Mechanism for Decreased Gene Expression of β4-Galactosyltransferase 5 upon Differentiation of 3T3-L1 Mouse Preadipocytes to Adipocytes
Mechanism for Decreased Gene Expression of β4-Galactosyltransferase 5 upon Differentiation of 3T3-L1 Mouse Preadipocytes to Adipocytes
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DOI：
10.1248/bpb.b18-00360
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发表时间：
2018-09-01
影响因子：
2
通讯作者：
Sato, Takeshi
中科院分区：
文献类型：
--
作者：
Ishii, Takayuki;Miyauchi, Kana;Sato, Takeshi
在细胞分化过程中，观察到细胞表面与脂质相连的糖链结构发生了显著的变化。乳糖神经酰胺(Lac-Cer)是一系列具有不同结构的神经鞘糖脂的共同前体。在本研究中，我们研究了3T3-L1小鼠前脂肪细胞分化为脂肪细胞时生物合成Lac-Cer的潜在机制。TLC分析显示，与3T3-L1前脂肪细胞相比，3T3-L1脂肪细胞的Lac-Cer含量减少。与此相对应，3T3-L1前脂肪细胞分化过程中，β4-半乳糖基转移酶(β4GalT)5的基因表达水平急剧下降。对β4GalT5基因转录机制的分析表明，核心启动子区域位于-299和-1之间，相对于翻译起始点。在脂肪细胞分化过程中，β4GalT5基因的表达水平和启动子活性急剧下降。由于启动子区域的特异性蛋白1(Sp1)结合部位对启动子活性起关键作用，提示Sp1在3T3-L1细胞中对β4GalT5基因的表达起重要作用。随着3T3-L1前脂肪细胞的分化，SPL基因和蛋白的表达显著降低。综上所述，本研究提示在3T3-L1脂肪细胞向脂肪细胞分化过程中，β4GalT5基因的表达通过降低SPL基因和蛋白的表达而减少，这可能导致3T3-L1脂肪细胞中Lac-Cer的数量减少。
Upon differentiation of cells, remarkable changes in the structures of glycans linked to lipids on cell surface have been observed. Lactosylceramide (Lac-Cer) serves as a common precursor for a series of glycosphingolipids with diverse structures. In the present study, we examined the underlying mechanism for the biosynthesis of Lac-Cer upon differentiation of 3T3-L1 mouse preadipocytes to adipocytes. TLC analysis showed that the amounts of Lac-Cer decrease in 3T3-L1 adipocytes compared to 3T3-L1 preadipocytes. In accordance with this change, the gene expression level of beta 4-galactosyltransferase (beta 4GalT) 5, which was identified as Lac-Cer synthase, decreased drastically upon differentiation of 3T3-L1 preadipocytes. The analysis of the transcriptional mechanism of the beta 4GalT5 gene demonstrated that the core promoter region is identified between nucleotides -299 and -1 relative to the translational start site. During adipocyte differentiation, the expression levels and promoter activities of the beta 4GalT5 gene decreased dramatically. Since the Specificity protein 1 (Sp1)-binding sites in the promoter region were critical for the promoter activity, it is suggested that Spl plays an important role for the expression of the beta 4GalT5 gene in 3T3-L1 cells. The gene and protein expression of Spl decreased significantly upon differentiation of 3T3-L1 preadipocytes. Taken together, the present study suggest that the expression of the beta 4GalT5 gene decreases through reduced expression of the Spl gene and protein upon differentiation of 3T3-L1 peradipocytes to adipocytes, which may lead to the decreased amounts of Lac-Cer in 3T3-L1 adipocytes.