Anisoosmotic regulation of the Nopp140 mRNA in H4IIE rat hepatoma cells and primary hepatocytes

Using the differential display polymerase chain reaction osmosensitive regu lation of mRNA levels of the nucleolar phosphoprotein of 140 kDa (Nopp140) was found in H4IIE; rat hepatoma cells. These levels were downregulated aft er hypoosmotic exposure in H4IIE cells and primary rat hepatocytes. Hyperos motic incubation increased Nopp140 mRNA levels in H4IIE cells but not in he patocytes. Inhibition of p38(MAPK) Or MAP kinase kinase upstream of Erk-1 a nd Erk-2 decreased Nopp140 mRNA levels but did not prevent their osmosensit ivity. Because Nopp140 is involved in the regulation of transcriptional act ivity it could play a role in the osmosignalling pathway towards gene expre ssion in H4IIE cells and hepatocytes. (C) 1999 Federation of European Bioch emical Societies.