title: Overexpression of heat shock protein 27 protects against ischaemia/reperfusion-induced cardiac dysfunction via stabilization of troponin I and T.
abstract: OBJECTIVE
  Heat shock protein 27 (Hsp27) renders cardioprotection from ischaemia/reperfusion (I/R) injury, but little is known about its role in myofilaments. We proposed that increased expression of Hsp27 may improve post-ischaemic contractile dysfunction by preventing I/R-induced cardiac troponin I (cTnI) and troponin T (cTnT) degradation.
  
  
  RESULTS
  Adenovirus-mediated Hsp27 overexpression improved contractile function in perfused rat hearts subjected to global no-flow I/R (30-min/30-min). Such improvement was further confirmed in Hsp27-overexpressing cardiomyocytes subjected to simulated I/R (20-min/30-min). Moreover, these cells showed restored myofilament response to Ca(2+) but not intracellular Ca(2+) transients. The protection correlated with attenuation of I/R-induced cTnI and cTnT degradation. Confocal microscopy revealed co-localization of Hsp27 with these proteins. Co-immunoprecipitation and pull-down assays further confirmed that Hsp27 interacted with the COOH-terminus of cTnI and the NH(2)-terminus of cTnT and that Hsp27 overexpression decreased the interaction between mu-calpain (a protease mediating proteolysis of cTnI and cTnT) and cTnI or cTnT under I/R.
  
  
  CONCLUSIONS
  The findings reveal a novel role of Hsp27 in the protection of cTnI and cTnT from I/R-induced degradation by preventing their proteolytic cleavage via interacting with these proteins. Such protection may result in restored post-ischaemic myofilament response to Ca(2+) and improved post-ischaemic contractile function.
authors.affiliation: Laboratory of Molecular Cardiology, Institute of Health Sciences , 225 Chong Qing Nan Rd, Build. No. 1 of Institute of Health Sciences, Rm. 613, Shanghai 200025, China.
authors.forename: Xi-Yuan
authors.initials: XY
authors.lastname: Lu
authors.forename: Le
authors.initials: L
authors.lastname: Chen
authors.forename: Xiao-Long
authors.initials: XL
authors.lastname: Cai
authors.forename: Huang-Tian
authors.initials: HT
authors.lastname: Yang
mesh_terms: D008841:Actin Cytoskeleton / Q000378:metabolism; D000256:Adenoviridae / Q000235:genetics; D000818:Animals; D020013:Calcium Signaling; D002154:Calpain / Q000378:metabolism; D002478:Cells, Cultured; D004195:Disease Models, Animal; D005822:Genetic Vectors; D055551:HSP27 Heat-Shock Proteins / Q000096:biosynthesis* / Q000235:genetics; D006801:Humans; D008297:Male; D009200:Myocardial Contraction; D015428:Myocardial Reperfusion Injury / Q000378:metabolism / Q000503:physiopathology / Q000517:prevention & control*; D009206:Myocardium / Q000378:metabolism*; D010477:Perfusion; D051381:Rats; D017207:Rats, Sprague-Dawley; D013997:Time Factors; D014161:Transduction, Genetic; D019210:Troponin I / Q000378:metabolism*; D020107:Troponin T / Q000378:metabolism*; D016277:Ventricular Function, Left
chemical_list: D055551:HSP27 Heat-Shock Proteins; D019210:Troponin I; D020107:Troponin T; D002154:Calpain; C449002:mu-calpain