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Assessment of Mitochondrial Functions and Cell Viability in Renal Cells Overexpressing Protein Kinase C Isozymes
15:43

Assessment of Mitochondrial Functions and Cell Viability in Renal Cells Overexpressing Protein Kinase C Isozymes

Published on: January 7, 2013

Effect of protein kinase C activation on agonist-mediated phosphositide metabolism in rabbit retinal cells

H Ghazi1, N N Osborne

  • 1Nuffield Laboratory of Ophthalmology, University of Oxford, Walton Street, Oxford OX2 6AW, England.

Neurochemistry International
|May 28, 2010
PubMed

Insights

4?-Phorbol 12-myrisate 13-acetate (PMA) and 1-oleoly-2-acetylglycerol (OAG) inhibit muscarinic and adrenergic receptor signaling in rabbit retinas. Protein kinase C activation mediates this inhibitory feedback, showing selectivity for specific receptor pathways.

Area of Science:

  • Neuroscience
  • Cell Biology
  • Biochemistry

Background:

  • Muscarinic and adrenergic receptors play crucial roles in retinal function.
  • Phosphoinositide (PI) signaling pathways are involved in receptor-mediated cellular responses.
  • Protein kinase C (PKC) is a key regulator of cellular processes.

Purpose of the Study:

  • To investigate the effects of phorbol ester (PMA) and diacylglycerol (OAG) on muscarinic and adrenergic receptor signaling in the rabbit retina.
  • To determine the role of protein kinase C (PKC) in modulating these receptor-mediated responses.
  • To explore the selectivity of PKC's modulatory effects on different signaling pathways.

Main Methods:

  • Experiments were conducted using rabbit retinal slices and primary retinal cultures.
  • Stimulation of PIP(2) breakdown, inositol phosphates (IPs) accumulation, and intracellular calcium ([Ca(2+)](i)) increase were measured.
  • Receptor activation was achieved using agonists like carbachol and noradrenaline.
  • The effects of PMA, OAG, and staurosporine (a PKC inhibitor) were assessed.

Main Results:

  • PMA and OAG inhibited muscarinic and adrenergic receptor-mediated stimulation of PIP(2) breakdown, IPs accumulation, and [Ca(2+)](i) increase.
  • These inhibitory effects were dependent on PKC activation, as evidenced by staurosporine's attenuation of the inhibition.
  • Serotonin-mediated responses were unaffected by PMA and OAG, indicating pathway selectivity.
  • Neither PMA nor OAG affected basal levels of phosphoinositides, IPs, or [Ca(2+)](i).

Conclusions:

  • PKC activation, induced by PMA or OAG, exerts an inhibitory feedback on muscarinic and adrenergic receptor signaling in the rabbit retina.
  • This PKC-mediated downregulation exhibits selectivity, sparing serotonergic responses.
  • The findings suggest a specific modulatory role for PKC in regulating retinal neurotransmission.

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