Genomic organization and functional characterization of the promoter for the human suppressor of cytokine signaling 6 gene

Rai Hua Lai, Mei Jung Wang, Shung Haur Yang, Jeou Yuan Chen*

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

15 Scopus citations

Abstract

In this study, we report the expression and genomic structure of the gene encoding human suppressor of cytokine signaling 6 (SOCS6), and the characterization of the functional promoter region. The human SOCS6 gene, spanning 40 kb on chromosome 18q22.2, is composed of two exons separated by an intron of 35 kb. Two transcripts are ubiquitously expressed, and both encode the full-length open reading frame of SOCS6. A primer extension assay revealed that the major transcription initiation site is located 469 bp upstream the ATG codon. Luciferase promoter analysis demonstrated that the 5′-flanking region is able to drive transcription, and the CpG-rich sequences near the transcription initiation site are important for the TATA-less SOCS6 promoter activity. Analogous to SOCS1 and SOCS3, which are down-regulated in several human cancers, SOCS6 is expressed at lower levels in carcinomas of stomach and colon. We demonstrated that hypermethylation of the SOCS6 promoter is one of the mechanisms for the epigenetic regulation of SOCS6 expression. Firstly, in vitro methylation of the reporter promoter plasmid significantly suppressed the promoter activity. Secondly, SOCS6 expression in vivo was enhanced by treating cells with a methyltransferase inhibitor. The SOCS6 gene from various species shares significant homology in amino acid sequences, transcription factor binding motifs in promoter regions and the two-exon genomic structure, suggesting that the SOCS6 gene is highly conserved.

Original languageEnglish
Pages (from-to)64-73
Number of pages10
JournalGene
Volume448
Issue number1
DOIs
StatePublished - 1 Dec 2009

Keywords

  • Genomic structure
  • Promoter analysis
  • Promoter hypermethylation
  • SOCS6

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