The Role Of Wip1,αB-crystallin And HspB2 In Myocardial Injury

The first part:The role of Wip1 deficiency in heart functionObjective:Wip1 plays a pivotal role in many diseases and physiological processes,but the relationship between Wip1 and heart function is unknown。This study is to explore the effect of Wip1 knockout on heart function,gene expression and protein expression in mice.Methods:The heart function and heart weight/body weight(HW/BW)ratio were detected in wildtype(WT)mice and Wip1 knockout(Wip1-KO)mice.The pathological morphology of heart tissues was observed by using Hematoxylin and eosin(HE)staining.The mRNA expression of ANP,BNP,MCP-1 and α-SMA were examined by Real-time PCR.The expression of Bcl-2,Bax and c-caspase3 were measured by western blot.Results:The expression of Wip1 mRNA was significantly reduced in Wip1-KO mice.Compared with WT mice,the ejection fraction and fraction shortening of Wip1-KO mice were impaired by Wip1 knockout.The left ventricular internal diameter at end-systolic of Wip1-KO mice was larger than WT mice.Though the heart weight is no difference between WT mice and Wip1-KO mice,the body weight of Wip1-KO mice is smaller than WT mice and the HW/BW ratio is much bigger in Wip1-KO mice than WT mice.The pathological morphology of heart tissues has no difference in the two types of mice.The mRNA expression of ANP,BNP,MCP-1 and α-SMA in Wip1-KO mice is similar to that in WT mice.There is no significant difference between WT mice and Wip1-KO mice in expression of Bcl-2,Bax and c-caspase3.Conclusion:Wip1 deficiency may impair the heart function of mice and the underline mechanism needs further explore.The second part:Wipl deficiency exacerbates myocardial infarction-induced ischemia injuryBackground:Wild-type p53-induced phosphatase 1(Wipl)has been studied extensively in the context of cancer and regulation of different types of stem cells,but the role of Wipl in the cardiac adaptation to MI is unknown.We investigated the significance of Wipl in mouse MI.Methods:We compared Wipl knockout(Wipl-KO)mice and wild-type(WT)mice for changes of cardiac function and survival in response to MI.Mouse MI was established by ligating the left anterior descending(LAD)coronary artery with 1.5%isoflurane.After MI,the survival of mice was observed for 4 weeks.Cardiac function was examined by echocardiography.HW/BW ratio was analyzed and cardiac hypertrophy was measured by wheat germ agglutinin(WGA)staining.Hematoxylin and Eeosin(HE)staining was used to detect the infarct size.Masson staining was used to detect the expression of cardiac fibrosis.Gene expression of Collagen I,IL-6,TNF-α and IL-1 β were performed by RT-PCR and the levels of stat3,p-stat3 and pS6 were detected by Western blot.Results:After MI,Wipl deficiency mice exhibited increased mouse mortality,promoted cardiac hypertrophy,and reduced cardiac function.HE staining indicated larger infarct size in Wipl-KO mice than WT mice.The cardiac fibrosis was no difference between Wipl-KO mice and WT mice.The expression of IL-6 and p-stat3 were down-regulated in Wipl-KO mice,while the expression of TNF-α,IL-1β and pS6 were almost the same in two groups of mice.Conclusion:We suggest that Wipl protects heart from MI-induced ischemia injury.The third part:a B-crystallin/HspB2 are critical for Tscl knockout induced myocardial injuryBackground:It is reported that mechanistic target of rapamycin(mTOR)promotes tumor proliferation through upregulation of a B-crystallin in fibroblasts and nude mice xenograft model.As small heat shock proteins,a B-crystallin and HspB2 function as molecular chaperone,which play an important role in cardiac homeostasis.Even though augmentation of mTOR signaling is known to cause cardiomyopathy,its underlying mechanism remains poorly understood.We examined the role of a B-crystallin and its adjacent duplicate gene,HspB2,in mTOR suppressor Tscl knockout-induced myocardial injury.Methods:First,we generated the Tscl heart conditional-KO(T1-hKO)mice,a B-crystallin/HspB2 double knockout(dKO)mice,cardiac-Tsc1;αB-crvstallin:HspB2 triple knockout(tKO)mice and control(CTL)mice.The survival of mice were observed,the cardiac function was detected using echocardiogram examination,the body weight and heart weight were collected and the heart weight/body weight(HW/BW)ratio was calculated.The physiological morphology of mice was observed by HE staining,the cardiomyocyte size was measured by WGA staining,and the cardiac fibrosis was detected by Masson staining.Cell ultrastructure was analyzed by transmission electron microscopy(TEM).The expression of ANP,BNP,a-SKA and β-MHC was detected by RT-PCR.The protein expressions were also measured by Western blot.Results:Knockout of a B-crystallin/HspB2 may alleviate the survival of Tl-hKO mice.The tKO mice had reduced lethality,improved cardiac function,and smaller HW/BW ratio compared with T1-hKO mice.Furthermore,loss of a B-crystallin/HspB2 reduced mTOR activation,fetal gene expression,mitochondrial damage,cardiomyocyte size and fibrosis in the hearts of T1-hKO mice.Conclusion:a B-crystallin and HspB2 play pivotal role in Tscl knockout-mediated cardiomyopathy.