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Updated: Jun 13, 2025
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Characterizing the Composition of Molecular Motors on Moving Axonal Cargo Using "Cargo Mapping" Analysis
Published on: October 30, 2014
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Systems mapping of bidirectional endosomal transport through the crowded cell
Marlieke L M Jongsma1, Nina Bakker1, Lenard M Voortman1
1Department of Cell and Chemical Biology, ONCODE institute, Leiden University Medical Center LUMC, Einthovenweg 20, 2333 ZC Leiden, the Netherlands.
Current Biology : CB
|September 14, 2024
Summary
This study presents a physiological model of bidirectional endosome transport in cells. Late endosomes move along microtubules, guided by microtubule-associated proteins and motor proteins, revealing new insights into intracellular trafficking.
Area of Science:
- Cell Biology
- Molecular Motors
- Intracellular Transport
Background:
- Kinesin and dynein-dynactin motors mediate bidirectional vesicle transport along microtubules, primarily studied in vitro.
- Understanding physiological transport in crowded cellular environments remains a challenge.
Purpose of the Study:
- To develop a physiological model of bidirectional endosome transport within a cellular context.
- To investigate the roles of motor proteins, microtubule-associated proteins, and membrane contact sites in directing endosome movement.
Main Methods:
- Utilized color-coded, endogenously tagged transport proteins to track endosome movement in vivo.
- Observed late endosomes (LEs) interacting with endoplasmic reticulum (ER) membrane contact sites and microtubules.
- Investigated the involvement of Rab7 GTPase effectors (RILP, FYCO1) and motor proteins (dynein, KIF5B).
Main Results:
- Late endosomes surf bidirectionally on Protrudin-enriched ER membrane contact sites, navigating cellular obstacles.
- Transport directionality is influenced by microtubule-associated proteins (MAPs) like MID1, EB1, and CEP169, which recruit dynein motors.
- Activated dynein motors at microtubule plus ends collaborate with Rab7-RILP for minus-end directed transport.
Conclusions:
- Endosome transport is a coordinated process involving ER membrane interactions, MAPs for motor activation, and endosomal anchors.
- This physiological model highlights the complexity of bidirectional transport in vivo, distinct from in vitro observations.
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