The Molecular Mechanism Of CAMR1 And CAMR2 Regulation Of Cardiac Hypertrophy

With tremendous improvment of people's life quality and diet structure, the cardiac hypertrophy related disease such as arrhythmia and so on showed a rapid upward trend in morbidity and mortality. It will still be one of the major diseases that threatening human health.The growing obesity and its related heart disease caused by cardiac hypertrophy becoming more and more serious. In China, obesity trend getting younger herald of the molecular mechanisms research of cardiac hypertrophy caused by obesity in adult population is an important issue which health field urgently needed. It has been reported that protein phosphatase 2A (PP2A) is closely connected with cardiac hypertrophy-related diseases caused by LTCC (L-type calcium channel) calcium concentration changes of heart. Moreover, it has also been confirmed that calcineurin phosphatase (Calcineurin, PP2B) signaling pathway Ca2+ -NFATc plays a role in cardiac hypertrophy process by many researchers. So, they closely affected by the intracellular important messenger-calcium. The CAMR1 and CAMR2 are the important regulatory factors of RyR (Ryanodine receptors) complex calcium channel regulation. The relationship among CAMR1, CAMR2 and RyR, voltage-gated LTCC structurally interconnected ultrastructure increasingly clear, they participate in the control of intracellular free calcium ions in and out, and then adjust the life activity related to EC (excitation-contraction) coupling.However, whether PP2A and RyR regulatory factors CAMR1, CAMR2 combined impact intracellular free calcium concentration, the molecular mechanisms of cardiac hypertrophy regulated by PP2A, and whether PP2A and the important cardiac hypertrophy signal PP2B have functionally relevance, many researchers want to unravel the mystery with more and more urgent.This study aimed at exploring the functional interaction of CAMR1 and CAMR2 and PP2A, PP2B in vitro system, molecular mechanisms of CAMR1 and CAMR2 regulating cardiac hypertrophy, analyzing cardiac hypertrophy induced to increase the cardiomyocytes quality is whether cardiomyocytes volume increased or not. With the depth study of CAMR1 and CAMR2, we look forward to confirming the role of Ca+ -NFATc signal pathways in cardiac hypertrophy process, it provides theoretical basis for developing effective drugs with CAMR1 and CAMR2 as target to prevent and treat cardiovascular disease caused by cardiac hypertrophy.This subject used the usual cell line models HEK293, CHO, C2C12 which can be induced differentiate to voluntary contraction cardiac mouse myoblasts, and mouse fibroblast cell line NIH/3T3 as the carriers. CAMR1 and CAMR2 was overexpressed in above cell lines, overexpression the target protein cells were synchronization treatment to compare their volume change, analysis the result of cardiac hypertrophy due to cell volume increased or not. Meanwhile, we used Western blot, qRT-PCR to detect the CAMR1 and CAMR2 impact on expression of PP2A, PP2B at protein and RNA level, which in order to study the molecular mechanisms of CAMR1 and CAMR2 regulation the cardiac hypertrophy. The results are as the following:1. Overexpression CAMR2 increase cell volumeIn HEK293 and CHO cells, overexpression of CAMR1 has no unified particular rule in cell volume change. Whereas, overexpression of CAMR2 result in the volume increase of HEK293 and CHO obviously, and the difference was significant. Moreover, in CHO cells, the significant increase of volume occurred in the 8 hrs after metaphase of the cell division.2. CAMR1 and CAMR2 regulate cardiac hypertrophy associated with their regulation proteinsWestern blot result showed that, PP2A A and PP2B A protein expression were significantly increased of CAMR1 and CAMR2 overexpressed cells compared with the control, the differences were significant. The PP2B B protein expression has no significant difference compared with the control. Moreover, in HEK293 cells, C2C12 cells and NIH/3T3 cells were obtained consistent results.3. CAMR1 and CAMR2 regulate cardiac hypertrophy associated with the related genes expression at mRNA levelqRT-PCR data showed that CAMR1 and CAMR2 can significantly regulate cardiac hypertrophy associated gene-PP2A A, PP2A B, PP2B A and PP2B B relative expression at mRNA level. CAMR1 co-expression vector down-regulated cardiac hypertrophy associated gene-PP2A A, PP2A B, PP2B A and PP2B B relative expression at mRNA level in C2C12 cells considerably while it make no difference in NIH/3T3 cells. CAMR2 obtain a consistent influence on the four cardiac hypertrophy related genes relative expression at mRNA levels both in C2C12 and NIH/3T3 cells. That is, CAMR2 co-expression vector up-regulated the four cardiac hypertrophy related genes relative expression at mRNA levels both in C2C12 and NIH/3T3 cells distinctly.Conclusion:The results of this study in vitro indicated that, CAMR1 and CAMR2 can regulate the cell volume increased, and adjust the protein phosphatase 2A and calcineurin phosphatase 2B expression at protein and mRNA level, particularly significant up-regulate the expression of PP2A A and PP2B A at protein and mRNA levels. Therefore, we conclude that this study will provide more adequate theoretical basis from mechanism for developing effective drugs with CAMR1 and CAMR2 as target to prevent and treat cardiac hypertrophy caused by cardiovascular disease.