We studied interactions between the mitogen-activated protein kinase (MAPK) signalling pathway and cAMP-protein kinase (PKA) signaling pathway in regulation of mitogenesis of mesangial cells (MC) determined by [3H]thymidine incorporation, with or without added EGF. Forskolin or dibutyryl cAMP strongly (by 60-70%) inhibited [3H]thymidine incorporation into MC. Cilostamide, lixazinone or cilostazol selective inhibitors of cAMP-phosphodiesterase (PDE) isozyme PDE-III, inhibited mitogenesis to similar extent as forskolin and DBcAMP and activated in situ PKA, but without detectable increase in cAMP levels. Cilostamide and cilostazol were more than three times more effective at inhibiting mesangial mitogenesis than rolipram and denbufylline, inhibitors of isozyme PDE-IV, even though PDE-IV was two times more abundant in MC than was PDE-III. On the other hand, when incubated with forskolin, rolipram-enhanced cAMP accumulation was far greater (10-100x) than with cilostamide. EGF increased MAPK activity (+300%); PDE isozyme inhibitors which suppressed mitogenesis also inhibited MAPK. PDE isozyme inhibitors also suppressed PDGF-stimulated MC proliferation. We conclude that cAMP inhibits the mitogen-dependent MAPK-signaling pathway probably by decreasing the activity of Raf-1 due to PKA-catalyzed phosphorylation. Further, we surmise that minor increase in the cAMP pool metabolized by PDE-III is intimately related to regulation of mesangial proliferation. Thus, PDE isozyme inhibitors have the potential to suppress MC proliferation by a focused effect upon signaling pathways.

• MeSH
• cAMP-fosfodiesterasy * antagonisté a inhibitory   MeSH
• chinolony farmakologie   MeSH
• destičkový růstový faktor farmakologie   MeSH
• epidermální růstový faktor farmakologie   MeSH
• glomerulární mesangium cytologie   enzymologie   účinky léků   MeSH
• izoenzymy * antagonisté a inhibitory   MeSH
• krysa rodu rattus MeSH
• kultivované buňky MeSH
• potkani Sprague-Dawley MeSH
• proteinkinasy závislé na cyklickém AMP * fyziologie   MeSH
• proteinkinasy závislé na vápníku a kalmodulinu metabolismus   MeSH
• pyrrolidinony farmakologie   MeSH
• rolipram MeSH
• thymidin metabolismus   MeSH
• zvířata MeSH
• Check Tag
• krysa rodu rattus MeSH
• mužské pohlaví MeSH
• zvířata MeSH
• Publikační typ
• práce podpořená grantem MeSH
• Research Support, U.S. Gov't, P.H.S. MeSH