Regulation of adipocyte differentiation of 3T3-L1 cells by PDZRN3
Regulation of adipocyte differentiation of 3T3-L1 cells by PDZRN3
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DOI：
10.1152/ajpcell.00343.2012
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发表时间：
2013-06-01
影响因子：
5.5
通讯作者：
Inui, Makoto
中科院分区：
文献类型：
--
作者：
Honda, Takeshi;Ishii, Aiko;Inui, Makoto
PDZRN3是PDZRN（或LNX）蛋白家族的一员，是间充质干细胞向肌管分化所必需的，但它在这些细胞向成骨细胞的分化中起抑制作用。鉴于间充质干细胞也能分化为脂肪细胞，我们研究了PDZRN3在小鼠3T3-L1前脂肪细胞脂肪形成中的可能作用。在成脂分化过程中，PDZRN3的mRNA和蛋白表达水平均下降。根据脂质积累评估，rnai介导的PDZRN3缺失增强了3T3-L1细胞向脂肪细胞的分化。在脂肪细胞分化过程中，aP2和CCAAT/增强子结合蛋白(C/EBP)- β的上调在pdzrn3缺失的细胞中也得到了增强，aP2和C/EBP α的上游调节剂过氧化物酶体增殖物激活受体- γ (PPAR γ)的mRNA和蛋白水平也得到了诱导。在控制PPAR γ表达的转录因子中，我们发现STAT5b而非STAT5a在pdzrn3缺失的细胞中mRNA和蛋白水平均上调。在分化的早期，PDZRN3缺失也增强了STAT5b的酪氨酸磷酸化，而STAT5a则没有。此外，在pdzrn3缺失的细胞中，诱导分化过程中C/EBP β在mRNA和蛋白水平上表达增强。因此，我们的研究结果表明，PDZRN3通过下调STAT5b和C/EBP β，进而抑制PPAR γ的表达，负性调节3T3-L1细胞的脂肪形成。
PDZRN3, a member of the PDZRN (or LNX) family of proteins, is essential for the differentiation of mesenchymal stem cells into myotubes, but it plays an inhibitory role in the differentiation of these cells into osteoblasts. Given that mesenchymal stem cells also differentiate into adipocytes, we examined the possible role of PDZRN3 in adipogenesis in mouse 3T3-L1 preadipocytes. The expression of PDZRN3 decreased at both the mRNA and protein levels during adipogenic differentiation. RNAi-mediated depletion of PDZRN3 enhanced the differentiation of 3T3-L1 cells into adipocytes as assessed on the basis of lipid accumulation. The upregulation of aP2 and CCAAT/enhancer-binding protein (C/EBP)-beta during adipocyte differentiation was also enhanced in the PDZRN3-depleted cells, as was the induction of peroxisome proliferator-activated receptor-gamma (PPAR gamma), an upstream regulator of aP2 and C/EBP alpha, at both the mRNA and protein levels. Among transcription factors that control the expression of PPAR gamma, we found that STAT5b, but not STAT5a, was upregulated in PDZRN3-depleted cells at both mRNA and protein levels. Tyrosine phosphorylation of STAT5b, but not that of STAT5a, was also enhanced at an early stage of differentiation by PDZRN3 depletion. In addition, the expression of C/EBP beta during the induction of differentiation was enhanced at the mRNA and protein levels in PDZRN3-depleted cells. Our results thus suggest that PDZRN3 negatively regulates adipogenesis in 3T3-L1 cells through downregulation of STAT5b and C/EBP beta and consequent suppression of PPAR gamma expression.