Impaired binding of ZASP/Cypher with phosphoglucomutase 1 is associated with dilated cardiomyopathy.
OBJECTIVE
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.


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.


CONCLUSIONS
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.
Department of Molecular Pathogenesis, Medical Research Institute, Tokyo Medical and Dental University, 1-5-45 Bunkyo-Ku, Tokyo, Japan.
Takuro
T
Arimura
Natsuko
N
Inagaki
Takeharu
T
Hayashi
Daisuke
D
Shichi
Akinori
A
Sato
Kunihiko
K
Hinohara
Matteo
M
Vatta
Jeffrey A
JA
Towbin
Taishiro
T
Chikamori
Akira
A
Yamashina
Akinori
A
Kimura
D048868:Adaptor Proteins, Signal Transducing / Q000235:genetics / Q000378:metabolism*; D000818:Animals; D019556:COS Cells; D002311:Cardiomyopathy, Dilated / Q000235:genetics / Q000378:metabolism* / Q000473:pathology; D002478:Cells, Cultured; D002522:Chlorocebus aethiops; D004195:Disease Models, Animal; D005091:Exons / Q000235:genetics; D006367:HeLa Cells; D006801:Humans; D060588:LIM Domain Proteins; D009154:Mutation / Q000235:genetics; D032383:Myocytes, Cardiac / Q000378:metabolism* / Q000473:pathology; D010733:Phosphoglucomutase / Q000235:genetics / Q000378:metabolism*; D010957:Plasmids / Q000235:genetics; D011485:Protein Binding / Q000235:genetics; D051381:Rats; D017207:Rats, Sprague-Dawley; D014162:Transfection
D048868:Adaptor Proteins, Signal Transducing; C120696:LDB3 protein, human; D060588:LIM Domain Proteins; C488050:PGM1 protein, human; D010733:Phosphoglucomutase