title: Removal of Abnormal Myofilament O-GlcNAcylation Restores Ca2+ Sensitivity in Diabetic Cardiac Muscle.
abstract: Contractile dysfunction and increased deposition of O-linked β-N-acetyl-d-glucosamine (O-GlcNAc) in cardiac proteins are a hallmark of the diabetic heart. However, whether and how this posttranslational alteration contributes to lower cardiac function remains unclear. Using a refined β-elimination/Michael addition with tandem mass tags (TMT)-labeling proteomic technique, we show that CpOGA, a bacterial analog of O-GlcNAcase (OGA) that cleaves O-GlcNAc in vivo, removes site-specific O-GlcNAcylation from myofilaments, restoring Ca(2+) sensitivity in streptozotocin (STZ) diabetic cardiac muscles. We report that in control rat hearts, O-GlcNAc and O-GlcNAc transferase (OGT) are mainly localized at the Z-line, whereas OGA is at the A-band. Conversely, in diabetic hearts O-GlcNAc levels are increased and OGT and OGA delocalized. Consistent changes were found in human diabetic hearts. STZ diabetic hearts display increased physical interactions of OGA with α-actin, tropomyosin, and myosin light chain 1, along with reduced OGT and increased OGA activities. Our study is the first to reveal that specific removal of O-GlcNAcylation restores myofilament response to Ca(2+) in diabetic hearts and that altered O-GlcNAcylation is due to the subcellular redistribution of OGT and OGA rather than to changes in their overall activities. Thus, preventing sarcomeric OGT and OGA displacement represents a new possible strategy for treating diabetic cardiomyopathy.
authors.affiliation: Division of Cardiology, Department of Pediatrics, Johns Hopkins University School of Medicine, Baltimore, MD gramirez@jhmi.edu.
authors.forename: Genaro A
authors.initials: GA
authors.lastname: Ramirez-Correa
authors.affiliation: Department of Biological Chemistry, Johns Hopkins University School of Medicine, Baltimore, MD.
authors.forename: Junfeng
authors.initials: J
authors.lastname: Ma
authors.affiliation: Department of Biochemistry and Molecular Biology, University of Kansas Medical Center, Kansas City, KS.
authors.forename: Chad
authors.initials: C
authors.lastname: Slawson
authors.affiliation: Department of Biological Chemistry, Johns Hopkins University School of Medicine, Baltimore, MD.
authors.forename: Quira
authors.initials: Q
authors.lastname: Zeidan
authors.affiliation: Division of Cardiology, Department of Pediatrics, Johns Hopkins University School of Medicine, Baltimore, MD.
authors.forename: Nahyr S
authors.initials: NS
authors.lastname: Lugo-Fagundo
authors.affiliation: Division of Cardiology, Department of Pediatrics, Johns Hopkins University School of Medicine, Baltimore, MD.
authors.forename: Mingguo
authors.initials: M
authors.lastname: Xu
authors.affiliation: Department of Anesthesiology and Critical Care Medicine, Johns Hopkins University School of Medicine, Baltimore, MD.
authors.forename: Xiaoxu
authors.initials: X
authors.lastname: Shen
authors.affiliation: Department of Anesthesiology and Critical Care Medicine, Johns Hopkins University School of Medicine, Baltimore, MD.
authors.forename: Wei Dong
authors.initials: WD
authors.lastname: Gao
authors.affiliation: Division of Cardiology, Department of Medicine, Johns Hopkins University School of Medicine, Baltimore, MD.
authors.forename: Viviane
authors.initials: V
authors.lastname: Caceres
authors.affiliation: Division of Cardiology, Department of Medicine, Johns Hopkins University School of Medicine, Baltimore, MD.
authors.forename: Khalid
authors.initials: K
authors.lastname: Chakir
authors.affiliation: Department of Biological Chemistry, Johns Hopkins University School of Medicine, Baltimore, MD.
authors.forename: Lauren
authors.initials: L
authors.lastname: DeVine
authors.affiliation: Department of Biological Chemistry, Johns Hopkins University School of Medicine, Baltimore, MD.
authors.forename: Robert N
authors.initials: RN
authors.lastname: Cole
authors.affiliation: Department of Oncology, Johns Hopkins University School of Medicine, Baltimore, MD.
authors.forename: Luigi
authors.initials: L
authors.lastname: Marchionni
authors.affiliation: Division of Cardiology, Department of Medicine, Johns Hopkins University School of Medicine, Baltimore, MD.
authors.forename: Nazareno
authors.initials: N
authors.lastname: Paolocci
authors.affiliation: Department of Biological Chemistry, Johns Hopkins University School of Medicine, Baltimore, MD.
authors.forename: Gerald W
authors.initials: GW
authors.lastname: Hart
authors.affiliation: Division of Cardiology, Department of Pediatrics, Johns Hopkins University School of Medicine, Baltimore, MD.
authors.forename: Anne M
authors.initials: AM
authors.lastname: Murphy
mesh_terms: D000117:Acetylglucosamine / Q000031:analogs & derivatives* / Q000378:metabolism; D000818:Animals; D002118:Calcium / Q000378:metabolism*; D003921:Diabetes Mellitus, Experimental / Q000150:complications* / Q000473:pathology; D058065:Diabetic Cardiomyopathies / Q000378:metabolism*; D015971:Gene Expression Regulation, Enzymologic; D006801:Humans; D008297:Male; D009206:Myocardium / Q000473:pathology / Q000648:ultrastructure; D009210:Myofibrils / Q000378:metabolism; D051381:Rats; D017207:Rats, Sprague-Dawley; D012518:Sarcomeres / Q000201:enzymology; D001619:beta-N-Acetylhexosaminidases / Q000235:genetics / Q000378:metabolism
chemical_list: D001619:beta-N-Acetylhexosaminidases; D002118:Calcium; D000117:Acetylglucosamine