The NIMA-family kinase Nek3 regulates microtubule acetylation in neurons

Abstract

NIMA-related kinases (Neks) belong to a large family of Ser/Thr kinases that have critical roles in coordinating microtubule dynamics during ciliogenesis and mitotic progression. The Nek kinases are also expressed in neurons, whose axonal projections are, similarly to cilia, microtubule-abundant structures that extend from the cell body. We therefore investigated whether Nek kinases have additional, non-mitotic roles in neurons. We found that Nek3 influences neuronal morphogenesis and polarity through effects on microtubules. Nek3 is expressed in the cytoplasm and axons of neurons and is phosphorylated at Thr475 located in the C-terminal PEST domain, which regulates its catalytic activity. Although exogenous expression of wild-type or phosphomimic (T475D) Nek3 in cultured neurons has no discernible impact, expression of a phospho-defective mutant (T475A) or PEST-truncated Nek3 leads to distorted neuronal morphology with disturbed polarity and deacetylation of microtubules via HDAC6 in its kinase-dependent manner. Thus, the phosphorylation at Thr475 serves as a regulatory switch that alters Nek3 function. The deacetylation of microtubules in neurons by unphosphorylated Nek3 raises the possibility that it could have a role in disorders where axonal degeneration is an important component.

Identification of NEK3 Kinase Threonine 165 as a Novel Regulatory Phosphorylation Site That Modulates Focal Adhesion Remodeling Necessary for Breast Cancer Cell Migration

“…The localization of exogenous NEK3 proteins were visualized by staining PRL-stimulated MCF-7 cells with ␣-V5 antibodies (red) and was found to be predominantly cytoplasmic (Fig. 6D), which is consistent with previously published reports in both fibroblasts (29) and neurons (30). No differences in NEK3 localization were observed between wild-type NEK3 and the phospho-mutants (NEK3-T161V or NEK3-T165V), which all showed enriched staining at the cell periphery and strong co-localization with actin in membrane ruffles (Fig.…”

“…To this end, key catalytic residues within the kinase domain of NEK3 were mutated by site-directed mutagenesis (D145A and K33R/D127A), which were predicted to render the protein kinase-inactive based upon homology to mouse NEK3 (29,30) or other human NEK kinases (31,32). Kinase-inactive NEK3 mutants were then subjected to in vitro autophosphorylation assays (Fig.…”

A Genome-wide CRISPR (Clustered Regularly Interspaced Short Palindromic Repeats) Screen Identifies NEK7 as an Essential Component of NLRP3 Inflammasome Activation

“…To this effect, it has been shown that Nek7 accelerates microtubule dynamic instability during interphase (22) and that it is able to phosphorylate ␣-and ␤-tubulin in vitro (23). Moreover, it has been demonstrated that the related family member Nek3 is able to control microtubule acetylation (24). Consequently, in light of the aforementioned study linking microtubule acetylation and Nlrp3 inflammasome signaling, we wondered whether Nek7 was involved in microtubule acetylation during Nlrp3 inflammasome activation.…”

Tubulin acetylation: responsible enzymes, biological functions and human diseases

“…As discussed above, for polarized epithelial cell migration, Paxillin binds to HDAC6 and stimulates microtubule acetylation [128]. Moreover, expression of two phosphorylation-defective mutants of NIMA (never in mitosis A)-related kinase 3 (NEK3) decreases tubulin acetylation, reduces neuronal polarity and alters cell morphology [134]. Pharmacological inhibition of HDAC6 reverses this effect [134], suggesting that through tubulin deacetylation, HDAC6 modulates neuronal polarity.…”