title: Disruption of Fyn SH3 domain interaction with a proline-rich motif in liver kinase B1 results in activation of AMP-activated protein kinase.
abstract: Fyn-deficient mice display increased AMP-activated Protein Kinase (AMPK) activity as a result of Fyn-dependent regulation of Liver Kinase B1 (LKB1) in skeletal muscle. Mutation of Fyn-specific tyrosine sites in LKB1 results in LKB1 export into the cytoplasm and increased AMPK activation site phosphorylation. This study characterizes the structural elements responsible for the physical interaction between Fyn and LKB1. Effects of point mutations in the Fyn SH2/SH3 domains and in the LKB1 proline-rich motif on 1) Fyn and LKB1 binding, 2) LKB1 subcellular localization and 3) AMPK phosphorylation were investigated in C2C12 muscle cells. Additionally, novel LKB1 proline-rich motif mimicking cell permeable peptides were generated to disrupt Fyn/LKB1 binding and investigate the consequences on AMPK activity in both C2C12 cells and mouse skeletal muscle. Mutation of either Fyn SH3 domain or the proline-rich motif of LKB1 resulted in the disruption of Fyn/LKB1 binding, re-localization of 70% of LKB1 signal in the cytoplasm and a 2-fold increase in AMPK phosphorylation. In vivo disruption of the Fyn/LKB1 interaction using LKB1 proline-rich motif mimicking cell permeable peptides recapitulated Fyn pharmacological inhibition. We have pinpointed the structural elements within Fyn and LKB1 that are responsible for their binding, demonstrating the functionality of this interaction in regulating AMPK activity.
authors.affiliation: Diabetes Research and Training Center, Department of Medicine, Albert Einstein College of Medicine, Bronx, New York, United States of America ; Department of Molecular Pharmacology, Albert Einstein College of Medicine, Bronx, New York, United States of America ; Department of Medicine and Molecular Science, Gunma University Graduate School of Medicine, Gunma, Japan.
authors.forename: Eijiro
authors.initials: E
authors.lastname: Yamada
authors.affiliation: Diabetes Research and Training Center, Department of Medicine, Albert Einstein College of Medicine, Bronx, New York, United States of America ; Division Metabolic and Vascular Health, Warwick Medical School, University of Warwick, Coventry, United Kingdom.
authors.forename: Claire C
authors.initials: CC
authors.lastname: Bastie
mesh_terms: D000091162:AMP-Activated Protein Kinase Kinases; D055372:AMP-Activated Protein Kinases / Q000378:metabolism*; D017667:Adipocytes / Q000166:cytology / Q000378:metabolism; D000818:Animals; D015153:Blotting, Western; D002478:Cells, Cultured; D005455:Fluorescent Antibody Technique; D006367:HeLa Cells; D006801:Humans; D047468:Immunoprecipitation; D008297:Male; D051379:Mice; D008810:Mice, Inbred C57BL; D018482:Muscle, Skeletal / Q000166:cytology / Q000378:metabolism; D009154:Mutation / Q000235:genetics; D010446:Peptide Fragments / Q000378:metabolism*; D010766:Phosphorylation; D055232:Proline-Rich Protein Domains / Q000502:physiology*; D011485:Protein Binding; D017346:Protein Serine-Threonine Kinases / Q000037:antagonists & inhibitors / Q000235:genetics / Q000378:metabolism*; D051076:Proto-Oncogene Proteins c-fyn / Q000037:antagonists & inhibitors / Q000235:genetics / Q000378:metabolism*; D014443:Tyrosine / Q000378:metabolism; D018909:src Homology Domains / Q000502:physiology*
chemical_list: D010446:Peptide Fragments; D014443:Tyrosine; C494957:FYN protein, human; D051076:Proto-Oncogene Proteins c-fyn; D017346:Protein Serine-Threonine Kinases; C109790:STK11 protein, human; D000091162:AMP-Activated Protein Kinase Kinases; D055372:AMP-Activated Protein Kinases