Cardiovascular Research Advance Access first published online on April 17, 2009
This version [Corrected Proof] published online on May 13, 2009
Cardiovascular Research, doi:10.1093/cvr/cvp119
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Impaired binding of ZASP/Cypher with phosphoglucomutase 1 is associated with dilated cardiomyopathy
1 Department of Molecular Pathogenesis, Medical Research Institute, Tokyo Medical and Dental University, 1-5-45 Bunkyo-Ku, Tokyo 113-8510, Japan
2 Second Department of Internal Medicine, Tokyo Medical University School of Medicine, Tokyo, Japan
3 Laboratory of Genome Diversity, School of Biomedical Science, Tokyo Medical and Dental University, Tokyo, Japan
4 Department of Pediatrics (Cardiology), Baylor College of Medicine, Houston, TX, USA
* Corresponding author. Tel: +81 3 5803 4905; fax: +81 3 5803 4907. E-mail address: akitis{at}mri.tmd.ac.jp
Aims: Z-band alternatively spliced PDZ-motif protein (ZASP)/Cypher is a Z-disc component of which several dilated cardiomyopathy (DCM)-associated mutations have been reported. Most of the mutations were found in exons 4 and 10 of ZASP/Cypher gene LDB3 and both exons were expressed preferentially in the heart. The aim of this study was to investigate the functional alteration of ZASP/Cypher caused by the DCM-associated mutations.
Methods and results: The yeast-two-hybrid method was used to identify the protein bound to a domain encoded by exon 4 of LDB3. Interaction of ZASP/Cypher with the binding protein was investigated in relation to the functional alterations caused by LDB3 mutations. Localization of the ZASP/Cypher-binding protein was examined at the cellular level in rat cardiomyocytes. Phosphoglucomutase 1 (PGM1), a metabolic enzyme involved in glycolysis and gluconeogenesis, was identified as a protein interacting with ZASP/Cypher. PGM1 bound to ZASP/Cypher at the domains encoded by exons 4 and 10. Two LDB3 mutations in exon 4 (Ser189Leu and Thr206Ile) and another mutation in exon 10 (Ile345Met) reduced the binding to PGM1. PGM1 showed diffuse localization in the cytoplasm of rat cardiomyocytes under standard culture conditions, and distribution at the Z-discs was observed under stressed culture conditions. Binding of endogenous PGM1 and ZASP/Cypher was found to be enhanced by stress in rat cardiomyocytes.
Conclusion: ZASP/Cypher anchors PGM1 to Z-disc under conditions of stress. The impaired binding of PGM1 to ZASP/Cypher might be involved in the pathogenesis of DCM.
KEYWORDS Cardiomyopathy; Energy metabolism; Mutation; ZASP/Cypher; Z-disc; Phosphoglucomutase 1
Time for primary review: 24 days
These authors contributed equally to this work.