Limits...
Rapid nitric oxide-induced desensitization of the cGMP response is caused by increased activity of phosphodiesterase type 5 paralleled by phosphorylation of the enzyme.

Mullershausen F, Russwurm M, Thompson WJ, Liu L, Koesling D, Friebe A - J. Cell Biol. (2001)

Bottom Line: Most of the effects of the signaling molecule nitric oxide (NO) are mediated by cGMP, which is synthesized by soluble guanylyl cyclase and degraded by phosphodiesterases.We found that guanylyl cyclase remained fully activated during the entire course of the cGMP response; thus, desensitization was not due to a switched off guanylyl cyclase.Thus, our data suggest that NO-induced desensitization of the cGMP response is caused by the phosphorylation and subsequent activity increase of phosphodiesterase type 5.

View Article: PubMed Central - PubMed

Affiliation: Abteilung für Pharmakologie und Toxikologie, Medizinische Fakultät, Ruhr-Universität Bochum, D-44780 Bochum, Germany.

ABSTRACT
Most of the effects of the signaling molecule nitric oxide (NO) are mediated by cGMP, which is synthesized by soluble guanylyl cyclase and degraded by phosphodiesterases. Here we show that in platelets and aortic tissue, NO led to a biphasic response characterized by a tremendous increase in cGMP (up to 100-fold) in less than 30 s and a rapid decline, reflecting the tightly controlled balance of guanylyl cyclase and phosphodiesterase activities. Inverse to the reported increase in sensitivity caused by NO shortage, concentrating NO attenuated the cGMP response in a concentration-dependent manner. We found that guanylyl cyclase remained fully activated during the entire course of the cGMP response; thus, desensitization was not due to a switched off guanylyl cyclase. However, when intact platelets were incubated with NO and then lysed, enhanced activity of phosphodiesterase type 5 was detected in the cytosol. Furthermore, this increase in cGMP degradation is paralleled by the phosphorylation of phosphodiesterase type 5 at Ser-92. Thus, our data suggest that NO-induced desensitization of the cGMP response is caused by the phosphorylation and subsequent activity increase of phosphodiesterase type 5.

Show MeSH
NO-induced desensitization of the cGMP response in human platelets. Platelets preincubated for 3 min with the indicated concentrations of GSNO were stimulated with a maximally effective GSNO concentration (300 μM; indicated by the arrow). cGMP accumulation at the indicated time points was determined by RIA. Shown is a representative experiment out of a total of three experiments performed in duplicates.
© Copyright Policy
Related In: Results  -  Collection


getmorefigures.php?uid=PMC2198829&req=5

fig2: NO-induced desensitization of the cGMP response in human platelets. Platelets preincubated for 3 min with the indicated concentrations of GSNO were stimulated with a maximally effective GSNO concentration (300 μM; indicated by the arrow). cGMP accumulation at the indicated time points was determined by RIA. Shown is a representative experiment out of a total of three experiments performed in duplicates.

Mentions: Next, to investigate the possible modulation of the cGMP response by NO, we performed preincubation experiments. First, we applied submaximally effective GSNO concentrations (3, 10, and 30 μM) for 3 min (Fig. 2), a period after which the intraplatelet cGMP levels had declined to almost basal levels (Fig. 1 A). After this 3-min preincubation, platelets were stimulated with the maximally effective concentration of GSNO (300 μM; Fig. 1), and cGMP levels were determined over time. As expected, under control conditions (0 μM GSNO during preincubation), the cGMP response to 300 μM GSNO resembled that seen in Fig. 1. However, GSNO preincubation attenuated the cGMP responses in a concentration-dependent manner, when induced by maximally effective GSNO. The use of 30 μM GSNO during preincubation almost totally abrogated the NO-induced cGMP response in platelets. These data indicate a rapidly induced desensitization of the cGMP response. Furthermore, the degree of NO sensitivity of the cGMP system appears to be inversely related to the amount of NO present during preincubation of the platelets.


Rapid nitric oxide-induced desensitization of the cGMP response is caused by increased activity of phosphodiesterase type 5 paralleled by phosphorylation of the enzyme.

Mullershausen F, Russwurm M, Thompson WJ, Liu L, Koesling D, Friebe A - J. Cell Biol. (2001)

NO-induced desensitization of the cGMP response in human platelets. Platelets preincubated for 3 min with the indicated concentrations of GSNO were stimulated with a maximally effective GSNO concentration (300 μM; indicated by the arrow). cGMP accumulation at the indicated time points was determined by RIA. Shown is a representative experiment out of a total of three experiments performed in duplicates.
© Copyright Policy
Related In: Results  -  Collection

Show All Figures
getmorefigures.php?uid=PMC2198829&req=5

fig2: NO-induced desensitization of the cGMP response in human platelets. Platelets preincubated for 3 min with the indicated concentrations of GSNO were stimulated with a maximally effective GSNO concentration (300 μM; indicated by the arrow). cGMP accumulation at the indicated time points was determined by RIA. Shown is a representative experiment out of a total of three experiments performed in duplicates.
Mentions: Next, to investigate the possible modulation of the cGMP response by NO, we performed preincubation experiments. First, we applied submaximally effective GSNO concentrations (3, 10, and 30 μM) for 3 min (Fig. 2), a period after which the intraplatelet cGMP levels had declined to almost basal levels (Fig. 1 A). After this 3-min preincubation, platelets were stimulated with the maximally effective concentration of GSNO (300 μM; Fig. 1), and cGMP levels were determined over time. As expected, under control conditions (0 μM GSNO during preincubation), the cGMP response to 300 μM GSNO resembled that seen in Fig. 1. However, GSNO preincubation attenuated the cGMP responses in a concentration-dependent manner, when induced by maximally effective GSNO. The use of 30 μM GSNO during preincubation almost totally abrogated the NO-induced cGMP response in platelets. These data indicate a rapidly induced desensitization of the cGMP response. Furthermore, the degree of NO sensitivity of the cGMP system appears to be inversely related to the amount of NO present during preincubation of the platelets.

Bottom Line: Most of the effects of the signaling molecule nitric oxide (NO) are mediated by cGMP, which is synthesized by soluble guanylyl cyclase and degraded by phosphodiesterases.We found that guanylyl cyclase remained fully activated during the entire course of the cGMP response; thus, desensitization was not due to a switched off guanylyl cyclase.Thus, our data suggest that NO-induced desensitization of the cGMP response is caused by the phosphorylation and subsequent activity increase of phosphodiesterase type 5.

View Article: PubMed Central - PubMed

Affiliation: Abteilung für Pharmakologie und Toxikologie, Medizinische Fakultät, Ruhr-Universität Bochum, D-44780 Bochum, Germany.

ABSTRACT
Most of the effects of the signaling molecule nitric oxide (NO) are mediated by cGMP, which is synthesized by soluble guanylyl cyclase and degraded by phosphodiesterases. Here we show that in platelets and aortic tissue, NO led to a biphasic response characterized by a tremendous increase in cGMP (up to 100-fold) in less than 30 s and a rapid decline, reflecting the tightly controlled balance of guanylyl cyclase and phosphodiesterase activities. Inverse to the reported increase in sensitivity caused by NO shortage, concentrating NO attenuated the cGMP response in a concentration-dependent manner. We found that guanylyl cyclase remained fully activated during the entire course of the cGMP response; thus, desensitization was not due to a switched off guanylyl cyclase. However, when intact platelets were incubated with NO and then lysed, enhanced activity of phosphodiesterase type 5 was detected in the cytosol. Furthermore, this increase in cGMP degradation is paralleled by the phosphorylation of phosphodiesterase type 5 at Ser-92. Thus, our data suggest that NO-induced desensitization of the cGMP response is caused by the phosphorylation and subsequent activity increase of phosphodiesterase type 5.

Show MeSH