Study of Ric-8B's function in mTOR activation by using an olfactory model

• Grant number: 17/00726-2
• Support type: Scholarships abroad - Research Internship - Post-doctor
• Effective date (Start): June 01, 2017
• Effective date (End): May 02, 2018
• Field of knowledge: Biological Sciences - Biochemistry - Molecular Biology
• Principal researcher: Bettina Malnic
• Grantee: Maíra Harume Nagai
• Supervisor abroad: Hiroaki Matsunami
• Home Institution: Instituto de Química (IQ). Universidade de São Paulo (USP). São Paulo , SP, Brazil
• Research place: Duke University, United States
• Associated to the scholarship: 14/15495-8 - Identification of the cellular processes altered in Ric-8B knockout mice by using transcriptome deep sequencing, BP.PD

Abstract

In vitro, RIC-8B interacts with specific ± subunits of heterotrimeric G proteins, acting as both a molecular chaperone and a non-canonic guanine nucleotide exchange factor. Previous findings from our laboratory suggest that RIC-8B may regulate the activation of the olfactory G± subunit, G±olf. G±olf is abundantly expressed in olfactory neurons, where it couples to the heptahelical odorant receptors to transduce odorant signaling. In order to characterize Ric-8B's function in vivo, we generated a Ric-8B mutant mouse line by using the gene trap strategy. We found that Ric-8B is essential during mouse development, and is involved in embryo growth and formation of the central nervous system. We used comparative whole transcriptome profiling to identify differentially expressed genes in the Ric-8B mutant embryo in relation to a wild-type littermate. Data analysis using Ingenuity Pathway Analysis revealed that the canonical pathways most significantly altered in the mutant embryo are related to protein synthesis, such as mTOR signaling. In the cell, the serine/threonine kinase mTOR is present in two distinct multi-protein complexes that are central regulators of cell metabolism, growth, proliferation, and survival. Western blot of whole-embryo lysates indicates that mTOR signaling is reduced in Ric-8B mutant embryos. Moreover, Ric-8B co-immunoprecipitates with mTOR, as well as with other proteins of mTOR complexes, in lysates from HEK293T cells. Our results suggest a so far unknown function for Ric-8B, which may be related to the activation of mTOR signaling pathway by a G-protein. Interestingly, it was recently reported that olfactory neurons responsive to an odorant can be distinguished by an increase in the phosphorylation of the S6 ribosomal protein, generating phosphoS6, which is one of the best well characterized outcomes of mTOR signaling. In this proposal, we aim to study Ric-8B's function in mTOR activation by using an olfactory model. (AU)

Scientific publications

(References retrieved automatically from Web of Science and SciELO through information on FAPESP grants and their corresponding numbers as mentioned in the publications by the authors)

IKEGAMI, KENTARO; DE MARCH, CLAIRE A.; NAGAI, MAIRA H.; GHOSH, SOUMADWIP; DO, MATTHEW; SHARMA, RUCHIRA; BRUGUERA, ELISE S.; LU, YUEYANG ERIC; FUKUTANI, YOSUKE; VAIDEHI, NAGARAJAN; YOHDA, MASAFUMI; MATSUNAMI, HIROAKI. Structural instability and divergence from conserved residues underlie intracellular retention of mammalian odorant receptors. PROCEEDINGS OF THE NATIONAL ACADEMY OF SCIENCES OF THE UNITED STATES OF AMERICA, v. 117, n. 6, p. 2957-2967, FEB 11 2020. Web of Science Citations: 0.

TRIMMER, C.; KELLER, A.; MURPHY, N. R.; SNYDER, L. L.; WILLER, J. R.; NAGAI, M. H.; KATSANIS, N.; VOSSHALL, L. B.; MATSUNAMI, H.; MAINLAND, J. D. Genetic variation across the human olfactory receptor repertoire alters odor perception. PROCEEDINGS OF THE NATIONAL ACADEMY OF SCIENCES OF THE UNITED STATES OF AMERICA, v. 116, n. 19, p. 9475-9480, MAY 7 2019. Web of Science Citations: 5.