MAP4K4 expression in cardiomyocytes: multiple isoforms, multiple phosphorylations and interactions with striatins
| Autor: | Daniel N. Meijles, Hajed O. Alharbi, Angela Clerk, Michelle A. Hardyman, Peter H. Sugden, Liam J. McGuffin, Joshua J Cull, Stephen J. Fuller, Nick S. Edmunds |
|---|---|
| Jazyk: | angličtina |
| Rok vydání: | 2021 |
| Předmět: |
cardiac myocytes
Protein Conformation Phosphatase Hyperphosphorylation Sequence Homology Nerve Tissue Proteins Protein Serine-Threonine Kinases Biochemistry Rats Sprague-Dawley Animals Humans Protein Isoforms Myocytes Cardiac Protein Interaction Domains and Motifs Amino Acid Sequence Protein Phosphatase Inhibitor Kinase activity Phosphorylation Molecular Biology Research Articles Molecular Interactions Kinase Chemistry Intracellular Signaling Peptides and Proteins JNK Mitogen-Activated Protein Kinases Membrane Proteins Computational Biology protein-serine-threonine kinases Cell Biology Protein phosphatase 2 Signaling Cell biology Rats Alternative Splicing HEK293 Cells Protein kinase domain Cardiovascular System & Vascular Biology Mutation Calmodulin-Binding Proteins Female protein phosphatases |
| Zdroj: | Biochemical Journal |
| ISSN: | 1470-8728 0264-6021 |
| Popis: | The Ser/Thr kinase MAP4K4, like other GCKIV kinases, has N-terminal kinase and C-terminal citron homology (CNH) domains. MAP4K4 can activate c-Jun N-terminal kinases (JNKs), and studies in the heart suggest it links oxidative stress to JNKs and heart failure. In other systems, MAP4K4 is regulated in striatin-interacting phosphatase and kinase (STRIPAK) complexes, in which one of three striatins tethers PP2A adjacent to a kinase to keep it dephosphorylated and inactive. Our aim was to understand how MAP4K4 is regulated in cardiomyocytes. The rat MAP4K4 gene was not properly defined. We identified the first coding exon of the rat gene using 5′-RACE, we cloned the full-length sequence and confirmed alternative-splicing of MAP4K4 in rat cardiomyocytes. We identified an additional α-helix C-terminal to the kinase domain important for kinase activity. In further studies, FLAG-MAP4K4 was expressed in HEK293 cells or cardiomyocytes. The Ser/Thr protein phosphatase inhibitor calyculin A (CalA) induced MAP4K4 hyperphosphorylation, with phosphorylation of the activation loop and extensive phosphorylation of the linker between the kinase and CNH domains. This required kinase activity. MAP4K4 associated with myosin in untreated cardiomyocytes, and this was lost with CalA-treatment. FLAG-MAP4K4 associated with all three striatins in cardiomyocytes, indicative of regulation within STRIPAK complexes and consistent with activation by CalA. Computational analysis suggested the interaction was direct and mediated via coiled-coil domains. Surprisingly, FLAG-MAP4K4 inhibited JNK activation by H2O2 in cardiomyocytes and increased myofibrillar organisation. Our data identify MAP4K4 as a STRIPAK-regulated kinase in cardiomyocytes, and suggest it regulates the cytoskeleton rather than activates JNKs. |
| Databáze: | OpenAIRE |
| Externí odkaz: |
|