Magun R, Burgering B M, Coffer P J, Pardasani D, Lin Y, Chabot J, Sorisky A
Loeb Medical Research Institute, University of Ottawa, Canada.
Endocrinology. 1996 Aug;137(8):3590-3. doi: 10.1210/endo.137.8.8754791.
Insulin/IGF-1 is required for differentiation of 3T3-L1 adipose cells. Downstream targets of insulin/IGF-1 that lead to adipocyte differentiation appear to include Ras, phosphatidylinositol (PI) 3-kinase, Raf, and mitogen-activated protein kinase. We have tested whether protein kinase B (PKB), a serine/threonine kinase activated by PI 3-kinase, is sufficient for 3T3-L1 preadipose cell differentiation. A plasmid vector encoding a version of PKB that is constitutively activated (Gag-PKB) was expressed in 3T3-L1 preadipose cells (Gag-PKB cells). Spontaneous morphological changes indicative of adipocyte differentiation were observed in Gag-PKB cells. The cells assumed a spherical shape and they acquired characteristic lipid droplets that stained positively for Oil Red O. Northern blot analysis detected upregulation of LPL and aP2 mRNA, specific indicators of adipocyte differentiation. Our data demonstrate that constitutive activation of PKB is sufficient to trigger adipocyte differentiation.
胰岛素/胰岛素样生长因子-1（IGF-1）是3T3-L1脂肪细胞分化所必需的。胰岛素/IGF-1导致脂肪细胞分化的下游靶点似乎包括Ras、磷脂酰肌醇（PI）3激酶、Raf和丝裂原活化蛋白激酶。我们已经测试了由PI 3激酶激活的丝氨酸/苏氨酸激酶蛋白激酶B（PKB）是否足以促进3T3-L1前脂肪细胞的分化。在3T3-L1前脂肪细胞（Gag-PKB细胞）中表达了一种编码持续激活形式的PKB（Gag-PKB）的质粒载体。在Gag-PKB细胞中观察到了指示脂肪细胞分化的自发形态变化。细胞呈球形，并获得了对油红O呈阳性染色的特征性脂滴。Northern印迹分析检测到脂蛋白脂肪酶（LPL）和aP2 mRNA的上调，这是脂肪细胞分化的特异性指标。我们的数据表明，PKB的持续激活足以触发脂肪细胞分化。
