Myocardial Remodeling Function Of Related Genes And Mutations

Cardiac remodeling is a common pathophysiological process occurring in most of cardiovascular diseases, during which compensatory cardiac hypertrophy transits into decompensatory and heart failure. Many factors, such as mechanical stretching, ischemia, the effects of hormones and cytokines and defects in cardiac genes, can result in cardiac remodeling. The alteration of gene expression and founction triggered by these factors are considered important in shaping the remodeling process. Therefore, we projected to investigate the mechanism of cardiac remodeling by studying lamin A/C Glu82Lys mutation and ablating the expression of CARP and CARK genes.Glu82Lys mutation within lamin A/C gene has been identified to lead malignant dilated cardiomyopathy in one Chinese family. In the first part of our work described in this thesis, we cloned the wild-type lamin A/C gene, and generated its mutant containing Glu82Lys mutation by using in vitro mutagenesis. Through transfecting the mutant into HEK 293 cell line, we studied the mechanism of Glu82Lys mutation in lamin A/C in causing cardiac dilation. In cells transfected with wild lamin A, both lamin A and emerin proteins were localized to the nuclear periphery, whereas cells transfected with mutant lamin A/C showed a decrease in nuclear rim localization, giving a more diffuse, nucleoplasmic staining. Both hochest33342 staining and flow cytometer analysis indicated that Glu82Lys mutation could dramatically increase apoptosis of HEK293 cell after being treated with H₂O₂. With electronic microscopy, we found that the nuclear membrane structure of HEK293 cells, stably transfected with mutated lamin A/C gene, was disrupted, locally collapsed or bulged, and partially fragmented. We also found that the heterochromatin was aggregated aberrantly and a prominent irregular electron-dense lamina region was associated with the inner nuclear envelope membrane in the nucleus. These changes could explain at least partly the cardiac dilation caused by lamin A/C Glu82Lys mutation.CARP and CARP were cloned from aortic-heart cDNA library. Our previous studies showed that CARP inhibits cell proliferation and induce apoptosis of tumor...