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Actin Quantification Using the Filamentous Actin Segmentation Tool (FAST)
Vineeth Aljapur1, Adam Gardner2, Jason Carayanniotis2
1MAAE, Carleton University, Ottawa, ON, Canada.
Bio-Protocol
|July 28, 2026
Summary
Filamentous actin segmentation tool (FAST) uses antibody-assisted annotation to accurately quantify actin structures in cells. This deep learning model provides a practical tool for analyzing cytoskeletal organization in various cellular processes and diseases.
Area of Science:
- Cell Biology
- Biophysics
- Computational Biology
Background:
- Actin-filament assembly is crucial for cellular functions and disease mechanisms.
- Quantifying diverse actin structures from microscopy images is challenging due to limited tools.
- Existing methods struggle with accurate segmentation of various actin organizations.
Purpose of the Study:
- To develop and validate a deep learning model for accurate actin structure quantification.
- To introduce a novel antibody-assisted annotation method for training machine learning models.
- To provide a user-friendly tool for analyzing cytoskeletal organization in cellular imaging data.
Main Methods:
- Antibody-assisted annotation to generate labeled datasets for training.
- Development of the Filamentous actin segmentation tool (FAST) using deep learning.
- Application of FAST on phalloidin-stained and live-cell confocal microscopy images.
Main Results:
- FAST achieves accurate and efficient quantification of distinct actin structure classes.
- The antibody-assisted approach enables robust model training without structure-specific antibodies.
- Generated segmentation masks allow for quantitative analysis of actin abundance and organization.
Conclusions:
- FAST is a powerful, open-source tool for researchers studying cytoskeletal dynamics.
- The antibody-assisted annotation protocol facilitates the creation of high-quality training datasets.
- FAST simplifies the analysis of actin organization, aiding research in cell biology and disease.
Related Concept Videos
Generation of Straight or Branched Actin Filaments
The straight or branched structure formation of actin filaments is controlled by nucleating proteins such as the formins and Arp2/3 complex. Formin-mediated assembly results in straight filaments, whereas Arp2/3 protein complex-mediated assembly results in branched actin filaments.
Arp2/3 Complex
Arp2/3 complex is a seven-subunit complex consisting of two proteins similar to actin- Arp2 and Arp3, and five other subunits that help keep Arp2 and Arp3 inactive. When required, the complex is...
Arp2/3 Complex
Arp2/3 complex is a seven-subunit complex consisting of two proteins similar to actin- Arp2 and Arp3, and five other subunits that help keep Arp2 and Arp3 inactive. When required, the complex is...
Introduction to Actin
Actin is a highly conserved cytoskeletal protein found abundantly in eukaryotic cells. It constitutes 10% weight of the total cellular protein in muscle cells, while in non-muscle cells, it is lower and makes up around 1–5 percent of the total cell protein. Actin found in the unicellular amoebae and complex multicellular animals is around 80% similar, demonstrating their conservation over a billion years of evolution. Actin coding genes are conserved within species and across different species.

