Depletion of Ric-8B leads to reduced mTORC2 activity

Autoři: Maíra H. Nagai aff001;  Victor P. S. Xavier aff001;  Luciana M. Gutiyama aff001;  Cleiton F. Machado aff001;  Alice H. Reis aff002;  Elisa R. Donnard aff003;  Pedro A. F. Galante aff003;  Jose G. Abreu aff002;  William T. Festuccia aff004;  Bettina Malnic aff001
Působiště autorů: Department of Biochemistry, University of São Paulo, São Paulo, Brazil aff001;  Institute of Biomedical Sciences, Federal University of Rio de Janeiro, Rio de Janeiro, Brazil aff002;  Centro de Oncologia Molecular, Hospital Sírio-Libanês, São Paulo, Brazil aff003;  Department of Physiology and Biophysics, Institute of Biomedical Sciences, University of São Paulo, São Paulo, Brazil aff004
Vyšlo v časopise: Depletion of Ric-8B leads to reduced mTORC2 activity. PLoS Genet 16(5): e32767. doi:10.1371/journal.pgen.1008255
Kategorie: Research Article
doi: 10.1371/journal.pgen.1008255


mTOR, a serine/threonine protein kinase that is involved in a series of critical cellular processes, can be found in two functionally distinct complexes, mTORC1 and mTORC2. In contrast to mTORC1, little is known about the mechanisms that regulate mTORC2. Here we show that mTORC2 activity is reduced in mice with a hypomorphic mutation of the Ric-8B gene. Ric-8B is a highly conserved protein that acts as a non-canonical guanine nucleotide exchange factor (GEF) for heterotrimeric Gαs/olf type subunits. We found that Ric-8B hypomorph embryos are smaller than their wild type littermates, fail to close the neural tube in the cephalic region and die during mid-embryogenesis. Comparative transcriptome analysis revealed that signaling pathways involving GPCRs and G proteins are dysregulated in the Ric-8B mutant embryos. Interestingly, this analysis also revealed an unexpected impairment of the mTOR signaling pathway. Phosphorylation of Akt at Ser473 is downregulated in the Ric-8B mutant embryos, indicating a decreased activity of mTORC2. Knockdown of the endogenous Ric-8B gene in cultured cell lines leads to reduced phosphorylation levels of Akt (Ser473), further supporting the involvement of Ric-8B in mTORC2 activity. Our results reveal a crucial role for Ric-8B in development and provide novel insights into the signals that regulate mTORC2.

Klíčová slova:

Apoptosis – Cell signaling – Embryos – Epithelium – G-protein signaling – Gene expression – Phenotypes – Polymerase chain reaction


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