Functional analysis of PI3K/PTEN pathway, a lipid mediator, in vivo

（1）肝细胞中的PTEN我们在小鼠（AlbCrePtenflox/flox小鼠）中产生了Pten的肝细胞特异性无效突变。AlbCrePtenflox/flox小鼠表现出大面积肝肿大和脂肪性肝炎伴甘油三酯蓄积，这是一种与人类非酒精性脂肪性肝炎相似的表型。参与脂肪生成和氧化的基因被诱导，可能是由于水平升高的反式激活因子PPAR_1和SREBP 1c。重要的是，肝脏中Pten功能的丧失导致肿瘤发生，47%的AlbCrePtenflox/flox肝脏在44周龄时发生肝细胞腺瘤。到74-78周龄时，100%的AlbCrePtenflox/flox肝脏显示腺瘤，66%患有肝细胞癌。（2）内皮细胞中的PTEN我们在小鼠体内构建了一个内皮细胞特异性突变的Pten（Tie 2CrePten）。Tie 2CrePtenflox/+小鼠显示出由于血管生长因子驱动的血管生成增加而增强的肿瘤发生。Tie 2CrePtenflox/flox小鼠在胚胎第11.5天（E11）前死亡 ...更多信息 .5）由于周细胞和血管平滑肌细胞向血管以及心肌细胞向内皮细胞的募集受损而引起的出血和心力衰竭。这些表型与Ang-1、VCAM-1、连接蛋白40和ephrinB 2的表达降低相关，但与Ang-2、VEGF-A、VEGFR 1和VEGFR 2的表达增加相关。（3）前列腺中的PTEN我们选择性地使MMTV-LTR启动子有活性的小鼠组织中的Pten失活，导致Pten缺失的皮肤和前列腺中的过度增殖和肿瘤变化。这些表型发病早，完全渗透。这些小鼠Pten突变前列腺中的脱落细胞表现出高度前列腺上皮内瘤变（HGPIN），经常进展为局灶性浸润性癌症。（4）骨骼肌中的PTEN我们发现，肌肉特异性缺失Pten可以保护小鼠免受胰岛素抵抗和高脂喂养引起的糖尿病。与同窝对照组相比，肌肉Pten的缺失导致高脂肪喂养时胰岛素刺激的2-脱氧葡萄糖摄取和Akt磷酸化增强，并且这些小鼠免于发生高胰岛素血症和胰岛增生。少

(l)PTEN in hepatocytesWe generated a hepatocyte-specific null mutation of Pten in mice (AlbCrePtenflox/flox mice). AlbCrePtenflox/flox mice showed massive hepatomegaly and steatohepatitis with triglyceride accumulation, a phenotype similar to human nonalcoholic steatohepatitis. Genes involved in lipogenesis and -oxidation were induced, possibly as a result of elevated levels of the transactivating factors PPAR_and SREBP1c. Importantly, the loss of Pten function in the liver led to tumorigenesis, with 47% of AlbCrePtenflox/flox livers developing liver cell adenomas by 44 weeks of age. By 74-78 weeks of age, 100% of AlbCrePtenflox/flox livers showed adenomas and 66% had hepatocellular carcinomas.(2)PTEN in endothelial cellsWe generated an endothelial cell-specific mutation of Pten (Tie2CrePten) in mice. Tie2CrePtenflox/+ mice displayed enhanced tumorigenesis due to an increase in angiogenesis driven by vascular growth factors. Tie2CrePtenflox/flox mice died before embryonic day 11.5 (E11 … More .5) due to bleeding and cardiac failure caused by impaired recruitment of pericytes and vascular smooth muscle cells to blood vessels, and of cardiomyocytes to the endocardium. These phenotypes were associated with decreased expression of Ang-1, VCAM-1, connexin 40, and ephrinB2 but increased expression of Ang-2, VEGF-A, VEGFR1, and VEGFR2.(3)PTEN in prostateWe selectively inactivated Pten in murine tissues in which the MMTV-LTR promoter is active, resulting in hyperproliferation and neoplastic changes in Pten-null skin and prostate. These phenotypes had early onset and were completely penetrant. Abnormalities in Pten mutant prostates from these mice exhibited high-grade prostatic intraepithelial neoplasia (HGPIN) that frequently progressed to focally invasive cancer.(4)PTEN in skeletal muscleWe show that muscle-specific deletion of Pten protected mice from insulin resistance and diabetes caused by high-fat feeding. Deletion of muscle Pten resulted in enhanced insulin-stimulated 2-deoxyglucose uptake and Akt phosphorylation compared to littermate controls upon high-fat feeding, and these mice were spared from developing hyperinsulinemia and islet hyperplasia. Less