title: Characterization of a novel human HMBOX1 splicing variant lacking the homeodomain and with attenuated transcription repressor activity.
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.
authors.affiliation: State Key Laboratory of Genetic Engineering, Institute of Genetics, School of Life Sciences, Fudan University, 220 Handan Road, Shanghai 200433, People's Republic of China.
authors.forename: Mingjun
authors.initials: M
authors.lastname: Zhang
authors.forename: Shuai
authors.initials: S
authors.lastname: Chen
authors.forename: Qiang
authors.initials: Q
authors.lastname: Li
authors.forename: Yichen
authors.initials: Y
authors.lastname: Ling
authors.forename: Jie
authors.initials: J
authors.lastname: Zhang
authors.forename: Long
authors.initials: L
authors.lastname: Yu
mesh_terms: D017398:Alternative Splicing / Q000235:genetics*; D000595:Amino Acid Sequence; D002460:Cell Line; D003001:Cloning, Molecular; D019295:Computational Biology; D005057:Eukaryotic Cells / Q000378:metabolism; D020869:Gene Expression Profiling; D005786:Gene Expression Regulation; D018398:Homeodomain Proteins / Q000737:chemistry* / Q000235:genetics* / Q000378:metabolism; D006801:Humans; D008969:Molecular Sequence Data; D017434:Protein Structure, Tertiary; D021381:Protein Transport; D012097:Repressor Proteins / Q000378:metabolism*; D013347:Subcellular Fractions / Q000378:metabolism; D014158:Transcription, Genetic
chemical_list: C512050:HMBOX1 protein, human; D018398:Homeodomain Proteins; D012097:Repressor Proteins