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Published on: March 15, 2014
Microtubule-targeting-dependent reorganization of filopodia
Joseph M Schober1, Yulia A Komarova, Oleg Y Chaga
1Department of Cell and Molecular Biology, Feinberg School of Medicine, Northwestern University, Chicago, IL 60611, USA. j-schober@northwestern.edu
Abstract:
Interaction between the microtubule system and actin cytoskeleton has emerged as a fundamental process required for spatial regulation of cell protrusion and retraction activities. In our current studies, analysis of digital fluorescence images revealed targeting of microtubules to filopodia in B16F1 melanoma cells and fibroblasts. We investigated the functional consequence of targeting on filopodia reorganization and examined mechanisms by which microtubules may be guided to, or interact with, filopodia. Live cell imaging studies show that targeting events in lamellipodia wings temporally correlated with filopodia turning toward the lamellipodium midline and with filopodia merging. Rapid uncoupling of targeting with nocodazole decreased filopodia merging events and increased filopodia density. Total internal reflection fluorescence microscopy identified microtubules near the ventral surface and upward movement of targeted filopodia. The role of adhesion sites and microtubule plus-end proteins in targeting was investigated. Correlation of adhesion sites with microtubule targeting to filopodia was not observed and depletion of microtubule plus-end proteins did not significantly alter targeting frequency. We propose that microtubules target filopodia, independent of focal adhesions and plus-end proteins, causing filopodia movement and microtubules regulate filopodia density in lamellipodia wings through filopodia merging events.
Insights
Microtubules target cell structures called filopodia, influencing their movement and merging. This interaction regulates cell shape changes and filopodia density, independent of focal adhesions.
Area of Science:
- Cell Biology
- Cytoskeleton Dynamics
- Cell Motility
Background:
- The interplay between microtubules and the actin cytoskeleton is crucial for regulating cell protrusion and retraction.
- Understanding how these cytoskeletal networks interact spatially is key to cell motility.
Purpose of the Study:
- To investigate the targeting of microtubules to filopodia in B16F1 melanoma cells and fibroblasts.
- To examine the functional consequences of microtubule targeting on filopodia reorganization.
- To elucidate the mechanisms underlying microtubule guidance and interaction with filopodia.
Main Methods:
- Digital fluorescence image analysis of microtubule targeting to filopodia.
- Live cell imaging to observe filopodia dynamics and microtubule interactions.
- Nocodazole treatment to assess the effect of microtubule disruption.
- Total internal reflection fluorescence microscopy to visualize ventral surface interactions.
- Investigation of the roles of focal adhesions and microtubule plus-end proteins.
Main Results:
- Microtubules were observed targeting filopodia in B16F1 melanoma cells and fibroblasts.
- Targeting events correlated with filopodia turning and merging in lamellipodia wings.
- Nocodazole treatment reduced filopodia merging and increased filopodia density.
- Microtubules were found near the ventral surface, associated with upward filopodia movement.
- Microtubule targeting was independent of focal adhesions and plus-end proteins.
Conclusions:
- Microtubules target filopodia independently of focal adhesions and plus-end proteins.
- Microtubule targeting induces filopodia movement.
- Microtubules regulate filopodia density in lamellipodia wings via filopodia merging events.
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