RESUMO
The death of serum-deprived undifferentiated PC12 cells shows both autophagic and apoptotic features. Since it is still controversial whether the autophagy is instrumental in the cell death or a mere epiphenomenon, we tested the effects of inhibiting the autophagy by a variety of phosphoinositide 3-kinase inhibitors, and provided evidence that the autophagy, or a related trafficking event, is indeed instrumental in the cell death. Furthermore, by comparing the effects of PI3-K inhibition and caspase-inhibition on autophagic and apoptotic cellular events, we showed that in this case the autophagic and apoptotic mechanisms mediate cell death by parallel pathways and do not act in series.
Assuntos
Apoptose/fisiologia , Autofagia/fisiologia , Meios de Cultura Livres de Soro/farmacologia , Células PC12/citologia , Fosfatidilinositol 3-Quinases/fisiologia , Fosfatase Ácida/análise , Animais , Apoptose/efeitos dos fármacos , Autofagia/efeitos dos fármacos , Inibidores de Caspase , Cromonas/farmacologia , Imuno-Histoquímica , Lisossomos/fisiologia , Microscopia Eletrônica , Morfolinas/farmacologia , Fosfatidilinositol 3-Quinases/biossíntese , Inibidores de Fosfoinositídeo-3 Quinase , RatosRESUMO
Cyclic AMP has been generally recognised as activator of cAMP-dependent protein kinases. However, there is little evidence about role of cAMP-dependent protein kinase (PKA), in particular izoenzymes PKA-I and PKA-II, in glomeruli contractility. We measured changes of glomerular inulin space (GIS) as a marker of its contractility in the presence of phosphodiesterase resistance cAMP analogues; activators and inhibitors of PKA. Activator of PKA i.e. (Sp) 8-Cl-cAMPS (0.1-100 microM) decreased GIS. (Rp) 8-Cl-cAMPS (0.1-100 microM), inhibitor of PKA, was ineffective but shifted concentration-response curve of (Sp) 8-Cl-cAMPS to right at 50 microM. Specific A site activation by N6-benzoyl-cAMP decreased GIS with maximum at 0.1 microM. Activation of B site by 8-aminobutyloamino-cAMP (0.1-100 microM) had no effect. However, specific activation of both sites on PKA-I or PKA-II by site-selective analogue pairs e.g. 8-aminobutyloamino-cAMP plus 8-piperidino-cAMP or N6-benzoyl-cAMP plus 8-piperidino-cAMP respectively, significantly increased sensitivity of glomeruli to analogues. Our data suggest that activation of PKA-I or PKA-II might have an important role in the regulation of glomerular contractility.
