Resistin Activates Endoplasmic Reticulum Stress-mediated Cardiac Hypertrophy Through LKB1-AMPK Signaling Pathway

Objective:This study verifies whether resistin could promote endoplasmic reticulum stress by inhibiting LKB1/AMPK signal pathway,thus mediating the molecular mechanism of cardiomyocyte hypertrophy.It provides the possibility for the prevention and treatment of myocardial hypertrophy and heart failure.Methods:H9c2 cardiomyocytes was cultured in DMEM medium(containing 5%fetal bovine serum and 1%penicillin streptomycin double antibody)in a cell incubator containing 5.6%CO~2 at 37℃.After the cell adhered to the wall,changed the cell culture medium and waited for the cells grow up to 70%to 80%for passage.The cardiomyocytes were inoculated on the six-well plates at the density of 10×10~5/ml.The experiment was divided into two parts.The first part was divided into four groups:control group(Con),resistin group(R),resistin plus 4-phenylbutyric acid group(R+4-PBA)and 4-phenylbutyric acid group(4-PBA).After 24 hours of culture,the cardiomyocytes were collected,and the expressions of BNF、β-MHC and endoplasmic reticulum stress-related proteins(GRP78,IRE1/p-IREI,PERK/p-PERK)were detected by RT-qPCR and Western blot,respectively.The second part was divided into four groups as well:control group(Con),resistin group(R),resistin plus metformin group(R+Met),and metformin group(Met).The cardiomyocytes were starved for 24 hours,followed 50 ng/ml of resistin or 2 mM of metformin was treated with corresponding groups for 24 hours.Resistin and metformin group was pretreated with metformin 2 mM for 2 hours,followed by resistin treatment for22 hours.The protein expressions of p-LKB1/LKB1,p-AMPK/AMPK,p-IRE1/IRE1,p-PERK/PERK and GRP78 were detected by Western blot.Results:(1)After resistin treatment for 24 hours,the surface area of cardiomyocytes in H9c2was increased(P<0.01),the expression of BNF andβ-MHC genes in hypertrophic embryos was up-regulated(P<0.01),and the protein synthesis was increased(P<0.05).(2)Compared with Con group,the expression of p-PERK,GRP78 and p-IRE1increased significantly after resistin treatment for 24 hours(P<0.01).After pretreatment with 4-PBA for 2 hours,the expression of p-IRE1,p-PERK and GRP78 was significantly lower than that in resistin group(P<0.05).(3)After 24 hours of resistin treatment,compared with Con group,the expression of p-LKB1 and p-AMPK decreased significantly(P<0.01),while the expression of p-IRE1,p-PERK and GRP78 increased significantly(P<0.05),while after 2 hours of metformin treatment,the expression of p-LKB1 and p-AMPK was higher than that of resistin group,and the expression of p-IRE1,p-PERK and GRP78 was significantly lower than that of resistin group(P<0.05).Conclusion:(1)Resistin can mediate H9c2 cardiomyocyte hypertrophy.(2)LKB1/AMPK pathway is involved in resistin-mediated cardiomyocyte hypertrophy.(3)Resistin-mediated cardiomyocyte hypertrophy is related to endoplasmic reticulum stress.(4)Resistin induces endoplasmic reticulum stress and results in H9c2 cardiomyocyte hypertrophy by inhibiting LKB1/AMPK pathway.