scholarly journals Rab2 regulates presynaptic precursor vesicle biogenesis at the trans-Golgi

2021 ◽  
Vol 220 (5) ◽  
Author(s):  
Torsten W.B. Götz ◽  
Dmytro Puchkov ◽  
Veronika Lysiuk ◽  
Janine Lützkendorf ◽  
Alexander G. Nikonenko ◽  
...  
Keyword(s):  
Synaptic Vesicle ◽  
Active Zone ◽  
Molecular Mechanisms ◽  
Neuronal Cell ◽  
Small Gtpase ◽  
Neuronal Cell Body ◽  
Synaptic Terminals ◽  
Vesicle Biogenesis ◽  
Lysosomal Membrane Protein ◽  
Vesicle Proteins

Reliable delivery of presynaptic material, including active zone and synaptic vesicle proteins from neuronal somata to synaptic terminals, is prerequisite for successful synaptogenesis and neurotransmission. However, molecular mechanisms controlling the somatic assembly of presynaptic precursors remain insufficiently understood. We show here that in mutants of the small GTPase Rab2, both active zone and synaptic vesicle proteins accumulated in the neuronal cell body at the trans-Golgi and were, consequently, depleted at synaptic terminals, provoking neurotransmission deficits. Ectopic presynaptic material accumulations consisted of heterogeneous vesicles and short tubules of 40 × 60 nm, segregating in subfractions either positive for active zone or synaptic vesicle proteins and LAMP1, a lysosomal membrane protein. Genetically, Rab2 acts upstream of Arl8, a lysosomal adaptor controlling axonal export of precursors. Collectively, we identified a Golgi-associated assembly sequence of presynaptic precursor biogenesis dependent on a Rab2-regulated protein export and sorting step at the trans-Golgi.

scholarly journals Presynaptic precursor vesicles originate from the trans-Golgi network, promoted by the small GTPase RAB2

2020 ◽  
Author(s):  
Torsten W. B. Götz ◽  
Dmytro Puchkov ◽  
Janine Lützkendorf ◽  
Alexander G. Nikonenko ◽  
Christine Quentin ◽  
...  
Keyword(s):  
Synaptic Vesicle ◽  
Active Zone ◽  
Molecular Mechanisms ◽  
Small Gtpase ◽  
Neuronal Somata ◽  
Synaptic Terminals ◽  
Vesicle Biogenesis ◽  
Lysosomal Membrane Protein ◽  
Golgi Network ◽  
Vesicle Proteins

SummaryReliable delivery of presynaptic material, including active zone and synaptic vesicle proteins from neuronal somata to synaptic terminals is prerequisite for faithful synaptogenesis and neurotransmission. However, molecular mechanisms controlling the somatic assembly of presynaptic precursors remain insufficiently understood. Here we show that in mutants of the small GTPase RAB2 active zone and synaptic vesicle proteins accumulated in the neuronal somata at the trans-Golgi network and were consequently depleted at synaptic terminals, provoking neurotransmission deficits. The ectopic presynaptic material accumulations consisted of heterogeneous vesicles and short tubules of 40×60 nm and segregated in subfractions either positive for active zone proteins or co-positive for synaptic vesicle proteins and LAMP1, a lysosomal membrane protein. Genetically, rab2 behaved epistatic over arl8, a lysosomal adaptor controlling axonal export of precursors. Collectively, we here identified a Golgi-associated assembly sequence in presynaptic precursor vesicle biogenesis controlled by RAB2 dependent membrane remodelling and protein sorting at the trans-Golgi.

Amyloid Precursor Protein Knockout Diminishes Synaptic Vesicle Proteins at the Presynaptic Active Zone in Mouse Brain

2014 ◽  
Vol 11 (10) ◽  
pp. 971-980 ◽  
Author(s):  
Melanie Laßek ◽  
Jens Weingarten ◽  
Amparo Acker-Palmer ◽  
Sandra Bajjalieh ◽  
Ulrike Muller ◽  
...  
Keyword(s):  
Amyloid Precursor Protein ◽  
Synaptic Vesicle ◽  
Mouse Brain ◽  
Active Zone ◽  
Precursor Protein ◽  
Presynaptic Active Zone ◽  
Vesicle Proteins

scholarly journals Molecular Mechanisms Underlying Synaptic and Axon Degeneration in Parkinson’s Disease

2021 ◽  
Vol 15 ◽  
Author(s):  
Nolwazi Z. Gcwensa ◽  
Drèson L. Russell ◽  
Rita M. Cowell ◽  
Laura A. Volpicelli-Daley
Keyword(s):  
Parkinson’S Disease ◽  
Parkinson's Disease ◽  
Molecular Mechanisms ◽  
Disease Onset ◽  
Neuronal Cell ◽  
Rem Sleep Behavior Disorder ◽  
Dopamine Neurons ◽  
Neuronal Cell Body ◽  
Substantia Nigra Pars Compacta ◽  
Cognitive Changes

Parkinson’s disease (PD) is a progressive neurodegenerative disease that impairs movement as well as causing multiple other symptoms such as autonomic dysfunction, rapid eye movement (REM) sleep behavior disorder, hyposmia, and cognitive changes. Loss of dopamine neurons in the substantia nigra pars compacta (SNc) and loss of dopamine terminals in the striatum contribute to characteristic motor features. Although therapies ease the symptoms of PD, there are no treatments to slow its progression. Accumulating evidence suggests that synaptic impairments and axonal degeneration precede neuronal cell body loss. Early synaptic changes may be a target to prevent disease onset and slow progression. Imaging of PD patients with radioligands, post-mortem pathologic studies in sporadic PD patients, and animal models of PD demonstrate abnormalities in presynaptic terminals as well as postsynaptic dendritic spines. Dopaminergic and excitatory synapses are substantially reduced in PD, and whether other neuronal subtypes show synaptic defects remains relatively unexplored. Genetic studies implicate several genes that play a role at the synapse, providing additional support for synaptic dysfunction in PD. In this review article we: (1) provide evidence for synaptic defects occurring in PD before neuron death; (2) describe the main genes implicated in PD that could contribute to synapse dysfunction; and (3) show correlations between the expression of Snca mRNA and mouse homologs of PD GWAS genes demonstrating selective enrichment of Snca and synaptic genes in dopaminergic, excitatory and cholinergic neurons. Altogether, these findings highlight the need for novel therapeutics targeting the synapse and suggest that future studies should explore the roles for PD-implicated genes across multiple neuron types and circuits.

scholarly journals The AP-3 Complex Required for Endosomal Synaptic Vesicle Biogenesis is Associated with a Casein Kinase Ια-Like Isoform

2000 ◽  
Vol 11 (8) ◽  
pp. 2591-2604 ◽  
Author(s):  
Victor V. Faundez ◽  
Regis B. Kelly
Keyword(s):  
Synaptic Vesicle ◽  
Synaptic Vesicles ◽  
Enzymatic Reaction ◽  
Casein Kinase ◽  
Small Gtpase ◽  
Casein Kinase I ◽  
Vesicle Membranes ◽  
Vesicle Biogenesis ◽  
Hinge Domain

The formation of small vesicles is mediated by cytoplasmic coats the assembly of which is regulated by the activity of GTPases, kinases, and phosphatases. A heterotetrameric AP-3 adaptor complex has been implicated in the formation of synaptic vesicles from PC12 endosomes ( Faundez et al., 1998 ). When the small GTPase ARF1 is prevented from hydrolyzing GTP, we can reconstitute AP-3 recruitment to synaptic vesicle membranes in an assembly reaction that requires temperatures above 15°C and the presence of ATP suggesting that an enzymatic step is involved in the coat assembly. We have now found an enzymatic reaction, the phosphorylation of the AP-3 adaptor complex, that is linked with synaptic vesicle coating. Phosphorylation occurs in the β3 subunit of the complex by a kinase similar to casein kinase 1α. The kinase copurifies with neuronal-specific AP-3. In vitro, purified casein kinase I selectively phosphorylates the β3A and β3B subunit at its hinge domain. Inhibiting the kinase hinders the recruitment of AP-3 to synaptic vesicles. The same inhibitors that prevent coat assembly in vitro also inhibit the formation of synaptic vesicles in PC12 cells. The data suggest, therefore, that the mechanism of AP-3-mediated vesiculation from neuroendocrine endosomes requires the phosphorylation of the adaptor complex at a step during or after AP-3 recruitment to membranes.

scholarly journals The synaptic vesicle proteins SV2, synaptotagmin and synaptophysin are sorted to separate cellular compartments in CHO fibroblasts.

1993 ◽  
Vol 123 (3) ◽  
pp. 575-584 ◽  
Author(s):  
M B Feany ◽  
A G Yee ◽  
M L Delvy ◽  
K M Buckley
Keyword(s):  
Plasma Membrane ◽  
Synaptic Vesicle ◽  
Cell Lines ◽  
Synaptic Vesicles ◽  
Vesicle Biogenesis ◽  
Intracellular Vesicles ◽  
Cellular Compartments ◽  
Vesicle Proteins

We expressed the synaptic vesicle proteins SV2, synaptotagmin, and synaptophysin in CHO fibroblasts to investigate the targeting information contained by each protein. All three proteins entered different cellular compartments. Synaptotagmin was found on the plasma membrane. Both SV2 and synaptophysin were sorted to small intracellular vesicles, but synaptophysin colocalized with early endosomal markers, while SV2 did not. SV2-containing vesicles did not have the same sedimentation characteristics as authentic synaptic vesicles, even though transfected SV2 was sorted from endosomal markers. We also created cell lines expressing both SV2 and synaptotagmin, both synaptotagmin and synaptophysin, and lines expressing all three synaptic vesicle proteins. In all cases, the proteins maintained their distinct compartmentalizations, were not found in the same organelle, and did not created synaptic vesicle-like structures. These results have important implications for models of synaptic vesicle biogenesis.

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