In vivo imaging and characterization of actin microridges

Area of Science:

• Cell Biology
• Developmental Biology
• Biophysics

Background:

• Actin microridges are organized structures on epithelial cells, crucial for mucosal surfaces.
• Their formation mechanisms and regulation are not well understood.
• Understanding microridge dynamics is key to comprehending cellular organization and function.

Purpose of the Study:

• To characterize the composition and dynamics of actin microridges in zebrafish larvae.
• To investigate the molecular mechanisms regulating microridge formation and maintenance.
• To establish zebrafish as a model for studying in vivo actin dynamics.

Main Methods:

• Live imaging of zebrafish larvae to observe microridge dynamics.
• Biochemical assays to determine microridge composition.
• Genetic manipulation (dominant-negative constructs) and pharmacological treatments (Latrunculin A, inhibitors) to probe regulatory pathways.

Main Results:

• Microridges contain phospho-tyrosine, cortactin, and VASP, but not focal adhesion kinase.
• Dynamic changes in microridge length and branching were observed in vivo.
• Microridge assembly is regulated by Rho, Rac, Arp2/3, and PI3K signaling pathways.
• F-actin filaments within microridges exhibit active treadmilling.

Conclusions:

• Zebrafish actin microridges provide a model for studying in vivo pattern formation.
• Arp2/3-mediated actin dynamics are critical for microridge structure and length.
• Rho and Rac signaling pathways influence microridge organization and spacing.