CODING SEQUENCE, EXON-INTRON STRUCTURE AND CHROMOSOMAL LOCALIZATION OF MURINE TNF-STIMULATED GENE-6 THAT IS SPECIFICALLY EXPRESSED BY EXPANDING CUMULUS CELL-OOCYTE COMPLEXES

Tumor necrosis factor stimulated gene-6 (TSG-6) has been previously sh own to be induced in vitro in several cell types by proinflammatory cy tokines, and in vivo in pathological conditions such as rheumatoid art hritis. In this study, we report the complete coding sequence for the mouse TSG-6 protein, and the exon-intron structure and the chromosomal localization of the gene. We have identified a 1605 nt cDNA. sequence from mouse cumulus cell-oocyte complexes (COCs) induced to expand in vivo. The sequence contains an open reading frame of 825 nt that codes for the 275 amino acid TSG-6 protein. The gene contains six exons sep arated by 1.1-5.8 kb introns and has been localized to the murine chro mosome 2 by linkage analysis. Comparative reverse transcription-polyme rase chain reaction studies have revealed that TSG-6 mRNA is specifica lly expressed after COC expansion induced in vivo, identifying the fir st non-pathological process in which TSG-6 may play an important role. Since TSG-6 binds to hyaluronan and interacts with inter-alpha-trypsi n inhibitor (I alpha I), molecules that are essential for matrix forma tion by COCs, this protein may have a structural role in the matrix or may enhance the antiproteolytic effect of I alpha I to protect the ma trix from degradation. (C) 1997 Elsevier Science B.V.