hnRNP-K and Pur(alpha) act together to repress the transcriptional activity of the CD43 gene promoter.
CD43 is an abundant, heavily glycosylated molecule expressed specifically on the surface of leukocytes and platelets. When leukocytes are at rest, CD43 acts to prevent both homotypic and heterotypic interactions. However, during leukocyte activation CD43 expression is repressed, facilitating the intercellular contact required for chemotaxis, phagocytosis, aggregation, adhesion to endothelium, and transendothelial migration. Consequently, CD43 repression plays a vital role both in innate and acquired immunity. Here we report that a dramatic down-regulation of CD43 mRNA levels occurs during activation of the leukocytic cell line K562. This repression coincides with repression of the transcriptional activity of the CD43 gene promoter. We have determined that heterogeneous nuclear ribonucleoprotein K (hnRNP-K) and Pur(alpha) act together to mediate repression of the CD43 promoter during K562 activation. The hnRNP-K molecule and Pur(alpha) bind single-stranded DNA. Therefore, exposure of single-stranded structures within the CD43 promoter probably plays a major role in effecting CD43 repression.
Da Silva
Nicolas
N
Renal Unit, Massachusetts General Hospital, Harvard Medical School, Charlestown 02129, USA.
Bharti
Ajit
A
Shelley
Carl S
CS
D015703:Antigens, CD; D017362:Cyclic AMP Response Element-Binding Protein / Q000235:genetics* / Q000494:pharmacology; D019175:DNA Methylation; D004268:DNA-Binding Proteins; D015536:Down-Regulation / Q000187:drug effects; D004357:Drug Synergism; D034641:Heterogeneous-Nuclear Ribonucleoprotein K / Q000235:genetics* / Q000494:pharmacology; D006801:Humans; D020014:K562 Cells; D007962:Leukocytes / Q000378:metabolism; D051917:Leukosialin; D008213:Lymphocyte Activation; D008969:Molecular Sequence Data; D011401:Promoter Regions, Genetic; D012795:Sialoglycoproteins / Q000235:genetics*; D014157:Transcription Factors; D024363:Transcription Initiation Site; D014158:Transcription, Genetic / Q000187:drug effects*; D014162:Transfection
D015703:Antigens, CD; D017362:Cyclic AMP Response Element-Binding Protein; D004268:DNA-Binding Proteins; D034641:Heterogeneous-Nuclear Ribonucleoprotein K; D051917:Leukosialin; C501130:PURA protein, human; C465014:SPN protein, human; D012795:Sialoglycoproteins; D014157:Transcription Factors