Studies On The Molecular Mechanism Of Neuronal Dendritic Golgi Outposts Dynamics In Drosophila By In Vivo Imaging

Dendritic Golgi outposts(GOs)are special Golgi complex that exist in the dendrites of neuron.Compared to the Golgi apparatus in the soma,GOs have two types of compartmental organization,namely multi-compartment GOs(mcGOs)and singlecompartment GOs(scGOs);GOs are highly dynamic,and can move bidirectionally in the dendrites.Previous studies show that GOs dynamics play roles in the local protein transport in the dendrites,and thus are involved in the development and plasticity of the dendrites.Abnormalities in GOs dynamics also have been found to be closely associated with the dendritic defects in neurodegenerative diseases.Here,based on review of the research progress of GOs,this dissertation investigated the dynamic characteristics of the two kinds of GOs with different compartmental organization,and revealed the molecular mechanism that regulated GOs dynamics,as well as the regulatory pathway related to model of dendritic defects of neurodegenerative diseases.The main results were as follows:The characteristics of GOs dynamics related to their compartmental organization were quantitatively described.Using the class Ⅲ dendritic arborization(C3da)neurons of Drosophila larva as model,the movements of mcGOs and scGOs were recorded by combining dual-color fluorescent protein labeling and in vivo time-lapse imaging,and the features of GOs dynamics were further analyzed,including the proportion of dynamicGOs,as well as the direction and net displacement of GOs movements.The motor protein subunits and adaptor proteins which regulated GOs movements were found by genetic screening.Utilizing the RNA interference technology,3 motor protein subunits which regulated the direction of GOs movements were identified,including the dynein heavy chain(Dhc)subunit,kinesin heavy chain and light chain subunits.Meanwhile,5 adaptor proteins regulating the direction of GOs movements also were identified through loss-of-function screening,including CG6218 and Zeste White 10 which specifically regulated scGOs movements,Sunday driver(Syd)which specifically regulated mcGOs movements,as well as Lava lamp and NudE which regulated both.The mechanism of the regulations on GOs dynamics by amyloid precursor protein(APP)was studied,which is a pathogenic factor of Alzheimer’s disease.Firstly,the regulations of APP on the dynamics of both mcGOs and scGOs were described.Then,change of the direction of mcGOs movements induced by APP was found can be rescued by knockdown of Dhc and Syd,which shows the molecular mechanism for APP to alter the direction of mcGOs movements.In addition,Syd also was involved in the dendritic branching defect induced by APP.In summary,the characteristics of GOs dynamics related to their compartmental organization were firstly analyzed using the C3 da neurons in Drosophila as model in this dissertation.Then,3 motor protein subunits and 5 related adaptor proteins which regulated the direction of GOs movements were screened out.Further,the regulations on GOs dynamics by APP were described,and the molecular mechanism by which APP regulated the direction of mcGOs movements was revealed: Dhc and Syd specifically mediated the alteration of the direction of mcGOs movements induced by APP.In addition,the findings also suggest the difference between the molecular mechanism for APP to alter the direction of mcGOs and scGOs movements.