Zonal induction of mixed lineage kinase ZPK/DLK/MUK gene expression in regenerating mouse liver

ZPK/DLK/MUK is a serine/threonine kinase believed to be involved in the regulation of cell growth and differentiation. To further explore the suggested participation of ZPK/DLK/MUK in this process, we examined the expression and cellular localization of ZPK/DLK/ MUK mRNA in regenerating mouse liver following partial hepatectomy by ribonuclease protection assay and in situ hybridization. The steady-state level of ZPK/ DLK/MUK mRNA was very low in normal and tram-operated mouse livers, whereas a marked and transient increase was observed in the regenerating liver. While ZPK/DLK/MUK mRNAs were rarely detected in hepatocytes from all zones of the normal liver, hepatocytes of regenerating liver exhibit a gradient of expression ranging from low in the periportal zone, to intermediate in the mid-zone, to high in the pericentral zone. These findings demonstrate a transient stimulation of ZPK/DLK/MUK gene expression that correlates with the growth response of hepatocyte subpopulations in regenerating liver. (C) 1998 Academic Press.