cUMP hydrolysis by PDE3A.
Naunyn Schmiedebergs Arch Pharmacol
; 390(3): 269-280, 2017 Mar.
Article
em En
| MEDLINE
| ID: mdl-27975297
ABSTRACT
As previously reported, the cardiac phosphodiesterase PDE3A hydrolyzes cUMP. Moreover, cUMP-degrading activity was detected in cow and dog hearts several decades ago. Our aim was to characterize the enzyme kinetic parameters of PDE3A-mediated cUMP hydrolysis and to investigate whether cUMP and cUMP-hydrolyzing PDEs are present in cardiomyocytes. PDE3A-mediated cUMP hydrolysis was characterized in time course, inhibitor, and Michaelis-Menten kinetics experiments. Intracellular cyclic nucleotide (cNMP) concentrations and the mRNAs of cUMP-degrading PDEs were quantitated in neonatal rat cardiomyocytes (NRCMs) and murine HL-1 cardiomyogenic cells. Moreover, we investigated cUMP degradation in HL-1 cell homogenates and intact cells. Educts (cNMPs) and products (NMPs) of the PDE reactions were detected by HPLC-coupled tandem mass spectrometry. PDE3A degraded cUMP (measurement of UMP formation) with a K M value of ~143 µM and a V max value of ~42 µmol/min/mg. PDE3A hydrolyzed cAMP with a K M value of ~0.7 µM and a V max of ~1.2 µmol/min/mg (determination of AMP formation). The PDE3 inhibitor milrinone inhibited cUMP hydrolysis (determination of UMP formation) by PDE3A (K i = 57 nM). Significant amounts of cUMP as well as of PDE3A mRNA (in addition to PDE3B and PDE9A transcripts) were detected in HL-1 cells and NRCMs. Although HL-1 cell homogenates contain a milrinone-sensitive cUMP-hydrolyzing activity, intact HL-1 cells may use additional PDE3-independent mechanisms for cUMP disposal. PDE3A is a low-affinity and high-velocity PDE for cUMP. Future studies should investigate biological effects of cUMP in cardiomyocytes and the role of PDE3A in detoxifying high intracellular cUMP concentrations under pathophysiological conditions.
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Base de dados:
MEDLINE
Assunto principal:
Uridina Monofosfato
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Miócitos Cardíacos
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Nucleotídeo Cíclico Fosfodiesterase do Tipo 3
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Nucleotídeos Cíclicos
Idioma:
En
Ano de publicação:
2017
Tipo de documento:
Article
País de afiliação:
Alemanha