Prabhu Yogikala, Müller Rolf, Anjard Christophe, Noegel Angelika A
Institute of Biochemistry I, Centre for Biochemistry, Medical Faculty, University of Cologne, Köln, Germany.
BMC Dev Biol. 2007 May 14;7:44. doi: 10.1186/1471-213X-7-44.
The G-protein-coupled receptor (GPCR) family represents the largest and most important group of targets for chemotherapeutics. They are extremely versatile receptors that transduce signals as diverse as biogenic amines, purins, odorants, ions and pheromones from the extracellular compartment to the interior via biochemical processes involving GTP-binding proteins. Until recently, the cyclic AMP receptors (cARs) were the only known G protein coupled receptors in Dictyostelium discoideum. The completed genome sequence revealed the presence of several families of GPCRs in Dictyostelium, among them members of the family 3 of GPCRs, the GABAB/glutamate like receptor family, which in higher eukaryotes is involved in neuronal signaling.
D. discoideum has seventeen Family 3 members of GPCRs, denoted GrlA through GrlR. Their transcripts are detected throughout development with increased levels during early and late development. We have examined here GrlJ. GFP-tagged GrlJ localises to the plasma-membrane and to internal membranes. Inactivation of the grlJ gene leads to precocious development, and the mutant completes development ~6 hours earlier. Alterations were also noted at the slug stage and in spore formation. grlJ- slugs were longer and broke apart several times on their way to culmination forming smaller but proportionate fruiting bodies. Spores from grlJ- fruiting bodies were malformed and less viable, although the spore differentiation factors were synthesized and sensed normally. Expression of a GFP-tagged full length GrlJ rescued the phenotype.
Our data suggest that GrlJ acts at several stages of Dictyostelium development and that it is a negative regulator in Dictyostelium development.
G蛋白偶联受体（GPCR）家族是化疗药物最重要的靶标群体，数量众多。它们是极其多样的受体，可通过涉及GTP结合蛋白的生化过程，将生物胺、嘌呤、气味剂、离子和信息素等多种信号从细胞外区室传导至细胞内部。直到最近，环磷酸腺苷受体（cARs）仍是盘基网柄菌中唯一已知的G蛋白偶联受体。完整的基因组序列显示，盘基网柄菌中存在多个GPCR家族，其中包括GPCR家族3的成员，即GABAB/谷氨酸样受体家族，在高等真核生物中该家族参与神经信号传导。
盘基网柄菌有17个GPCR家族3成员，命名为GrlA至GrlR。在整个发育过程中均可检测到它们的转录本，在发育早期和晚期水平升高。我们在此研究了GrlJ。绿色荧光蛋白标记的GrlJ定位于质膜和内膜。grlJ基因失活导致发育早熟，突变体完成发育的时间提前约6小时。在蛞蝓阶段和孢子形成过程中也观察到了变化。grlJ-蛞蝓更长，在发育成子实体的过程中会多次分裂，形成较小但比例合适的子实体。grlJ-子实体产生的孢子畸形且活力较低，尽管孢子分化因子的合成和感知正常。绿色荧光蛋白标记的全长GrlJ的表达挽救了该表型。
我们的数据表明，GrlJ在盘基网柄菌发育的多个阶段发挥作用，并且是盘基网柄菌发育的负调节因子。
