Characterization of soluble uterine cyclic nucleotide phosphodiesterase

Abstract

Soluble cyclic nucleotide phosphodiesterase of rat uterus displays distinct structural and regulatory properties. Like phosphodiesterases from many mammalian sources the soluble uterine enzyme system exhibits nonlinear Lineweaver--Burk kinetics with cyclic adenosine 3':5'-monophosphate (cAMP) as substrate (apparent Kms congruent to 3 and 20 micron) and linear kinetics with cyclic guanosine 3':5'-monophosphate (cGMP) as substrate (apparent Km congruent to 3 micron). Unlike most other mammalian phosphodiesterases, however, numerous separation procedures reveal only a single form of uterine phosphodiesterase which catalyzes the hydrolysis of both cAMP and cGMP. A single form of the enzyme is observed upon sucrose gradient centrifugation (7.9 S), agarose gel filtration, and DEAE-cellulose chromatography at either pH 8.0 OR 6.0. Heat denaturation (50 degrees C) of soluble uterine phosphodiesterase causes the loss of both cAMP and cGMP hydrolytic activities at the same rate. Isoelectric focusing reveals major (pI = 5.2) and minor forms (pI = 5.8) of phosphodiesterase which both catalyze the hydrolysis of the two cyclic nucleotide substrates. In vivo administration of estradiol produces identical decreases in the activities of cAMP and cGMP phosphodiesterase. These results raise the possibility that the uterus contains a single form of soluble phosphodiesterase which catalyzes the hydrolysis of both cAMP and cGMP.

Cyclic 3′:5′-Nucleotide Phosphodiesterase in Human Myometrium at the End of Pregnancy: Partial Purification and Characterization of the Different Soluble Isoenzymes

“…Up to now, few studies have been reported on the characterization of cyclic nucleotide PDE in myometrium. The discrepancy between our results and those of Gardner et al [19] in rat uterus could be due to the difference of spe cies and/or to the hormonal status of the tis sue used, and to the localization of the sam ples. Preliminary studies on the cyclic nu cleotide PDE conducted in the pregnant ma caque myometrium indicate that nonhuman primates may be a partially representative model of what happens in the pregnant hu man myometrium [5].…”

“…Peaks A and B hydrolyzed cGMP as well. The resolu tion of these different peaks, which corre spond to different molecular forms of PDE, contrasted with the single peak obtained in rat uterus by the same method [19]. The asso ciation of the two procedures showed that peak I obtained by DEAE-cellulose chroma tography is resolved onto sucrose density gra dient centrifugation into two molecular enti ties corresponding to peaks A and B de scribed above.…”

Evolution of cAMP phosphodiesterase activity in cultured myometrial cells: Effects of steroids and of successive subcultures

“…This activity was not affected by the number of subcultures, suggesting that cell aging did not interfere, although the mechanism underlying these inhibitory effects was not elucidated. In rat uterus, in vivo administration of estradiol decreased cyclic nucleotide PDE activity (Gardner et al, 1978). By contrast, in macaque myometrium, the decrease in PDE activity was only attributed to progesterone (Beatty et al, 1978).…”

“…It is still not known if myometrial tissue contains one or two different enzymatic forms (Gardner et al, 1978;Keravis et al, 1980;Leroy et al, in press). …”

“…The nonlinear kinetics which were also observed for cAMP PDE activity in myometrium of a wide variety of species (Stancel et al, 1975;Beatty et al, 1976;Ferre et al, 1977Ferre et al, , 1978Currie, 1980) suggest the presence of multiple molecular forms or of a single one exhibiting negative cooperativity. It is still not known if myometrial tissue contains one or two different enzymatic forms (Gardner et al, 1978;Keravis et al, 1980;Leroy et al, in press).…”