A NOVEL GENE (DRAD-1) EXPRESSED IN HEMATOPOIESIS-SUPPORTING STROMAL CELL-LINES, ST2, PA6 AND A54 PREADIPOCYTES - USE OF MESSENGER-RNA DIFFERENTIAL DISPLAY

We established a differentiation-inducible preadipocyte cell line, des ignated A54 preadipocytes, from C3H10T1/2 (10T1/2) mouse embryo fibrob lasts. A54 preadipocytes had marked hematopoiesis-supporting ability i n vitro but this ability was lost after terminal differentiation to ad ipocytes, In this study, to identify molecules that contribute to the hematopoiesis-supporting ability of A54 preadipocyte, we screened gene s that were differentially expressed in A54 preadipocytes and isolated seven novel genes by reverse transcriptase polymerase chain reaction mRNA differential display. An RNase protection assay confirmed that on e of these genes was expressed at high levels in parent 10T1/2 cells a nd A54 preadipocytes but to a much lesser extent in fully differentiat ed A54 adipocytes. This gene was defined as a gene that was downregula tcd during adipocyte differentiation-1 (drad-1). The size of drad-1 mR NA was 8.2 kb, and the gene was expressed in other mouse preadipocytes , namely, ST2 and PA6 cells, that have hematopoiesis-supporting abilit y, Moreover, drad-1 was also found to be expressed in bone marrow in v ivo. The function of the protein encoded by drad-1 is unknown, but the expression of the gene may be useful as a molecular marker of adipocy te differentiation.