In vitro and in vivo expression analysis of the interferon-inducible 203 gene

The interferon (IFN)-inducible protein family 200 is encoded by structurall y related genes located on mouse chromosome 1, The encoded proteins so far characterized and designated p202, p204, and pD3 contain at least one copy of a conserved 200 amino acid domain in addition to other regions that are different or missing among the various family members. We have recently cha racterized a cDNA clone (203 cDNA) encoding a 408 amino acid protein bearin g structural similarities to p202 and p204. Here, we report its pattern of expression in vitro and in vivo. In vitro, the mRNA and protein encoded by the 203 gene mere increased by IFN-alpha in several cell lines of different histologic origin. By contrast, no significant induction was observed in v ice in mice from C57BL/6 and BALB/c strains even after treatment with the I FN-inducer poly rI:rC, In addition, the constitutive expression of 203 gene was restricted to some myeloid and lymphoid tissues, namely, thymus, bone marrow, and spleen. Comparison of the expression pattern of the 203 and 202 genes in three mouse strains revealed that they exhibit a differential ind ucibility by IFN and a reciprocal expression pattern. The 203 mRNA was cons titutively expressed in C57BL/6 and BALB/c mice and undetectable in the spl een of DBA/2 mice. The 202 mRNA was strongly induced by poly rI:rC in the s pleen of DBA/2 and BALB/c mice but absent in C57BL/6 mice. Southern analysi s revealed a restriction fragment length polymorphism in the 203 locus, Tak en as a whole, these results demonstrate a remarkable difference in the in vivo IFN responsiveness of two members belonging to the same gene family wi th a similar degree of IFN inducibility in vitro, Moreover, the reciprocal expression pattern in C57BL/6 and DBA/2 mice could mean that p203 and p202 ply the same role in a mouse strain in which only one of them is expressed.