Proliferative defect and embryonic lethality in mice homozygous for a deletion in the p110α subunit of phosphoinositide 3-kinase
Proliferative defect and embryonic lethality in mice homozygous for a deletion in the p110α subunit of phosphoinositide 3-kinase
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DOI：
10.1074/jbc.274.16.10963
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发表时间：
1999-04-16
影响因子：
4.8
通讯作者：
Nussbaum, RL
中科院分区：
文献类型：
--
作者：
Bi, L;Okabe, I;Nussbaum, RL
磷脂酰肌醇3,4,5-三磷酸是一种磷脂信号分子，参与许多细胞功能，包括生长因子受体信号传导、细胞骨架组织、趋化性、凋亡和蛋白质运输。许多不同的3-激酶（分为I-A、I-B、II和III型）催化肌醇环3位点的磷酸化，但每种不同的3-激酶同工酶在胚胎发育和动物体内平衡过程中所起的生理作用尚不完全清楚。哺乳动物I-A型激酶同工酶是一种异源二聚体，当催化110-kDa亚基通过氨基末端结合域与调节的85-或55-kDa亚基相互作用时，在37℃下具有活性。利用基因靶向技术，我们在胚胎干细胞中删除了编码I-A型激酶α - kda催化亚基(Pik3ca) α同工酶α亚型的基因中的该结合域，导致p110催化亚基的表达缺失。我们发现，Pik3ca（del/del）胚胎在胚胎日(E) 9.5时发育迟缓，在E9.5和E10.5之间死亡。E9.5 Pik3ca（del/del）胚胎具有严重的增殖缺陷，但细胞凋亡未增加。观察到，即使添加生长因子，来自Pik3ca（del/del）胚胎的成纤维细胞也不能在Dulbecco的改良Eagle培养基和胎牛血清中复制，这一增殖缺陷得到了支持。
Phosphatidylinositol 3,4,5-trisphosphate is a phospholipid signaling molecule involved in many cellular functions including growth factor receptor signaling, cytoskeletal organization, chemotaxis, apoptosis, and protein trafficking. Phosphorylation at the 3 position of the inositol ring is catalyzed by many different 3-kinases (classified as types I-A, I-B, II, and III), but the physiological roles played by each of the different 3-kinase isozymes during embryonic development and in homeostasis in animals is incompletely understood, Mammalian type I-A kinase isozymes are heterodimers that are active at 37 degrees C when the catalytic 110-kDa subunit interacts through an amino-terminal binding domain with a regulatory 85- or 55-kDa subunit, Using gene targeting in embryonic stem cells, we deleted this binding domain in the gene encoding the alpha isoform of the 110-kDa catalytic subunit (Pik3ca) of the alpha isozyme of the type I-A kinases, leading to loss of expression of the p110 catalytic subunit. We show that Pik3ca(del/del) embryos are developmentally delayed at embryonic day (E) 9.5 and die between E9.5 and E10.5. E9.5 Pik3ca(del/del) embryos have a profound proliferative defect but no increase in apoptosis, A proliferative defect is supported by the observation that fibroblasts from Pik3ca(del/del) embryos fail to replicate in Dulbecco's modified Eagle's medium and fetal calf serum, even with supplemental growth factors.