Dataset Information

Par1b/MARK2 phosphorylates kinesin-like motor protein GAKIN/KIF13B to regulate axon formation.

ABSTRACT: Here we report that Par1b/MARK2 regulates axon formation via phosphorylation of a kinesin superfamily protein GAKIN/KIF13B. Accumulating evidence indicated the importance of the evolutionarily conserved kinase Par1b in the regulation of cell polarity. Using hippocampal neurons in culture, it has been shown that Par1b regulates axon specification, but the underlying mechanism remains uncharacterized. We identify GAKIN/KIF13B as a novel Par1b-binding protein and reveal that GAKIN/KIF13B is a physiological substrate for Par1b, and the phosphorylation sites are conserved from Drosophila. In hippocampal neurons, GAKIN/KIF13B accumulates at the distal part of the microtubules in the tips of axons, but not of dendrites. Overexpression of GAKIN/KIF13B by itself can induce the formation of extra axons, which is inhibited by the coexpression of Par1b in a manner dependent on its kinase activity. In contrast, small interfering RNA (siRNA)-mediated knockdown of GAKIN/KIF13B severely retards neurite extension and promotes the axonless phenotype. The extra axon phenotype caused by Par1b siRNA is suppressed by cointroduction of GAKIN/KIF13B siRNA, thus placing the GAKIN/KIF13B function downstream of Par1b. We also find that GAKIN/KIF13B acts downstream of the phosphatidylinositol 3-kinase (PI3K) signaling via Par1b phosphorylation. These results reveal that GAKIN/KIF13B is a key intermediate linking Par1b to the regulation of axon formation.

SUBMITTER: Yoshimura Y

PROVIDER: S-EPMC2863582 | biostudies-literature | 2010 May

REPOSITORIES: biostudies-literature

ACCESS DATA

Publications

Par1b/MARK2 phosphorylates kinesin-like motor protein GAKIN/KIF13B to regulate axon formation.

Yoshimura Yuta Y Terabayashi Takeshi T Miki Hiroaki H

Molecular and cellular biology 20100301 9

Here we report that Par1b/MARK2 regulates axon formation via phosphorylation of a kinesin superfamily protein GAKIN/KIF13B. Accumulating evidence indicated the importance of the evolutionarily conserved kinase Par1b in the regulation of cell polarity. Using hippocampal neurons in culture, it has been shown that Par1b regulates axon specification, but the underlying mechanism remains uncharacterized. We identify GAKIN/KIF13B as a novel Par1b-binding protein and reveal that GAKIN/KIF13B is a physi ...[more]

PMID: 20194617

Similar Datasets

Project description:BackgroundMicroglia, the resident immune cells of the brain, exhibit various morphologies that correlate with their functions under physiological and pathological conditions. In conditions such as aging and stress, microglia priming occurs, which leads to altered morphology and lower threshold for activation upon further insult. However, the molecular mechanisms that lead to microglia priming are unclear.MethodsTo understand the role of Par1b/MARK2 in microglia, we first expressed shRNA targeting luciferase or Par1b/MARK2 in primary microglial cells and imaged the cells using fluorescent microscopy to analyze for morphological changes. A phagocytosis assay was then used to assess functional changes. We then moved in vivo and used a Par1b/MARK2 knockout mouse model to assess for changes in microglia density, morphology, and phagocytosis using immunohistochemistry, confocal imaging, and 3D image reconstruction. Next, we used two-photon in vivo imaging in live Par1b/MARK2 deficient mice to examine microglia dynamics. In addition, a controlled-cortical impact injury was performed on wild-type and Par1b/MARK2-deficient mice and microglial response was determined by confocal imaging. Finally, to help rule out non-cell autonomous effects, we analyzed apoptosis by confocal imaging, cytokine levels by multiplex ELISA, and blood-brain barrier permeability using Evans Blue assay.ResultsHere, we show that loss of the cell polarity protein Par1b/MARK2 facilitates the activation of primary microglia in culture. We next found that microglia in Par1b/MARK2 deficient mice show increased density and a hypertrophic morphology. These morphological changes are accompanied with alterations in microglia functional responses including increased phagocytosis of neuronal particles early in development and decreased surveillance of the brain parenchyma, all reminiscent of a primed phenotype. Consistent with this, we found that microglia in Par1b/MARK2 deficient mice have a significantly lower threshold for activation upon injury.ConclusionsTogether, our studies show that loss of Par1b/MARK2 switches microglia from a surveillant to a primed state during development, resulting in an increased neuroinflammatory response to insults.

Dataset Information

Par1b/MARK2 phosphorylates kinesin-like motor protein GAKIN/KIF13B to regulate axon formation.

Publications

Par1b/MARK2 phosphorylates kinesin-like motor protein GAKIN/KIF13B to regulate axon formation.

Similar Datasets

OmicsDI is part of the ELIXIR infrastructure

Tweets