Study On Molecular Mechanisms And Proteomics Of Endoplasmic Reticulum Stress In Diabetic Cardiomyopathy

Objective1. The aim of the study was to compare the weight, FBG, TC, TG, and AGEs levels, and the pathological changes of myocardium via histology and ultrastructure between db/db diabetic mice group (DM group) and normal control group (CC group).2. To compare the differential expressed protein related to endoplasmic reticulum stress in myocardial tissue of diabetic mice by Isotope labeling of relative and absolute quantitative (iTRAQ) technology, hoping to clarify the mechanism of diabetic cardiomyopathy.MethodsMale C57BLKS/J db/db mice were selected randomly as a diabetic model group (DM group, n=8), C57BLKS/J db/m mice were selected as control group (CC, n=8). The mice were kept under observation for one week before starting the experiments. Then the two groups of mice were kept in the same suitable environment for 10 weeks. The mice were weighed every week from eight weeks to eighteen weeks. At the end of the experiments, all mice were sacrificed. Fasting blood glucose (FBG), total cholesterol (TC), triglycerides (TG), and serum advanced glycation end products (AGEs) were measured. HE staining was used to observe the pathological changes of the myocardial tissue, and transmission electron microscope was used to the observation of ultrastructural changes. Moreover, Proteomics of the heart tissue extracts by iTRAQ analysis was obtained from db/db mice.Result1. General observationThe mice of CC group appeared in a good state with smooth furs and active condition during the course of experiment. The db/db mice showed hyperdiuresis, polydipsia, polyphagia with lackluster furs and a sharply increased body mass.2. Changes in body weight, FBG, TC, TG, AGEs of the two groups.With the progress of the experiment, the weight of DM groups was higher than that of control group in 8,10,12,14,16,18 weeks (P<0.01). Serum FBG, TC, TG, and AGEs levels of DM group were significantly higher than those of control group (P<0.01).3. The pathological changes of the myocardial tissue.Under light microscopy, myocardial tissue stained by hematoxylin-eosin of CC group exhibited orderly myocardial fibers, normal mesenchyme, intact nucleus. However, myocardial hypertrophy and myofiber disarray accompanied by damaged nuclei and increased degeneration were observed in DM group by hematoxylin-eosin staining.4. The ultrastructural changes of the myocardial tissue.Under electron microscopy, myocardial tissue in CC group had normal sarcoplasmic reticulum and unbroken nuclear membrane. However, the structure disorder of sarcomere, sarcoplasmic reticulum expansion, swelling, edema and inflammatory cells were seen in DM group.5. Differentialy expressed proteins related to endoplasmic reticulumTwenty two differentially expressed proteins related to endoplasmic reticulum have been identified in myocardial tissue between db/db mice and control group. Six proteins were up-regulated and 16 proteins were down-regulated in db/db mice.Conclusion1. Compared with control group, db/db mice have a significant increasing in body weight, FBG, TC, TG, and AGEs.2. Compared with control group, myocardial hypertrophy and myofiber disarray accompanied by swelling sarcoplasmic reticulum and damaged nuclei were observed in DM group.3. The proteins related to endoplasmic reticulum stress such as valosin-containing protein, β-cell receptor-associated protein 31, lysophosphatidylcholineacyltransferase 3 play an important role in diabetic cardiomyopathy, and may provide fundamental basis for researching or finding new drug targets for prevention of diabetic cardiomyopathy.