PDE5 is converted to an activated state upon cGMP binding to the GAF A domain

Rybalkin, Sergei D.; Rybalkina, Irina G.; Shimizu‐Albergine, Masami; Tang, Xiao; Beavo, Joseph A.

doi:10.1093/emboj/cdg051

Cited by 214 publications

(219 citation statements)

References 22 publications

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“…PDE5 activity is not fixed, but it becomes enhanced when cGMP binds to the enzyme (17). This enhancement corresponds to a time-dependent increase in the limiting rate of hydrolysis (V p ), a reduction in the K m for cGMP, and an increase in the affinity of sildenafil (K i ).…”

Section: Methodsmentioning

confidence: 99%

“…The equations assume that the enhancement is irreversible, which, considering the short time intervals being analyzed, is justified (17,18). With values assigned to the variables, the cGMP profile is obtained by numerically solving the following equation.…”

Section: Methodsmentioning

confidence: 99%

“…Kinetics of PDE5-cGMP binding to PDE5 leads to an enhancement of the catalytic activity (17), but in cells, the rate at which it happens, the extent to which it occurs, and the impact it has on NO signal transduction were all open questions. We estimate that the maximal enhancement of PDE activity amounts to a rise in net catalytic efficiency (given by V p /K p ) of 30-fold.…”

Section: Differential Potency Of No For Gc-coupled Receptors In Cellsmentioning

confidence: 99%

“…The levels of cGMP in a cell reflect the interplay between the rate of synthesis, the rate of degradation by phosphodiesterase (PDE), and, possibly, the rate of extrusion into the extracellular fluid. The rates of cGMP synthesis and degradation may both change with time because of desensitization of the GC-coupled NO receptors (10) and enhancement of PDE activity (17,18), rendering the problem a complex one. To address it, we have chosen the simplest cells available, blood platelets.…”

mentioning

confidence: 99%

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Kinetics of a Cellular Nitric Oxide/cGMP/Phosphodiesterase-5 Pathway

Amin

Bianco³

et al. 2004

Journal of Biological Chemistry

103

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Rat platelets served as a model to evaluate quantitatively how guanylate cyclase (GC)-coupled nitric oxide (NO) receptors and phosphodiesterases (here phosphodiesterase-5) interact to transduce NO signals in cells. The platelets expressed mRNA only for the ␣ 1 and ␤ 1 GC-coupled receptor subunits. In intact platelets, the potency of NO for elevating cGMP (EC 50 ‫؍‬ 10 nM) was lower than in lysed platelets (EC 50 ‫؍‬ 1.7 nM). The limiting activities of GC and phosphodiesterase in intact platelets were both very high, being equivalent to about 100 M/s. With low phosphodiesterase activity (imposed by 100 M sildenafil), the cGMP response over time was hyperbolic in shape for a range of NO concentrations or GC activities due to GC desensitization. Without a phosphodiesterase inhibitor, NO generated only brief cGMP transients, peaking after 2-5 s but amounting maximally to about 150 M cGMP. The transients were caused partly by GC desensitization, which varied in rate (halftime up to 3 s) and extent (up to 80%) depending on the NO concentration, and partly by an enhancement of the phosphodiesterase catalytic activity with time, which was deduced to be up to 30-fold and to occur with a half-time of up to 5 s. The results were simulated by a quantitative model, which also explains the varied shapes of cGMP responses to NO found in other cells. Downstream phosphorylation in platelets was detectable within 2 s, and, with continuous exposure (1 min), this pathway could be engaged by subnanomolar NO concentrations (EC 50 ‫؍‬ 0.5 nM).Whereas the spatio-temporal dynamics of some of the primary steps of cellular signal transduction, such as synaptic transmission and changes in intracellular Ca 2ϩ , have become well understood in quantitative terms (1, 2), knowledge of downstream signaling cascades remains largely qualitative. Nevertheless, the kinetic properties of the second messenger cascades are likely to be similarly instrumental in determining how cells respond.A case in point is nitric oxide (NO) 1 signaling. NO acts as a diffusible chemical messenger throughout the body, where it subserves diverse functions, including smooth muscle relaxation, inhibition of platelet aggregation, and the induction of synaptic plasticity (3,4). NO elicits these and other physiological effects by binding to its guanylyl cyclase (GC)-coupled receptors, thereby evoking the accumulation of cGMP in target cells. The receptors are ␣␤-heterodimers, of which two main isoforms, ␣ 1 ␤ 1 and ␣ 2 ␤ 1 , exist at differing levels in different tissues (5). Studies on purified receptors (6) and intact cells (7) suggest that activation of GC occurs very rapidly, within a few ms or less of adding NO, and complete deactivation in cells (upon removal of NO) requires only about 500 ms (7). Furthermore, when studied in isolation, the receptors are highly sensitive NO detectors, with only about 1 nM being needed to evoke half-maximal GC activity (8). The shape of the resulting cGMP response in cells, however, varies greatly from one cell to another. For example,...

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Section: Methodsmentioning

confidence: 99%

Section: Methodsmentioning

confidence: 99%

Section: Differential Potency Of No For Gc-coupled Receptors In Cellsmentioning

confidence: 99%

mentioning

confidence: 99%

See 2 more Smart Citations

Kinetics of a Cellular Nitric Oxide/cGMP/Phosphodiesterase-5 Pathway

Amin

Bianco³

et al. 2004

Journal of Biological Chemistry

103

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“…3 For PDE5, enzyme activation most likely proceeds via phosphorylation of the catalytic subunits and allosteric changes in cGMP binding to the GAF domains. 20,21 (While PDE5 has been reported to copurify with the PDE6 g subunit, 22 the physiological significance is uncertain because the g subunit lacks binding or inhibitory activity toward PDE5 in vitro. 23 )…”

Section: Similarities and Differences Between Pde5 And Pde6mentioning

confidence: 99%

Characteristics of Photoreceptor PDE (PDE6): similarities and differences to PDE5

2004

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Phosphodiesterase 6 (PDE6) is highly concentrated in the retina. It is most abundant in the internal membranes of retinal photoreceptors, where it reduces cytoplasmic levels of cyclic guanosine monophosphate (cGMP) in rod and cone outer segments in response to light. The rod PDE6 holoenzyme comprises a and b catalytic subunits and two identical inhibitory c subunits. Each catalytic subunit contains three distinct globular domains corresponding to the catalytic domain and two GAF domains (responsible for allosteric cGMP binding). The PDE6 catalytic subunits resemble PDE5 in amino-acid sequence as well as in three-dimensional structure of the catalytic dimer; preference for cGMP over cyclic adenosine monophosphate (cAMP) as a substrate; and the ability to bind cGMP at the regulatory GAF domains. Most PDE5 inhibitors inhibit PDE6 with similar potency, and electroretinogram studies show modest effects of PDE5 inhibitors on visual function-an observation potentially important in designing PDE5-specific therapeutic agents.

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Phosphodiesterases and Cyclic Nucleotide Signaling In The CNS

Conti

Richter

2014

Cyclic‐Nucleotide Phosphodiesterases in the Central Nervous System

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PDE5 is converted to an activated state upon cGMP binding to the GAF A domain

Cited by 214 publications

References 22 publications

Kinetics of a Cellular Nitric Oxide/cGMP/Phosphodiesterase-5 Pathway

Kinetics of a Cellular Nitric Oxide/cGMP/Phosphodiesterase-5 Pathway

Characteristics of Photoreceptor PDE (PDE6): similarities and differences to PDE5

Phosphodiesterases and Cyclic Nucleotide Signaling In The CNS

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