Shanghai Jiaotong Daxue xuebao. Yixue ban (May 2023)
Bioinformatics analysis of pathological mechanism of degenerated tendon via stress deprivation
Abstract
Objective·To explore relevant molecular mechanisms of the stress deprivation model of newborn rats by using bioinformatics analysis.Methods·A total of 60 SD rats (10 d post-natal) were enrolled in the study. Those the left Achilles tendon of which was severed were chosen as the experimental group (stress deprivation group), and the right Achilles tendon of which was injured by clamping were chosen as the control group (stress group). On the 10th and 20th day after treatment, tissue samples were collected for gross observation of the tendon development, histological staining of the tendon structure, transmission electron microscope observation of the tendon ultrastructure and immunohistochemical analysis of CD31 expression. Differentially expressed proteins between the two groups at two time points were obtained by using protein mass spectrometry, and GO and KEGG enrichment analysis as well as protein-protein interaction (PPI) network anlysis were performed on differential proteins.Results·The stress-deprived tendon showed tissue enlargement and congestion, disorganized tendon tissue structure and immature collagen fibers. Transmission electron microscopy showed that the development and maturation of collagen fibrils were significantly impaired in the experimental group, and the diameter of collagen fibrils of the severed tendon became thinner on the 20th day after treatment (P=0.001). Immunohistochemistry showed that the severed tendon was relatively vascularized. The results of protein mass spectrometry analysis showed there were 1 865 and 965 differentially expressed proteins on the 10th and 20th day after treatment, including 1 835 and 837 upregulated proteins respectively. GO analysis showed that the upregulated proteins were involved in biological processes such as intracellular protein transport, protein stabilization, mRNA splicing via spliceosome, protein folding and protein import into nucleus. KEGG analysis indentified enhancement of vascular endothelial growth factor (VEGF) signal pathway, mammalian target of rapamycin (mTOR) signal pathway, endocytosis and other signal pathways in the experimental group. PPI network analysis showed various upregulated proteins including Akt1, Hspa4, Hspa5, Eef2, ACTC1 and RhoA.Conclusion·Stress deprivation can activate multiple signal pathways in tendon cells and lead to tissue vascularization, abnormal collagen development, etc., resulting in degenerative pathological changes of tendons.
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