Cytokine induction of Fas gene expression in insulin-producing cells requires the transcription factors NF-κB and C/EBP
Cytokine induction of Fas gene expression in insulin-producing cells requires the transcription factors NF-κB and C/EBP
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DOI：
10.2337/diabetes.50.8.1741
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发表时间：
2001-08-01
期刊：
影响因子：
7.7
通讯作者：
Eizirik, DL
中科院分区：
文献类型：
--
作者：
Darville, MI;Eizirik, DL
Fas介导的细胞死亡可能在1型糖尿病中胰腺β细胞的自身免疫破坏中起作用。β-细胞在生理条件下不表达Fas，但在暴露于奎宁的小鼠和人胰岛中诱导了Fas mRNA和蛋白质，使得β-细胞对Fas配体诱导的细胞凋亡敏感。本研究的目的是研究大鼠β细胞和胰岛素分泌细胞RINm 5 F中细胞因子对Fas的分子调控。在暴露于白细胞介素（IL）-1 β的荧光激活细胞分选纯化的大鼠β细胞中，Fas mRNA表达增加15倍，而γ-干扰素没有影响。将大鼠Fas启动子-荧光素酶报告基因构建体转染到纯化的大鼠β细胞和RINm 5 F胰岛素瘤细胞中的转染实验鉴定了核苷酸-223和-54之间的IL-1 β应答区。在该区域中两个相邻的NF-κ B和C/EBP位点的失活消除了RINm 5 F细胞中IL-1 β诱导的Fas启动子活性。通过凝胶迁移试验证实NF-κ B和C/EBP因子与其各自位点的结合。在共转染实验中，NF-κ B p65反式激活Fas启动子。NF-κ B p50和C/EBP β过表达本身对Fas启动子活性没有影响，但当与p65共转染时，每个因子都抑制p65的反式激活。这些结果表明NF-κ B和C/EBP因子在胰岛素产生细胞中Fas表达的精氨酸调节中起关键作用。
Fas-mediated cell death may play a role in the autoimmune destruction of pancreatic beta -cells in type 1 diabetes. beta -Cells do not express Fas under physiological conditions, but Fas mRNA and protein are induced in cytokine-exposed mouse and human islets, rendering the beta -cells susceptible to Fas ligand-induced apoptosis. The aim of the present study was to investigate the molecular regulation of Fas by cytokines in rat beta -cells and in insulin-producing RINm5F cells. Fas mRNA expression was increased 15-fold in fluorescence-activated cell sorting-purified rat beta -cells exposed to interleukin (IL)-l beta, whereas gamma -interferon had no effect. Transfection experiments of rat Fas promoter-luciferase reporter constructs into purified rat beta -cells and RINm5F insulinoma cells identified an IL-1 beta -responsive region between nucleotides -223 and -54. Inactivation of two adjacent NF-kappaB and C/EBP sites in this region abolished IL-1 beta -induced Fas promoter activity in RINm5F cells. Binding of NF-kappaB and C/EBP factors to their respective sites was confirmed by gel shift assays. In cotransfection experiments, NF-kappaB p65 transactivated the Fas promoter. NF-kappaB p50 and C/EBP beta overexpression had no effect by themselves on the Fas promoter activity, but when cotransfected with p65, each factor inhibited transactivation by p65. These results suggest a critical role for NF-kappaB and C/EBP factors in cytokine-regulation of Fas expression in insulin-producing cells.