FNDC5 inhibits autophagy of bone marrow mesenchymal stem cells and promotes their survival after transplantation by downregulating Sp1

SP1/COL1A2/ZEB1 axis promotes TGF-β2-induced lens epithelial cell proliferation, migration, invasion and EMT process

Posterior capsule opacification (PCO) is the most common complication after cataract surgery. In this study, we used transforming growth factor beta-2 (TGF-β2)-induced SRA01/04 cells to mimic PCO cell model and explored the functions and underlying mechanisms of specific protein 1 (SP1) in TGF-β2-induced SRA01/04 cell development. MTT assay and EdU assay were carried out to explore the proliferation of SRA01/04 cells. Transwell assay and wound-healing assay were performed to investigate SRA01/04 cell migration and invasion. Chromatin Immunoprecipitation (ChIP) assay, dual-luciferase reporter assay and Co-immunoprecipitation (Co-IP) assay were used to analyze the relations of SP1, COL1A2 and ZEB1. TGF-β2 treatment led to the promotion of SRA01/04 cell proliferation, migration, invasion and EMT process. COL1A2 level was induced by TGF-β2 treatment and COL1A2 knockdown inhibited TGF-β2-induced SRA01/04 cell proliferation, migration, invasion and EMT. SP1 could activate the transcription of COL1A2. SP1 overexpression promoted TGF-β2-induced SRA01/04 cell injury by regulating COL1A2 expression. Moreover, COL1A2 interacted with ZEB1 and COL1A2 knockdown-mediated effects on the proliferation, migration, invasion and EMT of TGF-β2-induced SRA01/04 cells were abrogated by elevating ZEB1. SP1 regulated COL1A2 and then mediated ZEB1 to affect the proliferation, migration, invasion and EMT of TGF-β2-induced SRA01/04 cells.

Maternal prednisone exposure during pregnancy elevates susceptibility to osteoporosis in female offspring: The role of mitophagy/FNDC5 alteration in skeletal muscle

Maternal exposure to glucocorticoids has been associated with adverse outcomes in offspring. However, the consequences and mechanisms of gestational exposure to prednisone on susceptibility to osteoporosis in the offspring remain unclear. Here, we found that gestational prednisone exposure enhanced susceptibility to osteoporosis in adult mouse offspring. In a further exploration of myogenic mechanisms, results showed that gestational prednisone exposure down-regulated FNDC5/irisin protein expression and activation of OPTN-dependent mitophagy in skeletal muscle of adult offspring. Additional experiments elucidated that activated mitophagy significantly inhibited the expression of FNDC5/irisin in skeletal muscle cells. Likewise, we observed delayed fetal bone development, downregulated FNDC5/irisin expression, and activated mitophagy in fetal skeletal muscle upon gestational prednisone exposure. In addition, an elevated total m6A level was observed in fetal skeletal muscle after gestational prednisone exposure. Finally, gestational supplementation with S-adenosylhomocysteine (SAH), an inhibitor of m6A activity, attenuated mitophagy and restored FNDC5/irisin expression in fetal skeletal muscle, which in turn reversed fetal bone development. Overall, these data indicate that gestational prednisone exposure increases m6A modification, activates mitophagy, and decreases FNDC5/irisin expression in skeletal muscle, thus elevating osteoporosis susceptibility in adult offspring. Our results provide a new perspective on the earlier prevention and treatment of fetal-derived osteoporosis.

mir-150-5p inhibits the osteogenic differentiation of bone marrow-derived mesenchymal stem cells by targeting irisin to regulate the p38/MAPK signaling pathway

PURPOSE

To study the effect of miR-150-5p on the osteogenic differentiation of bone marrow-derived mesenchymal stem cells (BMSCs), and further explore the relationship between its regulatory mechanism and irisin.

METHODS

We isolated mouse BMSCs, and induced osteogenic differentiation by osteogenic induction medium. Using qPCR to detect the expression of osteogenic differentiation-related genes, western blot to detect the expression of osteogenic differentiation-related proteins, and luciferase reporter system to verify that FNDC5 is the target of miR-150-5p. Irisin intraperitoneal injection to treat osteoporosis in mice constructed by subcutaneous injection of dexamethasone.

RESULTS

Up-regulation of miR-150-5p inhibited the proliferation of BMSCs, and decreased the content of osteocalcin, ALP activity, calcium deposition, the expression of osteogenic differentiation genes (Runx2, OSX, OCN, OPN, ALP and BMP2) and protein (BMP2, OCN, and Runx2). And down-regulation of miR-150-5p plays the opposite role of up-regulation of miR-150-5p on osteogenic differentiation of BMSCs. Results of luciferase reporter gene assay showed that FNDC5 gene was the target gene of miR-150-5p, and miR-150-5p inhibited the expression of FNDC5 in mouse BMSCs. The expression of osteogenic differentiation genes and protein, the content of osteocalcin, ALP activity and calcium deposition in BMSCs co-overexpressed by miR-150-5p and FNDC5 was significantly higher than that of miR-150-5p overexpressed alone. In addition, the overexpression of FNDC5 reversed the blocked of p38/MAPK pathway by the overexpression of miR-150-5p in BMSCs. Irisin, a protein encoded by FNDC5 gene, improved symptoms in osteoporosis mice through intraperitoneal injection, while the inhibitor of p38/MAPK pathway weakened this function of irisin.

CONCLUSION

miR-150-5p inhibits the osteogenic differentiation of BMSCs by targeting irisin to regulate the/p38/MAPK signaling pathway, and miR-150-5p/irisin/p38 pathway is a potential target for treating osteoporosis.