51. Urocortin 2 Gene Transfer for Systolic and Diastolic Dysfunction Due to Chronically Increased Left Ventricular Pressure
- Author
-
N. Chin Lai, Zhen Tan, Dimosthenis Giamouridis, Mei Hua Gao, and H. Kirk Hammond
- Subjects
Mice, Inbred C57BL ,Mice ,Angiotensin II ,Ventricular Pressure ,Genetics ,Animals ,Molecular Medicine ,Genetic Therapy ,Hypertrophy ,Molecular Biology ,Urocortins ,Ventricular Function, Left - Abstract
We used transverse aortic constriction (TAC) in mice to test the hypothesis thatiurocortin 2/i(iUcn2/i) gene transfer would increase left ventricular (LV) systolic and diastolic function in the pressure-stressed LV. Three groups were studied: (1) control mice (no TAC); (2) mice that received saline 6 weeks after TAC; and (3) mice that receivediUcn2/igene transfer 6 weeks after TAC, using adeno-associated virus 8 encoding murineiUcn2/i(AAV8.miUcn2/i; 2 × 10sup13/supgenome copies (gc)/kg, i.v. per mouse). Echocardiography was performed 6 and 12 weeks after TAC. In terminal studies 12 weeks after TAC, rates of LV pressure development and decay and Tau were measured, and LV cardiac myocytes (CMs) were isolated and cytosolic Casup2+/suptransients and sarcomere shortening rates recorded. Reverse transcription polymerase chain reaction and immunoblotting were used to measure key proteins in LV samples. A CM cell line (HL-1) was used to explore mechanisms. Concentric LV hypertrophy was evident on echocardiography 6 weeks after TAC. Twelve weeks after TAC, LV ejection fraction (EF) was higher in mice that receivediUcn2/igene transfer (TAC-saline: 65% ± 3%; TAC-Ucn2: 75% ± 2%;ip/i = 0.01), as was LV peak +dP/dt (1.9-fold increase;ip/i = 0.001) and LV peak -dP/dt (1.7-fold increase;ip/i = 0.017). Tau was more rapid (23% reduction,ip/i = 0.02), indicating improved diastolic function. The peak rates of sarcomere shortening (ip/i = 0.002) and lengthening (ip/i = 0.002) were higher in CMs from TAC-Ucn2 mice, and Tau was reduced (ip/i = 0.001). LV (Ser-16) phosphorylation of phospholamban (PLB) was increased in TAC-Ucn2 mice (ip/i = 0.025), and also was increased in HL-1 cells treated with angiotensin II to induce hypertrophy and incubated with Ucn2 peptide (ip/i = 0.001).iUcn2/igene transfer in TAC-induced heart failure with preserved ejection fraction increased cardiac function in the intact LV and provided corresponding benefits in CMs isolated from study animals, including increased myofilament Casup2+/supsensitivity during contraction. The mechanism includes enhanced CM Casup2+/suphandling associated with increased (Ser-16)-PLB.
- Published
- 2022