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Related Concept Videos

Actin Polymerization and Cell Motility01:13

Actin Polymerization and Cell Motility

Actin is a family of globular proteins that are highly abundant in eukaryotic cells. It makes up approximately 1-5% of total cell protein concentration. Actin monomers polymerize to form a complex network of polarized filaments, the actin cytoskeleton, that plays a crucial role in many cellular processes, including cell motility, division, endocytosis, and metastasis of cancer cells.
Actin cytoskeleton dynamics can produce pushing, pulling, and resistance forces that help the cell to migrate.
Mechanism of Filopodia Formation01:39

Mechanism of Filopodia Formation

Filopodia are thin, actin-rich cellular protrusions that play an important role in many fundamental cellular functions. They vary in their occurrence, length, and positioning in different cell types, suggesting their diverse roles.
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Coat Assembly and GTPases

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Mechanism of Lamellipodia Formation01:31

Mechanism of Lamellipodia Formation

Cells migrating in response to external stimuli form lamellipodia, which are thin membrane protrusions supported by a mesh of linked, branched, or unbranched actin filaments. These actin filaments interact with myosin motor proteins, creating the dynamic actomyosin complex within the cytoskeleton. Contractility, or the ability to generate contractile stress, is inherent to the actomyosin complex. It helps cells detect the stiffness of the surrounding ECM and exert contractile force for...
Formation of Higher-order Actin Filaments01:11

Formation of Higher-order Actin Filaments

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Related Experiment Video

Updated: Jul 13, 2026

In Vitro Polymerization of F-actin on Early Endosomes
12:15

In Vitro Polymerization of F-actin on Early Endosomes

Published on: August 28, 2017

Integrating actin assembly and endocytosis.

Michael G Roth1

  • 1Department of Biochemistry, University of Texas Southwestern Medical Center, Dallas, Texas 75390, USA. michael.roth@utsouthwestern.edu

Developmental Cell
|July 5, 2007
PubMed
Summary

This study explores how different types of endocytosis might be connected through a shared molecular mechanism. The researchers focused on a protein called SNX9, which interacts with several key components of endocytosis, including phosphatidylinositides, dynamin, and N-WASP. Their findings suggest that SNX9 may act as a bridge between actin assembly and endocytic events. Using fluorescence imaging and mutant constructs, they showed SNX9 is present at sites of active endocytosis and that disrupting SNX9 reduces endocytic efficiency. The study does not claim SNX9 is essential for all endocytic processes but highlights its potential role in coordinating multiple pathways. The authors propose SNX9 may serve as a central regulator of endocytic events.

Keywords:
SNX9 functionendocytosis pathwaysactin assemblymolecular regulation

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08:02

Using Microfluidics and Fluorescence Microscopy to Study the Assembly Dynamics of Single Actin Filaments and Bundles

Published on: May 5, 2022

Area of Science:

  • Cell biology
  • Molecular signaling pathways
  • Endocytosis mechanisms

Background:

Current understanding of endocytosis is fragmented. Multiple pathways exist, but how they overlap or differ remains unclear. Prior research has shown distinct routes for internalizing materials. However, the shared molecular logic is not well defined. This gap motivated researchers to explore unifying mechanisms. No prior work had resolved how actin assembly might connect diverse endocytic events. Existing models focus on individual pathways, not their coordination. This study aims to bridge that knowledge gap through focused analysis.

Purpose Of The Study:

The goal was to determine if endocytic pathways share common molecular regulators. Specifically, the study investigated SNX9's role in linking actin dynamics to endocytosis. SNX9 is known to interact with phosphatidylinositides and dynamin. The researchers sought to clarify how SNX9 might coordinate actin assembly with endocytic events. They aimed to uncover whether SNX9 serves as a central hub for multiple pathways. This work addresses a key uncertainty in endocytic regulation. By focusing on SNX9, the study explores a potential unifying mechanism. The findings could reshape how endocytosis is understood as a coordinated process.

Main Methods:

The researchers used a combination of biochemical and cell biological approaches. They analyzed SNX9's interactions with phosphatidylinositides and dynamin. Fluorescence imaging tracked SNX9 localization during endocytosis. They tested SNX9's role in clathrin-dependent and -independent pathways. Mutant constructs were used to disrupt SNX9's binding domains. Live-cell imaging captured actin assembly dynamics. The team compared endocytic efficiency with and without SNX9. These methods allowed them to assess SNX9's coordination role.

Main Results:

SNX9 was found to interact with multiple endocytic components simultaneously. It binds phosphatidylinositides, dynamin, and N-WASP in the same complex. This interaction suggests SNX9 coordinates actin assembly with endocytosis. The study showed SNX9 is present at sites of active endocytosis. Disrupting SNX9 reduced endocytic efficiency in multiple pathways. The protein was found to localize to both clathrin- and caveolae-mediated events. These findings indicate SNX9 may serve as a central regulator. The results support a model where SNX9 integrates actin dynamics with endocytic processes.

Conclusions:

The authors propose SNX9 functions as a bridge between actin assembly and endocytosis. Their findings suggest SNX9 coordinates multiple endocytic pathways. The protein's ability to bind diverse components implies a unifying role. The study does not claim SNX9 is essential for all endocytic events. Instead, it highlights SNX9's potential as a regulatory hub. The results support a model where SNX9 integrates signaling and actin dynamics. The authors suggest further work is needed to confirm these interactions in vivo. This work opens new questions about how endocytic pathways are coordinated.

SNX9 coordinates actin assembly with multiple endocytic processes. It interacts with phosphatidylinositides, dynamin, and N-WASP.

Researchers used fluorescence imaging and mutant constructs to track SNX9's interactions and localization.

Actin assembly provides structural support for endocytic vesicle formation. SNX9 may regulate this process through N-WASP.

The study examined clathrin-dependent and clathrin-independent endocytic pathways.

SNX9 was found at sites of both clathrin- and caveolae-mediated endocytosis.

The authors suggest SNX9 may serve as a central regulator of endocytic processes.