HIP/PAP gene, encoding a C-type lectin overexpressed in primary liver cancer, is expressed in nervous system as well as in intestine and pancreas of the postimplantation mouse embryo

We originally isolated the HIP/PAP gene in a differential screen of a human hepatocellular carcinoma cDNA Library. This gene is expressed at high leve ls in 25% of primary liver cancers but not in nontumorous liver. HIP/PAP be longs to the family of C-type lectins and acts as an adhesion molecule for hepatocytes. In normal adult human tissues, HIP/PAP expression is found in pancreas (exocrine and endocrine cells) and small intestine (Paneth and neu roendocrine cells). In order to gain insight into the possible role of HIP/ PAP in vivo, we have investigated the pattern of HIP/PAP expression in the developing postimplantation mouse embryo by in situ hybridization. Detailed analysis of developing mouse embryos revealed that HIP/PAP gene exhibits a restricted expression pattern during development. Thus, HIP/PAP transcript s are first observed within the nervous system from day 14.5 onwards in tri geminal ganglia, dorsal root ganglia, and spinal cord where it appears to b e an early specific marker of a subpopulation of motor neurons. At laster s tages, HIP/PAP transcripts were detected in intestine and pancreas at day 1 6.5 but not in embryonic liver. This highly restricted expression pattern s uggests that HIP/PAP might participate in neuronal as well as intestinal an d pancreatic cell development.