Switches in histone modifications epigenetically control vitamin D3‐dependent transcriptional upregulation of the CYP24A1 gene in osteoblastic cells

Abstract

In bone cells vitamin D dependent regulation of gene expression principally occurs through modulation of gene transcription. Binding of the active vitamin D metabolite, 1,25‐dihydroxy vitamin D3 (1,25(OH)2D3) to the vitamin D receptor (VDR) induces conformational changes in its C‐terminal domain enabling competency for interaction with physiologically relevant coactivators, including SRC‐1. Consequently, regulatory complexes can be assembled that support intrinsic enzymatic activities with competency to posttranslationally modify chromatin histones at target genomic sequences to epigenetically alter transcription. Here we examine specific transitions in representation and/or enrichment of epigenetic histone marks during 1,25(OH)2D3 mediated upregulation of CYP24A1 gene expression in osteoblastic cells. This gene encodes the 24‐hydroxylase enzyme, essential for biological control of vitamin D levels. We demonstrate that as the CYP24A1 gene promoter remains transcriptionally silent, there is enrichment of H4R3me2s together with its “writing” enzyme PRMT5 and decreased abundance of the istone H3 and H4 acetylation, H3R17me2a, and H4R3me2a marks as well as of their corresponding “writers.” Exposure of osteoblastic cells to 1,25(OH)2D3 stimulates the recruitment of a VDR/SRC‐1 containing complex to the CYP24A1 promoter to mediate increased H3/H4 acetylation. VDR/SRC‐1 binding occurs concomitant with the release of PRMT5 and the recruitment of the arginine methyltransferases CARM1 and PRMT1 to catalyze the deposition of the H3R17me2a and H4R3me2a marks, respectively. Our results indicate that these dynamic transitions of histone marks at the CYP24A1 promoter, provide a “chromatin context” that is transcriptionally competent for activation of the CYP24A1 gene in osteoblastic cells in response to 1,25(OH)2D3.

Protein Expression of AEBP1, MCM4, and FABP4 Differentiate Osteogenic, Adipogenic, and Mesenchymal Stromal Stem Cells

“…Overall, the applied algorithms revealed nine specific proteins for the osteoblastic differentiation, respectively. Analogous to BGN, cytochrome P450 family 24 subfamily A member 1 (CYP24A1), AE binding protein 1 (AEBP1), and collagen type III alpha 1 chain (COL3A1) concern functions of bone mineralization, osteoblastogenesis as well as matrix remodeling and thus confirmed a close association to the osteoblastic molecular differentiation module [ 56 , 57 , 58 , 59 , 60 ]. Strikingly, CYP24A1 presented the highest fold-change comparing OB to MSC (log 2 FC 3.65) and OB to AD (log 2 FC 3.52).…”

Protein arginine methyltransferases PRMT1, PRMT4/CARM1 and PRMT5 have distinct functions in control of osteoblast differentiation

“…Our findings on the distinct functions of PRMT1, PRMT4/CARM1 and PRMT5 complement and extend previous studies that examined the contribution of PRMTs and their cognate epigenetic modifications in vitamin D3-dependent transcriptional regulation in rat osteosarcoma cells. One previous study showed that PRMT1 and PRMT4/CARM1 support the vitamin D3 (1,25(OH) 2 D 3 ) dependent upregulation of CYP24A1 gene expression ( Moena et al, 2020b ). Examination of histone marks revealed that H4R3me2a and H3R17me2a and their corresponding writers PRMT1 and PRMT4, respectively, are recruited by vitamin D receptor (VDR) and its coactivator SRC-1/NCOA1.…”

“…PRMT1, PRMT4/CARM1, PRMT5 and PRMT7 are prevalent isoforms that are functionally expressed in myogenic cells and osteosarcoma cells ( Moena et al, 2020a ; Blanc and Richard, 2017 ; Rakow et al, 2020 ). Three PRMTs (i.e., PRMT1, PRMT4/CARM1 and PRMT5) have each been shown to control vitamin D3-dependent transcription in osteosarcoma cells via interactions with SRC-1/NCOA1 ( Moena et al, 2020b ), whereas PRMT5 binds to the SWI/SNF component BRG1/SMARCA4 in different cell types ( Seth-Vollenweider et al, 2014 ). These findings collectively suggest that PRMT proteins may also have a role in osteoblast differentiation.…”

“…Because PRMTs have broad biological functions, a key question in bone biology is whether and how PRMT family members control osteogenic differentiation of mesenchymal stem/stromal cells (MSCs) and osteoblasts, as well as bone formation and bone homeostasis (i.e., osteoblast and osteoclast interplay). Initial studies have suggested individual roles of PRMTs in musculoskeletal tissues, including skeletal myoblast differentiation, chondrocyte proliferation and osteoblastic cells ( Moena et al, 2020b ; Seth-Vollenweider et al, 2014 ; Ito et al, 2009 ). In this study we surveyed the expression and functional contributions of multiple PRMTs to osteoblast differentiation.…”

Ezh2‐dependent H3K27me3 modification dynamically regulates vitamin D3‐dependent epigenetic control of CYP24A1 gene expression in osteoblastic cells

“…In the last few years, several groups have examined the presence and function of epigenetic posttranslational modifications in chromosomal histone proteins that are associated with the CYP24A1 gene promoter (Fetahu et al, 2014;Meyer, Goetsch, & Pike, 2010b;Moena et al, 2020;Seth-Vollenweider et al, 2014). Our team has reported that specific transitions in enrichments of epigenetic histone marks accompany transcriptional upregulation of the CYP24A1 gene in osteoblastic cells exposed to 1,25(OH) 2 D 3 .…”