Direct regulation of complex I by mitochondrial MEF2D is disrupted in a mouse model of Parkinson disease and in human patients
Hua She, … , Claudia Testa, Zixu Mao
Hua She, … , Claudia Testa, Zixu Mao
Published February 14, 2011
Citation Information: J Clin Invest. 2011;121(3):930-940. https://doi.org/10.1172/JCI43871.
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Research Article Neuroscience

Direct regulation of complex I by mitochondrial MEF2D is disrupted in a mouse model of Parkinson disease and in human patients

Abstract

The transcription factors in the myocyte enhancer factor 2 (MEF2) family play important roles in cell survival by regulating nuclear gene expression. Here, we report that MEF2D is present in rodent neuronal mitochondria, where it can regulate the expression of a gene encoded within mitochondrial DNA (mtDNA). Immunocytochemical, immunoelectron microscopic, and biochemical analyses of rodent neuronal cells showed that a portion of MEF2D was targeted to mitochondria via an N-terminal motif and the chaperone protein mitochondrial heat shock protein 70 (mtHsp70). MEF2D bound to a MEF2 consensus site in the region of the mtDNA that contained the gene NADH dehydrogenase 6 (ND6), which encodes an essential component of the complex I enzyme of the oxidative phosphorylation system; MEF2D binding induced ND6 transcription. Blocking MEF2D function specifically in mitochondria decreased complex I activity, increased cellular H2O2 level, reduced ATP production, and sensitized neurons to stress-induced death. Toxins known to affect complex I preferentially disrupted MEF2D function in a mouse model of Parkinson disease (PD). In addition, mitochondrial MEF2D and ND6 levels were decreased in postmortem brain samples of patients with PD compared with age-matched controls. Thus, direct regulation of complex I by mitochondrial MEF2D underlies its neuroprotective effects, and dysregulation of this pathway may contribute to PD.

Authors

Hua She, Qian Yang, Kennie Shepherd, Yoland Smith, Gary Miller, Claudia Testa, Zixu Mao

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Figure 3

Identification of MEF2D regulatory target in mtDNA.

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Identification of MEF2D regulatory target in mtDNA. (A) Presence of a co...
(A) Presence of a conserved MEF2 consensus site in ND6 gene in mtDNA of different species. Underlined sequence indicates the MEF2 consensus site. Black-shaded areas show the conversed MEF2 site and sequences around it in ND6. (B) Specific binding of MEF2D to the consensus site in ND6 in vitro (n = 3). EMSA assay revealed that MEF2D bound to WT but not mutant (Mut) probe. Arrow indicates the specific binding complex. GST, glutathione S-transferase; GST-MEF2D(1-91), GST-fused MEF2D1–91 aa. Hot and cold refer to labeled and unlabeled probes, respectively. (C) Binding of MEF2D to the consensus site in ND6 in cells in vivo (n = 3). ChIP assay showed that MEF2D binds to ND6 in SN4741 cells. A fragment bound by anti-MEF2D antibody could only be specifically amplified by PCR with ND6 primers after immunoprecipitation. TFAM, a known mtDNA D-loop binding protein, was used as a control. Ab–, without primary antibody. (D) Sequence analysis of the purified PCR fragment bound by anti-MEF2D antibody in C confirmed that it is the predicted ND6 fragment and contains the MEF2 consensus sequence.