Language：English   Publisher：Biotechnology Journal  

Skeletal muscle satellite cells (SCs) are essential for muscle regeneration. Their proliferation and differentiation are influenced by fibroblast growth factor (FGF)-2. In this study, we screened for FGF-2-derived peptides that promote SC proliferation. Utilizing photocleavable peptide array technology, a library of 7-residue peptides was synthesized, and its effect on SC proliferation was examined using a mixture of five peptides. The results showed that peptides 1–5 (136%), 21–25 (136%), 26–30 (141%), 31–35 (159%), 71–75 (135%), 76–80 (144%), and 126–130 (137%) significantly increased SC proliferation. Further experiments revealed that peptide 33, CKNGGFF, enhanced SC proliferation. Furthermore, its extended form, peptide 33-13, CKNGGFFLRIHPD, promoted SC proliferation and increased the percentage of Pax7-positive cells, indicating that SCs were maintained in an undifferentiated state. The addition of FGF-2 and peptide 33-13 further induced cell proliferation but did not increase the percentage of Pax7-positive cells. A proliferation assay using an FGF receptor (FGFR) inhibitor suggested that peptide 33-13 acts through the FGFR-mediated and other pathways. Although further research is necessary to explore the mechanisms of action of these peptides and their potential for in vivo and in vitro use, the high sequence conservation of peptides 33 and 33-13 in FGF-2 across multiple species suggests their broad application prospects in biomedical engineering and biotechnology.

DOI： 10.1002/biot.202400278

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PubMed

Language：English   Publishing type：Research paper (scientific journal)   Publisher：Biochemical Engineering Journal  

Bile acid (BA) micelle-disrupting peptides are bioactive peptides (BPs) that suppress intestinal cholesterol adsorption and ameliorate blood cholesterol levels. To facilitate their application in the food industry, an effective and straightforward technology for BP separation and enrichment of BPs is required. For this purpose, we assessed the potential of heat-treated (HT) porous silica gels with an enhanced capacity for peptide adsorption/desorption (AD). Given the key characteristics of these peptides involving basic amino acid (AA) residues, we applied casein hydrolysate to HT silica gels for adsorption at neutral pH, where the surface yielded anionic silanolates through deprotonation. Subsequently, desorption was conducted at pH 2, at which point the surface returned to its neutral state. We confirmed a 335-fold increase in the BA micelle-disrupting activity of the resulting hydrolysates. LC-MS/MS analysis identified 783 peptides, confirming that the peptides containing cationic AA residues were selectively enriched, as expected. Moreover, a dose-response of randomly selected 27 peptides with various enrichment levels revealed the presence of multiple active peptides in the enriched groups. These results indicate that our method is effective for the separation and enrichment of BA micelle-disrupting peptides and holds promise for BP production.

DOI： 10.1016/j.bej.2024.109283

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：Biochemical and Biophysical Research Communications  

Extracellular vesicles (EVs) released into the blood during exercise mediate its whole-body health effects. The differentiation of EVs released by skeletal muscle cells in vivo from those released by other cells is challenging, therefore, it is unclear whether exercise increases the number of EVs secreted by skeletal muscle cells. In this study, we investigated whether exercise affects the quantity of EVs released from skeletal muscle cells using in vitro exercise models. C2C12 myotubes were cultured on a gel layer with 1 or 30 Hz electrical pulse stimulation (EPS) to induce contractions as an artificial simulating exercise. We found that tetanic contraction induced by 30 Hz EPS increased the number of secreted EVs. MicroRNA (miRNA)-seq analysis revealed that 30 Hz EPS altered the miRNA in the secreted EVs. Furthermore, expression analysis of genes related to the biogenesis and transport of EVs revealed that the expression of ALG-2 interacting protein X (Alix) was increased in response to 30 Hz EPS, and the peak value of intracellular Ca2+ in myotubes at 30 Hz EPS was higher than that at 1 Hz, indicating that the increase in intracellular Ca2+ concentration may be related to the increased secretion of EVs in response to 30 Hz EPS.

DOI： 10.1016/j.bbrc.2023.06.054

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PubMed

Language：English   Publishing type：Research paper (scientific journal)   Publisher：MDPI AG  

In vitro neuromuscular junction (NMJ) models are powerful tools for studying neuromuscular disorders. Although linearly patterned culture surfaces have been reported to be useful for the formation of in vitro NMJ models using mouse motor neuron (MNs) and skeletal muscle (SkM) myotubes, it is unclear how the linearly patterned culture surface increases acetylcholine receptor (AChR) clustering, one of the steps in the process of NMJ formation, and whether this increases the in vitro NMJ formation efficiency of co-cultured human MNs and SkM myotubes. In this study, we investigated the effects of a linearly patterned culture surface on AChR clustering in myotubes and examined the possible mechanism of the increase in AChR clustering using gene expression analysis, as well as the effects of the patterned surface on the efficiency of NMJ formation between co-cultured human SkM myotubes and human iPSC-derived MNs. Our results suggest that better differentiation of myotubes on the patterned surface, compared to the flat surface, induced gene expression of integrin α7 and AChR ε-subunit, thereby increasing AChR clustering. Furthermore, we found that the number of NMJs between human SkM cells and MNs increased upon co-culture on the linearly patterned surface, suggesting the usefulness of the patterned surface for creating in vitro human NMJ models.

DOI： 10.3390/cells11233760

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PubMed

Language：Japanese   Publishing type：Research paper (scientific journal)   Publisher：The Society for Biotechnology, Japan  

<p>For the prediction of protease digestion site, 1990 kinds of tetramer peptide were designed as a library, of which N terminal end was fluorescence labelled. Decrease of fluorescence intensity of each peptide was quantitatively determined and used as a training data for Random Forest (RF) modeling. All of dipeptides bond as a protease substrate were included in 1990 tetramer peptides. As an explanatory variable for model construction, 532 parameters were prepared and those were included not only appearance of amino acid residue or dipeptides but also positioning parameters (PP) or global parameters (GP) to explain the peptide property. Trypsin for biochemistry grade was used for hydrolysis. After digesting at pH 8, the histogram of digestion ratio was appeared that tetramers with arginine residue (R) and lysine residue (K) could be expectedly digested at higher ratio compared with tetramers without R or K. Constructed pH 8-RF model showed 77 % of prediction accuracy. The explanatory parameters with top 10 higher importance in pH 8-RF model were both of appearance of K and 9 GPs. GPs were including 4 isoelectric parameters and 1 polarity parameter, of which K or R residue have relatively large value. Digestion site of α-lactalbumin was determined using pH 8-RF model and the protein was actually digested by trypsin. When the hydrolysate was analyzed by LC-MS/MS, 42 peptides were identified. Fourteen sites among 19 predicted digestion sites were coincided with each other. Many peptide fragments digested at 69Y-70G site or 50F-51H site was detected and it was strongly suggested to be digested by chymotrypsin as a contaminated protease. These sites were fairly predicted by constructed RF model. In addition, trypsin digestion at pH 5 was carried out to investigate the effect of pH decrease on trypsin digestion. The prediction accuracy of pH 5-RF model was only 59 %. The parameters with top 10 higher importance in pH 5-RF model were including 4 GPs which was the same with 4 isoelectric parameter in pH 8 model. Twenty digestion sites of α-lactalbumin were predicted from pH 5-RF model. α-lactalbumin was digested at pH 5 by trypsin, and 64 peptides were identified. The predicted sites were compared with identified fragments at the region from 48T to 77K in which a lot of fragments were detected. It was concluded that constructed model could fairly predict some of newly identified sites and could roughly grasp slight modification of digestion site by pH change. The proposed methodology, which contained 1990 kinds of tetramer peptides as a library, 532 explanatory parameters and RF model, was effective for prediction of protease digestion site.</p>

DOI： 10.34565/seibutsukogaku.100.10_528

DOI： 10.34565/seibutsukogaku.100.10_528

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CiNii Research

Type：Academic society, research group, etc. 

Type：Academic society, research group, etc.