Dephosphorylation by calcineurin regulates translocation of Drp1 to mitochondria

Dulbecco-Telethon Institute, Padua, Italy.
Proceedings of the National Academy of Sciences (Impact Factor: 9.81). 11/2008; 105(41):15803-8. DOI: 10.1073/pnas.0808249105
Source: PubMed

ABSTRACT Changes in mitochondrial morphology that occur during cell cycle, differentiation, and death are tightly regulated by the balance between fusion and fission processes. Excessive fragmentation can be caused by inhibition of the fusion machinery and is a common consequence of dysfunction of the organelle. Here, we show a role for calcineurin-dependent translocation of the profission dynamin related protein 1 (Drp1) to mitochondria in dysfunction-induced fragmentation. When mitochondrial depolarization is associated with sustained cytosolic Ca(2+) rise, it activates the cytosolic phosphatase calcineurin that normally interacts with Drp1. Calcineurin-dependent dephosphorylation of Drp1, and in particular of its conserved serine 637, regulates its translocation to mitochondria as substantiated by site directed mutagenesis. Thus, fragmentation of depolarized mitochondria depends on a loop involving sustained Ca(2+) rise, activation of calcineurin, and dephosphorylation of Drp1 and its translocation to the organelle.

Download full-text


Available from: Luca Scorrano, Aug 24, 2015
  • Source
    • "Please cite this article in press as: Pyakurel et al., Extracellular Regulated Kinase Phosphorylates Mitofusin 1 to Control Mitochondrial Morphology and Apoptosis, Molecular Cell (2015), RESULTS MFN1 Is Phosphorylated at T562 Whether and how phosphorylation regulates mitochondrial fusion is unclear: we therefore set out to identify if MFNs are phosphorylated. Phosphorylated and non-phosphorylated Flag-tagged MFN1 or MFN2 expressed in untreated mouse embryonic fibroblasts (MEFs) were separated by affinity chromatography on a column that specifically binds phosphorylated residues (Cereghetti et al., 2008). Immunoblotting indicated that both Flag-MFN1 and MFN2 avidly bound to the column (Figure 1A). "
    [Show abstract] [Hide abstract]
    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 · 14.46 Impact Factor
  • Source
    • "Drp1 is intimately associated with the apoptotic process (Arnoult, 2007) in which Drp1-mediated mitochondrial fragmentation augments the release of cytochrome C from mitochondria, an early step in apoptosis (Cassidy-Stone et al., 2008). As a major regulator of Drp1 activity, cAMP-dependent protein kinase (PKA) phosphorylates Drp1 and leads to its cytosolic sequestration promoting an elongated mitochondrial network (Cereghetti et al., 2008; Chang and Blackstone, 2007; Cribbs and Strack, 2007). A neuroprotective role of PKA phosphorylation of Drp1 has been suggested as constitutive Drp1 phosphorylation at the consensus PKA site inhibits cytochrome C release and apoptosis in neuronal PC12 cells (Cribbs and Strack, 2007). "
    [Show abstract] [Hide abstract]
    ABSTRACT: Parkinson’s disease (PD), caused by selective loss of dopaminergic (DA) neurons in the substantia nigra, is the most common movement disorder with no cure or effective treatment. Exposure to the mitochondrial complex I inhibitor rotenone recapitulates pathological hallmarks of PD in rodents and selective loss of DA neurons in Drosophila. However, mechanisms underlying rotenone toxicity are not completely resolved. We previously reported a neuroprotective effect of human uncoupling protein 2 (hUCP2) against rotenone toxicity in adult fly DA neurons. In the current study, we show that increased mitochondrial fusion is protective from rotenone toxicity whereas increased fission sensitizes the neurons to rotenone-induced cell loss in vivo. In primary DA neurons, rotenone-induced mitochondrial fragmentation and lethality is attenuated as the result of hucp2 expression. To test the idea that the neuroprotective mechanism of hUCP2 involves modulation of mitochondrial dynamics, we detect preserved mitochondrial network, mobility and fusion events in hucp2 expressing DA neurons exposed to rotenone. hucp2 expression also increases intracellular cAMP levels. Thus, we hypothesize that cAMP-dependent protein kinase (PKA) might be an effector that mediates hUCP2-associated neuroprotection against rotenone. Indeed, PKA inhibitors block preserved mitochondrial integrity, movement and cell survival in hucp2 expressing DA neurons exposed to rotenone. Taken together, we present strong evidence identifying a hUCP2-PKA axis that controls mitochondrial dynamics and survival in DA neurons exposed to rotenone implicating a novel therapeutic strategy in modifying the progression of PD pathogenesis.
    Neurobiology of Disease 09/2014; 69. DOI:10.1016/j.nbd.2014.05.032 · 5.20 Impact Factor
    • "Overexpression of a mutant form of Drp1 (Drp1- K38A), which acts as a dominant negative (Smirnova et al, 1998), or using the Drp1 inhibitor mdivi-1, significantly attenuated the NMDA-mediated mitochondrial fragmentation during the first hour of NMDA treatment (Fig 2D and E). Excessive calcium uptake by mitochondria in excitotoxicity causes mitochondrial depolarization (Soriano et al, 2006b; Nicholls, 2009), this produces an increase in cytosolic calcium that can activate calcineurin which has been shown to de-phosphorylate Drp1 to promote its recruitment to mitochondria and fission (Cereghetti et al, 2008). We analyzed whether mitochondrial fission preceded or was posterior to mitochondrial depolarization. "
    [Show abstract] [Hide abstract]
    ABSTRACT: Mitochondrial fusion and fission is a dynamic process critical for the maintenance of mitochondrial function and cell viability. During excitotoxicity neuronal mitochondria are fragmented, but the mechanism underlying this process is poorly understood. Here, we show that Mfn2 is the only member of the mitochondrial fusion/fission machinery whose expression is reduced in in vitro and in vivo models of excitotoxicity. Whereas in cortical primary cultures, Drp1 recruitment to mitochondria plays a primordial role in mitochondrial fragmentation in an early phase that can be reversed once the insult has ceased, Mfn2 downregulation intervenes in a delayed mitochondrial fragmentation phase that progresses even when the insult has ceased. Downregulation of Mfn2 causes mitochondrial dysfunction, altered calcium homeostasis, and enhanced Bax translocation to mitochondria, resulting in delayed neuronal death. We found that transcription factor MEF2 regulates basal Mfn2 expression in neurons and that excitotoxicity-dependent degradation of MEF2 causes Mfn2 downregulation. Thus, Mfn2 reduction is a late event in excitotoxicity and its targeting may help to reduce excitotoxic damage and increase the currently short therapeutic window in stroke.
    The EMBO Journal 08/2014; 33(20). DOI:10.15252/embj.201488327 · 10.75 Impact Factor
Show more

Similar Publications