Yoo Jae Cheal, Park Nammi, Choi Hye Young, Park Jae-Yong, Yi Gwan-Su
Department of Bio and Brain Engineering, KAIST, Daejeon 34141, Republic of Korea.
Department of Physiology, College of Medicine, Inje University, Busan 47392, Republic of Korea.
Biochem Biophys Res Commun. 2018 Feb 26;497(1):424-429. doi: 10.1016/j.bbrc.2018.02.101. Epub 2018 Feb 12.
Copine1 (CPNE1), has tandem C2 domains and an A domain. We previously demonstrated that CPNE1 directly induces neuronal differentiation via Protein kinase B (AKT) phosphorylation in the hippocampal progenitor cell line, HiB5. To better understand its cellular function, we carried out a yeast two-hybrid screening to find CPNE1 binding partners. Among the identified proteins, Jun activation domain-binding protein 1 (JAB1) appears to directly interact with CPNE1. Between CPNE1 and JAB1, the physical interaction was confirmed in vitro and in vivo. In addition the specific binding regions of CPNE1 and JAB1 was confirmed with truncated mutant assay. Furthermore, our results also demonstrate that AKT phosphorylation and expression of the neuronal marker protein are increased when JAB1 is overexpressed in CPNE1 high expressed HiB5 cells. Moreover, overexpression of both CPNE1 and JAB1 in HiB5 cells effectively increased neurite outgrowth. Collectively, our findings suggest that JAB1 activates the neuronal differentiation ability of CPNE1 through the binding of C2A domain in CPNE1 with MPN domain in JAB1.
Copine1（CPNE1）具有串联的C2结构域和一个A结构域。我们之前证明，CPNE1通过在海马祖细胞系HiB5中磷酸化蛋白激酶B（AKT）直接诱导神经元分化。为了更好地理解其细胞功能，我们进行了酵母双杂交筛选以寻找CPNE1的结合伴侣。在鉴定出的蛋白质中，Jun激活域结合蛋白1（JAB1）似乎与CPNE1直接相互作用。在CPNE1和JAB1之间，体外和体内均证实了这种物理相互作用。此外，通过截短突变体分析证实了CPNE1和JAB1的特异性结合区域。此外，我们的结果还表明，当JAB1在高表达CPNE1的HiB5细胞中过表达时，AKT磷酸化和神经元标记蛋白的表达会增加。此外，在HiB5细胞中同时过表达CPNE1和JAB1可有效增加神经突生长。总体而言，我们的研究结果表明，JAB1通过CPNE1中的C2A结构域与JAB1中的MPN结构域结合来激活CPNE1的神经元分化能力。
