Nesca, a novel neuronal adapter protein, links the molecular motor kinesin with the pre-synaptic membrane protein, syntaxin-1, in hippocampal neurons

• Published in: Journal of neurochemistry Vol. 121; no. 6; pp. 861 - 880
• Main Authors: MacDonald, James I. S., Dietrich, Alfonso, Gamble, Sarah, Hryciw, Todd, Grant, Robert Ian, Meakin, Susan O.
• Format: Journal Article
• Language: English
• Published: Oxford, UK Blackwell Publishing Ltd 01-06-2012; Wiley-Blackwell
• Subjects: Adaptor Proteins, Signal Transducing - metabolism; Adaptor Proteins, Vesicular Transport - metabolism; Ageing, cell death; Animals; Biological and medical sciences; Blotting, Western; Cell physiology; Cells; Central nervous system; Central neurotransmission. Neuromudulation. Pathways and receptors; Cytoskeletal Proteins - metabolism; Cytoskeleton - metabolism; Fundamental and applied biological sciences. Psychology; hippocampal neurons; Hippocampus - metabolism; Humans; Immunohistochemistry; Immunoprecipitation; kinesin; Kinesin - metabolism; Membranes; Mice; Molecular and cellular biology; Molecular biology; molecular transport; Nesca; Neurochemistry; Neurogenesis - physiology; Neurons; Neurons - metabolism; Post-Synaptic Density - metabolism; Protein Transport - physiology; Proteins; SNAREs; Synaptic Membranes - metabolism; Syntaxin 1 - metabolism; syntaxin-1; Transfection; Vertebrates: nervous system and sense organs; Nesca; molecular transport; Membrane protein; SNARE protein; SNAP protein; Synaptic membrane; Interaction; Biological transport; kinesin; Central nervous system; In vitro; Survival; hippocampal neurons; Encephalon; syntaxin-1; Syntaxin; Neuron; Actin; SNAREs; Cytoskeleton; Microtubule; Localization; Hippocampus
• ISSN: 0022-3042; 1471-4159
• DOI: 10.1111/j.1471-4159.2012.07729.x

J. Neurochem. (2012) 121, 861–880.
Vesicular transport in neurons plays a vital role in neuronal function and survival. Nesca is a novel protein that we previously identified and herein describe its pattern of expression, subcellular localization and protein–protein interactions both in vitro and in vivo. Specifically, a large proportion of Nesca is in tight association with both actin and microtubule cytoskeletal proteins. Nesca binds to F‐actin, microtubules, βIII and acetylated α‐tubulin, but not neurofilaments or the actin‐binding protein drebrin, in in vitro‐binding assays. Nesca co‐immunoprecipitates with kinesin heavy chain (KIF5B) and kinesin light‐chain motors as well as with the synaptic membrane precursor protein, syntaxin‐1, and is a constituent of the post‐synaptic density. Moreover, in vitro‐binding assays indicate that Nesca directly binds KIF5B, kinesin light‐chain and syntaxin‐1. In contrast, Nesca does not co‐immunoprecipitate with the kinesin motors KIF1B, KIF3A nor does it bind syntaxin‐4 or the synaptosome‐associated protein 25 kDa (SNAP‐25) in vitro. Nesca expression in neurons is highly punctuate, co‐stains with syntaxin‐1, and is found in fractions containing markers of early endosomes and Golgi suggesting that it is involved in vesicular transport. Collectively, these data suggest that Nesca functions as an adapter involved in neuronal vesicular transport including vesicles containing soluble N‐ethylmaleimide sensitive factor attachment protein receptors that are essential to exocytosis.
Nesca is a novel adapter protein that is exclusively expressed in the nervous system. Until now, however, a functional role for Nesca has been unknown. Using cell biology, confocal microscopy and in vitro‐binding studies, we show that Nesca is a novel microtubule‐binding protein, that it binds the kinesin motor KIF5 and the synaptic membrane precursor protein syntaxin‐1. These studies suggest that Nesca serves a role, similar to syntabulin, in the anterograde transport of synaptic membrane precursor proteins essential to exocytosis.