Figure 4.

Phosphorylation of p70 S6K and JNK during TERT-induced hypertrophy in vivo and in vitro. (A) Telomerase activity in rat ventricular myocytes after viral gene transfer, measured by the TRAP assay. IC, internal control template. (B) TERT elicits cardiac hypertrophy, not G₁ exit, in cultured ventricular myocytes. (Top) DNA histograms after viral gene transfer, using FITC-MF20 plus propidium iodide (PI) for flow cytometry. Cells were visualized with MF20 Ab to sarcomeric MHC (red; Middle) or coexpressed green fluorescent protein (green; Bottom). [Bar = 20 μm.] (C) Northern blot analysis of myocardium, showing induction of ANF and βMHC by the TERT transgene. (D) Northern blot analysis of myocardium, showing no change in c-myc expression by TERT. (E) Northern blot analysis of cultured cardiac myocytes, showing induction of ANF by viral delivery of TERT. (F and G) Western blot analysis showing phosphorylation of p70 S6K and JNK in myocardium of TERT transgenic mice (F) and in myocytes 24 h after viral delivery of TERT (G). In G, cardiac myocytes were treated with serum for 30 min as a positive control. Blots were reprobed for TERT to confirm equal expression of the wild-type and mutant proteins.