Circular RNA-FK501 binding protein 51 boosts bone marrow mesenchymal stem cell proliferation and osteogenic differentiation via modulating microRNA-205-5p/Runt-associated transcription factor 2 axis

In brief, circ-FKBP5 boosted BMSC proliferation and OD by mediating the miR-205-5p/RUNX2 axis.

Bone marrow mesenchymal stem cells (BMSCs) were cultured and induced to osteogenic differentiation (OD). Then, oe-circ-FKBP5, oe-NC, si-circ-FKBP5, si-NC, miR-205-5p mimic, mimic NC, miR-205-5p inhibitor, inhibitor NC, sh-RUNX2, or sh-NC were transfected into BMSCs. Alkaline phosphatase (ALP) activity was detected by ALP staining, cell mineralization was detected by alizarin red staining, cell proliferation was detected by CCK-8, and cell apoptosis was detected by flow cytometry. Then, the expression of circ-FKBP5, miR-205-5p, RUNX2 and osteogenic marker genes was detected by RT-qPCR, and the expression of RUNX2 protein was detected by Western blot. Finally, the targeting relationship between miR-205-5p and circ-FKBP5 or RUNX2 was verified by bioinformation website analysis and dual luciferase reporter gene detection.

Osteogenesis is the key process of bone homeostasis differentiation. Numerous studies have manifested that circular RNA (circRNA) is a critical regulator of osteogenesis. The research was to explore circRNA-mediated mechanisms in osteogenesis.

Circ-FK501 binding protein 51 (FKBP5) was distinctly elevated during OD of BMSCs. Elevated circ-FKBP5 boosted the proliferation and OD, as well as expression of osteogenic marker genes while reduced apoptosis of BMSCs. Down-regulation of circ-FKBP5 inhibited BMSCs proliferation, OD and osteogenic marker gene expression, and promoted apoptosis of BMSCs. Subsequently, circ-FKBP5 combined with miR-205-5p and constrained miR-205-5p expression. Silenced miR-205-5p boosted proliferation, OD, and expression of osteogenic marker genes and suppressed apoptosis of BMSCs. However, up-regulation of miR-205-5p inhibited BMSC proliferation, OD and osteogenic marker gene expression, and promoted apoptosis. Additionally, miR-205-5p targeted Runt-associated transcription factor 2 (RUNX2). Repression of RUNX2 turned around the effect of circ-FKBP5 overexpression on BMSCs.