Antiapoptotic and Trophic Effects of Dominant-Negative Forms of Dual Leucine Zipper Kinase in Dopamine Neurons of the Substantia Nigra In Vivo

Department of Neurology, The College of Physicians and Surgeons, Columbia University, New York, New York 10032, USA.
The Journal of Neuroscience : The Official Journal of the Society for Neuroscience (Impact Factor: 6.34). 02/2008; 28(3):672-80. DOI: 10.1523/JNEUROSCI.2132-07.2008
Source: PubMed


There is extensive evidence that the mitogen-activated protein kinase (MAPK) signaling cascade mediates programmed cell death in neurons. However, current evidence that the mixed linage kinases (MLKs), upstream in this cascade, mediate cell death is based, in the in vivo context, entirely on pharmacological approaches. The compounds used in these studies have neither complete specificity nor selectivity among these kinases. Therefore, to better address the molecular specificity of the MLKs in mediating neuron death, we used dominant-negative constructs delivered by AAV (adenoassociated virus) vector transfer. We assessed effects in a neurotoxin model of parkinsonism, in which neuroprotection by pharmacologic MLK inhibition has been reported. We find that two dominant-negative forms of dual leucine zipper kinase (DLK) inhibit apoptosis and enhance long-term survival of dopamine neurons, but a dominant negative of MLK3 does not. Interestingly, the kinase-dead form of DLK not only blocks apoptosis but also has trophic effects on dopamine neurons. Although the MAPK cascade activates a number of downstream cell death mediators, we find that inhibition of DLK correlates closely with blockade of phosphorylation of c-jun and prevention of cell death. We conclude that DLK acts primarily through c-jun phosphorylation to mediate cell death in this model.

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Available from: Matthew During, Jan 17, 2015
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    • "Dual leucine zipper kinase (DLK) is a mitogen-activated protein kinase kinase kinase (MAPKKK) that can activate cJun N-terminal kinases (JNK) and p38 MAPK (Fan et al., 1996). In addition to its role for neural development (Bloom et al., 2007; Hirai et al., 2006; Itoh et al., 2011), DLK is involved in injury responses such as axon degeneration and neuronal apoptosis (Chen et al., 2008; Ghosh et al., 2011; Miller et al., 2009; Xiong and Collins, 2012). Moreover, recent studies in C. elegans and Drosophila have demonstrated that DLK is required for the regenerative response after axotomy; in the absence of DLK, reformation of a growth cone from the severed stump is disrupted (Hammarlund et al., 2009; Xiong et al., 2010; Yan et al., 2009), while in juvenile DLK gene-trap mice, there is less regrowth of axons from dissected and cultured dorsal root ganglion (DRG) explants (Itoh et al., 2009). "
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    ABSTRACT: Here we demonstrate that the dual leucine zipper kinase (DLK) promotes robust regeneration of peripheral axons after nerve injury in mice. Peripheral axon regeneration is accelerated by prior injury; however, DLK KO neurons do not respond to a preconditioning lesion with enhanced regeneration in vivo or in vitro. Assays for activation of transcription factors in injury-induced proregenerative pathways reveal that loss of DLK abolishes upregulation of p-STAT3 and p-cJun in the cell body after axonal injury. DLK is not required for the phosphorylation of STAT3 at the site of nerve injury but is necessary for retrograde transport of p-STAT3 to the cell body. These data demonstrate that DLK enhances regeneration by promoting a retrograde injury signal that is required for the activation of the neuronal proregenerative program.
    Neuron 06/2012; 74(6):1015-22. DOI:10.1016/j.neuron.2012.04.028 · 15.05 Impact Factor
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    • "Catherine, Ontario) Analytical Imaging Station under blinded conditions on coded slides. The region of whole striatum was determined as previously described (Chen et al. 2008). In a separate analysis, optical density of dorso-lateral striatum was determined by outlining that region. "
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    ABSTRACT: The mechanisms underlying the chronic neurodegeneration that occurs in Parkinson's disease (PD) are unknown. One emerging hypothesis is that neural systems deteriorate and eventually degenerate due to a primary failure of either extrinsic neurotrophic support or the intrinsic cellular pathways that mediate such support. One of the cellular pathways that have been often identified in mediating neurotrophic effects is that of PI3K/Akt signaling. In addition, recent observations have suggested a primary failure of PI3K/Akt signaling in animal models and in PD patients. Therefore, to explore the possible role of endogenous Akt signaling in maintaining the viability and functionality of substantia nigra (SN) dopamine neurons, one of the principal systems affected in PD, we have used an adeno-associated viral vector to transduce them with a dominant negative (DN) form of Akt, the pleckstrin homology (PH) domain alone (DN(PH)-Akt). In addition, we have examined the effect of DN(PH)-Akt in murine models of two risk factors for human PD: advanced age and increased expression of α-synuclein. We find that transduction of these neurons in normal adult mice has no effect on any aspect of their morphology at 4 or 7weeks. However, in both aged mice and in transgenic mice with increased expression of human α-synuclein we observe decreased phenotypic expression of the catecholamine synthetic enzyme tyrosine hydroxylase (TH) in dopaminergic axons and terminals in the striatum. In aged transgenic α-synuclein over-expressing mice this reduction was 2-fold as great. We conclude that the two principal risk factors for human PD, advanced age and increased expression of α-synuclein, reveal a dependence of dopaminergic neurons on endogenous Akt signaling for maintenance of axonal phenotype.
    Neurobiology of Disease 07/2011; 44(2):215-22. DOI:10.1016/j.nbd.2011.07.003 · 5.08 Impact Factor
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    • "Involvement of MLKs in apoptosis of motoneurons has been suggested by pharmacological studies using the MLK inhibitors, 3,9-bis[(ethylthio)methyl]-K-252a (CEP-1347/KT7515) and its derivative bis-isopropylthiomethyl-K-252a (CEP-11004) (Maroney et al., 1998; Glicksman et al., 1998; Murakata et al., 2002). Because these compounds inhibit a relatively broad range of the MLK family (Murakata et al., 2002; Chen et al., 2008), and activate Akt through an MLK-independent pathway (Roux et al., 2002), the identity of the MLK member that mediates activation of MAPK pathways leading to motoneuron NPCD remains an open question. "
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    ABSTRACT: Activation of mitogen-activated protein kinase pathways is critically involved in naturally occurring programmed cell death of motoneurons during development, but the upstream mediators remain undetermined. We found that mice deficient in ZPK, also called DLK (ZPK/DLK), an upstream kinase in these pathways, have twice as many spinal motoneurons as do their wild-type littermates. Nuclear HB9/MNX1-positive motoneuron pools were generated similarly in the spinal cord of both ZPK/DLK-deficient and wild-type embryos. Thereafter, however, significantly less apoptotic motoneurons were found in ZPK/DLK-deficient embryos compared with wild-type embryos, resulting in retention of excess numbers of motoneurons after birth. Notably, these excess motoneurons remained viable without atrophic changes in the ZPK/DLK-deficient mice surviving into adulthood. Analysis of the diaphragm and the phrenic nerve revealed that clustering and innervation of neuromuscular junctions were indistinguishable between ZPK/DLK-deficient and wild-type mice, whereas the proximal portion of the phrenic nerve of ZPK/DLK-deficient mice contained significantly more axons than the distal portion. This result supports the hypothesis that some excess ZPK/DLK-deficient motoneurons survived without atrophy despite failure to establish axonal contact with their targets. This study provides compelling evidence for a critical role for ZPK/DLK in naturally occurring programmed cell death of motoneurons and suggests that ZPK/DLK could become a strategic therapeutic target in motor neuron diseases in which aberrant activation of the apoptogenic cascade is involved.
    The Journal of Neuroscience : The Official Journal of the Society for Neuroscience 05/2011; 31(20):7223-8. DOI:10.1523/JNEUROSCI.5947-10.2011 · 6.34 Impact Factor
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