title: Knockdown of AT-rich interaction domain (ARID) 5B gene expression induced AMPKα2 activation in cardiac myocytes.
abstract: This study demonstrated that ARID5B mRNA is present in mouse cardiomyocyte HL-1 cells, and that ARID5B siRNA constantly knocked down ARID5B gene expression to the 40% level of control. AMPKα2 protein was elevated in such ARID5B knockdown HL-1 cells, and this was accompanied by an increase in the level of phosphorylated AMPKα. Since AMPKα2 mRNA levels did not change in ARID5B knockdown cells, the stability of AMPKα2 protein was investigated using inhibitors for protein synthesis and proteasomal degradation. Treatment of HL-1 cells with either cycloheximide or MG132 caused an appreciable increase in the amount of AMPKα2 protein in ARID5B knockdown cells, which suggests that knockdown of ARID5B mRNA extends the half-life of AMPKα2 protein in HL-1 cells via yet unidentified mechanisms. As for the expected downstream consequences of AMPKα2 activation, we found thus far that glucose uptake, fatty acid uptake, or fatty acid oxidation remained unchanged in HL-1 cells after knockdown of ARID5B. Further studies are required to understand the mechanisms for ARID5B knockdown and resulting AMPKα2 activation, and also to identify which metabolic pathways are affected by AMPKα2 activation in these cells. In summary, this study provided the foundation for an in vitro cell culture system to study possible roles of ARID5B in cardiomyocytes.
authors.affiliation: Department of Molecular & Cellular Biology, Beckman Research Institute of City of Hope.
authors.forename: Lisa
authors.initials: L
authors.lastname: Hirose-Yotsuya
authors.forename: Fumio
authors.initials: F
authors.lastname: Okamoto
authors.forename: Takahiro
authors.initials: T
authors.lastname: Yamakawa
authors.forename: Robert H
authors.initials: RH
authors.lastname: Whitson
authors.forename: Yoko
authors.initials: Y
authors.lastname: Fujita-Yamaguchi
authors.forename: Keiichi
authors.initials: K
authors.lastname: Itakura
mesh_terms: D055372:AMP-Activated Protein Kinases / Q000378:metabolism*; D000818:Animals; D002460:Cell Line; D003513:Cycloheximide / Q000494:pharmacology; D004268:DNA-Binding Proteins / Q000235:genetics / Q000378:metabolism / Q000502:physiology*; D005227:Fatty Acids / Q000378:metabolism; D055785:Gene Knockdown Techniques; D005947:Glucose / Q000378:metabolism; D007976:Leupeptins / Q000494:pharmacology; D008297:Male; D051379:Mice; D009206:Myocardium / Q000378:metabolism; D032383:Myocytes, Cardiac / Q000378:metabolism*; D010084:Oxidation-Reduction; D010766:Phosphorylation; D012333:RNA, Messenger / Q000378:metabolism; D015398:Signal Transduction; D014157:Transcription Factors / Q000235:genetics / Q000378:metabolism / Q000502:physiology*
chemical_list: C503806:Arid5b protein, mouse; D004268:DNA-Binding Proteins; D005227:Fatty Acids; D007976:Leupeptins; D012333:RNA, Messenger; D014157:Transcription Factors; D003513:Cycloheximide; C534978:Prkaa2 protein, mouse; D055372:AMP-Activated Protein Kinases; D005947:Glucose; C072553:benzyloxycarbonylleucyl-leucyl-leucine aldehyde