Isolation and functional analysis of human HMBOX1, a homeobox containing protein with transcriptional repressor activity

We have identified and isolated a novel human gene, HMBOXI (homeobox containing 1) from a pancreatic cDNA library. Human HMBOXI is widely expressed in 18 tissues, and it is highly expressed in pancreas. According to the genome database, HMBOXI is located at the boundary of 8p12.3 and 8p21.1. HMBOXI proteins are highly conserved in human, mouse, rat, chicken and Xenopus laevis. A phylogenetic tree shows that HMBOXI may represent a distinct group in HNF (Hepatocyte Nuclear Factor) transcriptional factors. Functional HMBOXI::EGFP (enhanced green fluorescent protein) fusion protein revealed that HMBOX1 accumulated more in cytoplasm than in nucleus. Co-transfection of HEK-293T cells with pM-HMBOX1 plasmid and reporter plasmid pGAL4(5)tkLUC indicates that HMBOX1 is a transcription repressor. In situ hybridization on paraffin sections of mouse tissues demonstrated that Hmbox1 is widely expressed in pancreas and the expression of this gene can also be detected in pallium, hippocampus and hypothalamus. Copyright (c) 2006 S. Karger AG, Basel.