Goetzl E J, Kong Y, Kenney J S
Department of Medicine, University of California Medical Center, San Francisco 94143-0711, USA.
Proc Assoc Am Physicians. 1999 May-Jun;111(3):259-69. doi: 10.1046/j.1525-1381.1999.99116.x.
The effects of lysophosphatidic acid (LPA) and sphingosine 1-phosphate (S1P) on T cell expression of heparin-binding epidermal growth factor-like growth factor (HB-EGF), the diphtheria toxin (DT) receptor, were investigated in the Tsup-1 cultured line of human CD4+ 8+ 3low T lymphoblastoma cells. Tsup-1 cells bear endothelial differentiation gene (edg)-2 and -4-encoded G protein-coupled receptors (GPCRs) for LPA and Edg-3 and -5 GPCRs for S1P. Suppression by DT of Tsup-1 cell protein synthesis was enhanced by LPA and S1P, with lipid structural specificity similar to that required for their recognition by Edg receptors. LPA and S1P increased the Tsup-1 cell level of immunoreactive HB-EGF, and neutralizing antibodies to HB-EGF inhibited LPA and S1P enhancement of Tsup-1 cell susceptibility to DT. Stabilized transfection of Tsup-1 cells with a combination of plasmids encoding Edg-2 plus -4 antisense mRNA suppressed the levels of Edg-2 and -4, but not Edg-3 and -5, in Western blots and reduced in parallel the increments in HB-EGF and susceptibility to DT evoked by LPA but not S1P. Similar transfection with Edg-3 plus -5 antisense plasmids suppressed Tsup-1 cell levels of immunoreactive Edg-3 and -5, but not Edg-2 or -4, and concurrently reduced S1P-, but not LPA-, induced Tsup-1 cell increases in both HB-EGF and susceptibility to DT. Edg GPCR-mediated LPA and S1P enhancement of T cell sensitivity to DT, thus, may be attributable to increased expression of the DT receptor HB-EGF.
在人CD4+8+3low T淋巴母细胞瘤细胞的Tsup-1培养系中，研究了溶血磷脂酸（LPA）和1-磷酸鞘氨醇（S1P）对肝素结合表皮生长因子样生长因子（HB-EGF）（白喉毒素（DT）受体）T细胞表达的影响。Tsup-1细胞带有内皮分化基因（edg）-2和-4编码的LPA G蛋白偶联受体（GPCR）以及Edg-3和-5 S1P GPCR。LPA和S1P增强了DT对Tsup-1细胞蛋白质合成的抑制作用，其脂质结构特异性类似于Edg受体识别它们所需的特异性。LPA和S1P增加了Tsup-1细胞中免疫反应性HB-EGF的水平，而针对HB-EGF的中和抗体抑制了LPA和S1P增强的Tsup-1细胞对DT的敏感性。用编码Edg-2加-4反义mRNA的质粒组合对Tsup-1细胞进行稳定转染，在蛋白质免疫印迹中抑制了Edg-2和-4的水平，但未抑制Edg-3和-5的水平，同时平行降低了LPA（而非S1P）诱导的HB-EGF增加和对DT的敏感性。用Edg-3加-5反义质粒进行类似转染，抑制了Tsup-1细胞中免疫反应性Edg-3和-5的水平，但未抑制Edg-2或-4的水平，同时降低了S1P（而非LPA）诱导的Tsup-1细胞HB-EGF增加和对DT的敏感性。因此，Edg GPCR介导的LPA和S1P增强T细胞对DT的敏感性可能归因于DT受体HB-EGF表达的增加。
