DEVELOPMENTAL PROFILE OF HOMEOBOX GENE-EXPRESSION DURING 3T3-L1 ADIPOGENESIS

The homeobox family of proteins are transcription factors are known to be important during the differentiation of a variety of mammalian tis sues, however, expression of the genes encoding homeobox proteins duri ng adipogenesis or in adipose tissue has not been described. To invest igate whether members of the homeobox gene family are expressed and re gulated during adipocyte differentiation, RNA was isolated from 3T3-L1 preadipocyte cells during the hormonal induced differentiation of thi s cell line into adipocytes. A reverse transcriptase-polymerase chain reaction strategy using degenerate oligonucleotide primers complementa ry to the highly conserved homeodomain resulted in the identification of 10 different homeobox genes expressed during 3T3-L1 adipogenesis. O ne of the clones appears to be unique and 9 of the clones represented known members of the homeobox gene family. Examination of the relative mRNA levels encoding these proteins by ribonuclease protection assay during adipocyte differentiation revealed that 3 members, Hox a4, Hox a7, and Hox d4, are regulated as a function of adipocyte development. Further examination of RNA isolated from murine retroperitoneal adipos e tissue revealed that these three regulated homeobox mRNAs are expres sed in vivo. Combined, these results suggest that members of the homeo box gene family may serve an important role during the differentiation of adipocytes. (C) 1997 Academic Press.