• Proceedings of the Korean Biophysical Society Conference
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• 2003.06a
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• pp.24-24
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• 2003

Actin filament is a major cytoskeleton in synapses and highly enriched in the presynaptic and postsynaptic compartments. Their roles in synaptic vesicle recycling and synaptogenesis have been extensively studied but functional evidence whether actin filaments are involved in these processes is as yet lacking. Dysfunction in synaptic vesicle recycling causes various diseases such as Alzheimer's disease, Schizophrenia, Bipolar disease, depression etc.

• Molecules and Cells
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• v.39 no.10
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• pp.762-767
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• 2016

Fasciclin II (FasII), the Drosophila ortholog of neural cell adhesion molecule (NCAM), plays a critical role in synaptic stabilization and plasticity. Although this molecule undergoes constitutive cycling at the synaptic membrane, how its membrane trafficking is regulated to ensure proper synaptic development remains poorly understood. In a genetic screen, we recovered a mutation in Drosophila mical-like that displays an increase in bouton numbers and a decrease in FasII levels at the neuromuscular junction (NMJ). Similar phenotypes were induced by presynaptic, but not postsynaptic, knockdown of mical-like expression. FasII trafficking assays revealed that the recycling of internalized FasII molecules to the cell surface was significantly impaired in mical-like-knockdown cells. Importantly, this defect correlated with an enhancement of endosomal sorting of FasII to the lysosomal degradation pathway. Similarly, synaptic vesicle exocytosis was also impaired in mical-like mutants. Together, our results identify Mical-like as a novel regulator of synaptic growth and FasII endocytic recycling.

• BMB Reports
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• v.44 no.2
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• pp.96-101
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• 2011

Calcineurin is a serine/threonine protein phosphatase controlled by $Ca^{2+}$ and calmodulin that has been implicated in various signaling pathways. Previously, we reported that calcineurin regulates coelomocyte endocytosis in Caenorhabditis elegans. So far, simple and powerful in vivo approaches have been developed to study various endocytic processes in C. elegans. Using these in vivo assays, we further analyzed the endocytic phenotypes of calcineurin mutants. We observed that the calcineurin mutants were defective in apical endocytosis in the intestine as well as synaptic vesicle recycling in the nerve cord. However, we found that calcineurin mutants displayed normal receptor-mediated endocytosis in oocytes. Therefore, our results suggest that calcineurin may regulate specific sets of endocytic processes in nematode.

• BMB Reports
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• v.52 no.9
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• pp.533-539
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• 2019

Recent evidence from genetics, animal model systems and biochemical studies suggests that defects in membrane trafficking play an important part in the pathophysiology of Parkinson's disease (PD). Mutations in leucine-rich repeat kinase 2 (LRRK2) constitute the most frequent genetic cause of both familial and sporadic PD, and LRRK2 has been suggested as a druggable target for PD. Although the precise physiological function of LRRK2 remains largely unknown, mounting evidence suggests that LRRK2 controls membrane trafficking by interacting with key regulators of the endosomal-lysosomal pathway and synaptic recycling. In this review, we discuss the genetic, biochemical and functional links between LRRK2 and membrane trafficking. Understanding the mechanism by which LRRK2 influences such processes may contribute to the development of disease-modifying therapies for PD.