Caveolin induces cardioprotection through epigenetic regulation

Abstract

Lipid rafts represent a sub-compartment of the plasma membrane that co-ordinate and regulate varieties of signalling processes, whereas caveolins are the integral membrane protein of the lipid raft. Recent evidence demonstrated the pivotal role of caveolins in cardioprotection against ischaemic injury, although their mechanism of action is not clear. However, new understanding of epigenetic modification during ischaemia reperfusion suggests additional targeted approaches that have not been explored before. To study the role of caveolin on epigenetic regulation, isolated mouse heart was prepared from wild-type (WT) and caveolin-1 knockout (Cav-1 KO) mouse and preconditioned them with four cyclic episodes of ischaemia/reperfusion followed by 30 min. global ischaemia and 120 min. reperfusion. We found that Cav-1 KO mouse abolished the acetylation of histone (H3 and H4) and increased the methylation of histone in the preconditioned heart. The increased histone methylation was significantly correlated with an increased level of histone methyltranferase G9a protein and increased the level of histone decaetylase (HDAC) activity. Cav-1 KO mouse also decreased the translocation of forkhead transcription factor (FOXO3a) to the nucleus and reduced the induction of the expression of SIRT-1 in the preconditioned heart. Cardioprotective property of Cav-1 was further confirmed by reduced ventricular function, increased cardiomyocyte apoptosis, increased expression of junas kinase (JNK) and Bax and decreased expression of phospho-adenosine monophosphate-activated protein kinase (AMPK), phospho-AKT and B cell lymphoma-2 (Bcl-2) in Cav-1 KO preconditioned heart. The results clearly indicate that Cav-1 induces cardioprotection through epigenetic regulation.

Fig 1

Effect on caveolin-1 on preconditioning of the heart. Results are showing different haemodynamic parameters of the mouse heart. Data represent mean ± S.E.M. *P < 0.05 versus WT I/R, †P < 0.05 versus Cav-1 KO PC. WT: wild-type mouse; Cav-1: caveolin-1 knockout mouse.

Fig 2

Effect of caveolin-1 on caspase-3 and cytochrome c. C: control; I/R: ischaemia/reperfusion; PC: precondition; WT: wild-type mouse; Cav-1: caveolin-1 knockout mouse. (A) Representative picture of Western blot analysis. (B) Densitometric scanning of the blots. Results are average ± S.E.M. of three different sets of blots. *P < 0.05 versus corresponding bots of Cav-1 KO.

Fig 3

Effect of caveolin-1 on acetylation and methylation of H3 and H4 histone protein. Ac-H3: acetylated H3 histone; Ac-H4: acetylated H4 histone; H3K9: histone H3 lysine 9; H3K27: histone H3 lysine 27; C: control; I/R: ischaemia/reperfusion; PC: precondition; WT: wild-type mouse; Cav-1: caveolin-1 knockout mouse.

Fig 4

Effect of caveolin-1 on HAT and HDAC activity. Results are mean ± S.E.M. *P < 0.05 versus WT I/R, †P < 0.05 versus Cav-1 KO PC. C: control; I/R: ischaemia/reperfusion; PC: precondition; WT: wild-type mouse; Cav-1: caveolin-1 knockout mouse.

Fig 5

Effect of caveolin-1 on (A) FOXO3a translocation and (B) SIRT-1 expression. C: control; I/R: ischaemia/reperfusion; PC: precondition; WT: wild-type mouse; Cav-1: caveolin-1 knockout mouse. (A) Representative picture of Western blot analysis. (B) Densitometric scanning of the blots. Results are average ± S.E.M. of three different sets of blots. *P < 0.05 versus corresponding bots of Cav-1 KO.

Fig 6

Effect of caveolin-1 on different survival and non-survival proteins. C: control; I/R: ischaemia/reperfusion; PC: precondition; WT: wild-type mouse: Cav-1: caveolin-1 knockout mouse.