Journal article
Molecular Determinants of Calpain-dependent Cleavage of Junctophilin-2 Protein in Cardiomyocytes
The Journal of biological chemistry, Vol.290(29), pp.17946-17955
07/17/2015
DOI: 10.1074/jbc.M115.652396
PMCID: PMC4505042
PMID: 26063807
Abstract
Background:
Down-regulation of junctophilin-2 is associated with a variety of cardiac diseases.
Results:
Junctophilin-2 is cleaved by calpain at multiple sites, resulting in dysfunctional junctophilin-2 truncations.
Conclusion:
Calpain-mediated proteolysis contributes to posttranslational down-regulation of junctophilin-2.
Significance:
These data reveal, for the first time, the detailed molecular determinants responsible for calpain proteolysis of junctophilin-2.
Junctophilin-2 (JP2), a membrane-binding protein that provides a structural bridge between the plasmalemma and sarcoplasmic reticulum, is essential for precise Ca
2+
-induced Ca
2+
release during excitation-contraction coupling in cardiomyocytes. In animal and human failing hearts, expression of JP2 is decreased markedly, but the molecular mechanisms underlying JP2 down-regulation remain incompletely defined. In mouse hearts, ischemia/reperfusion injury resulted in acute JP2 down-regulation, which was attenuated by pretreatment with the calpain inhibitor MDL-28170 or by transgenic overexpression of calpastatin, an endogenous calpain inhibitor. Using a combination of computational analysis to predict calpain cleavage sites and
in vitro
calpain proteolysis reactions, we identified four putative calpain cleavage sites within JP2 with three N-terminal and one C-terminal cleavage sites. Mutagenesis defined the C-terminal region of JP2 as the predominant calpain cleavage site. Exogenous expression of putative JP2 cleavage fragments was not sufficient to rescue Ca
2+
handling in JP2-deficient cardiomyocytes, indicating that cleaved JP2 is non-functional for normal Ca
2+
-induced Ca
2+
release. These data provide new molecular insights into the posttranslational regulatory mechanisms of JP2 in cardiac diseases.
Details
- Title: Subtitle
- Molecular Determinants of Calpain-dependent Cleavage of Junctophilin-2 Protein in Cardiomyocytes
- Creators
- Ang GuoDuane HallCaimei ZhangTianqing PengJordan D MillerWilliam KutschkeChad E GrueterFrances L JohnsonRichard Z LinLong-Sheng Song
- Resource Type
- Journal article
- Publication Details
- The Journal of biological chemistry, Vol.290(29), pp.17946-17955
- DOI
- 10.1074/jbc.M115.652396
- PMID
- 26063807
- PMCID
- PMC4505042
- NLM abbreviation
- J Biol Chem
- ISSN
- 0021-9258
- eISSN
- 1083-351X
- Publisher
- American Society for Biochemistry and Molecular Biology
- Grant note
- R01 HL090905 / National Institutes of Health
- Alternative title
- Molecular Determinants of Junctophilin-2 Cleavage
- Language
- English
- Date published
- 07/17/2015
- Academic Unit
- Cardiovascular Medicine; Craniofacial Anomalies Research Center; Fraternal Order of Eagles Diabetes Research Center; Biochemistry and Molecular Biology; Internal Medicine
- Record Identifier
- 9984094311602771
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