IDENTIFICATION OF HOMEOBOX GENES EXPRESSED DURING THE PROCESS OF RAT-LIVER REGENERATION AFTER PARTIAL-HEPATECTOMY

Homeobox (HBox) genes are well-known to be involved in development and differentiation. To ascertain a role of HBox genes in the process of liver regeneration, we identified HBox genes expressed at various time s after partial hepatectomy in rats (at 0 hr, 1 hr, 2 days, and 4 days ) by using reverse transcription-polymerase chain reaction (RT-PCR), c loning, and sequencing techniques. By the competitive RT-PCR method us ing generic primers, expression levels of HBox genes in regenerating l ivers were estimated at as low as only 0.4-2% of that in 14-day embryo nic liver; however; we identified multiple HBox genes at different sta ges. Comparing sets of HBox genes identified at different stages, we c ould find two candidates of stage specifically expressed HBox genes (o ne rat caudal-related gene, RCdx-3, stimulated at 1 hr, and one rat Ho x gene, RHoxB5, repressed after hepatectomy) and continuous expression of five Hox genes (RHoxA1, A4, A5, B2, and B3) before and after hepat ectomy. These HBox genes are considered to correlate with the process of liver regeneration.