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.
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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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    • "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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