Regulation of enterocyte apoptosis by acyl-CoA synthetase 5 splicing
Regulation of enterocyte apoptosis by acyl-CoA synthetase 5 splicing
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DOI：
10.1053/j.gastro.2007.06.005
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发表时间：
2007-08-01
期刊：
影响因子：
29.4
通讯作者：
Kopitz, Juergen
中科院分区：
文献类型：
--
作者：
Gassler, Nikolaus;Roth, Wilfried;Kopitz, Juergen
背景与目的：人小肠隐窝绒毛轴(CVA)上肠细胞的持续更新是由于细胞固有的变化导致衰老的肠上皮细胞的凋亡性死亡。本研究的目的是研究绒毛顶端细胞死亡的潜在分子机制。方法：通过克隆、重组蛋白表达、生化方法以及多种功能和原位分析，对人酰基辅酶A合成酶5(ACSL5)进行鉴定。结果：我们的数据显示，在人类肠上皮细胞中发现了不同数量的酰辅酶A合成酶5-全长(ACSL5-fl)和一个迄今未知的缺失外显子20的剪接变异体(ACSL5-Delta 20)。与剪接变异体ACSL5-Delta20相比，重组和纯化的ACSL5-F1蛋白在高度碱性的pH下具有活性。ACSL5-f1蛋白的过度表达与神经酰胺依赖的抗凋亡翻转蛋白的减少和死亡受体TRAIL-RI在细胞表面的表达增加有关。表达分析表明，ACSL5-fl/ACSL5-Delta 20的比率沿着CVA增加，从而使绒毛末端以ACSL5-fl为主的细胞对死亡配体TRAIL敏感，这一点得到了人类小肠粘膜样本和永生化的人类小肠细胞细粒的功能研究的证实。结论：我们的结果提示ACSL5依赖的调节机制有助于人类小肠中沿CVA的细胞更新。ACSL5-F1/ACSL5-Delta 20在CVA沿线细胞成熟和脱落过程中的稳态失调也可能与肠道肿瘤的发生有关。
Background & Aims: The constant renewal of enterocytes along the crypt-villus axis (CVA) of human small intestine is due to cell-inherent changes resulting in the apoptotic cell death of senescent enterocytes. The aim of the present study was to examine underlying molecular mechanisms of the cell death at the villus tip. Methods: Characterization of human acyl-coenzyme A (CoA) synthetase 5 (ACSL5) was performed by cloning, recombinant protein expression, biochemical approaches, and several functional and in situ analyses. Results: Our data show that different amounts of acyl-CoA synthetase 5-full length (ACSL5-fl) and a so far unknown splice variant lacking exon 20 (ACSL5-Delta 20) are found in human enterocytes. In contrast with the splice variant ACSL5-Delta 20, recombinant and purified ACSL5-fl protein is active at a highly alkaline pH. Over expression of ACSL5-fl protein is associated with a decrease of the anti-apoptotic FLIP protein in a ceramide-dependent manner and an increased cell-surface expression of the death receptor TRAIL-RI. Expression analyses revealed that the ACSL5-fl/ACSL5-Delta 20 ratio increases along the CVA, thereby sensitizing ACSL5-fl-dominated cells at the villus tip to the death ligand TRAIL, which is corroborated by functional studies with human small intestinal mucosal samples and an immortalized human small intestinal cell fine. Conclusions: Our results suggest an ACSL5-dependent regulatory mechanism that contributes to the cellular renewal along the CVA in human small intestine. Deregulation of the ACSL5-fl/ACSL5-Delta 20 homeostasis in the maturation and shedding of cells along the CVA might also be of relevance for the development of intestinal neoplasia.