Drp1 levels constitutively regulate mitochondrial dynamics and cell survival in cortical neurons Academic Article uri icon

Overview

MeSH Major

  • Cerebral Cortex
  • GTP Phosphohydrolases
  • Microtubule-Associated Proteins
  • Mitochondria
  • Mitochondrial Proteins
  • Neurons

abstract

  • Mitochondria exist as dynamic networks that are constantly remodeled through the opposing actions of fusion and fission proteins. Changes in the expression of these proteins alter mitochondrial shape and size, and may promote or inhibit the propagation of apoptotic signals. Using mitochondrially targeted EGFP or DsRed2 to identify mitochondria, we observed a short, distinctly tubular mitochondrial morphology in postnatal cortical neurons in culture and in retinal ganglion cells in vivo, whereas longer, highly interconnected mitochondrial networks were detected in cortical astrocytes in vitro and non-neuronal cells in the retina in vivo. Differential expression patterns of fusion and fission proteins, in part, appear to determine these morphological differences as neurons expressed markedly high levels of Drp1 and OPA1 proteins compared to non-neuronal cells. This finding was corroborated using optic tissue samples. Moreover, cortical neurons expressed several splice variants of Drp1 including a neuron-specific isoform which incorporates exon 3. Knockdown or dominant-negative interference of endogenous Drp1 significantly increased mitochondrial length in both neurons and non-neuronal cells, but caused cell death only in cortical neurons. Conversely, depletion of the fusion protein, Mfn2, but not Mfn1, caused extensive mitochondrial fission and cell death. Thus, Drp1 and Mfn2 in normal cortical neurons not only regulate mitochondrial morphology, but are also required for cell survival. The present findings point to unique patterns of Drp1 expression and selective vulnerability to reduced levels of Drp1 expression/activity in neurons, and demonstrate that the regulation of mitochondrial dynamics must be tightly regulated in neurons.

publication date

  • August 2009

Research

keywords

  • Academic Article

Identity

Language

  • eng

PubMed Central ID

  • PMC2733949

Digital Object Identifier (DOI)

  • 10.1016/j.expneurol.2009.05.010

PubMed ID

  • 19445933

Additional Document Info

start page

  • 274

end page

  • 85

volume

  • 218

number

  • 2