1α,25‐Dihydroxyvitamin D₃ modulation in lipid metabolism in established bone marrow‐derived stromal cells, MC3T3‐G2/PA6

Abstract

MC3T3-G2/PA6 (PA6) cells established from newborn mouse calvaria are preadipocytic stromal cells, which differentiate into adipocytes in response to glucocorticoids. We examined the effects of 1 alpha,25-dihydroxyvitamin D3[1 alpha,25(OH)2D3] on adipogenesis in PA6 cells. When PA6 cells were cultured with 10(-8) M dexamethasone, adipocytes containing oil red O-positive droplets first appeared on day 7 (3 days after confluence was attained) and the maximal synthesis of neutral lipids occurred on day 12. Simultaneous addition of 1 alpha,25(OH)2D3 at 10(-9)M completely blocked this dexamethasone-induced neutral lipid synthesis throughout the 14-day culture period. Dose-response studies of vitamin D3 derivatives showed that 1 alpha,25(OH)2D3 was the most potent in inhibiting neutral lipid synthesis in PA6 cells, followed by 1 alpha-hydroxyvitamin D3, 25-hydroxyvitamin D3, and 24R,25-dihydroxyvitamin D3, in that order. Dexamethasone greatly enhanced incorporation of [14C]-acetic acid into triacylglycerol in PA6 cells. The incorporation was markedly inhibited by the addition of 10(-9) M 1 alpha,25(OH)2D3. Instead, 1 alpha,25(OH)2D3 greatly increased incorporation of [14C]-acetic acid into phospholipids, such as phosphatidylcholine and phosphatidylethanolamine, irrespective of the presence or absence of dexamethasone. These results suggest that 1 alpha,25(OH)2D3 modulation of lipid metabolism in bone marrow stromal cells is receptor mediated.

The Action of Vitamin D in Adipose Tissue: Is There the Link between Vitamin D Deficiency and Adipose Tissue-Related Metabolic Disorders?

“…Primary mouse BM-MSCs also presented a reduced expression of adipsin and AP2 in response to calcitriol [94,95]. Reduced lipid accumulation was presented in response to calcitriol in ST2 and PA6 cells [96,97]. In turn, Kelly et al revealed that calcitriol significantly suppressed glucocorticoid-or thiazolidinedionestimulated adipogenesis and inhibited the expression of adipsin and AP2 without an effect on LPL expression in BMS2 cells [95].…”

Recent insights into vitamin D, adipocyte, and adipose tissue biology

“…In addition, 1,25(OH) 2 D in 3T3‐L1 can increase the expression of the eight‐twenty‐one protein (ETO/MTG8), which inhibits adipogenesis through repression of C/EBPβ and inhibition of PPARγ 80 . Inhibition of adipogenesis has also been reported in mouse brown adipocytes 64 and in bone marrow cell lines 81,82 . Nevertheless, adipogenic stimulatory effect of 1,25(OH) 2 D has also been shown in 3T3‐L1 cells 83 and in mouse primary preadipocytes, 29 and unliganded VDR seems to be required for adipogenic programming 80 .…”

“…80 Inhibition of adipogenesis has also been reported in mouse brown adipocytes 64 and in bone marrow cell lines. 81,82 Nevertheless, adipogenic stimulatory effect of 1,25(OH) 2 D has also been shown in 3T3-L1 cells 83 and in mouse primary preadipocytes, 29 and unliganded VDR seems to be required for adipogenic programming. 80 Note that the studies with VDR À/À mice reported a reduction of adipose tissue, 67,68 suggesting that adipogenesis could be impacted.…”

Differentiation of Human Marrow Stromal Precursor Cells: Bone Morphogenetic Protein-2 Increases OSF2/CBFA1, Enhances Osteoblast Commitment, and Inhibits Late Adipocyte Maturation

“…The factors regulating differentiation of marrow stromal precursors into one or the other of these pathways are not well understood and almost nothing is known about this regulation in humans. Although regulation has been studied in vitro using rodent marrow stromal cells and preosteoblastic 9–13 or preadipocytic 14–16 cell lines, it is difficult to generalize from these data because of species differences with human cells and because most of these cell lines were already committed to either the osteoblast or the adipocyte differentiation pathways. Thus, the lack of a model system for uncommitted human marrow stromal (hMS) cells that is capable of differentiating into either the osteoblast or the adipocyte pathway has been a major barrier to defining regulation of this reciprocal process.…”