Title : Transcriptional regulation of the
KEL gene and
Kell protein expression in erythroid and non-erythroid cells
Abstract :
- The Kell blood-group antigen was originally reported to be a protein expressed in erythroid tissue only
- Transcriptional analysis of the KEL promoter activity in human erythroleukaemia K562 and epithelial HeLa cells by electrophoretic mobility-shift and supershift assays, chloramphenicol acetyltransferase assays, co-transfection studies and site-directed mutagenesis provided the following results: (i) the KEL promoter exhibits a strong transcriptional activity in K562 cells and, unexpectedly, a basal non-erythroid activity in HeLa cells, (ii) up-regulation of the 5' distal promoter activity occurs only in the erythroid context, and (iii) two motifs localized in the exon 1 region , which bind the Sp1 / Sp3 and the human GATA-1 / Ku70 /80 factors , were required for down-regulation of the promoter activity, but inhibition of the promoter activity by the repressing factors in HeLa cells was incomplete
- KEL expression in HeLa cells was performed further by primer-extension analysis, which revealed the presence of a low amount of Kell transcript correlating with basal expression of the Kell protein in these cells, as shown by immunopurification and Western-blot analysis
- DNA sequencing of the transcript revealed a sequence identical to that obtained from erythroid tissue
- In human tissues, KEL expression was investigated by dot-blot analysis and revealed high levels of Kell mRNAs, particularly in brain tissues, testis and lymphoid tissues
- Moreover, most tissues analysed exhibited low levels of Kell transcripts
- The Kell protein was also detected by immunohistochemistry in the Sertoli cells of the testis and in lymphoid tissues like spleen and tonsil, specifically localized in the follicular dendritic cells
- Altogether, the results indicated that KEL expression is not restricted to erythroid tissue
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Output(Part-Of) (sent_index,
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*Output_Site_Fusion* (sent_index,
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