Diminished acyl-CoA synthetase isoform 4 activity in INS 832/13 cells reduces cellular epoxyeicosatrienoic acid levels and results in impaired glucose-stimulated insulin secretion.
Diminished acyl-CoA synthetase isoform 4 activity in INS 832/13 cells reduces cellular epoxyeicosatrienoic acid levels and results in impaired glucose-stimulated insulin secretion.
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DOI：
10.1074/jbc.m113.481077
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发表时间：
2013-07-26
期刊：
影响因子：
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通讯作者：
Coleman, Rosalind A
中科院分区：
文献类型：
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作者：
Klett, Eric L;Chen, Shufen;Coleman, Rosalind A
葡萄糖刺激胰岛素分泌（GSIS）在胰腺β细胞是由脂肪酸（FA）增强。细胞内FA代谢的第一步是由长链酰基辅酶a合成酶（Acsls）转化为酰基辅酶a。由于在INS 832/13细胞中主要表达的Acsl亚型是Acsl4和-5，我们通过siRNA敲低Acsl4或Acsl5来表征这些Acsls在β细胞功能中的作用。与对照细胞相比，Acsl4抑制80%使GSIS和fa增强的GSIS分别降低32%和54%。Acsl5基因的敲除对GSIS没有影响。Acsl4敲除不改变FA氧化或长链酰基辅酶a水平。在Acsl4基因敲除的情况下，用17 mm葡萄糖孵育可增加环氧二碳三烯酸（EETs），并降低EETs的细胞膜水平。此外，外源性EET降低了INS 832/13细胞的GSIS，在Acsl4敲低的细胞中，EET受体拮抗剂部分挽救了GSIS。这些结果强烈表明Acsl4激活eet形成eet - coa，并将其结合到甘油磷脂中，从而隔离eet。将INS 832/13细胞暴露于花生四烯酸酯或亚油酸中可降低Acsl4 mRNA和蛋白的表达，并降低GSIS。这些数据表明，Acsl4通过调节未酯化eet的水平来调节GSIS，花生四烯酸酯控制其激活剂Acsl4的表达。
Glucose-stimulated insulin secretion (GSIS) in pancreatic beta-cells is potentiated by fatty acids (FA). The initial step in the metabolism of intracellular FA is the conversion to acyl-CoA by long chain acyl-CoA synthetases (Acsls). Because the predominantly expressed Acsl isoforms in INS 832/13 cells are Acsl4 and -5, we characterized the role of these Acsls in beta-cell function by using siRNA to knock down Acsl4 or Acsl5. Compared with control cells, an 80% suppression of Acsl4 decreased GSIS and FA-potentiated GSIS by 32 and 54%, respectively. Knockdown of Acsl5 did not alter GSIS. Acsl4 knockdown did not alter FA oxidation or long chain acyl-CoA levels. With Acsl4 knockdown, incubation with 17 mm glucose increased media epoxyeicosatrienoic acids (EETs) and reduced cell membrane levels of EETs. Further, exogenous EETs reduced GSIS in INS 832/13 cells, and in Acsl4 knockdown cells, an EET receptor antagonist partially rescued GSIS. These results strongly suggest that Acsl4 activates EETs to form EET-CoAs that are incorporated into glycerophospholipids, thereby sequestering EETs. Exposing INS 832/13 cells to arachidonate or linoleate reduced Acsl4 mRNA and protein expression and reduced GSIS. These data indicate that Acsl4 modulates GSIS by regulating the levels of unesterified EETs and that arachidonate controls the expression of its activator Acsl4.