Role of phosphoinositide 3-kinase regulatory isoforms in development and actin rearrangement
Role of phosphoinositide 3-kinase regulatory isoforms in development and actin rearrangement
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DOI：
10.1128/mcb.25.7.2593-2606.2005
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发表时间：
2005-04-01
影响因子：
5.3
通讯作者：
Cantley, LC
中科院分区：
文献类型：
--
作者：
Brachmann, SA;Yballe, CA;Cantley, LC
Ia类磷脂酰肌醇3-激酶（PI 3 Ks）是p110催化亚基和p85调节亚基的异二聚体，其介导对生长和分化因子的多种细胞应答。尽管胚胎发育在缺乏p85 α基因的所有同种型（p85 α（-/-）p55 α（-/-）p50 α（-/-））或缺乏p85 β基因（p85 β（-/-））的小鼠中没有受损（D. A. Fruman，F. Mauvais-Jarvis，D. A.波拉德角M. Yballe，D.巴西河T.布朗森角R. Kahn和L. C. Cantley，Nat Genet. 26：379-382，2000; K.植木角M. Yballe，S. M. Brachmann，D. Vicent，J. M.瓦特角R. Kahn和L. C. Cantley，Proc. Natl. Acad. Sci. USA 99：419-424，2002），我们在此显示两种基因的缺失导致胚胎第12.5天（E12.5）的致死性。这些胚胎的表型，包括在E8时位于神经管侧面的表皮下大泡和在转向过程中出血进入大泡，与在血小板衍生生长因子受体α无效（PDGFR α（-/-））小鼠中观察到的缺陷相似（P. Soriano，Development 124：2691-2700，1997），表明PI 3 K是该发育阶段PDGFR α信号传导的重要介质。p85 α（-/-）p55 α（+/+）p50 α（+/+）p85 β（-/-）小鼠具有类似但不太严重的缺陷，表明p85 α和p85 β在发育中具有关键和冗余的功能。缺乏所有p85 α和p85 β基因产物（p85 α（-/-）p55 α（-/-）p50 α（-/-）p85 β（-/-））的小鼠胚胎成纤维细胞在PDGF诱导的膜皱褶中有缺陷。Rac特异性GDP-GTP交换因子Vav 2的过表达或p85 α或p85 β的重新引入挽救了膜皱褶缺陷。令人惊讶的是，p50 α的重新引入也恢复了PDGF依赖的膜皱褶。这些结果表明，Ia类PI 3 K是关键的PDGF依赖性肌动蛋白重排，但SH 3结构域和Rho/Rac/Cdc 42相互作用域的p85，缺乏p50 α，不需要这种反应。
Class Ia phosphoinositide 3-kinases (PI3Ks) are heterodimers of p110 catalytic and p85 regulatory subunits that mediate a variety of cellular responses to growth and differentiation factors. Although embryonic development is not impaired in mice lacking all isoforms of the p85 alpha gene (p85 alpha(-/-) p55 alpha(-/-) p50 alpha(-/-)) or in mice lacking the p85 beta gene (p85 beta(-/-)) (D. A. Fruman, F. Mauvais-Jarvis, D. A. Pollard, C. M. Yballe, D. Brazil, R. T. Bronson, C. R. Kahn, and L. C. Cantley, Nat Genet. 26:379-382, 2000; K. Ueki, C. M. Yballe, S. M. Brachmann, D. Vicent, J. M. Watt, C. R. Kahn, and L. C. Cantley, Proc. Natl. Acad. Sci. USA 99:419-424, 2002), we show here that loss of both genes results in lethality at embryonic day 12.5 (E12.5). The phenotypes of these embryos, including subepidermal blebs flanking the neural tube at E8 and bleeding into the blebs during the turning process, are similar to defects observed in platelet-derived growth factor receptor alpha null (PDGFR alpha(-/-)) mice (P. Soriano, Development 124:2691-2700, 1997), suggesting that PI3K is an essential mediator of PDGFR alpha signaling at this developmental stage. p85 alpha(-/-) p55 alpha(+/+) p50 alpha(+/+) p85 beta(-/-) mice had similar but less severe defects, indicating that p85 alpha and p85 beta have a critical and redundant function in development. Mouse embryo fibroblasts deficient in all p85 alpha and p85 beta gene products (p85 alpha(-/-) p55 alpha(-/-) p50 alpha(-/-) p85 beta(-/-)) are defective in PDGF-induced membrane ruffling. Overexpression of the Rac-specific GDP-GTP exchange factor Vav2 or reintroduction of p85 alpha or p85 beta rescues the membrane ruffling defect. Surprisingly, reintroduction of p50 alpha also restored PDGF-dependent membrane ruffling. These results indicate that class Ia PI3K is critical for PDGF-dependent actin rearrangement but that the SH3 domain and the Rho/Rac/Cdc42-interacting domain of p85, which lacks p50 alpha, are not required for this response.