Research On Regulation Mechanisms Of Cardiac Remodeling Induced By High Glucose And Pressure Overload

Cardiovascular disease is one of main disease threating on human health, and it makes huge social cost. Decreasing the mortality rate from cardiovascular disease needs to explore the molecular mechanism of cardiovascular disease and develop new method for treatment. Pressure overloaded and high glucose can induce pathological cardiac remodeling and make cardiac structure change and heart function decline. The research on molecular mechanism of cardiac remodeling is the most important to find effective method for therapy pathological cardiac remodeling and heart function declining induced by different stimulus.The activation of many signaling pathway participated in the regulation of cardiac remodeling, includ ing the post-transcriptional regulation and post-translational regulation. PTEN and CKIP-1 are key moleculars of signa ling pathway. This project focused on PTEN and CKIP-1, and studied the molecular mechanisms of cardiac remodeling induced by high glucose and pressure overload at the post-transcriptional level and post-translational level respectively.At the post- transcriptional regulation level, this project screened the PTEN competing endogenous RN As(ce RN As) in heart isolated from diabetic mice and detected the ce RNAs expression levels in heart isolated from 2 types of diabetic mice. Eventually, DKK1 was identified as PTEN ce RN A. DKK1 can regulate the interaction between mi RN As and three prime untranslated regions(3′UTR) of PTEN m RNA. And DKK1 also can regulate PTEN levels depended on mi RN A. Moreover, the common mi RN As between DKK1 and PTEN were verified by reporter gene experiments and si RN A experiments. Meantime, the regulation of DKK1 on PTEN as a ce RN A manner can adjust Akt activity which is the downstream of PTEN, and this effect contributed to cardiac remodeling induced by high glucose. These results explored the molecular mechanis m of cardiac remodeling induced by high glucose at the post-transcriptional level.This project also detected the m RNA and protein levels of CKIP-1 in heart tissues isolated from mice taken thoracic aorta constriction(TAC) surgery and heart tissues of patient using q-PCR, Western blotting and immunohistochemistry stained respectively. The results showed high levels of CKIP-1 in the early phase and low levels of CK IP-1 in the late phase of cardiac remodeling induced by pressure overload. Moreover, this paper studied the regulation of CK IP-1 on cardiac remodeling induced by pressure overload in vivo. The results of histology and echocardiography demonstrated CKIP-1-deficient mice developed age-dependent cardiac remodeling and hypersensit ivity to pressure overload- induced cardiac remodeling. Moreover, this paper constructed the myocardial-specific CKIP-1 transgenic mice, and the results showed overexpression of CKIP-1 in heart inhibited cardiac remodeling induced by pressure overload. The regulation of CK IP-1 on cardiac remodeling induced by overload was verified.At the post- translation level, this project studied the molecular mechanism of regulation of CK IP-1 on pressure overload- induced cardiac remodeling. The interactions of CKIP-1 and members of class IIa histone deacetylase(HDAC) family were verified by GST-pull down and protein co- immunoprecipitated experiments. Moreover, CK IP-1 can regulate the transcriptional activity of MEF2 which is downstream of HDAC4. Meantime, the regulation of CK IP-1 on HDAC4 phosphorylation and HDAC4 localization in cells was verified by reporter gene assay and immunohistochemically experiments. The interaction between CKIP-1 and PP2 AC were also demonstrated by GST-pull down and protein co- immunoprecipitated experiment. Eventually, the results indicated that CKIP-1 increased the interaction between HDAC4 and PP2 AC, promoted the dephosphorylation of HDAC4, and was aggregated in cell nuclear, thus regulated cardiac remodeling induced by pressure overload.In summary, this paper found the regulation of ce RN A on high glucose induced cardiac remodeling at the post- transcriptional regulation level, and CKIP-1 was found to be an inhibitor of cardiac hypertrophy by upregulating the dephosphorylation of HDAC4 through the recruit ment of protein phosphatase 2A. These results demonstrated a unique function of CK IP-1, by which it suppresses cardiac hypertrophy through its capacity to regulate HDAC4 dephosphorylation and fetal cardiac genes expression.