Promoter characterization and regulation of expression of an imprinted gene SLC22A18AS.
The SLC22A18/SLC22A18AS genes are a sense-antisense pair located at human chromosome segment 11p15.5. These genes are paternally imprinted: paternal alleles are silenced and maternal alleles are expressed. Although SLC22A18 is a well-characterized gene, very little is known regarding its antisense partner SLC22A18AS. We therefore sought to identify the potential cis-regulating elements including the promoter of this gene, differentially methylated regions (DMRs) and the translation of its putative ORF. Dual promoters (P1 and P2) were identified for this gene and both are devoid of consensus TATA and CCAAT boxes. However, the P1 promoter harbors a putative Sp1 binding site. Sp1 binds to the P1 promoter in vivo and positively regulates its activity. Promoter and CpG II island regions showed heavy methylation of CpG sites, but no DMRs were observed. Treatment of a non-SLC22A18AS expressing HuH7 cells with the methyltransferase inhibitor 5-aza-2'-deoxycytidine restored expression of this gene. The histone deacetylase (HDAC) inhibitor Trichostatin-A, on the other hand, failed to induce its expression. We suggest that the expression of this gene is methylation-dependent, but histone acetylation-independent. This gene was found to be translated with a cytoplasmic localization. The present data will help to understand the regulation of this gene and its role in tumorigenesis.
Bajaj
Vineeta
V
Department of Molecular Reproduction, Development and Genetics, Indian Institute of Science, Bangalore 560012, India.
Singhmar
Pooja
P
Kumar
Arun
A
D000230:Adenocarcinoma; D001483:Base Sequence; D002460:Cell Line; D045744:Cell Line, Tumor; D002880:Chromosomes, Human, Pair 11; D004247:DNA / Q000235:genetics / Q000302:isolation & purification; D019175:DNA Methylation; D005786:Gene Expression Regulation; D017930:Genes, Reporter; D015894:Genome, Human; D018392:Genomic Imprinting; D006801:Humans; D008113:Liver Neoplasms; D008175:Lung Neoplasms; D008565:Membrane Proteins / Q000235:genetics* / Q000378:metabolism; D008969:Molecular Sequence Data; D020411:Oligonucleotide Array Sequence Analysis; D011401:Promoter Regions, Genetic; D012313:RNA / Q000235:genetics / Q000302:isolation & purification; D012333:RNA, Messenger / Q000235:genetics; D014157:Transcription Factors / Q000378:metabolism; D014162:Transfection
D008565:Membrane Proteins; D012333:RNA, Messenger; C406488:SLC22A18AS protein, human; D014157:Transcription Factors; D012313:RNA; D004247:DNA