Department of Physiology, China Pharmaceutical University, Nanjing 210009, China.
Neurosci Lett. 2013 May 10;542:53-8. doi: 10.1016/j.neulet.2013.03.012. Epub 2013 Mar 21.
Activin is a neurotrophic and neuroprotective factor in the central nervous system. Activin receptor-interacting protein 1 and 2 (ARIP1 and ARIP2) are identified as activin signal proteins in mouse brain. However, whether ARIP1 and ARIP2 are co-expressed in nerve cells and the differences of their biological activities are not well characterized. In the present study, we found that ARIP1 and ARIP2 mRNA expressions were detectable in mouse brain and their proteins were co-localized at the hypothalamus of cerebrum and granular layers in cerebellum, especially in Purkinje cells. Furthermore, ARIP1 and ARIP2 were co-expressed in mouse Neuro-2a cells, which is similar to the co-localization of ARIP1 and ARIP2 in hypothalamus neurons and Purkinje cells. Overexpression of ARIP1 in Neuro-2a cells inhibited activin signal transduction induced by activin A and Smad3, and activin A-induced voltage-gated Na(+) current (INa), while ARIP2 was only a negative regulator of signal transduction induced by activin A and did not alter activin A-induced INa. Taken together, these data demonstrate that ARIP1 and ARIP2 are co-expressed in some nerve cells and their biological activities are distinct.
激活素是中枢神经系统中的一种神经营养和神经保护因子。激活素受体相互作用蛋白 1 和 2（ARIP1 和 ARIP2）被鉴定为小鼠脑中的激活素信号蛋白。然而，ARIP1 和 ARIP2 是否在神经细胞中共表达以及它们的生物学活性差异尚未得到很好的描述。在本研究中，我们发现 ARIP1 和 ARIP2 mRNA 表达可在小鼠脑中检测到，其蛋白在大脑下丘脑和小脑颗粒层共定位，尤其是在浦肯野细胞中。此外，ARIP1 和 ARIP2 在小鼠 Neuro-2a 细胞中共表达，这与 ARIP1 和 ARIP2 在下丘脑神经元和浦肯野细胞中的共定位相似。ARIP1 在 Neuro-2a 细胞中的过表达抑制了激活素 A 和 Smad3 诱导的激活素信号转导，以及激活素 A 诱导的电压门控 Na(+)电流（INa），而 ARIP2 仅是激活素 A 诱导的信号转导的负调节剂，不会改变激活素 A 诱导的 INa。综上所述，这些数据表明 ARIP1 和 ARIP2 在一些神经细胞中共表达，它们的生物学活性不同。
