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Dexamethasone-dependent modulation of cyclic GMP synthesis in podocytes.

Lewko B, Waszkiewicz A, Maryn A, Gołos M, Latawiec E, Daca A, Witkowski JM, Angielski S, Stępiński J - Mol. Cell. Biochem. (2015)

Bottom Line: In the presence of DEX these effects were prevented.We conclude that DEX modulates the production of cGMP in podocytes stimulated with vasoactive factors such as Ang II, ANP, and NO, and the effect is time-dependent. cGMP increases podocyte motility, which is prevented by DEX.This mechanism may account for the antiproteinuric effect of glucocorticoids.

View Article: PubMed Central - PubMed

Affiliation: Department of Pharmaceutical Pathophysiology, Medical University of Gdansk, Debinki 7, 80-211, Gdansk, Poland. blew@gumed.edu.pl.

ABSTRACT
Podocytes may be direct target for glucocorticoid therapy in glomerular proteinuric disease. Permeability of podocytes largely depends on their capacity to migrate which involves the contractile apparatus in their foot processes. In this study, we examined the effect of synthetic glucocorticoid dexamethasone (DEX) on the ability of podocytes to produce cyclic guanosine monophosphate (cGMP) in the presence of vasoactive factors, atrial natriuretic peptide (ANP), nitric oxide (NO), and angiotensin II (Ang II). We investigated also the effects of cGMP and DEX on podocyte motility. Primary rat podocytes and immortalized mouse podocytes were pretreated with 1 µM DEX for 4 or 24 h. Glomerular hypertension was mimicked by subjecting the cells to mechanical stress. Total and subcellular cGMP levels were determined in podocytes incubated with 0.1 µM ANP, 1 µM S-nitroso-N-acetyl penicillamine (SNAP), and 1 µM Ang II. Cell motility was estimated by a wound-healing assay. The ANP-dependent production of cGMP increased after 4 h exposition to DEX, but was attenuated after 24 h. Adversely, a 24-h pretreatment with DEX augmented the NO-dependent cGMP synthesis. Ang II suppressed the ANP-dependent cGMP production and the effect was enhanced by DEX in mechanical stress conditions. Mechanical stress reduced total cGMP production in the presence of all stimulators, whereas extracellular to total cGMP ratio increased. 8-Br cGMP enhanced podocyte migration which was accompanied by F-actin disassembly. In the presence of DEX these effects were prevented. We conclude that DEX modulates the production of cGMP in podocytes stimulated with vasoactive factors such as Ang II, ANP, and NO, and the effect is time-dependent. cGMP increases podocyte motility, which is prevented by DEX. This mechanism may account for the antiproteinuric effect of glucocorticoids.

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Dexamethasone did not influence the inhibitory effect of Ang II on ANP-dependent production of cGMP. Mouse podocytes were preincubated for 24 h in the presence or absence of 1 µM DEX. 0.1 μM ANP and/or 1 μM Ang II were added for 15 min, as described in “Materials and methods.” Results are presented as means from 4 independent experiments ±SEM. **P < 0.01 versus control
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Fig4: Dexamethasone did not influence the inhibitory effect of Ang II on ANP-dependent production of cGMP. Mouse podocytes were preincubated for 24 h in the presence or absence of 1 µM DEX. 0.1 μM ANP and/or 1 μM Ang II were added for 15 min, as described in “Materials and methods.” Results are presented as means from 4 independent experiments ±SEM. **P < 0.01 versus control

Mentions: Figure 4 demonstrates that incubation with Ang II of the DEX-pretreated mouse podocytes did not change significantly the ANP-induced cGMP production, as compared to the cells exposed to Ang II or to DEX alone. While both, Ang II and DEX separately decreased the cGMP level, their effects were not additive. Similar results were obtained in rat podocytes (Table 2, non-stressed NS cells). However, elevated intrarenal Ang II levels in vivo are frequently associated with glomerular hypertension, which exposes podocytes to additional mechanical forces. In order to mimick these conditions, we applied mechanical strain and we examined whether it affected the cGMP response in the presence of Ang II and DEX. Cultured rat podocytes were subjected for 24 h to mechanical stress with or without DEX, and the effect of Ang II on ANP-dependent cGMP production was measured. As shown in Table 2, similarly to NS podocytes, Ang II markedly inhibited the effect of ANP in the stressed (S) cells. Moreover, in contrast to NS group, DEX further significantly suppressed the cGMP level in the presence of Ang II. These findings suggest that mechanical stress and DEX synergistically sensitized the podocytes to Ang II.Table 2


Dexamethasone-dependent modulation of cyclic GMP synthesis in podocytes.

Lewko B, Waszkiewicz A, Maryn A, Gołos M, Latawiec E, Daca A, Witkowski JM, Angielski S, Stępiński J - Mol. Cell. Biochem. (2015)

Dexamethasone did not influence the inhibitory effect of Ang II on ANP-dependent production of cGMP. Mouse podocytes were preincubated for 24 h in the presence or absence of 1 µM DEX. 0.1 μM ANP and/or 1 μM Ang II were added for 15 min, as described in “Materials and methods.” Results are presented as means from 4 independent experiments ±SEM. **P < 0.01 versus control
© Copyright Policy - OpenAccess
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4589550&req=5

Fig4: Dexamethasone did not influence the inhibitory effect of Ang II on ANP-dependent production of cGMP. Mouse podocytes were preincubated for 24 h in the presence or absence of 1 µM DEX. 0.1 μM ANP and/or 1 μM Ang II were added for 15 min, as described in “Materials and methods.” Results are presented as means from 4 independent experiments ±SEM. **P < 0.01 versus control
Mentions: Figure 4 demonstrates that incubation with Ang II of the DEX-pretreated mouse podocytes did not change significantly the ANP-induced cGMP production, as compared to the cells exposed to Ang II or to DEX alone. While both, Ang II and DEX separately decreased the cGMP level, their effects were not additive. Similar results were obtained in rat podocytes (Table 2, non-stressed NS cells). However, elevated intrarenal Ang II levels in vivo are frequently associated with glomerular hypertension, which exposes podocytes to additional mechanical forces. In order to mimick these conditions, we applied mechanical strain and we examined whether it affected the cGMP response in the presence of Ang II and DEX. Cultured rat podocytes were subjected for 24 h to mechanical stress with or without DEX, and the effect of Ang II on ANP-dependent cGMP production was measured. As shown in Table 2, similarly to NS podocytes, Ang II markedly inhibited the effect of ANP in the stressed (S) cells. Moreover, in contrast to NS group, DEX further significantly suppressed the cGMP level in the presence of Ang II. These findings suggest that mechanical stress and DEX synergistically sensitized the podocytes to Ang II.Table 2

Bottom Line: In the presence of DEX these effects were prevented.We conclude that DEX modulates the production of cGMP in podocytes stimulated with vasoactive factors such as Ang II, ANP, and NO, and the effect is time-dependent. cGMP increases podocyte motility, which is prevented by DEX.This mechanism may account for the antiproteinuric effect of glucocorticoids.

View Article: PubMed Central - PubMed

Affiliation: Department of Pharmaceutical Pathophysiology, Medical University of Gdansk, Debinki 7, 80-211, Gdansk, Poland. blew@gumed.edu.pl.

ABSTRACT
Podocytes may be direct target for glucocorticoid therapy in glomerular proteinuric disease. Permeability of podocytes largely depends on their capacity to migrate which involves the contractile apparatus in their foot processes. In this study, we examined the effect of synthetic glucocorticoid dexamethasone (DEX) on the ability of podocytes to produce cyclic guanosine monophosphate (cGMP) in the presence of vasoactive factors, atrial natriuretic peptide (ANP), nitric oxide (NO), and angiotensin II (Ang II). We investigated also the effects of cGMP and DEX on podocyte motility. Primary rat podocytes and immortalized mouse podocytes were pretreated with 1 µM DEX for 4 or 24 h. Glomerular hypertension was mimicked by subjecting the cells to mechanical stress. Total and subcellular cGMP levels were determined in podocytes incubated with 0.1 µM ANP, 1 µM S-nitroso-N-acetyl penicillamine (SNAP), and 1 µM Ang II. Cell motility was estimated by a wound-healing assay. The ANP-dependent production of cGMP increased after 4 h exposition to DEX, but was attenuated after 24 h. Adversely, a 24-h pretreatment with DEX augmented the NO-dependent cGMP synthesis. Ang II suppressed the ANP-dependent cGMP production and the effect was enhanced by DEX in mechanical stress conditions. Mechanical stress reduced total cGMP production in the presence of all stimulators, whereas extracellular to total cGMP ratio increased. 8-Br cGMP enhanced podocyte migration which was accompanied by F-actin disassembly. In the presence of DEX these effects were prevented. We conclude that DEX modulates the production of cGMP in podocytes stimulated with vasoactive factors such as Ang II, ANP, and NO, and the effect is time-dependent. cGMP increases podocyte motility, which is prevented by DEX. This mechanism may account for the antiproteinuric effect of glucocorticoids.

No MeSH data available.


Related in: MedlinePlus