| Summary: | 博士 === 國立臺灣大學 === 分子醫學研究所 === 99 === Death-associated protein kinase (DAPK) is a key player in several modes of neuronal death/injury and has been implicated in the late-onset Alzheimer’s disease (AD). DAPK promotes cell death partly through its effect on regulating actin cytoskeletons. Here, we report that DAPK inhibits microtubule (MT) assembly by activating MARK/PAR-1 family kinases MARK1/2, which destabilize MT by phosphorylating tau and related MAP2/4. DAPK death domain, but not catalytic activity, is responsible for this activation by binding to MARK1/2 spacer region, thereby disrupting an intramolecular interaction that inhibits MARK1/2. Accordingly, DAPK-/- mice brain displays a reduction of tau phosphorylation and DAPK enhances the effect of MARK2 on regulating polarized neurite outgrowth. Using a well characterized Drosophila model of tauopathy, we show that DAPK acts in part through MARK Drosophila ortholog PAR-1 to induce rough eye and loss of photoreceptor neurons. Furthermore, DAPK enhances tau toxicity through a PAR-1 phosphorylation-dependent mechanism. Together, our study reveals a novel mechanism of MARK activation, uncovers DAPK functions in modulating MT assembly and neuronal differentiation, and provides a molecular link of DAPK to tau phosphorylation, an event associated with AD pathology.
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