Cribbs JT, Strack S.. Reversible phosphorylation of Drp1 by cyclic AMP-dependent protein kinase and calcineurin regulates mitochondrial fission and cell death. EMBO Rep 8: 939-944

Department of Pharmacology, University of Iowa Carver College of Medicine, Iowa City, Iowa 52242, USA.
EMBO Reports (Impact Factor: 9.06). 11/2007; 8(10):939-44. DOI: 10.1038/sj.embor.7401062
Source: PubMed


Opposing mitochondrial fission and fusion reactions determine the shape and interconnectivity of mitochondria. Dynamin-related protein 1 (Drp1) is an ancient mechanoenzyme that uses GTP hydrolysis to power the constriction and division of mitochondria. Although Drp1-mediated mitochondrial fragmentation is recognized as an early event in the apoptotic programme, acute regulation of Drp1 activity is poorly understood. Here, we identify a crucial phosphorylation site that is conserved in all metazoan Drp1 orthologues. Ser 656 is phosphorylated by cyclic AMP-dependent protein kinase and dephosphorylated by calcineurin, and its phosphorylation state is controlled by sympathetic tone, calcium levels and cell viability. Pseudophosphorylation of Drp1 by mutation of Ser 656 to aspartic acid leads to the elongation of mitochondria and confers resistance to various pro-apoptotic insults. Conversely, the constitutively dephosphorylated Ser656Ala mutant Drp1 promotes mitochondrial fragmentation and increases cell vulnerability. Thus, Drp1 phosphorylation at Ser 656 provides a mechanism for the integration of cAMP and calcium signals in the control of mitochondrial shape, apoptosis and other aspects of mitochondrial function.

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    • "So far, most of the studies addressing mitochondrial fragmentation have been limited to a categorization of cells -fragmented / no fragmented mitochondria, or to the manual analysis of single mitochondria (Cribbs and Strack, 2007; Magrane et al., 2009; Raimondi et al., 2006; Song et al., 2011). Mitochondrial segments can be discriminated near the cell membrane or in neurites, but the analysis of organelle network over the whole cell is almost impossible by manual analyses, especially around the nucleus where mitochondria are dense. "
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    ABSTRACT: The function of intact organelles, whether mitochondria, Golgi apparatus or endoplasmic reticulum (ER), relies on their proper morphological organization. It is recognized that disturbances of organelle morphology are early events in disease manifestation, but reliable and quantitative detection of organelle morphology is difficult and time-consuming. Herewe present a novel computer vision algorithm for the assessment of organelle morphology inwhole cell 3D images. The algorithm allows the numerical and quantitative description of organelle structures, including total number and length of segments, cell and nucleus area/volume as well as novel texture parameters like lacunarity and fractal dimension. Applying the algorithm we performed a pilot study in cultured motor neurons from transgenic G93A hSOD1 mice, a model of human familial amyotrophic lateral sclerosis. In the presence of the mutated SOD1 and upon excitotoxic treatment with kainate we demonstrate a clear fragmentation of the mitochondrial network, with an increase in the number of mitochondrial segments and a reduction in the length of mitochondria. Histogram analyses show a reduced number of tubular mitochondria and an increased number of small mitochondrial segments. The computer vision algorithmfor the evaluation of organellemorphology allows an objective assessment of disease-related organelle phenotypes with greatly reduced examiner bias and will aid the evaluation of novel therapeutic strategies on a cellular level.
    Mitochondrion 10/2015; 25. DOI:10.1016/j.mito.2015.10.003 · 3.25 Impact Factor
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    • "If the lack of phosphorylation is determined by different topology or subcellular localization of Mfn2 is unknown, but worth testing, especially in the light of the functional difference between the two Mfns. While DRP1 post-translational modifications are well established players in apoptosis (Cribbs and Strack, 2007), necrosis (Wang et al., 2012), and autophagy (Gomes et al., 2011), our knowledge of how mitochondrial fusion is modulated during cell death is scarcer. Fusion inhibition is an established consequence of apoptosis induction, and it occurs around the time of BAX activation (Karbowski et al., 2004). "
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    ABSTRACT: Controlled changes in mitochondrial morphology participate in cellular signaling cascades. However, the molecular mechanisms modifying mitochondrial shape are largely unknown. Here we show that the mitogen-activated protein (MAP) kinase cascade member extracellular-signal-regulated kinase (ERK) phosphorylates the pro-fusion protein mitofusin (MFN) 1, modulating its participation in apoptosis and mitochondrial fusion. Phosphoproteomic and biochemical analyses revealed that MFN1 is phosphorylated at an atypical ERK site in its heptad repeat (HR) 1 domain. This site proved essential to mediate MFN1-dependent mitochondrial elongation and apoptosis regulation by the MEK/ERK cascade. A mutant mimicking constitutive MFN1 phosphorylation was less efficient in oligomerizing and mitochondria tethering but bound more avidly to the proapoptotic BCL-2 family member BAK, facilitating its activation and cell death. Moreover, neuronal apoptosis following oxygen glucose deprivation and MEK/ERK activation required an intact MFN1(T562). Our data identify MFN1 as an ERK target to modulate mitochondrial shape and apoptosis. Copyright © 2015 The Authors. Published by Elsevier Inc. All rights reserved.
    Molecular cell 03/2015; 104(2). DOI:10.1016/j.molcel.2015.02.021 · 14.02 Impact Factor
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    • "Neuronal activity enhances mitochondrial Ca 2+ uptake , which stimulates ATP production and increases mitochondrial NAD ( P ) H levels ( Jonas , 2014 ) . Ca 2+ also influences mitochondrial function by promoting fragmentation of mitochondria triggered by calcineurin - mediated dephosphorylation of Drp1 ( Cribbs & Strack , 2007 ; Cereghetti et al . 2008 ; Wang et al . "
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    ABSTRACT: The classical view of mitochondria as housekeeping organelles acting in the background to simply maintain cellular energy demands has been shaken by mounting evidence of their direct and active participation in synaptic plasticity in neurons. Time-lapse imaging has revealed that mitochondria are motile in dendrites, with their localization and fusion and fission events regulated by synaptic activity. The positioning of mitochondria directly influences function of nearby synapses through multiple pathways including control over local concentrations of ATP, Ca+2, and reactive oxygen species. Recent studies have also shown that mitochondrial protein cascades classically associated with apoptosis are involved in neural plasticity in healthy cells. These findings link mitochondria to the plasticity- and metaplasticity-associated activity-dependent transcription factor MEF2 further repositioning mitochondria as potential command centers for regulation of synaptic plasticity. Intriguingly, MEF2 and mitochondrial functions appear to be intricately intertwined, as MEF2 is a target of mitochondrial apoptotic caspases and in turn, MEF2 regulates mitochondrial genome transcription essential for production of superoxidase and hydrogen peroxidase. Here, we review evidence supporting mitochondria as central organelles controlling the spatiotemporal expression of neuronal plasticity, and attempt to disentangle the MEF2-mitochondria relationship mediating these functions.This article is protected by copyright. All rights reserved
    The Journal of Physiology 12/2014; 593(16). DOI:10.1113/jphysiol.2014.282459 · 5.04 Impact Factor
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