GPC-1, a G Protein γ-Subunit, Regulates Olfactory Adaptation in caenorhabditis elegans
GPC-1, a G Protein γ-Subunit, Regulates Olfactory Adaptation in caenorhabditis elegans
复制标题
DOI：
10.1534/genetics.108.099002
复制
发表时间：
2009-04-01
期刊：
影响因子：
3.3
通讯作者：
Iino, Yuichi
中科院分区：
文献类型：
--
作者：
Yamada, Koji;Hirotsu, Takaaki;Iino, Yuichi
秀丽隐杆线虫基因组携带两个G - γ基因gpc-1和gpc-2，以及两个G - β基因gpb-1和gpb-2。其中，gpc-2和gpb-1普遍表达，对生存至关重要。通过基因筛选，我们发现gpc-1对嗅觉适应至关重要。虽然野生型动物在短暂的预暴露后对气味剂苯甲醛的趋化性降低，但gpc-1突变体在相同的预暴露后仍然被气味剂吸引。细胞特异性救援实验表明，gpc-1在AWC嗅觉神经元中起作用。GPC-1和GPB-1的共表达，而不是GPB-2的共表达，导致适应性增强，表明GPC-1可能与GPB-1共同作用。另一方面，细胞靶向RNAi敲低gpc-2导致未适应的动物对气味的趋化性降低，这表明gpc-2主要作用于嗅觉感觉，两个G γ具有不同的功能。尽管如此，AWC神经元中gpc-2的过表达挽救了gpc-1突变体的适应性缺陷，提示两种G γ γ的部分功能重叠。我们进一步测试了gpc-1与其他几个参与嗅觉适应的基因的遗传相互作用。我们的分析将goa-1和let-60 Ras与gpc-1并行。相反，egl-30 Gq α的功能获得突变对gpc-1是上位性的，这表明gpc-1 G γ可能作用于egl-30 Gq α的上游。
Caenorhabditis elegans genome carries two G gamma genes, gpc-1 and gpc-2, and two G beta genes, gpb-1 and gpb-2. Of these, gpc-2 and gpb-1 are expressed ubiquitously and are essential for viability. Through a genetic screen, we identified gpc-1 as essential for olfactory adaptation. While wild-type animals show decreased chemotaxis to the odorant benzaldehyde after a short preexposure to the odorant, gpc-1 mutants are still attracted to the odorant after the same preexposure. Cell-specific rescue experiments show that gpc-1 acts in the AWC olfactory neurons. Coexpression of GPC-1 and GPB-1, but not GPB-2, caused enhanced adaptation, indicating that GPC-1 may act with GPB-1. On the other hand, knock down of gpc-2 by cell-targeted RNAi caused reduced chemotaxis to the odorant in unadapted animals, indicating that GPC-2 mainly act for olfactory sensation and the two G gamma's have differential functions. Nonetheless, overexpression of gpc-2 in AWC neurons rescued the adaptation defects of gpc-1 mutants, suggesting partially overlapping functions of the two G gamma's. We further tested genetic interaction of gpc-1 with several other genes involved in olfactory adaptation. Our analyses place goa-1 Go alpha and let-60 Ras in parallel to gpc-1. In contrast, a gain-of-function mutation in egl-30 Gq alpha was epistatic to gpc-1, suggesting the possibility that gpc-1 G gamma may act upstream of egl-30 Gq alpha.