Molecular cloning of a novel retinoic acid-responsive gene, HA1R-62, which is also up-regulated in Hoxa-1-overexpressing cells.

Using a PCR-based cDNA subtractive hybridization method (L. Diatchenko et al., Proc. Natl. Acad. Sci. USA, 93: 6025-6030, 1996), we cloned a cDNA fragment of a novel gene that is highly expressed in F9-10; F9-10 is an F9 teratocarcinoma stem cell line that expresses high levels of exogenous Hoxa-1 mRNA and protein in comparison to F9 wild-type stem cells, which do not express endogenous Hoxa-1 mRNA in the absence of retinoic acid (RA). Rapid amplification of cDNA ends was used to clone the full-length cDNA of this gene, designated HA1R-62 (Hoxa1 regulated-62). We have shown that HA1R-62 is also a RA-responsive gene and that it is expressed (mRNA size, approximately 4.3 kb) in adult mouse thymus, lung, kidney, and ovary as well as in 12.5-day mouse embryos. DNA sequence analysis and in vitro translation experiments have shown that HA1R-62 encodes a protein with a molecular mass of approximately 26 kDa. Elucidation of the function of the HA1R-62 gene product will provide new insights into the functions of RA and homeobox genes.