Multiply regulated adenylyl cyclases (AC) and phosphodiesterases (PDE) can yield complex intracellular cAMP signals. Ca2+-sensitive ACs have received far greater attention than the Ca2+/calmodulin-dependent PDE (PDE1) family in governing intracellular cAMP dynamics in response to changes in the cytosolic Ca2+ concentration ([Ca2+]i). Here, we have stably expressed two isoforms of PDE1, PDE1A2 and PDE1C4, in HEK-293 cells to determine whether they exert different impacts on cellular cAMP. Fractionation and imaging showed that both PDEs occurred mainly in the cytosol. However, PDE1A2 and PDE1C4 differed considerably in their ability to hydrolyze cAMP and in their susceptibility to inhibition by the non-selective PDE inhibitor, IBMX and the PDE1-selective inhibitor, MMX. PDE1A2 had an approximately 30-fold greater Km for cAMP than PDE1C4 and yet was more susceptible to inhibition by IBMX and MMX than was PDE1C4. These differences were mirrored in intact cells when thapsigargin-induced capacitative Ca2+ entry (CCE) activated the PDEs. Mirroring their kinetic properties, PDE1C4 was active at near basal cAMP levels, whereas PDE1A2 required agonist-triggered levels of cAMP, produced in response to stimulation of ACs. The effectiveness of IBMX and MMX to inhibit PDE1A2 and PDE1C4 in functional studies was inversely related to their respective affinities for cAMP. To assess the impact of the two isoforms on cAMP dynamics, real-time cAMP measurements were performed in single cells expressing the two PDE isoforms and a fluorescent Epac-1 cAMP biosensor, in response to CCE. These measurements showed that prostaglandin E1-mediated cAMP production was markedly attenuated in PDE1C4-expressing cells upon induction of CCE and cAMP hydrolysis occurred at a faster rate than in cells expressing PDE1A2 under similar conditions. These results prove that the kinetic properties of PDE isoforms play a major role in determining intracellular cAMP signals in response to physiological elevation of [Ca2+]i and thereby provide a rationale for the utility of diverse PDE1 species.

Download full-text PDF

Source
http://dx.doi.org/10.1016/j.cellsig.2007.10.024DOI Listing

Publication Analysis

Top Keywords

intracellular camp
16
camp
15
kinetic properties
12
camp dynamics
12
pde1a2 pde1c4
12
dynamics response
8
cytosolic ca2+
8
camp signals
8
ibmx mmx
8
cells expressing
8

Similar Publications

Ca/Calmodulin-Dependent Protein Kinase II (CaMKII) Regulates Basal Cardiac Pacemaker Function: Pros and Cons.

Cells

December 2024

Laboratory of Cardiovascular Science, Intramural Research Program, National Institute on Aging, National Institute of Health, Baltimore, MD 21224, USA.

The spontaneous firing of the sinoatrial (SA) node, the physiological pacemaker of the heart, is generated within sinoatrial nodal cells (SANCs) and is regulated by a "coupled-clock" pacemaker system, which integrates a "membrane clock", the ensemble of ion channel currents, and an intracellular "Ca clock", sarcoplasmic reticulum-generated local submembrane Ca releases via ryanodine receptors. The interactions within a "coupled-clock" system are modulated by phosphorylation of surface membrane and sarcoplasmic reticulum proteins. Though the essential role of a high basal cAMP level and PKA-dependent phosphorylation for basal spontaneous SANC firing is well recognized, the role of basal CaMKII-dependent phosphorylation remains uncertain.

View Article and Find Full Text PDF

Shenghui decoction inhibits neuronal cell apoptosis to improve Alzheimer's disease through the PDE4B/cAMP/CREB signaling pathway.

Phytomedicine

January 2025

Collaborative Innovation Center of Prevention and Treatment of Major Diseases by Chinese and Western Medicine, Henan Province, Henan University of Chinese Medicine, Zhengzhou 450046, Henan, China; Collaborative Innovation Center of Research and Development on the whole Industry Chain of Yu-Yao, Henan University of Chinese Medicine, Zhengzhou 450046, Henan, China. Electronic address:

Background: Shenghui Decoction (SHD) is a frequently utilized traditional Chinese medicine formula in clinical settings for addressing cognitive impairment in elderly individuals. Nevertheless, the precise mechanism by which SHD exerts its effects on the most prevalent form of dementia, Alzheimer's disease (AD), remains to be elucidated.

Methods: Temperature-induced transgenic C.

View Article and Find Full Text PDF

Activators of the 26S proteasome when protein degradation increases.

Exp Mol Med

January 2025

Department of Cell Biology, Harvard Medical School, 240 Longwood Avenue, Boston, MA, 02115, USA.

In response to extra- and intracellular stimuli that constantly challenge and disturb the proteome, cells rapidly change their proteolytic capacity to maintain proteostasis. Failure of such efforts often becomes a major cause of diseases or is associated with exacerbation. Increase in protein breakdown occurs at multiple steps in the ubiquitin-proteasome system, and the regulation of ubiquitination has been extensively studied.

View Article and Find Full Text PDF

NPA7: A Dual Receptor Activating Peptide That Inhibits Cardiac Oxidative Stress.

Hypertension

January 2025

Cardiorenal Research Laboratory, Department of Cardiovascular Medicine, Mayo Clinic, Rochester, MN. (Xiaoyu Ma, J.C.M., D.G.M., Xiao Ma, Y.Z., S.P., Y.W., S.J.S., J.C.B.).

Background: Cardiomyocyte oxidative stress significantly contributes to the progression of hypertension-induced heart failure, highlighting the need for targeted therapies. We developed a novel peptide, NPA7, that coactivates the GC-A (guanylyl cyclase A)/cGMP and MasR (Mas receptor)/cAMP pathway. This study aimed to test NPA7's ability to inhibit oxidative stress by modulating the p62-KEAP1 (Kelch-like ECH-associated protein 1)-NRF2 (nuclear factor erythroid 2-related factor 2) pathway in human cardiomyocytes (HCMs) and a rat model of hypertension.

View Article and Find Full Text PDF

Pharmacotherapy for depression includes drugs such as monoamine oxidase inhibitors (MAOIs), tricyclic antidepressants (TCAs), selective serotonin reuptake inhibitors (SSRIs), noradrenaline (NA) and serotonin (5-HT) reuptake inhibitors (NaSSAs), and atypical antidepressants; these drugs exert differentially beneficial effects on symptoms of depression after acute and chronic treatment in animal models. Said effects are established through neuroplastic mechanisms involving changes in neurogenesis and synaptogenesis as result of the activation of intracellular signaling pathways associated with neurochemical and behavioral changes. Antidepressants increase the synaptic availability of monoamines (monoaminergic hypothesis) such as 5-HT, NA, and gamma-aminobutyric acid (GABA) by inhibiting their reuptake or degradation and activating intracellular signaling pathways such as the responsive element binding protein (cAMP-CREB) cascade, which regulates the expression of genes related to neuroplasticity and neurogenesis, such as brain-derived neurotrophic factor (BDNF), in various brain structures implicated in depression.

View Article and Find Full Text PDF

Want AI Summaries of new PubMed Abstracts delivered to your In-box?

Enter search terms and have AI summaries delivered each week - change queries or unsubscribe any time!