The slow delayed rectifier potassium current (IKs) significantly contributes to cardiac repolarization under specific conditions, particularly at stimulation by the protein kinase A (PKA) during increased sympathetic tone. Impaired PKA-mediated stimulation of IKs channels may considerably aggravate dysfunction of the channels induced by mutations in the KCNQ1 gene that encodes the structure of the α-subunit of IKs channels. These mutations are associated with several subtypes of inherited arrhythmias, mainly long QT syndrome type 1, less commonly short QT syndrome type 2, and atrial fibrillation. The impaired PKA reactivity of IKs channels may significantly increase the risk of arrhythmia in these patients. Unfortunately, only approximately 2.7% of the KCNQ1 variants identified as putatively clinically significant have been studied with respect to this problem. This review summarizes the current knowledge in the field to stress the importance of the PKA-mediated regulation of IKs channels, and to appeal for further analysis of this regulation in KCNQ1 mutations associated with inherited arrhythmogenic syndromes. On the basis of the facts summarized in our review, we suggest several new regions of the α-subunit of the IKs channels as potential contributors to PKA stimulation, namely the S4 and S5 segments, and the S2-S3 and S4-S5 linkers. Deeper knowledge of mechanisms of the impaired PKA response in mutated IKs channels may help to better understand this regulation, and may improve risk stratification and management of patients suffering from related pathologies.
- MeSH
- beta-adrenergní receptory fyziologie MeSH
- draslíkový kanál KCNQ1 genetika MeSH
- fosforylace MeSH
- lidé MeSH
- mutace MeSH
- pozdní usměrňovače draslíkových kanálů fyziologie MeSH
- převodní systém srdeční fyziologie MeSH
- proteinkinasy závislé na cyklickém AMP fyziologie MeSH
- syndrom dlouhého QT genetika patofyziologie MeSH
- Check Tag
- lidé MeSH
- Publikační typ
- časopisecké články MeSH
- práce podpořená grantem MeSH
- přehledy MeSH
To define signaling pathways that drive FSH- and epidermal growth factor (EGF)-like peptide-induced cumulus expansion and oocyte meiotic resumption, in vitro cultured pig cumulus-oocyte complexes were treated with specific protein kinase inhibitors. We found that FSH-induced maturation of oocytes was blocked in germinal vesicle (GV) stage by protein kinase A (PKA), MAPK14, MAPK3/1, and EGF receptor (EGFR) tyrosine kinase inhibitors (H89, SB203580, U0126, and AG1478 respectively) whereas phosphoinositide-3-kinase/v-akt murine thymoma viral oncogene homolog (PI3K/AKT) inhibitor (LY294002) blocked maturation of oocytes in metaphase I (MI). Amphiregulin (AREG)-induced maturation of oocytes was efficiently blocked in GV by U0126, AG1478, and low concentrations of LY294002; H89, SB203580, and high concentrations of LY294002 allowed the oocytes to undergo breakdown of GV and blocked maturation in MI. Both FSH- and AREG-induced cumulus expansion was incompletely inhibited by H89 and completely inhibited by SB203580, U0126, AG1478, and LY294002. The inhibitors partially or completely inhibited expression of expansion-related genes (HAS2, PTGS2, and TNFAIP6) with two exceptions: H89 inhibited only TNFAIP6 expression and LY294002 increased expression of PTGS2. The results of this study are consistent with the idea that PKA and MAPK14 pathways are essential for FSH-induced transactivation of the EGFR, and synthesis of EGF-like peptides in cumulus cells and MAPK3/1 is involved in regulation of transcriptional and posttranscriptional events in cumulus cells required for meiotic resumption and cumulus expansion. PI3K/AKT signaling is important for regulation of cumulus expansion, AREG-induced meiotic resumption, and oocyte MI/MII transition. The present data also indicate the existence of an FSH-activated and PKA-independent pathway involved in regulation of HAS2 and PTGS2 expression in cumulus cells.
- MeSH
- cyklooxygenasa 2 genetika MeSH
- erbB receptory fyziologie MeSH
- folikuly stimulující hormon farmakologie MeSH
- glukuronosyltransferasa genetika MeSH
- glykoproteiny farmakologie MeSH
- inhibitory proteinkinas farmakologie MeSH
- kumulární buňky fyziologie MeSH
- meióza účinky léků fyziologie MeSH
- mezibuněčné signální peptidy a proteiny farmakologie MeSH
- mitogenem aktivovaná proteinkinasa 14 antagonisté a inhibitory fyziologie MeSH
- oocyty účinky léků fyziologie MeSH
- proteinkinasy závislé na cyklickém AMP antagonisté a inhibitory fyziologie MeSH
- regulace genové exprese fyziologie MeSH
- signální transdukce účinky léků fyziologie MeSH
- Sus scrofa fyziologie MeSH
- zvířata MeSH
- Check Tag
- ženské pohlaví MeSH
- zvířata MeSH
- Publikační typ
- časopisecké články MeSH
- práce podpořená grantem MeSH
- MeSH
- embryo savčí růst a vývoj MeSH
- insulinu podobný růstový faktor I fyziologie MeSH
- králíci MeSH
- mitogenem aktivované proteinkinasy fyziologie MeSH
- nukleotidy cyklické biosyntéza MeSH
- proteinkinasy závislé na cyklickém AMP fyziologie MeSH
- steroidy sekrece MeSH
- zvířata MeSH
- Check Tag
- králíci MeSH
- zvířata MeSH
- MeSH
- folikulární buňky metabolismus účinky léků MeSH
- insulinu podobný růstový faktor I sekrece MeSH
- oxytocin sekrece MeSH
- progesteron sekrece MeSH
- proteinkinasy závislé na cyklickém AMP antagonisté a inhibitory fyziologie MeSH
- růstový hormon fyziologie MeSH
- skot MeSH
- zvířata MeSH
- Check Tag
- skot MeSH
- zvířata MeSH
- Publikační typ
- techniky in vitro MeSH
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
