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 th e regulation of cell growth and differentiation. To further explore th e suggested participation of ZPK/DLK/MUK in this process, we examined the expression and cellular localization of ZPK/DLK/ MUK mRNA in regen erating mouse liver following partial hepatectomy by ribonuclease prot ection assay and in situ hybridization. The steady-state level of ZPK/ DLK/MUK mRNA was very low in normal and tram-operated mouse livers, w hereas a marked and transient increase was observed in the regeneratin g liver. While ZPK/DLK/MUK mRNAs were rarely detected in hepatocytes f rom all zones of the normal liver, hepatocytes of regenerating liver e xhibit a gradient of expression ranging from low in the periportal zon e, to intermediate in the mid-zone, to high in the pericentral zone. T hese findings demonstrate a transient stimulation of ZPK/DLK/MUK gene expression that correlates with the growth response of hepatocyte subp opulations in regenerating liver. (C) 1998 Academic Press.