脂多糖促进的小鼠原代星形神经胶质细胞中TGF-α的释放不依赖于ADAM17的剪切作用  

Lipopolysaccharide Induced TGF-αRelease is Independent of ADAM17 in Primary Astrocytes

作　　者：刘丽萍[1] 曹宋天祎 王劲桁 刘彬[1] 郑煜芳[1] 

机构地区：[1]复旦大学生命科学学院生理学和生物物理学系,上海200433

出　　处：《复旦学报（自然科学版）》2013年第6期731-736,745,共7页Journal of Fudan University：Natural Science

基　　金：国家自然科学基金(3080322);上海市浦江人才计划(08PJ1401300);上海市重点学科B111;教育部高等学校新教师基金(200802461050);国家重点基础研究发展计划(973计划)(2011CB503703)资助项目

摘　　要：转化生长因子-α(TGF-α)是调控细胞生长的一种肽类生长因子.其前体pro-TGF-α是一类跨膜蛋白,在一些金属蛋白酶(如去整合素金属蛋白酶17,ADAM17)的切割作用下细胞外50个氨基酸左右的可溶性片段被释放,为成熟的TGF-α.TGF-α与其受体EGFR结合,激活EGFR下游信号通路,该通路对星形胶质细胞的生长和增殖有重大的影响.一定剂量的脂多糖(LPS)能够促进星形胶质细胞的增殖和活化,但脂多糖激活星形胶质细胞的途径并不清楚.实验发现,在原代星形胶质细胞中,1μg/mL的LPS作用1h,就能显著提高TGF-α的释放.相反,1μg/mL的LPS不影响人胶质瘤细胞系U251和中国仓鼠肺细胞CHL中TGF-α的释放,表明原代细胞对LPS的刺激作用更为敏感.金属蛋白酶抑制剂GM6001对LPS诱导的原代星形胶质细胞TGF-α释放增加作用无显著抑制,表明这种促进释放作用是不依赖于ADAM17的.在原代星形胶质细胞中,1μg/mL的LPS作用48h对ADAM17的mRNA表达无影响;而在U251细胞中,1μg/mL的LPS作用48h能够显著提高ADAM17蛋白的表达.不同于胶质瘤细胞,LPS对于原代星形胶质细胞的活化可能是通过直接促进TGF-α的释放来完成,且此释放不依赖于ADAM17.Transforming growth factor-α is a peptide growth factor which could regulate cell growth. The pro- TGF-α is a membrane-anchored protein which can be shedded by several transmembrane metalloproreases including ADAM17. A 50aa matured TGF-α is released and it can activate EGFR signaling pathway in a paracrine manner. TGF-α has great effect on the growth and proliferation of astrocytes. Lipopolysaccharide （LPS） could increase the proliferation and activation of astrocytes, but the activation pathways by LPS are still not clear. We tested the effect of 1μg/mL LPS stimulation on TGF-α release in both primary astrocytes and glioma U251 cells. The release of TGF-α was largely increased in primary astrocytes and such increase was not inhibited by metalloproteases inhibitor GM6001, indicating that LPS function on TGF-α release was independent on ADAM17 in primary astrocytes. On the other hand, LPS had no effect on the release of TGF-α in U251 and CHL cells. Furthermore, long term exposure to LPS also had different effects on the expression level of the ADAM17 in primary astrocyte and glioma cell. LPS had no effect on the mRNA expression level of ADAM17 in primary astrocyte cells, but could largely induce the expression of the ADAM17 protein in U251 cells. Therefore, our results suggested that LPS could activate the astroeytes by stimulating the release of TGF-α which was independent of ADAM17.

关 键 词：LPS TGF-Α ADAM17 原代星形胶质细胞 U251 

分 类 号：Q189[生物学—神经生物学]