RhoA GEF Mcf2lb regulates rosette integrity during collective cell migration

Area of Science:

• Developmental Biology
• Cell Biology
• Genetics

Background:

• Multicellular rosettes are transient epithelial structures vital for organogenesis.
• The zebrafish posterior lateral line primordium (pLLP) forms epithelial rosettes that develop into sensory neuromasts (NMs).

Purpose of the Study:

• To investigate the role of the RhoA Guanine nucleotide Exchange Factor (GEF) Mcf2lb in zebrafish pLLP rosette morphogenesis.
• To understand how Mcf2lb influences cell organization and RhoA signaling during NM development.

Main Methods:

• Single-cell RNA-sequencing and whole-mount in situ hybridization to analyze mcf2lb expression.
• Live imaging and 3D analysis of mcf2lb mutant zebrafish to observe rosette formation and cell behavior.
• Assessment of cell polarity markers (ZO-1, Par-3) and RhoA pathway components (RhoA, Rock2a, non-muscle Myosin II).

Main Results:

• mcf2lb is expressed in the pLLP during migration.
• mcf2lb mutants exhibit disrupted apical constriction and rosette organization.
• RhoA activity and downstream effectors (Rock2a, non-muscle Myosin II) are diminished apically in mcf2lb mutants.
• Mutants show an increased number of deposited neuromasts.

Conclusions:

• Mcf2lb-dependent RhoA activation is essential for maintaining epithelial rosette integrity.
• Proper rosette organization, regulated by Mcf2lb and RhoA, is critical for accurate neuromast deposition.