Characterization of a novel human HMBOX1 splicing variant lacking the homeodomain and with attenuated transcription repressor activity

Mol Biol Rep. 2010 Jul;37(6):2767-72. doi: 10.1007/s11033-009-9815-9. Epub 2009 Sep 15.

Abstract

We previously identified the human HMBOX1 (homeobox containing 1) gene, which represents a distinct group of HNF transcription factors, and is a potential transcription repressor with highly expression in pancreas. In our present work, we found that there exists a splicing variant of HMBOX1, designated HMBOX1b. Compared to HMBOX1, HMBOX1b encodes a 304 amino acids protein that shares the N-terminal region but has no homeodomain and the C-terminal region because of an alternative exon 7 which results in reading frame shifting. Unlike the highly pancreatic expression of HMBOX1, HMBOX1b was ubiquitous expressed in all human tissues detected by RT-PCR. Immunofluorescence staining showed that HMBOX1b accumulated in both cytoplasm and nucleus, and transcriptional reporter assays indicated that HMBOX1b only retained faint transcriptional repressive activity. Taken together, our findings suggest a distinct role of HMBOX1b, and the control of mRNA splicing might be involved in homeobox genes regulation.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Alternative Splicing / genetics*
  • Amino Acid Sequence
  • Cell Line
  • Cloning, Molecular
  • Computational Biology
  • Eukaryotic Cells / metabolism
  • Gene Expression Profiling
  • Gene Expression Regulation
  • Homeodomain Proteins / chemistry*
  • Homeodomain Proteins / genetics*
  • Homeodomain Proteins / metabolism
  • Humans
  • Molecular Sequence Data
  • Protein Structure, Tertiary
  • Protein Transport
  • Repressor Proteins / metabolism*
  • Subcellular Fractions / metabolism
  • Transcription, Genetic*

Substances

  • HMBOX1 protein, human
  • Homeodomain Proteins
  • Repressor Proteins