Host-cell specific effects of the nicotinic acetylcholine receptor chaperone RIC-3 revealed by a comparison of human and Drosophila RIC-3 homologues
Host-cell specific effects of the nicotinic acetylcholine receptor chaperone RIC-3 revealed by a comparison of human and Drosophila RIC-3 homologues
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DOI：
10.1111/j.1471-4159.2008.05235.x
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发表时间：
2008-06-01
影响因子：
4.7
通讯作者：
Millar, Neil S.
中科院分区：
文献类型：
--
作者：
Lansdell, Stuart J.;Collins, Toby;Millar, Neil S.
RIC-3是一种促进神经烟碱乙酰胆碱受体（nAChRs）成熟（折叠和组装）的跨膜蛋白。在这项研究中，我们报道了11个选择性剪接的果蝇RIC-3 （DmRIC-3）异构体的克隆和特征。选择性剪接DmRIC-3亚型的异源表达研究表明，nAChR伴侣活性不需要完全位于外显子7内的预测卷曲结构域。相比之下，含有额外外显子（外显子2）的异构体，位于富含脯氨酸的n端区域，其促进nAChR成熟的能力大大降低。DmRIC-3影响nAChR成熟的能力在与人类α - 7 nAChR以及含有果蝇和大鼠nAChR亚基的杂交nAChR共表达研究中得到了检验。当DmRIC-3剪接变异体在果蝇细胞系中表达时，其促进nAChR成熟的程度明显高于在人类RIC-3中观察到的程度。相反，当在人细胞系中表达时，人RIC-3比DmRIC-3更有效地促进了nAChR的成熟。11个选择性剪接的DmRIC-3异构体的克隆和表征有助于确定影响RIC-3伴侣活性的结构域。此外，在不同表达系统中进行的研究表明，其他宿主细胞因子可能调节RIC-3的伴侣活性。
RIC-3 is a transmembrane protein which enhances maturation (folding and assembly) of neuronal nicotinic acetylcholine receptors (nAChRs). In this study, we report the cloning and characterisation of 11 alternatively spliced isoforms of Drosophila melanogaster RIC-3 (DmRIC-3). Heterologous expression studies of alternatively spliced DmRIC-3 isoforms demonstrate that nAChR chaperone activity does not require a predicted coiled-coil domain which is located entirely within exon 7. In contrast, isoforms containing an additional exon (exon 2), which is located within a proline-rich N-terminal region, have a greatly reduced ability to enhance nAChR maturation. The ability of DmRIC-3 to influence nAChR maturation was examined in co-expression studies with human alpha 7 nAChRs and with hybrid nAChRs containing both Drosophila and rat nAChR subunits. When expressed in a Drosophila cell line, several of the DmRIC-3 splice variants enhanced nAChR maturation to a significantly greater extent than observed with human RIC-3. In contrast, when expressed in a human cell line, human RIC-3 enhanced nAChR maturation more efficiently than DmRIC-3. The cloning and characterisation of 11 alternatively spliced DmRIC-3 isoforms has helped to identify domains influencing RIC-3 chaperone activity. In addition, studies conducted in different expression systems suggest that additional host cell factors may modulate the chaperone activity of RIC-3.