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Assessment of Mitochondrial Functions and Cell Viability in Renal Cells Overexpressing Protein Kinase C Isozymes
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Activation of mitochondrial ATP-sensitive potassium channels increases cell viability against rotenone-induced cell

Kwok-Keung Tai1, Zoe A McCrossan, Geoffrey W Abbott

  • 1The Parkinson's and Movement Disorder Institute, Long Beach Memorial Medical Center, 2625 Pasadena Avenue, Long Beach, CA 90806, USA. kktai@yahoo.com

Journal of Neurochemistry
|February 27, 2003
PubMed

Insights

Mitochondrial ATP-sensitive potassium (KATP) channels protect PC12 cells from rotenone neurotoxicity. Activating these channels with diazoxide, but not plasma membrane KATP channels, confers cell survival against mitochondrial complex I inhibition.

Area of Science:

  • Neuroscience
  • Cell Biology
  • Biochemistry

Background:

  • ATP-sensitive potassium (KATP) channels are implicated in cellular protection.
  • Rotenone, a mitochondrial complex I inhibitor, induces neurotoxicity.
  • The precise location of KATP channels mediating protection in PC12 cells was previously unknown.

Purpose of the Study:

  • To determine the specific locus of KATP channels responsible for protection against rotenone-induced neurotoxicity in PC12 cells.
  • To investigate the role of mitochondrial versus plasma membrane KATP channels in this protective mechanism.

Main Methods:

  • Utilized diazoxide (mitochondrial KATP channel opener) and 5-hydroxydecanoic acid (5-HD, mitochondrial KATP channel antagonist).
  • Employed HMR-1098 (plasma membrane KATP channel antagonist) and P-1075 (plasma membrane KATP channel opener).
  • Performed trypan blue exclusion assays for cell viability and Western blot analysis for protein expression in mitochondria-enriched fractions.
  • Conducted whole-cell patch-clamp electrophysiology to assess KATP channel activity.

Main Results:

  • Diazoxide pre-treatment dose-dependently protected PC12 cells against rotenone toxicity.
  • The protective effect was blocked by 5-HD but not by HMR-1098, indicating a mitochondrial locus.
  • Immunoreactive proteins for SUR1 and Kir6.1 were detected in the mitochondria-enriched fraction.
  • Patch-clamp studies showed negligible functional plasma membrane KATP channel activity.

Conclusions:

  • Mitochondrial KATP channels, not plasma membrane KATP channels, mediate protection against rotenone-induced cell death in PC12 cells.
  • This study provides the first evidence for the activation of mitochondrial KATP channels eliciting neuroprotection.
  • Findings highlight the therapeutic potential of targeting mitochondrial KATP channels in neurodegenerative conditions involving mitochondrial dysfunction.

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