Regulation of cellular release of proteins in Parkinson neurodegeneration

点击翻译按钮获取中文摘要

DESCRIPTION (provided by applicant): The personal and societal costs of Parkinson's disease (PD) are expected to increase significantly in the next two decades. The mechanisms of neurodegeneration are not well understood, and no treatment clearly slows the neurodegenerative process in PD. Alpha-synuclein (αsyn) is a protein that is central to PD pathogenesis, and recent studies show that the transmission of αsyn between different cell populations is key to its ability to cause toxicity. Release of αsyn is the first critical componen of transmission, and occurs through exosomal and non-exosomal mediated pathways. A second key feature of prion-like spread of αsyn is the uptake in target neurons, leading to consequent misfolding of endogenous αsyn. What mechanisms regulate the release and spread of αsyn pathology are not known. The 14-3-3 proteins are chaperone-like proteins that can reduce protein aggregation, regulate protein secretion, and promote cell survival. We have previously shown that 14-3-3s are protective in several models of PD and can regulate the exosomal release of LRRK2, a key protein implicated in PD. In this proposal, we present preliminary data that overexpression of the 14-3-3θ isoform in αsyn-producing cells reduces the toxicity of released αsyn. Our central hypothesis is that 14-3-3 proteins can protect against αsyn toxicity by reducing the transmission of toxic αsyn species. In Aims 1 and 2, we will investigate whether 14-3-3s can regulate αsyn release through exosomes or alternative non-exosomal pathways and assess how any changes in release impacts paracrine αsyn toxicity. For these studies, we will use a paracrine inducible αsyn culture system in which released αsyn induced cell death in separately culture primary neurons. In Aim 1, we will use biochemical and imaging approaches to determine if 14-3-3s alter the amount and conformation of αsyn in exosomes. We will also assess how alterations in exosomal αsyn impact paracrine αsyn toxicity. In Aim 2, we will use similar techniques to test if 14-3-3s reduce αsyn release and toxicity through inhibition of the recycling endosomal pathway. In Aim 3, we will focus on the effects of 14-3-3s in target cells exposed to extracellular αsyn. Specifically, we will use in vitro and in vivo αsyn fibril models to test whether 14-3-3s can reduce αsyn uptake, aggregation, and toxicity in these models. If we can establish that 14-3-3s regulate the pathological transmission of αsyn, this would justify exploration of potential PD therapies targeting the 14-3-3s.