Molecular mechanisms of phenotypic modulation and growth of smooth muscle cells

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The purpose of the present research was to elucidate the molecular mechanisms underlying phenotypic modulation and growth of vascular smooth muscle cells. To this end, our objective was to determine the intrinsic and external factors which affect gene expression of molecular markers in vascular smooth muscle cells, and to apply this knowledge to the development of new therapies for vascular diseases such as atherosclerosis. Studies were grouped into three main research fields ; 1) regulation of specific gene expression and transcription in smooth muscle cells and elucidation of mechanisms underlying phenotypic modulation, 2) growth factors and cell signaling pathways underlying smooth muscle cell growth and phenotypic modulation, and 3) efficient gene therapy techniques for the vasculature and atherosclerosis with a particular focus on smooth muscle genes.Research achievements during the four year research term are as follows : 1) functional characterization of transcription factors ex … More pressed in dedifferentiated smooth muscle cells : the transcriptional regulation of the smooth muscle myosin heavy chain SMemb gene which is a molecular marker of dedifferentiated smooth muscle cells was analyzed which resulted in the isolation of the transcription factor BTEB2. Analysis of BTEB2 further resulted in elucidation of its activation mechanism and mechanisms of transcriptional induction in addition to a correlative role in human coronary restenotic lesions ; 2) elucidation of transcriptional mechanisms in smooth muscle cells : transcriptional machinery involved in smooth muscle transcription, namely chromatin remodeling factors (CIA) and histone acetyltransferases (Tip60, p300) were analyzed and their roles in transcriptional activation mechanisms were elucidated ; 3) regulatory mechanisms of HB-EGF on smooth muscle cell growth ; HB-EGF was shown to be upregulated for gene expression, protein production and shedding on smooth muscle growth and chemotaxic stimuli. The HB-EGF shedding inhibitor KB-R7785 was isolated. Additionally, the role of the ADAM faimily members which are candidates for shedding enzymes were analyzed. 4) Molecular characterization of the aging suppressor gene Klotho ; The klotho gene is expressed principally in t**npotant tissues for calcium homeostasis. Klotho plays a critical role for the regulation of electrolyte metabolism. The deficiency of the klotho gene results in degradation of cells and tissues by the actibation □calpain. Importantly, the increased activation of □calpain occurs in tissues of old mice together with the downregulation of klotho gene expression. 5) Genetic knockout analysis of the functional role of calponin hl ; the calponin hl gene was knocked out in mice which showed that calponin is involved in the muscle contractile apparatus. 6) Regulation of smooth muscle cell phenotypic modulation by gene transfer : Decoy approaches against transcription factors involved in smooth muscle growth (E2F, NFKB) were done and were extended to human clinical studies. New gene transfer methods were also developed. Less