Rab2 regulates presynaptic precursor vesicle biogenesis at the trans-Golgi

Area of Science:

• Neuroscience
• Cell Biology
• Molecular Biology

Background:

• Efficient transport of presynaptic components from neuronal cell bodies to terminals is vital for synaptogenesis and neurotransmission.
• The molecular mechanisms governing the assembly of these presynaptic precursors within the cell body are not fully understood.

Purpose of the Study:

• To investigate the role of the small GTPase Rab2 in the somatic assembly and transport of presynaptic proteins.
• To elucidate the molecular pathway controlling the export of active zone and synaptic vesicle proteins from the trans-Golgi network.

Main Methods:

• Utilized genetic mutants of the small GTPase Rab2 in a neuronal model.
• Analyzed the localization of active zone and synaptic vesicle proteins using cell biology techniques.
• Performed biochemical fractionation to characterize ectopic protein accumulations.
• Investigated the genetic relationship between Rab2 and Arl8.

Main Results:

• Rab2 mutants exhibited accumulation of active zone and synaptic vesicle proteins in the neuronal cell body at the trans-Golgi.
• Synaptic terminals in Rab2 mutants were depleted of these essential presynaptic proteins, leading to neurotransmission deficits.
• Ectopic accumulations comprised heterogeneous vesicles and tubules, with distinct segregation of active zone/synaptic vesicle proteins and LAMP1.
• Rab2 was found to act upstream of Arl8, a lysosomal adaptor involved in axonal precursor export.

Conclusions:

• A Golgi-associated pathway for presynaptic precursor biogenesis has been identified.
• This pathway relies on a Rab2-dependent protein export and sorting mechanism at the trans-Golgi.
• Rab2 plays a critical role in regulating the transport of essential synaptic components, impacting overall neurotransmission.