Histone deacetylation mediates the rejuvenation of osteoblastogenesis by the combination of 25(OH)D3 and parathyroid hormone in MSCs from elders

Abstract

Vitamin D metabolites are important effectors of bone and mineral homeostasis. Human bone marrow stromal cells (hMSCs) are targets of 1α,25-dihydroxyvitamin D [1α, 25(OH)2D] action to promote their differentiation to osteoblasts. Osteoblastogenesis is also stimulated by 25-hydroxyvitamin D [25(OH)D], an effect that requires conversion to 1α, 25(OH)2D3 by 25-hydroxyvitamin D3 1α-hydroxylase (CYP27B1). These findings support an autocrine/paracrine role of vitamin D metabolism in osteoblastogenesis of hMSCs. In this study, we assessed whether and by what mechanisms osteoblastogenesis could be rejuvenated with hMSCs from elders. First, knockdown studies with VDR-siRNA showed that both the pro-differentiation and anti-proliferative effects of 1α, 25(OH)2D3 required VDR. Second, 100 nM 25(OH)D3 (p<0.01 vs. control, ANOVA) and 100 nM PTH1-34 (p<0.05) significantly stimulated alkaline phosphatase activity (a measure of osteoblastogenesis), with a synergistic effect when combined (p<0.001). Scriptaid, an inhibitor of histone deacetylase, blocked the effect of 25(OH)D3 and PTH on osteoblastogenesis. Scriptaid alone downregulated VDR in hMSCs. These data demonstrate that histone deacetylation is required for the synergistic effect of 25(OH)D3 and PTH on osteoblastogenesis in hMSCs. Both VDR siRNA and Scriptaid dowregulated VDR mRNA and inhibited osteoblastogenesis. Thus, epigenetic regulation of the VDR may be central to rejuvenating osteoblastogenesis in hMSCs from elders.

Vitamin D metabolism in human bone marrow stromal (mesenchymal stem) cells

“…As proof-of-principle, we showed that dexamethasone upregulated PTHR1 and restored the effects of PTH on hMSCs [11]. More recent evidence that 25(OH)D 3 upregulates PTHR1 [63] indicates further beneficial interactions between PTH and vitamin D metabolism in hMSCs.…”

“…Accordingly, 12-hour pre-treatment with PTH1-34 provided hMSCs from elders with responsiveness to the pro-osteoblastogenic effects of 25(OH)D 3 , with increased osteoblast differentiation. In the second series of studies, hMSCs were treated simultaneously and continuously with PTH and 25(OH)D 3 [63]. Osteoblast differentiation was significantly stimulated 170% by PTH1-34 (100 nM) and 280% by 25(OH)D 3 , but by 650% with simultaneous combination of PTH1-34 and 25(OH)D 3 .…”

“…Not only was the synergy due to upregulation of CYP27B1, but in addition, PTH upregulated the VDR, and 25OHD 3 upregulated PTHR1. Further, the synergistic effects on osteoblast differentiation were blocked in the presence of a small molecule inhibitor of histone deacetylase, Scriptaid (R) [63]. Thus, epigenetic regulation may be central to rejuvenating osteoblastogenesis in hMSCs from elders.…”

Epigenetic Pathways Regulating Bone Homeostasis: Potential Targeting for Intervention of Skeletal Disorders

“…HDAC3 null mice exhibited a marrow filled with massive numbers of adipocytes. The importance specifically of lysine acetylation (e.g., H3K9Ac, H3K27ac) and the actions of HDACs in regulating osteogenesis have been recognized [43–45]. …”

“…Numerous profiling studies have revealed miRNAs that are characteristic of human OS tissue or OS cell lines when compared to normal bone marrow derived human stromal cells or osteoblast cell lines [43, 128, 129]. While many studies focus on a single microRNA, other studies showed miRNAs correlated with deregulated cellular pathways, disease subtypes and treatment outcomes [126, 129, 130].…”