Structural basis and physiological consequences of alpha-Synuclein binding to neurexin 1beta

University Of Pennsylvania, Philadelphia PA

Investigators

Linked publications, trials & patents

Abstract

Project Summary/Abstract ?-Synuclein is a small, soluble neuronal protein that is the primary component of the Lewy body aggregates that are the hallmark of Parkinson's disease. While the mechanistic details are not yet well-understood, emerging evidence suggests that cell-to-cell transmission of toxic forms of ?-Synuclein is the basis of disease propagation. Our lab has recently identified complex N-linked glycans as mediators of cellular internalization of both monomer and aggregate forms of ?-Synuclein bearing an N-terminal acetyl group, a physiological modification of the protein. We specifically identified the neuronal glycoprotein neurexin 1? as capable of driving internalization of ?-Synuclein in a glycan-dependent manner. The goal of our proposed research is to characterize the structural basis of ?-Synuclein binding to neurexin 1?, the role of both N-terminal acetylation and glycosylation in conferring specificity in this interaction, and determine the molecular mechanisms resulting cellular internalization of ?-Synuclein following binding neurexin 1?. Our hypothesis is that cell-to-cell transmission of ?S is dependent on interactions with neurexin 1? and that the selectivity in these interactions is dependent on transient structural changes in ?-Synuclein conferred by the N-terminal acetyl group. To investigate this hypothesis, we have developed three specific aims with the following goals: determine the structural features of ?-Synuclein bound to neurexin 1?, including defining a minimal ?-Synuclein construct required for binding (Aim 1); determine the mechanisms by which binding to neurexin 1? results in cellular internalization of ?-Synuclein (Aim 2); and understand the functional impact of ?-Synuclein binding to neurexin 1? (Aim 3). To achieve these goals, we will carry out in vitro coarse grain and high resolution structural characterization of ?-Synuclein:neurexin 1? complexes and use live-cell imaging to quantify internalization of ?-Synuclein and the ability of internalized ?-Synuclein to seed aggregation of endogenous ?-Synuclein. We will contrast WT monomer, PD-associated point mutants and fibrillar forms of ?-Synuclein. Through this research we expect to characterize key interactions involved in propagation of ?-Synuclein pathology in Parkinson's disease, as well as to gain insight into the structural features of ?-Synuclein:neurexin 1? complexes. Ultimately, the characterization of ?-Synuclein: neurexin 1? interactions carried out through our studies may provide a new target for Parkinson's disease treatment and serve as the basis identifying novel small molecule therapeutics.