Screening for rat vascular calcification related genes using suppression subtractive hybridization / 中华肾脏病杂志

ABSTRACT

Objective To determine the differentially expressed genes in the development of vascular medium calcification in rats using the suppression subtractive hybridization (SSH). Methods Twenty-four 6-week old SD rats of specific pathogen free grade were recruited and randomly allocated into calcified group (n=12) and control group (n=12). Rats were made for vascular calcification model in calcified group (vitamin D3 plus nicotine, VDN). All rats were sacrificed to measure concentration of calcium in the arterial tissue and examine the pathological lesion changes. RNA in rat aortic tunica tissue was extracted and reverse transcripted into cDNA. cDNA fragments which highly expressed calcification were isolated in calcified group using the SSH. Differentially expressed genes with cDNA fragment were inserted into PMD18-T plasmid vector and transformed to competent DH-5α by means of heating transfer. cDNA libraries of differentially expressed gene between calcified group and control group were successfully constructed. Recombinant vectors were analyzed by colony PCR. Positive genes were randomly selected for sequencing and analyzed by BLAST. Six genes, for example, were randomly selected for RT-PCR certification. Results (1) The pathological examination results demonstrated that in calcified group there were obvious calcium diposits and media squirm in tunica media of rat aortic wall, while in control group no calcium diposit was found. (2) There was statistical significance in calcium concentration in vascular tissue between calcified group[(15.34 ± 2.51)mg/g] and control group [(5.20 ± 0.75) mg/g] (P＜0.01). (3) Subtracted libraries in vascular calcification was successfully established. Ninety-two positive clones in positive library and 18 positive clones in reverse library were obtained after the colony PCR identification. The length of insertion fragments was concentrated between 150 bp and 400 bp. Calcification-related 43 up-regulated genes and 11 down-regulated genes were obtained through sequencing and BLAST analysis in positive clones. RT-PCR validation indicated that the expressions of 5 genes such as CytoP450 and Nell1 had greater increase in calcified group than those in control group, the average fold change was 1.71.Conclusions Model of vascular calcification induced by vitamin D3 plus nicotine is successfully constructed. Related gene expression spectrum is changed in the process of vascular calcification.Some ossification genes and genes associated with apoptosis, oxidation, inflammation and cytokines are up-regulated. At the same time, some genes which possibly inhibit vascular calcification are down -regulated.