DIFFERENTIAL EXPRESSION OF CGMP-INHIBITED CYCLIC-NUCLEOTIDE PHOSPHODIESTERASES IN HUMAN HEPATOMA-CELL LINES

PDE3 or cGMP-inhibited cyclic nucleotide phosphodiesterase (cGI PDE) a ctivity was detected in homogenates of HepG2, Hep3B and HuH7, but not SK-Hep-1, human hepatoma cells, In HepG2 and Hep3B cells PDE3 activity was found predominantly in particulate fractions; in HuH7, in both pa rticulate and supernatant fractions. cDNAs encoding two human PDE3s (a n 'adipocyte' type, HcGIP1, and a 'cardiovascular' type, HcGIP2) have been cloned, HcGIP1 cDNA hybridized strongly with poly(A)(+) RNA speci es from HepG2 and Hep3B, Both HcGIP1 and HcGIP2 mRNAs were expressed i n Hep3B and HuH7 cells, The nucleotide sequence of an similar to 300-b p cDNA fragment, isolated after RT-PCR cloning from HepG2 RNA, was ide ntical to a sequence within the conserved domain of HcGIP1 cDNA, consi stent with the presence of HcGIP1 mRNA in HepG2 cells.