Inhibition of phospholamban phosphorylation by O-GlcNAcylation: implications for diabetic cardiomyopathy

Glycobiology. 2010 Oct;20(10):1217-26. doi: 10.1093/glycob/cwq071. Epub 2010 May 18.


Cardiac-type sarco(endo)plasmic reticulum Ca(2)-ATPase (SERCA2a) plays a major role in cardiac muscle contractility. Phospholamban (PLN) regulates the function of SERCA2a via its Ser(16)-phosphorylation. Since it has been proposed that the Ser/Thr residues on cytoplasmic and nuclear proteins are modified by O-linked N-acetylglucosamine (O-GlcNAc), we examined the effect of O-GlcNAcylation on PLN function in rat adult cardiomyocytes. Studies using enzymatic labeling and co-immunoprecipitation of wild type and a series of mutants of PLN showed that PLN was O-GlcNAcylated and Ser(16) of PLN might be the site for O-GlcNAcylation. In cardiomyocytes treated with O-(2-acetamido-2-deoxy-D-glucopyranosylidene)amino-N-phenylcarbamate (PUGNAc), the O-GlcNAcylation was significantly increased compared to non-treated cells. Simultaneously, Ser(16)-phosphorylation of PLN was reduced. In Chinese hamster ovary cells where PLN cDNA and O-GlcNAc transferase siRNA were co-transfected, the Ser(16)-phosphorylation of PLN was significantly increased compared to controls. The same results were observed in heart homogenates from diabetic rats. In a co-immunoprecipitation of PLN with SERCA2a, the physical interaction between the two proteins was increased in PUGNAc-treated cardiomyocytes. Unlike non-treated cells, the activity of SERCA2a and the profiles of calcium transients in PUGNAc-treated cardiomyocytes were not significantly changed even after treatment with catecholamine. These data suggest that PLN is O-GlcNAcylated to induce the inhibition of its phosphorylation, which correlates to the deterioration of cardiac function. This might define a novel mechanism by which PLN regulation of SERCA2a is altered under conditions where O-GlcNAcylation is increased, such as those occurring in diabetes.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Acetylglucosamine / analogs & derivatives
  • Acetylglucosamine / pharmacology
  • Acylation
  • Animals
  • Blotting, Western
  • CHO Cells
  • Calcium / metabolism
  • Calcium-Binding Proteins / genetics
  • Calcium-Binding Proteins / metabolism*
  • Catecholamines / pharmacology
  • Cricetinae
  • Cricetulus
  • Cyclic AMP-Dependent Protein Kinases / metabolism
  • Diabetes Mellitus, Experimental / complications*
  • Diabetes Mellitus, Experimental / metabolism
  • Diabetes Mellitus, Experimental / pathology
  • Diabetic Cardiomyopathies / etiology*
  • Diabetic Cardiomyopathies / metabolism
  • Diabetic Cardiomyopathies / pathology
  • HeLa Cells
  • Humans
  • Immunoprecipitation
  • Male
  • Mutagenesis, Site-Directed
  • Mutation
  • Myocytes, Cardiac / cytology
  • Myocytes, Cardiac / drug effects
  • Myocytes, Cardiac / metabolism*
  • N-Acetylglucosaminyltransferases / antagonists & inhibitors
  • N-Acetylglucosaminyltransferases / genetics
  • N-Acetylglucosaminyltransferases / metabolism*
  • Oximes / pharmacology
  • Phenylcarbamates / pharmacology
  • Phosphorylation / drug effects
  • Rats
  • Rats, Sprague-Dawley
  • Sarcoplasmic Reticulum Calcium-Transporting ATPases / metabolism*
  • beta-N-Acetylhexosaminidases / antagonists & inhibitors


  • Calcium-Binding Proteins
  • Catecholamines
  • Oximes
  • Phenylcarbamates
  • phospholamban
  • N-acetylglucosaminono-1,5-lactone O-(phenylcarbamoyl)oxime
  • N-Acetylglucosaminyltransferases
  • O-GlcNAc transferase
  • Cyclic AMP-Dependent Protein Kinases
  • beta-N-Acetylhexosaminidases
  • Sarcoplasmic Reticulum Calcium-Transporting ATPases
  • Calcium
  • Acetylglucosamine