ABSTRACT
The ZNF202 gene resides in a chromosomal region linked genetically to low high density lipoprotein cholesterol in Utah families. Here we show that the ZNF202 gene product is a transcriptional repressor that binds to elements found predominantly in genes that participate in lipid metabolism. Among its targets are structural components of lipoprotein particles (apolipoproteins AIV, CIII, and E), enzymes involved in lipid processing (lipoprotein lipase, lecithin cholesteryl ester transferase), and several genes involved in processes related to energy metabolism and vascular disease. Based on the linkage and apparent transcriptional function of ZNF202, we propose that ZNF202 is a candidate susceptibility gene for human dyslipidemia.
Subject(s)
Carrier Proteins/metabolism , Lipid Metabolism , Zinc Fingers/genetics , Alternative Splicing/genetics , Apolipoproteins/metabolism , Binding Sites , Carrier Proteins/genetics , Cell Line , Chromosome Mapping , Chromosomes, Human, Pair 11 , DNA-Binding Proteins/genetics , DNA-Binding Proteins/metabolism , Databases, Factual , Gene Expression Regulation , Genetic Linkage , Humans , Hyperlipidemias/etiology , Hyperlipidemias/genetics , Repressor Proteins/genetics , Repressor Proteins/metabolism , Sequence Alignment , Transcription Factors/genetics , Transcription Factors/metabolism , UtahABSTRACT
Deletion or epigenetic inactivation of the tumor suppressor gene p16INK4/CDKN2 (p16) has been observed in multiple human tumors. We assayed hybrid cell lines between human diploid fibroblasts and fibrosarcoma cells for p16 allelic status and expression and found that p16 was expressed in the parental diploid fibroblast cell lines used, whereas the parental fibrosarcoma cell line HT1080.6TG exhibited homozygous deletion of p16. Most immortalized hybrid cell lines derived from these parent cell lines, whether tumorigenic or nontumorigenic, exhibited loss of fibroblast-derived p16 alleles. All p16-negative hybrid cell lines also exhibited deletion of p15INK4B (p15). Hybrid cell lines yielded tumors upon s.c. injection into athymic nude mice regardless of p16/p15 status. Tumors derived from six p16/p15-positive hybrid cells, however, revealed deletions of both p16 and p15. When human diploid fibroblasts were fused with A388.6TG squamous cell carcinoma cells, which exhibit aberrant methylation of p16, the resulting hybrids again exhibited deletion of the unmethylated fibroblast-derived p16 alleles. Transfection of both HT1080.6TG and A388.6TG cells with wild-type p16 expression vector resulted in decreased clonogenicity in culture. Although the determinants directing genetic versus epigenetic inactivation of p16 and p15 remain unclear, these results demonstrate that p16-mediated growth suppression could be abrogated by either mechanism in somatic cell hybrids.
