EXPRESSION AND REGULATION OF HUMAN AND RAT PHOSPHODIESTERASE TYPE-IV ISOGENES

Type IV phosphodiesterases (PDE IV) specifically hydrolyze cAMP and ar e inhibited by rolipram. RT-PCR was applied to analyze the expression patterns of mRNAs for four cloned human and rat phosphodiesterase type IV isogenes (PDE IV-A, -B, -C and -D). Although these patterns were m ostly coincident for the human and rat PDE IV genes, some differences were found between the two species. PDE IV-A expression was detectable in human blood but not in rat blood, suggesting a species-specific di fference in the expression of this PDE IV isogene. PDE IV-C was neithe r detected in human or rat blood nor in different cell populations of the human immune system. It is further demonstrated that the PDE IV is ogene expression is differentially regulated by cAMP in different cell types.