We have identified and isolated a novel human gene, HMBOX1 (homeobox containing 1) from a pancreatic cDNA library. Human HMBOX1 is widely expressed in 18 tissues, and it is highly expressed in pancreas. According to the genome database, HMBOX1 is located at the boundary of 8p12.3 and 8p21.1. HMBOX1 proteins are highly conserved in human, mouse, rat, chicken and Xenopus laevis. A phylogenetic tree shows that HMBOX1 may represent a distinct group in HNF (Hepatocyte Nuclear Factor) transcriptional factors. Functional HMBOX1::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 pGAL4₅tkLUC 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.

Human ASB-17 (Ankyrin Repeat and SOCS Box-containing 17) is a recently identified gene belonging to the ASB family, isolated from testis cDNA library. Human ASB-17 is expressed exclusively in testis among 16 tissues, revealed by Northern blot. Mouse Asb-17 was shown to be expressed from the third week post birth to adult by semi-quantitative RT-PCR analysis. In situ hybridization on frozen sections demonstrated that Asb-17 is expressed in spermatogenic cells in adult mouse, but not in Leydig cell and epididymis in adult mouse. ASB-17 proteins are highly conserved in mammals including human, mouse, rat, Canis familiaris and Macaca fascicularis.

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