THE HORMONAL CONTROL OF FETAL GROWTH

描述：(改编自申请人的摘要)培养中，胰岛素样 生长因子-I(IGF-I)刺激祖细胞增加神经元数量 通过促进神经元及其前体细胞的存活来促进细胞的增殖。老鼠 随着IGF-I表达或作用的基因组变化展示了研究结果 与IGF-I在神经发生和促进中的体内作用一致 神经元存活。研究人员已经培育出转基因(TG)小鼠品系 出生后在大脑中过度表达IGF-I的人。在这些转基因小鼠中，大脑 过度生长的特征是神经元数量增加，而神经元数量减少 凋亡神经元的数量，以及神经元胞体大小和 神经性突起。IGF-I转基因小鼠也表现出增加的数量。 表达中间丝蛋白Nestin的神经元 神经干细胞及其后代。相比之下，具有异位大脑的TG小鼠 IGF作用抑制因子IGF结合蛋白-I在脑中的表达 细胞数量减少的生长迟缓，以及IGF-I或IGF-I消融的小鼠 I型胰岛素样生长因子受体(IGFlR)基因功能(基因敲除或KO小鼠)具有较小的 大脑。研究人员建议检验IGF-I放大的假设 抑制神经干细胞和神经元凋亡的体内神经元数量 祖先。他有三个具体目标。1)测定IGF-I抗细胞凋亡作用 小脑的作用机制，这是一个出生后生长的大脑区域 IGF-I对其有明显的刺激作用。他将使用IGF-I TG、IGF-I KO小鼠和正常小鼠 小鼠，并确定已知的表达和活性的变化 细胞凋亡的调节因子，包括特定的Bcl2家族成员，抑制因子 细胞凋亡蛋白(IAP)和半胱氨酸氨基转移酶(Caspase)。2)调查员将确定IGF-I 在体内对神经干细胞的作用：a)定义神经干细胞 IGF-I TG、IGF-I KO和正常小鼠的细胞凋亡、增殖和迁移 在出生后发育期间，以及b)定义IGF-I在胚胎中的作用 神经发生：1)在神经干细胞中过表达IGF-I的转基因小鼠 细胞利用巢蛋白内含子调控元件直接表达IGF-I， 和ii)使用Cre-lox在神经干细胞中消融IGF1R的小鼠 策略。在每一条线路上，他将确定细胞凋亡数和 增殖的神经干细胞，并描绘它们的命运。3)他将识别基因 抑制消减技术在神经发生过程中受IGF-I的调节 胰岛素样生长因子-I功能正常和异常小鼠来源基因的杂交。

DESCRIPTION: (Adapted from the applicant's abstract) In culture, insulin-like growth factor-I (IGF-I) increases neuron number by stimulating progenitor proliferation and by promoting survival of neurons and their progenitors. Mice with genomic alterations in IGF-I expression or actions exhibit findings consistent with an in vivo role for IGF-I in neurogenesis and in promoting neuron survival. The investigator has generated transgenic (Tg) mouse lines that overexpress IGF-I in the brain postnatally. In these Tg mice, brain overgrowth is characterized by increases in neuron number and decreases in the number of apoptotic neurons, as well as increases in neuron cell body size and neuritic outgrowth. The IGF-I Tg mice also exhibit an increase in the number of neurons that immunostain for nestin, an intermediate filament protein expressed by neural stem cells and their progeny. In contrast, Tg mice with ectopic brain expression of IGF binding protein-I, an inhibitor of IGF action, exhibit brain growth retardation with decreased cell number, and mice with ablated IGF-I or type 1 IGF receptor (IGFlR) gene function (knock-out or KO mice) have small brains. The investigator proposes testing the hypothesis that IGF-I amplifies neuron number in vivo by inhibiting apoptosis of neural stem cells and neuron progenitors. He has three specific aims. 1) Determine IGF-I anti-apoptotic mechanisms of action in the cerebellum, a brain region whose postnatal growth is markedly stimulated by IGF-I. He will use IGF-I Tg, IGF-I KO mice and normal mice, and determine alterations in the expression and activity of known regulators of apoptosis, including selected Bcl-2 family members, inhibitor of apoptosis proteins (IAP) and caspases. 2) The investigator will determine IGF-I actions on neural stem cells in vivo by: a) defining neural stem cell apoptosis, proliferation and migration in IGF-I Tg, IGF-I KO and normal mice during postnatal development, and b) defining IGF-I actions in embryonic neurogenesis by creating: i) Tg mice that overexpress IGF-I in neural stem cells using nestin intronic regulatory elements to direct expression of IGF-I, and ii) mice in whom the IGF1R is ablated in neural stem cells using a Cre-lox strategy. In each line he will determine the number of apoptotic and proliferative neural stem cells, and map their fates. 3) He will identify genes regulated by IGF-I during neurogenesis using suppression subtractive hybridization of cDNA derived from mice with normal and altered IGF-I function.