repair was assessed using a rat cranial defect model. Characterization of the nanocomposites confirmed the successful synthesis of TMSB10@ZIF-8, with a TMSB10 encapsulation efficiency of 88.21 %. The sustained release of TMSB10 from TMSB10@ZIF-8 has significantly enhanced tube formation in human umbilical vein endothelial cells (HUVECs) in vitro and promoted angiogenesis in the chicken chorioallantoic membrane (CAM) model in vivo. It has markedly improved the osteogenic differentiation ability of MC 3 T3-E1 cells in vitro. 8 weeks post-implantation, the TMSB10@ZIF-8/ Sericin hydrogel group exhibited significant bone healing (86.77 ± 8.91 %), outperforming controls. Thus, the TMSB10@ZIF-8/Sericin hydrogel, leveraging ZIF-8 for TMSB10 delivery, emerges as a promising bone regeneration scaffold with substantial clinical application potential., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 The Authors. Published by Elsevier B.V. All rights reserved.)

Introduction: Thymosins are small proteins found mainly in the thymus. They are involved in several biological processes, including immunoregulation, angiogenesis, and anti-inflammatory activity. Due to these multiple activities, thymosins are widely used as therapeutics. In fact, these peptides have shown interesting results in the treatment of eye disorders, anticancer therapy, and dysregulated immune disorders., Area Covered: We analyzed the thymosins therapeutic patent landscape describing the most significant patents published after 2018 and originally written in English, classified according to the different type of functions and diseases. We searched 'Thymosin' on Patentscope and Espacenet., Expert Opinion: Thymalfasin (Zadaxin) is the only FDA-approved thymosine-based drug used to treat chronic hepatitis B and C and as a chemotherapy inducer. This outcome demonstrates how thymosins can be exploited as therapeutics, especially in immunological and anti-cancer therapies. However, the development of modified thymosins could expand their therapeutic interest and application in different diseases. In fact, by chemical modifications, it is possible to increase proteolytic stability in the biological environment, enhance cell permeability, and stabilize the secondary structure of the peptide. Finally, the development of shorter sequences could reduce the cost and production time of these thymosin-based drugs.

Thymosin β4 (Tβ4) is the β-thymosin (Tβs) with the highest expression level in human cells; it makes up roughly 70-80% of all Tβs in the human body. Combining the mechanism and activity studies of Tβ4 in recent years, we provide an overview of the subtle molecular mechanism, pharmacological action, and clinical applications of Tβ4. As a G-actin isolator, Tβ4 inhibits the polymerization of G-actin by binding to the matching site of G-actin in a 1:1 ratio through conformational and spatial effects. Tβ4 can control the threshold concentration of G-actin in the cytoplasm, influence the balance of depolymerization and polymerization of F-actin (also called Tread Milling of F-actin), and subsequently affect cell's various physiological activities, especially motility, development and differentiation. Based on this, Tβ4 is known to have a wide range of effects, including regulation of inflammation and tumor metastasis, promotion of angiogenesis, wound healing, regeneration of hair follicles, promotion of the development of the nervous system, and improving bone formation and tooth growth. Tβ4 therefore has extensive medicinal applications in many fields, and serves to preserve the kidney, liver, heart, brain, intestine, and other organs, as well as hair loss, skin trauma, cornea repairing, and other conditions. In this review, we focus on the mechanism of action and clinical application of Tβ4 for its main biological functions., (Copyright© Bentham Science Publishers; For any queries, please email at epub@benthamscience.net.)

With the aging of population and the development of social economy, the incidence of chronic wounds is increasing day by day, while the incidence of burns and trauma remains at a high level, making wound repair an increasingly concerned area in clinical practice. Thymosin β4 is a naturally occurring small molecule protein in vivo, which is widely distributed in a variety of body fluids and cells, especially in platelets. Thymosin β4 has biological activities of promoting angiogenesis, anti-inflammation, anti-apoptosis, and anti-fibrosis, and has many important functions in wound repair. Thymosin β4 has been observed to promote the healing of various wounds, such as burns, diabetic ulcers, pressure ulcers. This paper will review the molecular structure, mechanism of wound healing promotion, pharmacokinetics, and clinical application of thymosin β4, aiming to introduce its potential in wound treatment and the shortcomings of current researches.

Background: Rheumatic heart valve disease (RHVD) is a leading cause of cardiovascular death in low- and middle-income countries and affects predominantly women. The underlying mechanisms of chronic valvular damage remain unexplored and regulators of sex predisposition are unknown., Methods: Proteomics analysis of human heart valves (nondiseased aortic valves, nondiseased mitral valves [NDMVs], valves from patients with rheumatic aortic valve disease, and valves from patients with rheumatic mitral valve disease; n=30) followed by system biology analysis identified ProTα (prothymosin alpha) as a protein associated with RHVD. Histology, multiparameter flow cytometry, and enzyme-linked immunosorbent assay confirmed the expression of ProTα. In vitro experiments using peripheral mononuclear cells and valvular interstitial cells were performed using multiparameter flow cytometry and quantitative polymerase chain reaction. In silico analysis of the RHVD and Streptococcus pyogenes proteomes were used to identify mimic epitopes., Results: A comparison of NDMV and nondiseased aortic valve proteomes established the baseline differences between nondiseased aortic and mitral valves. Thirteen unique proteins were enriched in NDMVs. Comparison of NDMVs versus valves from patients with rheumatic mitral valve disease and nondiseased aortic valves versus valves from patients with rheumatic aortic valve disease identified 213 proteins enriched in rheumatic valves. The expression of the 13 NDMV-enriched proteins was evaluated across the 213 proteins enriched in diseased valves, resulting in the discovery of ProTα common to valves from patients with rheumatic mitral valve disease and valves from patients with rheumatic aortic valve disease. ProTα plasma levels were significantly higher in patients with RHVD than in healthy individuals. Immunoreactive ProTα colocalized with CD8 + T cells in RHVD. Expression of ProTα and estrogen receptor alpha correlated strongly in circulating CD8 + T cells from patients with RHVD. Recombinant ProTα induced expression of the lytic proteins perforin and granzyme B by CD8 + T cells as well as higher estrogen receptor alpha expression. In addition, recombinant ProTα increased human leukocyte antigen class I levels in valvular interstitial cells. Treatment of CD8 + T cells with specific estrogen receptor alpha antagonist reduced the cytotoxic potential promoted by ProTα. In silico analysis of RHVD and S pyogenes proteomes revealed molecular mimicry between human type 1 collagen epitope and bacterial collagen-like protein, which induced CD8 + T-cell activation in vitro., Conclusions: ProTα-dependent CD8 + T-cell cytotoxicity was associated with estrogen receptor alpha activity, implicating ProTα as a potential regulator of sex predisposition in RHVD. ProTα facilitated recognition of type 1 collagen mimic epitopes by CD8 + T cells, suggesting mechanisms provoking autoimmunity.

Thymosin β4 (Tβ4) was extracted forty years agofrom calf thymus. Since then, it has been identified as a G-actin binding protein involved in blood clotting, tissue regeneration, angiogenesis, and anti-inflammatory processes. Tβ4 has also been implicated in tumor metastasis and neurodegeneration. However, the precise roles and mechanism(s) of action of Tβ4 in these processes remain largely unknown, with the binding of the G-actin protein being insufficient to explain these multi-actions. Here we identify for the first time the important role of Tβ4 mechanism in ferroptosis, an iron-dependent form of cell death, which leads to neurodegeneration and somehow protects cancer cells against cell death. Specifically, we demonstrate four iron 2+ and iron 3+ binding regions along the peptide and show that the presence of Tβ4 in cell growing medium inhibits erastin and glutamate-induced ferroptosis in the macrophage cell line. Moreover, Tβ4 increases the expression of oxidative stress-related genes, namely BAX, hem oxygenase-1, heat shock protein 70 and thioredoxin reductase 1, which are downregulated during ferroptosis. We state the hypothesis that Tβ4 is an endogenous iron chelator and take part in iron homeostasis in the ferroptosis process. We discuss the literature data of parallel involvement of Tβ4 and ferroptosis in different human pathologies, mainly cancer and neurodegeneration. Our findings confronted with literature data show that controlled Tβ4 release could command on/off switching of ferroptosis and may provide novel therapeutic opportunities in cancer and tissue degeneration pathologies.

β-thymosin 4 (Tβ4) is a prototypical actin-monomer sequestering protein that plays an important role in mammalian cells and tissues. In vertebrates, Tβ4 is involved in various physiological and pathophysiological processes, such as angiogenesis, hair follicle and hair regeneration, nervous system development, inflammatory response, wound healing, tumour metastasis, and liver and heart protection. Additionally, thymosin domain-containing protein was discovered in invertebrates and was recently shown to be more homologous to Tβ4. However, the structural and functional properties are more complex and diverse than those of Tβ4. In this review article, we will discuss in detail the structural and functional aspects of β-thymosin in invertebrates., (Copyright© Bentham Science Publishers; For any queries, please email at epub@benthamscience.net.)

Motifs within proteins help us categorize their functions. Intrinsically disordered proteins (IDPs) are rich in short linear motifs, conferring them many different roles. IDPs are also frequently highly charged and, therefore, likely to interact with ions. Canonical calcium-binding motifs, such as the EF-hand, often rely on the formation of stabilizing flanking helices, which are a key characteristic of folded proteins, but are absent in IDPs. In this study, we probe the existence of a calcium-binding motif relevant to IDPs. Upon screening several carefully selected IDPs using NMR spectroscopy supplemented with affinity quantification by colorimetric assays, we found calcium-binding motifs in IDPs which could be categorized into at least two groups-an Excalibur-like motif, sequentially similar to the EF-hand loop, and a condensed-charge motif carrying repetitive negative charges. The motifs show an affinity for calcium typically in the ~100 μM range relevant to regulatory functions and, while calcium binding to the condensed-charge motif had little effect on the overall compaction of the IDP chain, calcium binding to Excalibur-like motifs resulted in changes in compaction. Thus, calcium binding to IDPs may serve various structural and functional roles that have previously been underreported.

We describe furan as a triggerable 'warhead' for site-specific cross-linking using the actin and thymosin β4 (Tβ4)-complex as model of a weak and dynamic protein-protein interaction (PPI) with known 3D structure and with application potential in disease contexts. The identified cross-linked residues demonstrate that lysine is a target for the furan warhead. The presented in vitro validation of covalently acting 'furan-armed' Tβ4-variants provides initial proof to further exploit furan-technology for covalent drug design targeting lysines.

Actin is the most abundant protein in eukaryotic cells and is key to many cellular functions. The filamentous form of actin (F-actin) can be studied with help of natural products that specifically recognize it, as for example fluorophore-labeled probes of the bicyclic peptide phalloidin, but no synthetic probes exist for the monomeric form of actin (G-actin). Herein, we have panned a phage display library consisting of more than 10 billion bicyclic peptides against G-actin and isolated binders with low nanomolar affinity and greater than 1000-fold selectivity over F-actin. Sequence analysis revealed a strong similarity to a region of thymosin-β4, a protein that weakly binds G-actin, and competition binding experiments confirmed a common binding region at the cleft between actin subdomains 1 and 3. Together with F-actin-specific peptides that we also isolated, we evaluated the G-actin peptides as probes in pull-down, imaging, and competition binding experiments. While the F-actin peptides were applied successfully for capturing actin in cell lysates and for imaging, the G-actin peptides did not bind in the cellular context, most likely due to competition with thymosin-β4 or related endogenous proteins for the same binding site.

The amount of bonds between constituting parts of a protein aggregate were determined in wild type (WT) and A53T α-synuclein (αS) oligomers, amyloids and in the complex of thymosin-β 4 -cytoplasmic domain of stabilin-2 (Tβ 4 -stabilin CTD). A53T αS aggregates have more extensive βsheet contents reflected by constant regions at low potential barriers in difference (to monomers) melting diagrams ( MD s). Energies of the intermolecular interactions and of secondary structures bonds, formed during polymerization, fall into the 5.41 kJ mol -1 ≤ E a ≤ 5.77 kJ mol -1 range for αS aggregates. Monomers lose more mobile hydration water while forming amyloids than oligomers. Part of the strong mobile hydration water-protein bonds break off and these bonding sites of the protein form intermolecular bonds in the aggregates. The new bonds connect the constituting proteins into aggregates. Amyloid-oligomer difference MD showed an overall more homogeneous solvent accessible surface of A53T αS amyloids. From the comparison of the nominal sum of the MD s of the constituting proteins to the measured MD of the Tβ 4 -stabilin CTD complex, the number of intermolecular bonds connecting constituent proteins into complex is 20(1) H 2 O/complex. The energies of these bonds are in the 5.40(3) kJ mol -1 ≤ E a ≤ 5.70(5) kJ mol -1 range.

The hair follicle (HF) is an important mini-organ of the skin, composed of many types of cells. Dermal papilla cells are important signalling components that guide the proliferation, upward migration and differentiation of HF stem cell progenitor cells to form other types of HF cells. Thymosin β4 (Tβ4), a major actin-sequestering protein, is involved in various cellular responses and has recently been shown to play key roles in HF growth and development. Endogenous Tβ4 can activate the mouse HF cycle transition and affect HF growth and development by promoting the migration and differentiation of HF stem cells and their progeny. In addition, exogenous Tβ4 increases the rate of hair growth in mice and promotes cashmere production by increasing the number of secondary HFs (hair follicles) in cashmere goats. However, the molecular mechanisms through which Tβ4 promotes HF growth and development have rarely been reported. Herein, we review the functions and mechanisms of Tβ4 in HF growth and development and describe the endogenous and exogenous actions of Tβ4 in HFs to provide insights into the roles of Tβ4 in HF growth and development., (© 2021 The Authors. Journal of Cellular and Molecular Medicine published by Foundation for Cellular and Molecular Medicine and John Wiley & Sons Ltd.)

Wide-line 1 H NMR measurements were extended and all results were interpreted in a thermodynamics-based new approach on aqueous solutions of thymosin-β 4 (Tβ 4 ), stabilin cytoplasmic domain (CTD), and their 1 : 1 complex. Energy distributions of potential barriers controlling the motion of protein-bound water molecules were determined. Heterogeneous and homogeneous regions were found in the protein-water interface. The measure of heterogeneity of this interface gives quantitative value for the portion of disordered parts in the protein. Ordered structural elements were found extending up to ∼20 % of the individual whole proteins. About 40 % of the binding sites of free Tβ 4 get involved in bonds holding the complex together. The complex has the most heterogeneous solvent accessible surface (SAS) in terms of protein-water interactions. The complex is more disordered than Tβ 4 or stabilin CTD. The greater SAS area of the complex is interpreted as a clear sign of its open structure., (© 2020 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.)

Microfiber yarns (MY) have been widely employed to construct tendon tissue grafts. However, suboptimal ultrastructure and inappropriate environments for cell interactions limit their clinical application. Herein, we designed a modified electrospinning device to coat poly(lactic-co-glycolic acid) PLGA nanofibers onto polylactic acid (PLA) MY to generate PLGA/PLA hybrid yarns (HY), which had a well-aligned nanofibrous structure, resembling the ultrastructure of native tendon tissues and showed enhanced failure load compared to PLA MY. PLGA/PLA HY significantly improved the growth, proliferation, and tendon-specific gene expressions of human adipose derived mesenchymal stem cells (HADMSC) compared to PLA MY. Moreover, thymosin beta-4 (Tβ4) loaded PLGA/PLA HY presented a sustained drug release manner for 28 days and showed an additive effect on promoting HADMSC migration, proliferation, and tenogenic differentiation. Collectively, the combination of Tβ4 with the nano-topography of PLGA/PLA HY might be an efficient strategy to promote tenogenesis of adult stem cells for tendon tissue engineering., (Copyright © 2019 Elsevier B.V. All rights reserved.)

Metallacarboranes are anionic boron clusters with high affinity to serum albumin, ability to cross biological membranes, and no apparent toxicity in vitro and in vivo. Thus, conjugation with cobalt bis(1,2-dicarbollide), [COSAN] - , ([3,3'-Co(1,2-C 2 B 9 H 11 ) 2 ] - ) may improve the properties of therapeutic peptides or proteins at both molecular and systemic levels. Here, we conjugated [COSAN] - with the therapeutic peptide thymosin β4 (Tβ4), which has a pleiotropic activity that results in enhanced healing and regeneration of injured tissues. Using fluorescence quenching of human serum albumin and surface plasmon resonance techniques, we showed that the conjugates have a high affinity to human serum albumin. Using an in vitro wound closure assay, we showed that conjugation with [COSAN] - enhances the activity of Tβ4 toward fibroblasts (MSU1.1 cell line). These results indicate an application of metallacarboranes in the development of analogs of various therapeutic peptides/proteins with superior pharmacological properties., (© 2019 New York Academy of Sciences.)

Intrinsically disordered proteins (IDPs) explore diverse conformations in their free states and, a few of them, also in their molecular complexes. This functional plasticity is essential for the function of IDPs, although their dynamics in both free and bound states is poorly understood. NUPR1 is a protumoral multifunctional IDP, activated during the acute phases of pancreatitis. It interacts with DNA and other IDPs, such as prothymosin α (ProTα), with dissociation constants of ~0.5 μM, and a 1:1 stoichiometry. We studied the structure and picosecond-to-nanosecond (ps-ns) dynamics by using both NMR and SAXS in: (i) isolated NUPR1; (ii) the NUPR1/ProTα complex; and (iii) the NUPR1/double stranded (ds) GGGCGCGCCC complex. Our SAXS findings show that NUPR1 remained disordered when bound to either partner, adopting a worm-like conformation; the fuzziness of bound NUPR1 was also pinpointed by NMR. Residues with the largest values of the relaxation rates (R 1 , R 1ρ , R 2 and η xy ), in the free and bound species, were mainly clustered around the 30s region of the sequence, which agree with one of the protein hot-spots already identified by site-directed mutagenesis. Not only residues in this region had larger relaxation rates, but they also moved slower than the rest of the molecule, as indicated by the reduced spectral density approach (RSDA). Upon binding, the energy landscape of NUPR1 was not funneled down to a specific, well-folded conformation, but rather its backbone flexibility was kept, with distinct motions occurring at the hot-spot region., (Copyright © 2019 Elsevier B.V. All rights reserved.)

The β-thymosin (Tβ) proteins participate in numerous biological processes, such as cell proliferation and differentiation, anti-inflammatory and antimicrobial mechanism. To date, Tβ proteins have been well studied in vertebrates, especially mammals. While limited Tβ or Tβ-like proteins have been reported in invertebrates. Moreover, rare information of Tβ or Tβ-like proteins is available in scallop species yet. In the present study, two Tβ homologues, AiTβ and CfTβ, were identified and characterized from two scallop species bay scallop Argopecten irradians and Zhikong scallop Chlamys farreri. They were both 41 amino acid peptide and contained one THY domain, a highly conserved actin-binding motif and two conserved helix forming regions. Tissue distribution and expression profiles of their mRNA transcripts were roughly similar yet different in detail, while their recombinant proteins exhibited different immunomodulation activity on the downstream immune parameters. These results collectively indicated that the function of Tβ family in scallop were functionally differentiated., (Copyright © 2018. Published by Elsevier Ltd.)

Thymosins β are actin-binding proteins that play a variety of different functions in inflammatory responses, wound healing, cell migration, angiogenesis, and stem cell recruitment and differentiation. In crayfish, thymosins participate in antiviral immunology. However, the roles of thymosin during bacterial infection in shrimp remain unclear. In the present study, four thymosins were identified from kuruma shrimp, Marsupenaeus japonicus, and named as Mjthymosin2, Mjthymosin3, Mjthymosin4, and Mjthymosin5 according the number of their thymosin beta actin-binding motifs. Mjthymosin3 was selected for further study because its expression level was the highest in hemocytes. Expression analysis showed that Mjthymosin3 was upregulated in hemocytes after challenged by Vibrio anguillarum or Staphylococcus aureus. The recombinant Mjthymosin3 protein could inhibit the growth of certain bacteria in an in vitro antibacterial test. Mjthymosins could facilitate external bacterial clearance in shrimp, and were beneficial to shrimp survival post V. anguillarum or S. aureus infection. The results suggested that Mjthymosins played important roles in the antibacterial immune response of kuruma shrimp., (Copyright © 2018 Elsevier Ltd. All rights reserved.)

It was recently reported that human linker histone H1.0 and its chaperone prothymosin-α (ProTα) form an extremely disordered 1:1 complex with an ultrahigh affinity (equilibrium dissociation constant K D of ∼2 × 10 -12 M) measured using a single-molecule Förster resonance energy transfer method. It was hypothesized that the ultrahigh affinity and extreme disorder may be required for the chaperone function of ProTα, in which it displaces the linker histone from condensed chromatin. Here, we measure the binding affinity for the ProTα-H1.0 complex using isothermal titration calorimetry and report a K D value of (4.6 ± 0.5) × 10 -7 M. In addition, we show that ProTα facilitates the formation of the H1.0-nucleosome complex in vitro. The results of our study contrast with those of the previous report and provide new insights into the chaperone function of ProTα. Possible causes for the observed discrepancy in binding affinity are discussed.

Prothymosin-α is a small, multifunctional intrinsically disordered protein associated with cell survival and proliferation which binds multiple Zn 2+ ions and undergoes partial folding. The interaction between prothymosin-α and at least two of its protein targets is significantly enhanced in the presence of Zn 2+ ions, suggesting that Zn 2+ binding plays a role in the protein's function. The primary sequence of prothymosin-α is highly acidic, with almost 50% comprised of Asp and Glu, and is unusual for a Zn 2+ -binding protein as it lacks Cys and His residues. To gain a better understanding of the nature of the Zn 2+ -prothymosin-α interactions and the protein's ability to discriminate Zn 2+ over other divalent cations (e.g., Ca 2+ , Co 2+ , Mg 2+ ) we synthesized a set of three model peptides and characterized the effect of metal binding using electrospray ionization mass spectrometry (ESI MS) and circular dichroism (CD) spectroscopy. ESI MS data reveal that the native peptide model of the glutamic acid rich region binds 4 Zn 2+ ions with apparent, stepwise K d values that are, at highest, in the tens of micromolar range. A peptide model with the same amino acid composition as the native sequence, but with the residues arranged randomly, showed no evidence of structural change by CD upon introduction of Zn 2+ . These results suggest that the high net negative charge of the glutamic acid-rich region of prothymosin-α is not a sufficient criterion for Zn 2+ to induce a structural change; rather, Zn 2+ binding to prothymosin-α is sequence specific, providing important insight into the behavior of intrinsically disordered proteins.

Anionic boron clusters are man-made, inorganic compounds with potential applications in therapeutic peptides modification to improve their biological activity and pharmacokinetics, e.g., by enabling complexation with serum albumin. However, the conjugation of anionic boron clusters and peptides remains poorly understood. Here, we report a solid-state, thermal reaction to selectively conjugate carboxylic groups in the peptide thymosin β4 (Tβ4) with cyclic oxonium derivatives of anionic boron clusters (dodecaborate anion [B 12 H 12 ] 2- and cobalt bis(1,2-dicarbollide), [COSAN] - [3,3'-Co(1,2-C 2 B 9 H 11 ) 2 ] - ). Modification of the carboxylic groups retains the negative charge at the modification site and leads to the formation of ester bonds. The ester bonds in the conjugates undergo hydrolysis at different rates depending on the site of the modification. We obtained conjugates with dramatically different stabilities (τ 1/2 from 3-836 h (Tβ4-[B 12 H 12 ] 2- conjugates) and 9-1329 h (Tβ4-[COSAN] - conjugates)) while retaining or improving the prosurvival activity of Tβ4 toward cardiomyocytes (H9C2 cell line).

Thymosin α1 (Tα1), a hormone containing 28 amino acids, has been approved in several cancer therapies, but the lack of tumor-targeting hinders its full use in tumor treatment. We designed a new peptide by connecting Tα1 and RGDR, generating a product, Tα1-RGDR, where RGDR is located in the C-end with both tumor-homing and cell internalizing properties (C-end rule peptides, a consensus R/KXXR/K motif). This work aimed to study the antitumor and immunological activities of Tα1-RGDR, and its differences compared with the wild-type Tα1. The antitumor and immunological activities of Tα1-RGDR were measured using the B16F10 tumor and immunologic suppression models. Tα1-RGDR treatment led to significant inhibition of tumor growth at a dose at which Tα1 showed a slight effect in the B16F10 tumor growth model. In the immunologic suppression model, Tα1-RGDR shared almost equivalent immunomodulatory effect with Tα1. These results demonstrated the better therapeutic effects after treatment with Tα1-RGDR compared with Tα1. Moreover, both Tα1-RGDR and Tα1 shared a helical conformation in the presence of trifluoroethanol based on CD spectroscopy. Our dock information of Tα1-RGDR when combined with integrin αvβ3 or neuropilin-1 further confirmed previous experimental results. All these findings suggest that Tα1-RGDR might be a useful therapy for tumors by overcoming its wild type limitation of tumor homing., (Copyright © 2018 Elsevier B.V. and Société Française de Biochimie et Biologie Moléculaire (SFBBM). All rights reserved.)

Tumor-targeted therapy is an attractive strategy for cancer treatment. Peptide hormone thymosin α1 (Tα1) has been used against several diseases, including cancer, but its activity is pleiotropic. Herein, we designed a fusion protein Tα1-iRGD by introducing the tumor homing peptide iRGD to Tα1. Results show that Tα1-iRGD can promote T-cell activation and CD86 expression, thereby exerting better effect and stronger inhibitory against melanoma and lung cancer, respectively, than Tα1 in vivo. These effects are indicated by the reduced densities of tumor vessels and Tα1-iRGD accumulation in tumors. Moreover, compared with Tα1, Tα1-iRGD can attach more B16F10 and H460 cells and exhibits significantly better immunomodulatory activity in immunosuppression models induced by hydrocortisone. Circular dichroism spectroscopy and structural analysis results revealed that Tα1 and Tα1-iRGD both adopted a helical confirmation in the presence of trifluoroethanol, indicating the structural basis of their functions. These findings highlight the vital function of Tα1-iRGD in tumor-targeted therapy and suggest that Tα1-iRGD is a better antitumor drug than Tα1., (Copyright © 2018 Elsevier B.V. All rights reserved.)

Objectives: We reevaluated a lyophilized sample of thymosin fraction 5, stored for 37 years at room temperature, by high-resolution mass spectrometry in terms of stability and yet uncharacterized polypeptides that could be biological important substances., Methods: A top-down proteomic platform based on high-performance liquid chromatography (HPLC) coupled to high-resolution LTQ-Orbitrap mass spectrometry (MS) was applied to molecular characterization of polypeptides present in thymosin fraction 5., Results: We detected more than 100 monoisotopic masses corresponding to thymosin β4 and truncated forms of ubiquitin, prothymosin α, thymosin β4, and thymosin β9. Additionally, we discovered a new polypeptide present in thymosin fraction 5 and identified it as intact SH3 domain-binding glutamic acid-rich-like protein 3., Conclusion: In spite of the well-known proteolytic processes inherent to the preparation of thymosin fraction 5, still uncharacterized polypeptides as well as truncated forms of already well-known thymosins are present in fraction 5 after long-term storage. Therefore, continuing characterization of thymosin fraction 5 is even nowadays highly promising.

Objectives: Hepatic stellate cells (HSC) trans-differentiation is central to the development of liver fibrosis, marked by the expression of pro-fibrogenic genes and the proliferation and migration of activated HSC. Therefore, preventing and/or reverting the activation, proliferation, and migration of HSC may lead to new therapies for treating fibrosis/cirrhosis. Thymosin β4 (Tβ4) inhibits PDGF-BB-induced fibrogenesis, proliferation and migration of HSC by blocking Akt phosphorylation. Here, we utilized Tβ4-derived peptides: amino-terminal-Ac-SDKPDMAEIEKFDKS (1-15aa) and actin-binding-LKKTETQ (17-23aa) to investigate the molecular mechanisms in the anti-fibrogenic actions of Tβ4., Methods: We used RT-PCR, Western blot, and proliferation and migration assays in early passages of human HSC cultures treated with PDGF-BB and/or Tβ4 peptides., Results: We showed that 17-23aa but not 1-15aa inhibited PDGF-BB-dependent up-regulation of PDGFβ receptor, α-SMA, and collagen 1. It also blunted the phosphorylation of Akt at T 308 and S473, resulting in the inhibition of phosphorylation of PRAS40, and HSC proliferation and migration. Interestingly, 1-15aa blocked Akt phosphorylation at S473, but not T308 by inhibiting mTOR phosphorylation, thus, it did not have any effect on HSC proliferation and migration., Conclusion: These findings suggest that while 1-15aa has a minor effect on Akt phosphorylation, the anti-fibrogenic actions of Tβ4 are exerted via 17-23aa.

Wide-line 1 H NMR measurements were extended and all results were reinterpreted in a new thermodynamics-based approach to study aqueous solutions of thymosin-β 4 (Tβ 4 ), stabilin C-terminal domain (CTD) and their 1:1 complex. The energy distributions of the potential barriers, which control motion of protein-bound water molecules, were determined. Heterogeneous and homogeneous regions were found at the protein-water interface. The measure of heterogeneity gives a quantitative value for the portion of disordered parts in the protein. Ordered structural elements were found extending up to 20 % of the whole proteins. About 40 % of the binding sites of free Tβ 4 become involved in bonds holding the complex together. The complex has the most heterogeneous solvent accessible surface (SAS) in terms of protein-water interactions. The complex is more disordered than Tβ 4 or stabilin CTD. The greater SAS area of the complex is interpreted as a clear sign of its open structure., (© 2018 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.)

Molecular communication in biology is mediated by protein interactions. According to the current paradigm, the specificity and affinity required for these interactions are encoded in the precise complementarity of binding interfaces. Even proteins that are disordered under physiological conditions or that contain large unstructured regions commonly interact with well-structured binding sites on other biomolecules. Here we demonstrate the existence of an unexpected interaction mechanism: the two intrinsically disordered human proteins histone H1 and its nuclear chaperone prothymosin-α associate in a complex with picomolar affinity, but fully retain their structural disorder, long-range flexibility and highly dynamic character. On the basis of closely integrated experiments and molecular simulations, we show that the interaction can be explained by the large opposite net charge of the two proteins, without requiring defined binding sites or interactions between specific individual residues. Proteome-wide sequence analysis suggests that this interaction mechanism may be abundant in eukaryotes.

We have prepared 125 I-labeled cholera toxin B subunit ( 125 I-labeled CT-B, a specific activity of 98Ci/mmol) and found that it binds to rat IEC-6 and human Caco-2 intestinal epithelial cells with high affinity (K d 3.6 and 3.7nM, respectively). The binding of labeled protein was completely inhibited by unlabeled thymosin-α 1 (TM-α 1 ), interferon-α 2 (IFN-α 2 ), and the synthetic peptide LKEKK that corresponds to residues 16-20 in TM-α 1 and 131-135 in IFN-α 2 , but was not inhibited by the synthetic peptide KKEKL with inverted amino acid sequence (K i >10μM). Thus, TM-α 1 , IFN-α 2 , and the peptide: LKEKK bind with high affinity and specificity to the cholera toxin receptor on IEC-6 and Caco-2 cells. It was found that CT-B and the peptide: LKEKK at concentrations of 10-1000nM increased in a dose-dependent manner the nitric oxide production and the soluble guanylate cyclase activity in IEC-6 and Caco-2 cells., (Copyright © 2017 Elsevier Ltd. All rights reserved.)

Thymosin α1 (Tα1), is a peptidic hormone, whose immune regulatory properties have been demonstrated both in vitro and in vivo and approved in different countries for treatment of several viral infections and cancers. Tα1 assumes a conformation in negative membranes upon insertion into the phosphatidylserine exposure as found in several pathologies and in apoptosis. These findings are in agreement with the pleiotropy of Tα1, which targets both normal and tumor cells, interacting with multiple cellular components, and have generated renewed interest in the topic. Hyaluronan (HA) occurs ubiquitously in the extracellular matrix and on cell surfaces and has been related to a variety of diseases, and developmental and physiological processes. Proteins binding HA, among them CD44 and the Receptor for HA-mediated motility (RHAMM) receptors, mediate its biological effects. NMR spectroscopy indicated preliminarily that an interaction of Tα1 with HA occurs specifically around lysine residues of the sequence LKEKK of Tα1 and is suggestive of a possible interference of Tα1 in the binding of HA with CD44 and RHAMM. Further studies are needed to deepen these observations because Tα1 is known to potentiate the T-cell immunity and anti-tumor effect. The binding inhibitory activity of Tα1 on HA-CD44 or HA-RHAMM interactions can suppress both T-cell reactivity and tumor progression., Competing Interests: The authors declare that they do not have any conflict of interest.

Thymosin beta belongs to the thymosin family, which consists of a series of highly conserved peptides involved in various biological processes. In teleosts, understanding of the immunological functions of thymosin beta is limited, particularly in vivo, which is essentially unknown. In the current study, we cloned and identified thymosin beta 4 from the teleost fish Golden pompano (Trachinotus ovatus), which we have named TroTβ4. We investigated the expression patterns and functions of TroTβ4 in both in vivo and in vitro assays. TroTβ4 is composed of 44 amino acids and shares high sequence identities with known thymosin β4 species in other teleosts, which contains a highly conserved actin-binding motif (LKKTET). The expression of TroTβ4 was most abundant in immune organs, and was significantly up-regulated in response to infection bacterial with one of a number of bacteria (including Edwardsiella tarda, Vibrio harveyi, and Streptococcus agalactiae). Purified recombinant TroTβ4 (rTroTβ4) inhibited the growth of bacteria, as measured using an automatic growth curve analyzer, indicating that TroTβ4 has antimicrobial functions. When administered in vivo, overexpression of TroTβ4 in T. ovatus, bacterial colonization of tissues was significantly reduced. In contrast, when a DNA vector-based siRNA technology was used to knock down TroTβ4 expression, bacterial dissemination and colonization of tissues increased significantly. Taken together, these results provide the first in vivo evidence to indicate that teleost thymosin beta 4 plays a significant role in innate antibacterial immune responses in addition to in vitro bacteriostatic activity. This provides valuable information regarding the biological functions of teleost thymosin beta., (Copyright © 2017. Published by Elsevier Ltd.)

Proteins that lack tertiary stability under normal conditions, known as intrinsically disordered, exhibit a wide range of biological activities. Molecular descriptions for the biology of intrinsically disordered proteins (IDPs) consequently rely on disordered structural models, which in turn require experiments that assess the origins to structural features observed. For example, while hydrodynamic size is mostly insensitive to sequence composition in chemically denatured proteins, IDPs show strong sequence-specific effects in the hydrodynamic radius (R h ) when measured under normal conditions. To investigate sequence-modulation of IDP R h , disordered ensembles generated by a hard sphere collision model modified with a structure-based parameterization of the solution energetics were used to parse the contributions of net charge, main chain dihedral angle bias, and excluded volume on hydrodynamic size. Ensembles for polypeptides 10-35 residues in length were then used to establish power-law scaling relationships for comparison to experimental R h from 26 IDPs. Results showed the expected outcomes of increased hydrodynamic size from increases in excluded volume and net charge, and compaction from chain-solvent interactions. Chain bias representing intrinsic preferences for α helix and polyproline II (PP II ), however, modulated R h with intricate dependence on the simulated propensities. PP II propensities at levels expected in IDPs correlated with heightened R h sensitivity to even weak α helix propensities, indicating bias for common (φ, ψ) are important determinants of hydrodynamic size. Moreover, data show that IDP R h can be predicted from sequence with good accuracy from a small set of physicochemical properties, namely intrinsic conformational propensities and net charge. Proteins 2017; 85:296-311. © 2016 Wiley Periodicals, Inc., (© 2016 Wiley Periodicals, Inc.)

Background/objective: Prothymosin alpha (proTα) is a ubiquitous polypeptide first isolated by Haritos in 1984, whose role still remains partly elusive. We know that proTα acts both, intracellularly, as an anti-apoptotic and proliferation mediator, and extracellularly, as a biologic response modifier mediating immune responses similarly to molecules termed as "alarmins". Our research team pioneered the elucidation of the mechanisms underlying the observed activities of proTα., Results: We were the first to demonstrate that proTα levels increase during normal and abnormal cell proliferation. We showed that proTα acts pleiotropically, inducing immunomodulatory effects on immune cell populations. We revealed that the immunoreactive region of proTα is the carboxyterminal decapeptide proTα(100-109) and both molecules stimulate innate immune responses, signaling through Toll-like receptors (TLRs), specifically TLR-4. We reported that proTα and proTα(100-109) bind on the surface of human neutrophils on sites involving TLR-4, and cell activation is complemented by cytoplasmic calcium ion influx. Further, we showed that proTα and proTα(100-109) act as adjuvants upstream of lymphocyte stimulation and, in the presence of antigen, promote the expansion of antigen-reactive effectors. Most recently, we reported that proTα(100-109) may accumulate in experimentally inflamed sites and can serve as a surrogate biomarker in severe bacterial infections, proposing that extracellular release of proTα or proTα(100- 109) alerts the immune system during conditions of danger., Conclusion: We, therefore, suggest that proTα, and likely proTα(100-109), act as alarmins, being important immune mediators as well as biomarkers, and could eventually become targets for new therapeutic/diagnostic approaches in immune-related diseases like cancer, inflammation, and sepsis., (Copyright© Bentham Science Publishers; For any queries, please email at epub@benthamscience.org.)

Understanding the structural basis of actin cytoskeleton remodeling requires stabilization of actin monomers, oligomers, and filaments in complex with partner proteins, using various biochemical strategies. Here, we report a dramatic destabilization of the dynamic interaction with a model β-thymosin/WH2 domain induced by mutations in actin. This result underlines that mutant actins should be used with prudence to characterize interactions with intrinsically disordered partners as destabilization of dynamic interactions, although identifiable by NMR, may be invisible to other structural techniques. It also highlights how both β-thymosin/WH2 domains and actin tune local structure and dynamics in regulatory processes involving intrinsically disordered domains., (© 2016 Federation of European Biochemical Societies.)

The synthetic peptide LKEKK corresponding to sequence 16-20 of human thymosin-α1 and 131-135 of human interferon-α2 was labeled with tritium to specific activity 28 Ci/mol. The [3H]LKEKK bound with high affinity (Kd = 3.7 ± 0.3 nM) to donor blood T-lymphocytes. Treatment of cells with trypsin or proteinase K did not abolish [3H]LKEKK binding, suggesting the non-protein nature of the peptide receptor. The binding was inhibited by thymosin-α1, interferon-α2, and cholera toxin B subunit (Ki = 2.0 ± 0.3, 2.2 ± 0.2, and 3.6 ± 0.3 nM, respectively). Using [3H]LKEKK, we demonstrated the existence of a non-protein receptor common for thymosin-α1, interferon-α2, and cholera toxin B-subunit on donor blood T-lymphocytes.

Conventional antibiotics might fail in the treatment of biofilm-associated infections causing infection recurrence and chronicity. The search for antimicrobial peptides has been performed with the aim to discover novel anti-infective agents active on pathogens in both planktonic and biofilm associated forms. The fragment 9-19 of human thymosin β4 was studied through 1 μs MD simulation. Two main conformations of the peptide were detected, both constituted by a central hydrophobic core and by the presence of peripheral charged residues suggesting a possible mechanism of interaction with two models of biological membranes, related to eukaryotic or bacterial membrane respectively. In addition, the peptide was chemically synthesized and its antimicrobial activity was tested in vitro against planktonic and biofilm form of a group of reference strains of Staphylococcus spp. and one P. aeruginosa strain. The human thymosin β4 fragment EIEKFDKSKLK showed antibacterial activity against staphylococcal strains and Pseudomonas aeruginosa ATCC 15442 at concentrations from 12.5 to 6.2 mg/ml and inhibited biofilm formation at sub-inhibitory concentrations (3.1-0.75 mg/ml). The activity of the fragment in inhibiting biofilm formation, could be due to the conformations highlighted by the MD simulations, suggesting its interaction with the bacterial membrane. Human thymosin β4 fragment can be considered a promising lead compound to develop novel synthetic or recombinant derivatives with improved pharmaceutical potential.

Thymosin β4 is a 43 amino acid long peptide with an acetylated N-terminal serin that has a high potential as a remedy for healing ulcers, wounds and burns. Although protein biosynthesis offers attractive opportunities in terms of a large-scale production, currently thymosin β4 is mainly produced by chemical synthesis. The problems that hinder the successful commercialization of the biotechnological approach are associated with the small peptides expression and N-terminal acetylation. This work presents an innovative biotechnological method for thymosin β4 production that employs the peptide acetylation in vivo. A genetically engineered construct was created, where the Tβ4 coding sequence fused with the intein Mxe GyrA sequence and chitin-binding domain was combined with the acetyltransferase coding sequence to form a polycistronic construct under a stringent control of T7 promoter. This plasmid construct provided for the expression of the Tβ4-intein fusion protein. In the process of the post-translational modification in vivo formyl methionine was completely removed from the target peptide N-terminus and followed by the Tβ4 precursor N-terminal acetylation. The use of the intein-mediated expression system made it possible to extract thymosin β4 in only 2 chromatographic runs. The method is straightforward to implement and scale up., (Copyright © 2016. Published by Elsevier B.V.)

Thymosin α1 is a peptidic hormone already used in the therapy of several diseases. Until now, the description of the precise receptor and mechanism for its action still remains elusive. The interaction of Thymosin α1, which is unstructured in water solution, has been recently studied in sodium dodecylsulphate micellar systems and it was reported that Thymosin α1 inserts in micelle assuming a conformation with two tracts of helix with a structural break in between. An investigation of its interaction both with micelles of dodecylphosphocholine alone and with mixed dodecylphosphocholine-sodium dodecylsulphate micelles is here reported. In these environments the results indicate that Thymosin α1 in phospholipidic membrane exposing choline polar heads interacts by aspecific modality and, oppositely, in the mixed dodecylphosphocholine-sodium dodecylsulphate micelles an insertion in the micellar hydrophobic region conformationally similar to that found in sodium dodecylsulphate micelles occurs. In presence of mixed micelles the insertion and structuration occur in preferred regions when the membrane models are negatively charged. From the point of view of the mechanism of action, insertion its N terminus in negative regions of membrane led to hypothesize that this process would be similar to a binding to phosphatidylserine exposed like in apoptotic cells. Thymosin α1 when inserted may interact with nearby proteins and/or receptors acting as effector and causing a biological signaling cascade. The recent attention to the phosphatidylserine exposure in cells may enforce the interest for these findings.

Thymosin α1 is a peptidic hormone with pleiotropic activity and is used in the therapy of several diseases. It is unstructured in water solution and interacts with negative regions of vesicles by assuming two tracts of helical conformation with a structural break between them. This study reports on Thymosin α1's interaction with mixed phospholipids phosphatidylcholine and phosphatidylserine, the negative component of the membranes, by ¹H and natural abundance ¹⁵N nuclear magnetic resonance (NMR). The results indicate that interaction occurs when the membrane is negatively charged by exposing phosphatidylserine. Moreover, the direct interaction of Thymosin α1 with K562 cells with an overexposure of phosphatidylserine as a consequence of resveratrol-induced apoptosis was conducted. Thymosin α1's interaction with human serum albumin was also investigated by NMR spectroscopy. Steady-state saturation transfer, transfer nuclear Overhauser effect spectroscopy, and diffusion-ordered spectroscopy methodologies all reveal that the C-terminal region of Thymosin α1 is involved in the interaction with serum albumin. These results may shed more light on Thymosin α1's mechanism of action by its insertion in negative regions of membranes due to the exposure of phosphatidylserine. Once Thymosin α1's N-terminus has been inserted into the membrane, the rest may interact with nearby proteins and/or receptors acting as effectors and causing a biological signaling cascade, thus exerting thymosin α1's pleiotropy.

The repertoire of peptides displayed in vivo by MHC II molecules derives from a wide spectrum of proteins produced by different cell types. Although intracellular endosomal processing in dendritic cells and B cells has been characterized for a few antigens, the overall range of processing pathways responsible for generating the MHC II peptidome are currently unclear. To determine the contribution of non-endosomal processing pathways, we eluted and sequenced over 3000 HLA-DR1-bound peptides presented in vivo by dendritic cells. The processing enzymes were identified by reference to a database of experimentally determined cleavage sites and experimentally validated for four epitopes derived from complement 3, collagen II, thymosin β4, and gelsolin. We determined that self-antigens processed by tissue-specific proteases, including complement, matrix metalloproteases, caspases, and granzymes, and carried by lymph, contribute significantly to the MHC II self-peptidome presented by conventional dendritic cells in vivo. Additionally, the presented peptides exhibited a wide spectrum of binding affinity and HLA-DM susceptibility. The results indicate that the HLA-DR1-restricted self-peptidome presented under physiological conditions derives from a variety of processing pathways. Non-endosomal processing enzymes add to the number of epitopes cleaved by cathepsins, altogether generating a wider peptide repertoire. Taken together with HLA-DM-dependent and-independent loading pathways, this ensures that a broad self-peptidome is presented by dendritic cells. This work brings attention to the role of "self-recognition" as a dynamic interaction between dendritic cells and the metabolic/catabolic activities ongoing in every parenchymal organ as part of tissue growth, remodeling, and physiological apoptosis., (© 2016 by The American Society for Biochemistry and Molecular Biology, Inc.)

Keap1 protein plays an essential role in regulating cellular oxidative stress response and is a crucial binding hub for multiple proteins, several of which are intrinsically disordered proteins (IDP). Among Kelch's IDP binding partners, NRF2 and PTMA are the two most interesting cases. They share a highly similar binding motif; however, NRF2 binds to Kelch with a binding affinity of approximately 100-fold higher than that of PTMA. In this study, we perform an exhaustive sampling composed of 6 μs well-tempered metadynamics and 2 μs unbiased molecular dynamics (MD) simulations aiming at characterizing the binding mechanisms and structural properties of these two peptides. Our results agree with previous experimental observations that PTMA is remarkably more disordered than NRF2 in both the free and bound states. This explains PTMA's lower binding affinity. Our extensive sampling also provides valuable insights into the vast conformational ensembles of both NRF2 and PTMA, supports the hypothesis of coupled folding-binding, and confirms the essential role of linear motifs in IDP binding.

Thymosin β4 (Tβ4) is a 43-amino acid signature motif peptide that defines the beta-thymosin (βT) family of proteins. βTs are intrinsically unstructured in their free states and undergo disorder-to-order transitions in carrying out their biological functions. This property poses challenges in determining their 3D structures, mainly favoring structural studies on the complexes formed between βTs and their interaction partners. One of the βTs' primary binding partners is monomeric actin, a major component of the cytoskeleton in eukaryotic cells. Tβ4's role in this system is to maintain the highly concentrated pool of monomeric actin that can be accessed through profilin by actin filament nucleating machineries. Here, we give an account of the structures of βTs that have been illuminated by nuclear magnetic resonance (NMR) and X-ray crystallography. NMR has been the method of choice for probing regions that have intrinsic conformational preference within the largely disordered βTs in their native states in solution. X-ray crystallography has demonstrated at atomic detail how βTs interact with actin. Detailed analysis of these structures highlights the disorder-to-order transition of Tβ4 in binding to actin and its isoform specificity., (© 2016 Elsevier Inc. All rights reserved.)

Thymosinα1 is a peptidic hormone with pleiotropic activity, which is used in the therapy of several diseases. It is unstructured in water solution and interacts with negative regions of micelles and vesicles assuming two tracts of helical conformation with a structural flexible break in between. The studies of the interaction of Thymosinα1 with micelles of mixed dipalmitoylphosphatidylcholine and sodium dodecylsulfate and vesicles with mixed dipalmitoylphosphatidylcholine/dipalmitoylphosphatidylserine, the latter the negative component of the membranes, by (1)H and natural abundance (15)N NMR are herewith reported, reviewed, and discussed. The results indicate that the preferred interactions are those where the surface is negatively charged due to sodium dodecylsulfate or due to the presence of dipalmitoylphosphatidylserine exposed on the surface. In fact the unbalance of dipalmitoylphosphatidylserine on the cellular surface is an important phenomenon present in pathological conditions of cells. Moreover, the direct interaction of Thymosinα1 with K562 cells presenting an overexposure of phosphatidylserine as a consequence of resveratrol-induced apoptosis was carried out., (© 2016 Elsevier Inc. All rights reserved.)

Treatment with thymosin beta 4 (Tβ4) reduces infarct volume and preserves cardiac function in preclinical models of cardiac ischemic injury. These effects stem in part from decreased infarct size, but additional benefits are likely due to specific antifibrotic and proangiogenic activities. Injected or transgenic Tβ4 increase blood vessel growth in large and small animal models, consistent with Tβ4 converting hibernating myocardium to an actively contractile state following ischemia. Tβ4 and its degradation products have antifibrotic effects in in vitro assays and in animal models of fibrosis not related to cardiac injury. This large number of pleiotropic effects results from Tβ4's many interactions with cellular signaling pathways, particularly indirect regulation of cellular motility and movement via the SRF-MRTF-G-actin transcriptional pathway. Variation in effects and effect sizes in animal models may potentially be due to variable distribution of Tβ4. Preclinical studies of PK/PD relationships and a reliable pharmacodynamic biomarker would facilitate clinical development of Tβ4., (© 2016 Elsevier Inc. All rights reserved.)

The thymus gland produces soluble molecules, which mediate significant immune functions. The first biologically active thymic extract was thymosin fraction V, the fractionation of which led to the isolation of a series of immunoactive polypeptides, including prothymosin alpha (proTα). ProTα displays a dual role, intracellularly as a survival and proliferation mediator and extracellularly as a biological response modifier. Accordingly, inside the cell, proTα is implicated in crucial intracellular circuits and may serve as a surrogate tumor biomarker, but when found outside the cell, it could be used as a therapeutic agent for treating immune system deficiencies. In fact, proTα possesses pleiotropic adjuvant activity and a series of immunomodulatory effects (eg, anticancer, antiviral, neuroprotective, cardioprotective). Moreover, several reports suggest that the variable activity of proTα might be exerted through different parts of the molecule. We first reported that the main immunoactive region of proTα is the carboxy-terminal decapeptide proTα(100-109). In conjunction with data from others, we also revealed that proTα and proTα(100-109) signal through Toll-like receptor 4. Although their precise molecular mechanism of action is yet not fully elucidated, proTα and proTα(100-109) are viewed as candidate adjuvants for cancer immunotherapy. Here, we present a historical overview on the discovery and isolation of thymosins with emphasis on proTα and data on some immune-related new activities of the polypeptide and smaller immunostimulatory peptides thereof. Finally, we propose a compiled scenario on proTα's mode of action, which could eventually contribute to its clinical application., (© 2016 Elsevier Inc. All rights reserved.)

β-Thymosins are a family of heat-stable multifunctional polypeptides that are expressed as small proteins of about 5kDa (~45 amino acids) almost exclusively in multicellular animals. They were first isolated from the thymus. As full-length or truncated polypeptides, they appear to stimulate a broad range of extracellular activities in various signaling pathways, including tissue repair and regeneration, inflammation, cell migration, and immune defense. However, their cell surface receptors and structural mechanisms of regulations in these multiple pathways remain still poorly understood. Besides their extracellular activities, they belong to a larger family of small, intrinsically disordered actin-binding domains called WH2/β-thymosin domains that have been identified in more than 1800 multidomain proteins found in different taxonomic domains of life and involved in various actin-based motile processes including cell morphogenesis, motility, adhesions, tissue development, intracellular trafficking, or pathogen infections. This review briefly surveys the main recent findings to understand how these small, intrinsically disordered but functional domains can interact with many unrelated partners and can thus integrate and coordinate various intracellular activities in actin self-assembly dynamics and cell signaling pathways linked to their cytoskeleton remodeling., (© 2016 Elsevier Inc. All rights reserved.)

The thymosin proteins are all short, highly charged, intrinsically unstructured proteins under natural conditions. However, structure can be induced in many of the thymosin proteins by providing charge neutralization at low pH or by the addition of Zn(2+) ions, organic reagents such as trifluoroethanol, hexafluoropropanol, or n-dodecyltrimethylammonium bromide, or interactions with their natural binding partner proteins. The differing structures of thymosin alpha and thymosin beta proteins have been studied by circular dichroism, nuclear magnetic resonance, and crystallographic methods in order to better understand the role of these proteins. In this structural biology review the structures of prothymosin, parathymosin, thymosin alpha-1, and several beta thymosin proteins, in both native states and under secondary structure-inducing conditions are discussed., (© 2016 Elsevier Inc. All rights reserved.)

Thymosin alpha 1 (Tα1) is commonly used for treating several diseases; however its usage has been limited because of poor penetration of the target tissue, such as tumor cells. In the present study, Tα1-iRGD, a peptide by conjugating Tα1 with the iRGD fragment, was evaluated its performance in MCF-7 and MDA-MB-231 human breast cancer cells. Compared with the wild-type peptide, Tα1-iRGD was more selective in binding tumor cells in the cell attachment assay. Furthermore, the MTT assay confirmed that Tα1-iRGD proved more effective in significantly inhibiting the growth of MCF-7 cells in contrast to the general inhibition displayed by Tα1. Further, conjugation of Tα1 with iRGD preserved the immunomodulatory activity of the drug by increasing the proliferation of mouse spleen lymphocytes. Further, compared with Tα1 treatment, Tα1-iRGD treatment of MCF-7 cells considerably increased the number of cells undergoing apoptosis, resulting in a dose-dependent inhibition of cancer cell growth, which was associated with a much better effect on up-regulation of the expression of BCL2-associated X protein (Bax), caspase 9, etc. More importantly, treatment with Ta1-iRGD was more efficacious than treatment with Ta1 in vivo. This study highlights the importance of iRGD on enhancement of cell penetration and tumor accumulation. In summary, our findings demonstrate that the novel modified Tα1 developed in this study has the potential to be used for treating breast cancer.

Titanium (Ti) is the most widely used implant material in dentistry and orthopedics but the release of metal ions from Ti implants results in increased bone resorption by enhancing the production of inflammatory cytokines from the macrophages and facilitating osteoclast differentiation. Thymosin β4 (Tβ4) has several biological activities, such as promoting wound healing, angiogenesis, cell proliferation and migration in mammalian cells. This study examined the role of Tβ4 in osteoblasts via focal adhesions (FAs) and ERK1/2 signaling related to cell adhesion and proliferation for cell survival on the Ti surface. As a result, cell adhesion and proliferation increased in the Tβ4 treated cells (Tβ4/MC3T3-E1) but was significantly lower in the Tβ4 knock-down cells by Tβ4-siRNA (si-Tβ4/MC3T3-E1) than that of the untreated cells. The levels of FAK phosphorylation, paxillin expression, and paxillin localization were higher in the Tβ4/IMC3T3-E1 cells than that of the untreated cells but lower in the si-Tβ4/MC3T3-E1 cells. In addition, the levels of cell proliferation, Grb2 and Ras protein expression and phosphorylation of ERK1/2 were higher in the Tβ4/MC3T3-E1 cells than in the untreated cells but lower in the si-Tβ4/IMC3T3-E1 cells. These results suggest that Tβ4 might be a good nanomolecule that promotes osteoblast survival by facilitating adhesion and proliferation on the Ti surface.

An antimicrobial peptide, ∼5 kDa in size, was isolated and purified in its active form from the mantle of the Pacific oyster Crassostrea gigas by C18 reversed-phase high-performance liquid chromatography. Matrix-assisted laser desorption ionisation time-of-flight analysis revealed 4656.4 Da of the purified and unreduced peptide. A comparison of the N-terminal amino acid sequence of oyster antimicrobial peptide with deduced amino acid sequences in our local expressed sequence tag (EST) database of C. gigas (unpublished data) revealed that the oyster antimicrobial peptide sequence entirely matched the deduced amino acid sequence of an EST clone (HM-8_A04), which was highly homologous with the β-thymosin of other species. The cDNA possessed a 126-bp open reading frame that encoded a protein of 41 amino acids. To confirm the antimicrobial activity of C. gigas β-thymosin, we overexpressed a recombinant β-thymosin (rcgTβ) using a pET22 expression plasmid in an Escherichia coli system. The antimicrobial activity of rcgTβ was evaluated and demonstrated using a bacterial growth inhibition test in both liquid and solid cultures., (Copyright © 2015 Elsevier Ltd. All rights reserved.)

Kelch-like ECH-associated protein 1 (Keap1) plays an important regulatory role in the nuclear factor erythroid 2-related factor 2 (Nrf2)-dependent oxidative stress response pathway. It functions as a repressor of Nrf2, a key transcription factor that initiates the expression of cytoprotective enzymes during oxidative stress to protect cells from damage caused by reactive oxygen species. Recent studies show that mutations of Keap1 can lead to aberrant activation of the antioxidant pathway, which is associated with different types of cancers. To gain a mechanistic understanding of the links between Keap1 mutations and cancer pathogenesis, we have investigated the molecular effects of a series of mutations (G333C, G350S, G364C, G379D, R413L, R415G, A427V, G430C and G476R) on the structural and target recognition properties of Keap1 by using nuclear magnetic resonance (NMR) spectroscopy, circular dichroism (CD) and isothermal titration calorimetry (ITC). Depending on their locations in the protein, these mutations are found to exert differential effects on the protein stability and target binding. Together with the proposed hinge-and-latch mechanism of Nrf2-Keap1 binding in the literature, our results provide important insight into the molecular affect of different somatic mutations on Keap1's function as an Nrf2 repressor.