Gao P, Watkins D C, Malbon C C
Department of Molecular Pharmacology, State University of New York-Stony Brook 11794-8651, USA.
Am J Physiol. 1995 Jun;268(6 Pt 1):C1460-6. doi: 10.1152/ajpcell.1995.268.6.C1460.
In F9 teratocarcinoma stem cells, retinoic acid induces a primitive endoderm-like phenotype and a sharp decline in G alpha i-2, a response mimicked by expression of RNA antisense to G alpha i-2 in the absence of this morphogen (D. C. Watkins, G. L. Johnson, and C. C. Malbon. Science Wash. DC 258: 1373-1375, 1992). The role of the GS alpha/G alpha i-2 axis in cellular differentiation was explored. In the absence of retinoic acid, F9 stem cells stably expressing a constitutively active mutant of GS alpha (G225T) progressed to the primitive endoderm phenotype, as judged by morphological and differentiation markers, such as tissue plasminogen activator. Although elevated in cells expressing G225T GS alpha, adenosine 3',5'-cyclic monophosphate does not mimic retinoic acid action and alone fails to induce stem cells to primitive endoderm. In the absence of retinoic acid, expression of a null mutant of G alpha i-2 (G203T) also induced stem cells to primitive endoderm. These observations establish G proteins in the GS alpha/G alpha i-2 axis as a control point for regulating progression to primitive endoderm independent of adenylate cyclase, in the present study's model of early mouse development.
在F9畸胎瘤干细胞中，视黄酸可诱导出一种原始内胚层样表型，并使Gαi-2急剧下降，在缺乏这种形态发生素的情况下，对Gαi-2的反义RNA表达可模拟这种反应（D.C.沃特金斯、G.L.约翰逊和C.C.马尔邦。《科学》华盛顿特区258:1373 - 1375,1992）。研究了GSα/Gαi-2轴在细胞分化中的作用。在缺乏视黄酸的情况下，稳定表达GSα组成型活性突变体（G225T）的F9干细胞进展为原始内胚层表型，这可通过形态学和分化标志物（如组织纤溶酶原激活剂）来判断。尽管在表达G225T GSα的细胞中腺苷3',5'-环磷酸升高，但它并不能模拟视黄酸的作用，单独也无法诱导干细胞分化为原始内胚层。在缺乏视黄酸的情况下，Gαi-2无效突变体（G203T）的表达也可诱导干细胞分化为原始内胚层。在本研究早期小鼠发育模型中，这些观察结果确立了GSα/Gαi-2轴中的G蛋白是独立于腺苷酸环化酶调节向原始内胚层进展的控制点。
