AGS-3 AltersCaenorhabditis elegansBehavior after Food Deprivation via RIC-8 Activation of the Neural G Protein Gα_o

Abstract

Proteins containing the G Protein Regulator (GPR) domain bind the major neural G protein Gαo in vitro. However, the biological functions of GPR proteins in neurons remain undefined, and based on the in vitro activities of GPR proteins it is unclear whether these proteins activate or inhibit G protein signaling in vivo. We found that the conserved GPR domain protein AGS-3 activates Gαo signaling in vivo to allow C. elegans to alter several behaviors after food deprivation, apparently so that the animals can more effectively seek food. AGS-3 undergoes a progressive change in its biochemical fractionation upon food deprivation, suggesting that effects of food deprivation are mediated by modifying this protein. We analyzed one C. elegans food-regulated behavior in depth: AGS-3 activates Gαo in the ASH chemosensory neurons to allow food-deprived animals to delay response to the aversive stimulus octanol. Genetic epistasis experiments show that 1) AGS-3 and the guanine nucleotide exchange factor RIC-8 act in ASH in a mutually-dependent fashion to activate Gαo; 2) this activation requires interaction of the GPR domains of AGS-3 with Gαo; and 3) Gαo-GTP is ultimately the signaling molecule that acts in ASH to delay octanol response. These results identify a biological role for AGS-3 in response to food deprivation and indicate the mechanism for its activation of Gαo signaling in vivo.

Activators of G Protein Signaling Exhibit Broad Functionality and Define a Distinct Core Signaling Triad

“…1). In mammalian systems, AGS3 is implicated in asymmetric cell division, neuronal plasticity and addiction, autophagy, membrane protein trafficking, polycystic kidney disease, renal response to ischemia, immune cell chemotaxis, insulin-like growth factor-1 mediated ciliary resorption, cardiovascular regulation, and metabolism (Blumer et al, 2002(Blumer et al, , 2006(Blumer et al, , 2008Ghosh et al, 2003;Gotta et al, 2003;Pattingre et al, 2003;Bowers et al, 2004Bowers et al, , 2008Sato et al, 2004;Yao et al, 2005Yao et al, , 2006Groves et al, 2007;Willard et al, 2008;Groves et al, 2010;Nadella et al, 2010;Vural et al, 2010;Hofler and Koelle, 2011;Regner et al, 2011;Chauhan et al, 2012;Kwon et al, 2012;Conley and Watts, 2013;Kamakura et al, 2013;Yeh et al, 2013). AGS3 single nucleotide polymorphisms are associated with diabetes and glucose handling (Scott et al, 2012;Hara et al, 2014;Huyghe et al, 2013).…”

“…D. melanogaster has one GPR protein (partner of inscuteable) that has a domain structure similar to mammalian AGS3 and AGS5 and plays an important functional role in asymmetric cell division and cell polarity (Parmentier et al, 2000;Schaefer et al, 2000Schaefer et al, , 2001Yu et al, 2000;Nipper et al, 2007;Cabernard et al, 2010;Yoshiura et al, 2012;Bergstralh et al, 2013). C. elegans has two GPR proteins, one of which is similar to AGS3 and AGS5 and may integrate neural signals required for system adaptation (Hofler and Koelle, 2011). A second C. elegans GPR protein, GPR1/2, is required for asymmetric cell division during early development (Colombo et al, 2003;Gotta et al, 2003;Srinivasan et al, 2003).…”

“…For example, during neutrophil chemotaxis the GaiAGS3 complex acts as a docking site for polarized formation of a mInsc-Par3-Par6-aPKC complex, which is important for efficient chemokine-directed migration (Kamakura et al, 2013). Such a GaGPR complex could also serve as a target for group I AGS proteins, as suggested for signaling events associated with feeding behavior in C. elegans (Hofler and Koelle, 2011). Such signaling events may be cyclic and could result in the generation of different combinations of Ga and Gbg by subunit exchange (Fig.…”

Translocation of Activator of G-protein Signaling 3 to the Golgi Apparatus in Response to Receptor Activation and Its Effect on the trans-Golgi Network

“…ity, autophagy, protein trafficking, hearing, morphogenesis, and the renal response to injury (15)(16)(17)(18)(19)(20)(21)(22)(23)(24)(25)(26)(27)(28)(29)(30). Although the majority of G␣ within the cell probably exists as part of the G␣␤␥ heterotrimer at the cell cortex, a subpopulation of G␣ i is apparently complexed with GPR proteins.…”

A Novel Strategy for Cell-Autonomous Gene Knockdown in Caenorhabditis elegans Defines a Cell-Specific Function for the G-Protein Subunit GOA-1

“…Worms were grown in 125 ml liquid cultures as described in Hofler and Koelle (2011). Animals were cleaned using a 30% sucrose solution and washed twice with 0.1 M NaCl.…”