Wilson M, Burt A R, Milligan G, Anderson N G
Hannah Research Institute, Ayr KA6 5HL, Scotland, United Kingdom.
J Biol Chem. 1996 Apr 12;271(15):8537-40. doi: 10.1074/jbc.271.15.8537.
In order to study the regulation of the ribosomal protein S6 kinase, p70s6k, by G protein-coupled receptors, Rat-1 fibroblasts were stably transfected with two versions of the alpha2 adrenergic receptor. Stimulation of clone 1C cells, which express 3.5 pmol/mg of protein of the human alpha2C10 receptor, with the alpha2 agonist UK 14304 led to a transient increase in p70s6k activity. UK 14304 also activated p70s6k in a clone expressing the porcine alpha2A receptor (400 fmol/mg of protein). Lysophosphatidic acid (LPA), acting through endogenous G protein-coupled receptors, also activated p70s6k in alpha2 receptor-transfected and in nontransfected cells. Activation of p70s6k by both UK 14304 and LPA was accompanied by increased phosphorylation of the protein. Rapamycin completely blocked the activation of p70s6k by both agents. Activation of p70s6k by UK 14304 and by LPA, but not by platelet-derived growth factor (PDGF), was blocked by preincubation of cells with pertussis toxin. Wortmannin, a selective inhibitor of phosphoinositide (PI) 3-OH kinase, prevented activation of p70s6k by UK 14304, LPA, and PDGF. These data indicate that p70s6k is regulatable by Gi-coupled receptor agonists in a pertussis toxin-sensitive fashion in Rat-1 fibroblasts and that activation of p70s6k by such agents appears to involve an isoform of PI 3-kinase.
为了研究G蛋白偶联受体对核糖体蛋白S6激酶（p70s6k）的调控作用，用两种版本的α2肾上腺素能受体对大鼠1型成纤维细胞进行稳定转染。用α2激动剂UK 14304刺激表达3.5 pmol/mg人α2C10受体蛋白的克隆1C细胞，导致p70s6k活性短暂增加。UK 14304还能激活表达猪α2A受体（400 fmol/mg蛋白）的克隆中的p70s6k。溶血磷脂酸（LPA）通过内源性G蛋白偶联受体发挥作用，也能激活转染了α2受体的细胞和未转染细胞中的p70s6k。UK 14304和LPA对p70s6k的激活都伴随着该蛋白磷酸化的增加。雷帕霉素完全阻断了这两种药物对p70s6k的激活。用百日咳毒素预孵育细胞可阻断UK 14304和LPA对p70s6k的激活，但血小板衍生生长因子（PDGF）不能。渥曼青霉素是一种磷酸肌醇（PI）3-OH激酶的选择性抑制剂，可阻止UK 14304、LPA和PDGF对p70s6k的激活。这些数据表明，在大鼠1型成纤维细胞中，p70s6k可被Gi偶联受体激动剂以百日咳毒素敏感的方式调节，并且此类药物对p70s6k的激活似乎涉及PI 3激酶的一种同工型。
