Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UMLS:C0002895 (sickle cell disease)
 11,747 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

A critical step in the synthesis of unsaturated fatty acids is catalysed by stearoyl-CoA desaturase (Scd). To determine the regulation of human Scd, we characterized the gene and its transcripts. Screening a human keratinocyte cDNA library and analysis of 3'-RACE (rapid amplification of cDNA ends) products from various tissues yielded a 5.2 kb cDNA encoding a 359 amino acid protein with a calculated molecular mass of 41.5 kDa. Analysis of 3'-RACE products suggested that alternative usage of polyadenylation sites generates two transcripts of 3.9 and 5.2 kb, a result consistent with Northern analysis. Southern analysis demonstrated the existance of two SCD loci in the human genome. Chromosomal mapping localized one locus to chromosome 10, and the second locus to chromosome 17. Characterization of genomic clones isolated from chromosome-specific libraries revealed that only the locus on chromosome 10 contained introns. Sequence analysis of the intron-less locus displayed multiple nucleotide insertions and deletions, as well as in-frame stop codons. Reverse transcriptase-PCR analysis performed with primers specific to the intron-less locus failed to produce a PCR product from brain, liver and skin RNA, indicating that the locus on chromosome 17 is most likely a transcriptionally inactive, fully processed pseudogene. These results suggest strongly that there is one structural SCD gene in the human genome, and that it generates two transcripts by use of alternative polyadenyation sites. Although the primary sequence and intron-exon structure of SCD is phylogenetically conserved, divergence between rodent and human is seen in the number of SCD genes and in the generation of alternative transcripts, suggesting a species-specific component of SCD regulation and function.
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PMID:Human stearoyl-CoA desaturase: alternative transcripts generated from a single gene by usage of tandem polyadenylation sites. 1022 81

Stearoyl-CoA desaturase is the rate-limiting enzyme in the production of mono-unsaturated fatty acids. We have recently cloned and characterized the human Scd cDNA and SCD (the stearoyl-CoA desaturase structural gene) on chromosome 10, as well as the non-transcribed pseudogene on chromosome 17. In order to further define SCD regulation and function, we have isolated and characterized the promoter of the structural gene. Screening of chromosome-10-specific libraries resulted in the isolation of 4.1 kb of SCD sequence upstream of the translation start site. Binding sites for transcription factors critical for mouse Scd1 and Scd2 promoter activity, such as sterol-regulated-element-binding protein and nuclear factor Y, were present in the human SCD promoter (Scd is the mouse stearoyl-CoA desaturase gene). Deletion analysis in HaCaT keratinocytes identified a critical region for promoter activity between nts 496-609 upstream of the translation start site. Site-directed mutagenesis of binding sites in this region identified the CCAAT box as the critical cis-element for SCD promoter activity. An electrophoretic mobility-shift assay confirmed that this element binds nuclear proteins from HaCaT keratinocytes. The polyunsaturated-fatty-acid (PUFA) response element, previously identified in the promoters of mouse Scd1 and Scd2, was found to be conserved in the human SCD promoter, and contained the critical CCAAT cis-element. A minimal promoter construct including this region was responsive to fatty acids, with oleate and linoleate decreasing transcription and stearate increasing it. These studies indicate that CCAAT-box-binding proteins activate SCD transcription in cultured keratinocytes and that fatty acids modulate transcription, most likely through the conserved PUFA response element.
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PMID:Isolation and characterization of the human stearoyl-CoA desaturase gene promoter: requirement of a conserved CCAAT cis-element. 1141 48