Emerging roles of the neural adaptor FE65 in neurite outgrowth.
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ABSTRACT:
SUBMITTER: Li W
PROVIDER: S-EPMC6199926 | biostudies-literature |
REPOSITORIES: biostudies-literature
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Project description:FE65 is an adaptor protein that binds to the amyloid precursor protein (APP). As such, FE65 has been implicated in the pathogenesis of Alzheimer's disease. In addition, evidence suggests that FE65 is involved in brain development. It is generally believed that FE65 participates in these processes by recruiting various interacting partners to form functional complexes. Here, we show that via its first phosphotyrosine binding (PTB) domain, FE65 binds to the small GTPase ADP-ribosylation factor 6 (ARF6). FE65 preferentially binds to ARF6-GDP, and they colocalize in neuronal growth cones. Interestingly, FE65 stimulates the activation of both ARF6 and its downstream GTPase Rac1, a regulator of actin dynamics, and functions in growth cones to stimulate neurite outgrowth. We show that transfection of FE65 and/or ARF6 promotes whereas small interfering RNA knockdown of FE65 or ARF6 inhibits neurite outgrowth in cultured neurons as compared to the mock-transfected control cells. Moreover, knockdown of ARF6 attenuates FE65 stimulation of neurite outgrowth and defective neurite outgrowth seen in FE65-deficient neurons is partially corrected by ARF6 overexpression. Notably, the stimulatory effect of FE65 and ARF6 on neurite outgrowth is abrogated either by dominant-negative Rac1 or knockdown of Rac1. Thus, we identify FE65 as a novel regulator of neurite outgrowth via controlling ARF6-Rac1 signaling.
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Project description:Targeting protein-protein interactions (PPIs) is a promising, but under-exploited, approach in the development of drugs for many indications. 14-3-3 proteins are a family of adaptor molecules with ubiquitous and critical functions in dozens of cell signaling networks. 14-3-3s bind to hundreds of ‘client proteins’ in a stereotyped fashion, altering client protein function, localization and stability. 14-3-3s are especially abundant in the central nervous system, and the small molecule fusicoccin-A (FC-A), a tool compound that can be used to manipulate 14-3-3 PPIs, enhances neurite outgrowth in cultured neurons. New semisynthetic FC-A derivatives with improved binding affinity for 14-3-3 complexes have recently been developed. Here we employ a series of screens that identify these compounds as potent inducers of neurite outgrowth through a polypharmacological mechanism. Using proteomics and x-ray crystallography, we discover that these compounds extensively perturb the 14-3-3 interactome through a unique and previously undescribed mechanism involving direct stabilization and inhibition of 14-3-3 PPIs. These results provide new insights into the development of drugs to target 14-3-3 PPIs, a potential therapeutic strategy for CNS diseases.
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