The MAPK pathway bisects heterotrimeric G protein signaling through control of G protein subunit biosynthetic protein folding

• DOI: 10.1096/fasebj.31.1_supplement.665.13
• Publication Date: 2023-11-26T17:22:04Z
• Authors: Makaía M Papaserg...; Bharti R. Patel; Meital Gabbay; Gregory Tall
• Keywords: G beta-gamma complex; Casein kinase 2

G‐protein coupled receptor (GPCR) signaling is broadly utilized across physiologic systems and the aberrant of pathways contributes to pathologies including cardiovascular, neurodegenerative, endocrine diseases. The correct folding heterotrimeric G protein α subunits requisite for GPCR signal transduction. Our lab identified Ric‐8A Ric‐8B as necessary biosynthetic chaperones i/q/13 Gα s/olf subunit classes, respectively. In Ric‐8 gene deletion or depletion models are folded improperly, fail become membrane associated, degraded more rapidly. Although function an essential chaperone reasonably well understood, mechanisms regulating activity have not been addressed. We found that mammalian constitutively phosphorylated at multiple sites. Recombinant purified from E.coli enzymatically dephosphorylated insect cells had markedly less than in stimulation vitro guanine nucleotide exchange. Using a combination mass spectrometry‐based phospho‐site identification, analysis phospho‐deficient phospho‐mimetic mutants, −/− genetic complementation assays we two phosphorylation sites required efficient capacity. casein‐kinase 2 (CK2) consensus phospho‐sites, S435 T440, reside acidic region invariantly conserved. When E.coli‐ produced was with CK2, full restored. To further investigate regulation vivo immortalized mouse flox/flox melanocytes transformed made stably express active HRas‐G12V. profound observation HRAS‐G12V ‐transformed HRAS ‐ G12V expressing marked reductions steady state levels, no change transcript levels. dephosphorylation event downstream Ras recapitulated NIH3T3 KRAS‐G13D positive human colorectal cancer cell lines. Moreover, HEK293 Mouse Embryonic Fibroblasts epidermal growth factor led rapid dephosphorylation. These data support our hypothesis “on” due constitutive CK2‐phosphorylation, but can be down regulated via Specifically, MAPK pathway oncogenes ( e.g. RAS‐G V/D ) exposure mitogenic factors may activate phosphatase dephosphorylates Ric‐8A. This means by which acts reduce total cellular Gαi/q/13 levels enhance proliferation given knock‐out enhanced rates. Support Funding Information NIH RO1GM088242 G.G.T., PhRMA Foundation Pre‐doctoral Fellowship M.M.P.S., T32‐GM068411 HHMI “Med‐into‐Grad” M.M.P.S.