title: A Phosphoproteomic Screen Identifies a Guanine Nucleotide Exchange Factor for Rab3A Protein as a Mitogen-activated Protein (MAP) Kinase Phosphatase-5-regulated MAP Kinase Target in Interleukin 6 (IL-6) Secretion and Myogenesis.
abstract: The mitogen-activated protein kinases (MAPKs) have been shown to regulate skeletal muscle function. Previously, we showed that MAPK phosphatase-5 (MKP-5) negatively regulates myogenesis and regeneration of skeletal muscle through inhibition of p38 MAPK and c-Jun N-terminal kinase (JNK). However, the identity and contribution of MKP-5-regulated MAPK targets in the control of skeletal muscle function and regenerative myogenesis have not been established. To identify MKP-5-regulated MAPK substrates in skeletal muscle, we performed a global differential phospho-MAPK substrate screen in regenerating skeletal muscles of wild type and MKP-5-deficient mice. We discovered a novel MKP-5-regulated MAPK substrate called guanine nucleotide exchange factor for Rab3A (GRAB) that was hyperphosphorylated on a phospho-MAPK motif in skeletal muscle of MKP-5-deficient mice. GRAB was found to be phosphorylated by JNK on serine 169. Myoblasts overexpressing a phosphorylation-defective mutant of GRAB containing a mutation at Ser-169 to Ala-169 (GRAB-S169A) inhibited the ability of C2C12 myoblasts to differentiate. We found that GRAB phosphorylation at Ser-169 was required for the secretion of the promyogenic cytokine interleukin 6 (IL-6). Consistent with this observation, MKP-5-deficient mice exhibited increased circulating IL-6 expression as compared with wild type mice. Collectively, these data demonstrate a novel mechanism whereby MKP-5-mediated regulation of JNK negatively regulates phosphorylation of GRAB, which subsequently controls secretion of IL-6. These data support the notion that MKP-5 serves as a negative regulator of MAPK-dependent signaling of critical skeletal muscle signaling pathways.
authors.affiliation: From the Department of Pharmacology and.
authors.forename: Hojin
authors.initials: H
authors.lastname: Lee
authors.affiliation: From the Department of Pharmacology and.
authors.forename: Kisuk
authors.initials: K
authors.lastname: Min
authors.affiliation: From the Department of Pharmacology and.
authors.forename: Jae-Sung
authors.initials: JS
authors.lastname: Yi
authors.affiliation: the Department of Animal and Poultry Sciences, Virginia Polytechnic Institute and State University, Blacksburg, Virginia 24060.
authors.forename: Hao
authors.initials: H
authors.lastname: Shi
authors.affiliation: the Department of Biology Education, College of Education, Pusan National University, Busan 609-735, Republic of Korea, and.
authors.forename: Woochul
authors.initials: W
authors.lastname: Chang
authors.affiliation: Program in Public Health, University of California, Irvine, California 92697.
authors.forename: Leandra
authors.initials: L
authors.lastname: Jackson
authors.affiliation: From the Department of Pharmacology and anton.bennett@yale.edu.|Program in Integrative Cell Signaling and Neurobiology of Metabolism, Yale University, New Haven, Connecticut 06520.
authors.forename: Anton M
authors.identifier: 0000-0001-5187-7599
authors.initials: AM
authors.lastname: Bennett
mesh_terms: D020816:Amino Acid Motifs; D000818:Animals; D002465:Cell Movement; D049109:Cell Proliferation; D054637:Dual-Specificity Phosphatases / Q000378:metabolism*; D015971:Gene Expression Regulation, Enzymologic; D020662:Guanine Nucleotide Exchange Factors / Q000378:metabolism*; D015850:Interleukin-6 / Q000378:metabolism*; D020935:MAP Kinase Signaling System; D051379:Mice; D018345:Mice, Knockout; D024510:Muscle Development; D018482:Muscle, Skeletal / Q000378:metabolism; D009154:Mutation; D032446:Myoblasts / Q000378:metabolism; D010766:Phosphorylation; D040901:Proteomics; D012038:Regeneration; D012694:Serine / Q000737:chemistry; D020826:rab3A GTP-Binding Protein / Q000378:metabolism*
chemical_list: D020662:Guanine Nucleotide Exchange Factors; D015850:Interleukin-6; C000620981:Rab3il1 protein, mouse; C577686:interleukin-6, mouse; D012694:Serine; C505617:Dusp10 protein, mouse; D054637:Dual-Specificity Phosphatases; D020826:rab3A GTP-Binding Protein
keywords: cytokine; dual specificity phosphoprotein phosphatase; mitogen-activated protein kinase (MAPK); myogenesis; phosphoproteomics; skeletal muscle