Differentially expressed genes in cultured aortic smooth muscle cells by cholesterol-loading

Differentially expressed genes generated by cholesterol-loading in the culture medium of aortic smooth muscle cells (SMC) were screened using the DDRT-PCR technique in order to identify the genes that are possibly involved in the pathogenesis of atherosclerosis in the artery. Twenty-eight genes were initially isolated and three differentially expressed cDNAs were finally selected by Northern blot analysis. All three cDNAs were up-regulated (designated CRGSM-1 through -3) by the cholesterol-loading. Upon nucleotide sequencing and homology search in the databases, the first cDNA (CRGSM-1) had a high homology (97%) with the corresponding segment of the acyl-CoA synthetase II gene from rat brain, which participates in fatty acid synthesis. The second one (CRGSM-2) had a high homology (91%) with a part of Mus musculus (mouse) LIM protein 1, and with human skeletal muscle LIM-protein 1 genes (80%) and the third gene (CRGSM-3) had no significant homology match in the database. A full size cDNA isolated from the cDNA library of rat aortic smooth muscle cell using the CRGSM-2 as a probe was identified to have a high homology with muscle LIM protein (MLP). The isolated cDNA contained a segment of DNA that encodes for a zinc-finger motif and two LIM domains. Proteins bearing the LIM domain, defined as a unique double zinc-finger structure associated with a subclass of proteins involved in the determination of cell identity, cell differentiation and control of cell growth, have previously been suggested to play an important role in the pathogenesis of atherosclerosis by others.