Jie Sun
Yajing Peng
Pei Wang
Xin Chen
Wei Zhao
Yeqiong Li
Lisha Wei
Wei Wang
Yanyan Zheng
Ye Wang
Xuena Zhang
Min-Sheng Zhu
Model Animal Research Center, State Key Laboratory of Pharmaceutical Biotechnology, Department of Neurology of the Affiliated Nanjing Drum Tower Hospital of Nanjing University Medical School, Nanjing University, Nanjing, 210061, China
More InformationCorresponding author: E-mail address: zhums@nju.edu.cn (Min-Sheng Zhu)
Received Date: 2018-10-20
Accepted Date:2019-02-19
Rev Recd Date:2019-01-14
Available Online: 2019-02-23 Publish Date:2019-02-01
Abstract
Abstract
As a critical guanine nucleotide exchange factor (GEF) regulating neurite outgrowth, Trio coordinates multiple processes of cytoskeletal dynamics through activating Rac1, Cdc42 and RhoA small GTPases by two GEF domains, but the in?vivo roles of these GEF domains and corresponding downstream effectors have not been determined yet. We established multiple lines of knockout mice and assessed the respective roles of Trio GEF domains and Rac1 in axon outgrowth. Knockout of total Trio in cerebellar granule neurons (CGNs) led to an impaired F-actin rearrangement of growth cone and hence a retarded neurite outgrowth. Such a retardation was reproduced by inhibition of GEF1 domain or knockdown of Cdc42 and restored apparently by introduction of active Cdc42. As Rac1 deficiency did not affect the neurite outgrowth of CGNs, we suggested that Trio GEF1-mediated Cdc42 activation was required for neurite outgrowth. We established a GEF2-knockout line with deletion of all Trio isoforms except a cerebella-specific Trio8, a short isoform of Trio without GEF2 domain, and used this line as a GEF2-deficient animal model. The GEF2-deficient CGNs had a normal neurite outgrowth but abolished Netrin-1-promoted growth, without affecting Netrin-1 induced Rac1 activation. We thus suggested that Trio GEF1-mediated Cdc42 activation rather than Rac1 activation drives the F-actin dynamics necessary for neurite outgrowth, while GEF2 functions in Netrin-1-promoted neurite elongation. Our results delineated the distinct roles of Trio GEF domains in neurite outgrowth, which is instructive to understand the pathogenesis of clinical Trio-related neurodevelopmental disorders.Keywords: Trio,
GEF,
Rho GTPases,
Axon outgrowth,
Cerebellar granule neuron
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