Topalli Ilir, Etgen Anne M
Department of Neuroscience, Forchheimer 113, Albert Einstein College of Medicine, Bronx, NY 10461, USA.
Brain Res. 2004 Dec 24;1030(1):116-24. doi: 10.1016/j.brainres.2004.09.057.
Estradiol (E(2)) and insulin-like growth factor-I (IGF-I) can act independently or in concert to promote neurite outgrowth in vivo and in cultured neurons. This study examined the role of crosstalk between estrogen receptor (ER)alpha and the IGF-I receptor as a critical mediator of hormone- and growth factor-dependent neurite outgrowth in a homogenous cell system. We used control PC12 cells and PC12 cells stably transfected with ER alpha, both of which express IGF-I receptor. Cells were treated for 1 week with vehicle, 1 nM E(2) or 100 ng/ml IGF-I alone or with E(2) or IGF-I in the presence of either the IGF-I receptor antagonist JB1 or the ER antagonist ICI 182,780. IGF-I significantly increased neurite outgrowth, as measured by the percentage of process-bearing cells, and absolute neurite length per cell in both control and ER alpha-transfected PC12 cells. In contrast, E(2) increased process formation and extension only in PC12 cells that were stably transfected with ER alpha. ICI 182,780 and JB1 blocked the IGF-I-induced increases in neurite length in both cell types. The efficacy of ICI 182,780 in control PC12 cells may have been due to the upregulation of ER alpha in these cells by the 7-day treatment with IGF-I. The ER and IGF-I receptor antagonists similarly blocked the E(2)-induced increase in neurite lengths in ER alpha-transfected cells. Immunofluorescent analysis of the cellular distribution of an axonal marker, phospho-neurofilament, verified that the processes extended by PC12 cells were neurites. These data suggest that receptor crosstalk between IGF-I receptors and ER alpha has an important role in neurite formation and extension even in a single-cell system.
雌二醇（E₂）和胰岛素样生长因子-I（IGF-I）可独立或协同作用，以促进体内及培养神经元的神经突生长。本研究在一个同质细胞系统中，检测了雌激素受体（ER）α与IGF-I受体之间的相互作用作为激素和生长因子依赖性神经突生长关键介质的作用。我们使用了对照PC12细胞和稳定转染ERα的PC12细胞，这两种细胞均表达IGF-I受体。细胞分别用溶剂、1 nM E₂或100 ng/ml IGF-I单独处理1周，或在存在IGF-I受体拮抗剂JB1或ER拮抗剂ICI 182,780的情况下，与E₂或IGF-I共同处理。通过有突起细胞的百分比以及每个细胞的绝对神经突长度来衡量，IGF-I显著增加了对照和ERα转染的PC12细胞中的神经突生长。相比之下，E₂仅在稳定转染ERα的PC12细胞中增加了突起的形成和延伸。ICI 182,780和JB1均阻断了两种细胞类型中IGF-I诱导的神经突长度增加。ICI 182,780在对照PC12细胞中的作用效果可能是由于IGF-I 7天的处理使这些细胞中ERα上调所致。ER和IGF-I受体拮抗剂同样阻断了ERα转染细胞中E₂诱导的神经突长度增加。对轴突标记物磷酸化神经丝的细胞分布进行免疫荧光分析，证实PC12细胞延伸出的突起是神经突。这些数据表明，即使在单细胞系统中IGF-I受体与ERα之间的受体相互作用在神经突形成和延伸中也具有重要作用。
