# Quantitative optical nanoscopy of mitochondrial-derived vesicles in neurons classifies pre-peroxisomal and clearing organelles

## TL;DR

This study uses advanced imaging to classify different types of mitochondrial-derived vesicles in neurons and their roles in organelle biogenesis and waste clearance.

## Contribution

The study introduces a novel method using multicolour STED nanoscopy to classify and functionally characterize mitochondrial-derived vesicles in live neurons.

## Key findings

- Three populations of mitochondrial-derived vesicles were identified based on their cargo and function.
- Evidence suggests de novo peroxisome biogenesis occurs via fusion of endoplasmic reticulum and mitochondrial-derived vesicles.
- Vesicles transport degradation products and newly synthesized proteins for organelle maintenance and biogenesis.

## Abstract

Healthy mitochondria are crucial for maintaining neuronal homeostasis. Their activity depends on a dynamic lipid and protein exchange through fusion, fission, and vesicular trafficking. Studying vesicles in neurons is challenging with conventional microscopy due to their small size, heterogeneity, and dynamics. We use multicolour stimulated emission depletion nanoscopy to uncover the ultrastructure of mitochondrial-derived vesicles (MDVs) in live neurons, biosensors to define their functional state, and a pulse-chase strategy to identify their turnover in situ. We identified three populations of vesicular structures: one transporting degradation products originating from oxidative stress, one shuttling cargo and newly translated proteins for local organelle biogenesis and one consisting of small, functional mitochondria. Furthermore, we provide evidence supporting that de novo peroxisomes biogenesis occurs via the fusion of endoplasmic reticulum and MDVs at mitochondrial sites. Our data provide mechanistic insight into organelle biogenesis driven by significant diversity in MDV morphology, functional state, and molecular composition.

STED nanoscopy reveals structural and functional diversity in Neuronal MDVs including degradation and protein transport for organelle biogenesis.