CLONING OF THE HUMAN INTERFERON-RELATED DEVELOPMENTAL REGULATOR (IFRD1) GENE CODING FOR THE PC4 PROTEIN, A MEMBER OF A NOVEL FAMILY OF DEVELOPMENTALLY-REGULATED GENES

The rat PC4 gene had been initially isolated as a nerve growth factor- inducible sequence in PC12 cells. Although its function remains unknow n, recently it has been shown that PC4 is necessary to muscle differen tiation and that it might have a role in signal transduction, We repor t the isolation of the human homolog of the rat PC4 gene, renamed here IFRD1 (interferon-related developmental regulator 1), Several human I FRD1 clones were identified by searching the EST database using the ra t IFRD1 (PC4) cDNA as a query, An EST clone containing the entire ORF was chosen for sequencing, Human IFRD1 presented a predicted protein p roduct of 453 amino acids, highly conserved (90.2% identity) compared to the rat IFRD1 (PC4) protein sequences. The mapping assignment of hu man IFRD1 to chromosome 7q22-q31 was retrieved from the UniGene databa se maintained at NCBI. A comparison of human IFRD1 (PC4) protein to da tabases revealed 47% identity to the protein encoded by the human gene SKMc15, originally isolated from a chromosome 3-specific library. The refore, SKMc15 is a gene related to IFRD1, being the second member of a novel family. We analyzed their expression during murine development , and we found that mouse IFRD1 appears more expressed in specific dif ferentiating structures at midgestation, while mouse SKMc15 is highly expressed soon after gastrulation and in the hepatic primordium, sugge sting an involvement in early hematopoiesis. (C) 1998 Academic Press.