Reddy Haritha P, Yakubovich Daniel, Keren-Raifman Tal, Tabak Galit, Tsemakhovich Vladimir A, Pedersen Maria H, Shalomov Boris, Colombo Sophie, Goldstein David B, Javitch Jonathan A, Bera Amal K, Dascal Nathan
Department of Physiology and Pharmacology, School of Medicine, Tel Aviv University, Tel Aviv 6997801, Israel.
Department of Biotechnology, Bhupat and Jyoti Mehta School of Biosciences, Indian Institute of Technology Madras, Chennai 600036, India.
iScience. 2021 Aug 21;24(9):103018. doi: 10.1016/j.isci.2021.103018. eCollection 2021 Sep 24.
Mutations in the gene, encoding the Gβ subunit of heterotrimeric G proteins, cause Encephalopathy. Patients experience seizures, pointing to abnormal activity of ion channels or neurotransmitter receptors. We studied three Gβ mutations (K78R, I80N and I80T) using computational and functional approaches. In heterologous expression models, these mutations did not alter the coupling between G protein-coupled receptors to G, or the Gβγ regulation of the neuronal voltage-gated Ca channel Ca2.2. However, the mutations profoundly affected the Gβγ regulation of the G protein-gated inwardly rectifying potassium channels (GIRK, or Kir3). Changes were observed in Gβ protein expression levels, Gβγ binding to cytosolic segments of GIRK subunits, and in Gβγ function, and included gain-of-function for K78R or loss-of-function for I80T/N, which were GIRK subunit-specific. Our findings offer new insights into subunit-dependent gating of GIRKs by Gβγ, and indicate diverse etiology of Encephalopathy cases, bearing a potential for personalized treatment.
编码异源三聚体G蛋白Gβ亚基的基因突变会导致脑病。患者会出现癫痫发作，这表明离子通道或神经递质受体存在异常活动。我们使用计算和功能方法研究了三种Gβ突变（K78R、I80N和I80T）。在异源表达模型中，这些突变并未改变G蛋白偶联受体与G之间的偶联，也未改变神经元电压门控钙通道Ca2.2的Gβγ调节。然而，这些突变对G蛋白门控内向整流钾通道（GIRK，即Kir3）的Gβγ调节产生了深远影响。在Gβ蛋白表达水平、Gβγ与GIRK亚基胞质段的结合以及Gβγ功能方面均观察到了变化，包括K78R的功能增强或I80T/N的功能丧失，这些都是GIRK亚基特异性的。我们的研究结果为Gβγ对GIRKs的亚基依赖性门控提供了新的见解，并表明脑病病例存在多种病因，具有个性化治疗的潜力。
