Stochastic Subcellular Organization of Dense-Core Vesicles Revealed by Point Pattern Analysis

Area of Science:

• Neuroscience
• Cell Biology
• Biophysics

Background:

• Dense-core vesicles (DCVs) are key secretory organelles in neurons, transporting proteins vital for synaptic plasticity and differentiation.
• Understanding the subcellular organization of DCVs is crucial for elucidating their functional mechanisms in hippocampal neurons.

Purpose of the Study:

• To develop a quantitative model for DCV subcellular organization in spontaneously active hippocampal neurons.
• To test the hypothesis of synaptic enrichment for DCVs and its impact on cargo function.

Main Methods:

• Utilized fluorescence microscopy to visualize DCVs in hippocampal neurons.
• Applied statistical analyses, including variance-to-mean ratio, frequency distribution, and Moran's autocorrelation, to model DCV distribution.
• Quantified DCV occupancy in presynaptic boutons versus extrasynaptic axonal sites.

Main Results:

• DCV distribution along neuronal shafts and within synapses adheres to Poisson statistics, indicating stochastic organization.
• DCV occupancy in presynaptic boutons is approximately threefold higher than at nearby extrasynaptic sites, confirming local presynaptic enrichment.
• Stochastic organization and presynaptic enrichment are consistent with maintaining cargo function and preventing presynaptic depletion.

Conclusions:

• Stochastic organization is a fundamental principle governing DCV distribution, supporting their role in synaptic plasticity.
• Presynaptic enrichment of DCVs ensures the availability of essential cargo at active synaptic sites.
• Randomness plays a significant role in the organization and composition of synaptic structures.