- 作者: Yu-Shuo Wu, Chien-Chang Chen, Chen-Li Chien, Hsing-Lin Lai, Si-Tse Jiang, Yong-Cyuan Chen, Lin-Ping Lai, Wei-Fan Hsiao, Wen-Pin Chen and Yijuang Chern
- 作者服務機構: 1. Graduate Institute of Life Sciences, National Defense Medical Center, Taipei, Taiwan 2. Institute of Biomedical Sciences, Academia Sinica, Taipei, Taiwan 3. National Laboratory Animal Center, National Applied Research Laboratories, Taipei, Taiwan 4. Institute of Internal Medicine, College of Medicine, National Taiwan University, Taipei, Taiwan 5. Institute of Pharmacology, College of Medicine, National Taiwan University, Taipei, Taiwan
- 中文摘要:
- 英文摘要:
Background
The type VI adenylyl cyclase (AC6) is a main contributor of cAMP production in the heart. The amino acid (aa) sequence of AC6 is highly homologous to that of another major cardiac adenylyl cyclase, AC5, except for its N-terminus (AC6-N, aa 1–86). Activation of AC6, rather than AC5, produces cardioprotective effects against heart failure, while the underlying mechanism remains to be unveiled. Using an AC6-null (AC6−/−) mouse and a knockin mouse with AC6-N deletion (AC6 ΔN/ΔN), we aimed to investigate the cardioprotective mechanism of AC6 in the heart.
Methods
Western blot analysis and immunofluorescence staining were performed to determine the intracellular distribution of AC6, AC6-ΔN (a truncated AC6 lacking the first 86 amino acids), and STAT3 activation. Activities of AC6 and AC6-ΔN in the heart were assessed by cAMP assay. Apoptosis of cardiomyocytes were evaluated by the TUNEL assay and a propidium iodine-based survival assay. Fibrosis was examined by collagen staining.
Results
Immunofluorescence staining revealed that cardiac AC6 was mainly anchored on the sarcolemmal membranes, while AC6-ΔN was redistributed to the sarcoplasmic reticulum. AC6ΔN/ΔN and AC6−/− mice had more apoptotic myocytes and cardiac remodeling than WT mice in experimental models of isoproterenol (ISO)-induced myocardial injury. Adult cardiomyocytes isolated from AC6ΔN/ΔN or AC6−/− mice survived poorly after exposure to ISO, which produced no effect on WT cardiomyocytes under the condition tested. Importantly, ISO treatment induced cardiac STAT3 phosphorylation/activation in WT mice, but not in AC6ΔN/ΔN and AC6−/− mice. Pharmacological blockage of PKA-, Src-, or STAT3- pathway markedly reduced the survival of WT myocytes in the presence of ISO, but did not affect those of AC6ΔN/ΔN and AC6−/− myocytes, suggesting an important role of AC6 in mediating cardioprotective action through the activation of PKA-Src-STAT3-signaling.
Conclusions
Collectively, AC6-N controls the anchorage of cardiac AC6 on the sarcolemmal membrane, which enables the coupling of AC6 with the pro-survival PKA-STAT3 pathway. Our findings may facilitate the development of novel therapies for heart failure. - 中文關鍵字:
- 英文關鍵字: Type V adenylyl cyclase, AC6, cAMP, STAT3, Microdomain