| First Author | Sheridan DJ | Year | 2000 |
| Journal | Cardiovasc Res | Volume | 47 |
| Issue | 1 | Pages | 133-41 |
| PubMed ID | 10869539 | Mgi Jnum | J:162755 |
| Mgi Id | MGI:4819709 | Doi | 10.1016/s0008-6363(00)00065-1 |
| Citation | Sheridan DJ, et al. (2000) Beta(2)-adrenergic receptor overexpression driven by alpha-MHC promoter is downregulated in hypertrophied and failing myocardium. Cardiovasc Res 47(1):133-41 |
| abstractText | OBJECTIVE: The alpha-myosin heavy chain (alpha-MHC) promoter is frequently used to direct cardiac specific transgene expression. We studied whether transgene expression controlled by this promoter was altered under conditions of cardiac hypertrophy and failure. METHODS: Transgenic (TG) mice overexpressing human beta(2)-adrenergic receptors (beta(2)AR) and wild type (WT) controls were subjected to thoracic aortic constriction (TAC) or sham operation and studied at 1, 3 and 8 weeks after surgery. RESULTS: Sham operated TG mice had higher heart rates and left ventricular (LV) contractility than WT (all P<0.01), demonstrating enhanced betaAR activation. TAC at 1, 3 and 8 weeks produced progressive LV hypertrophy which was similar between WT and TG mice. Evidence of heart failure was more marked in TG mice with a greater increase in weights of the right ventricle and lungs and a higher prevalence of atrial thrombus (P<0.05 in each case). In hypertrophied TG hearts, endogenous alpha-MHC mRNA transcripts in LV were maintained at 1 and 3 weeks, but were reduced by approximately 40% relative to the sham-operated group at 8 weeks after TAC. Transgene expression, measured as human beta(2)AR mRNA, was reduced by 45% at 1 and 3 weeks and by 70% at 8 weeks after TAC. beta(2)AR binding sites were reduced by 35, 47 and 65%, respectively, at 1, 3 and 8 weeks. CONCLUSION: Cardiac hypertrophy and failure cause downregulation of the endogenous alpha-MHC as well as cardiac specific overexpression of the transgene directed by an alpha-MHC promoter. |
