Phased ERK responsiveness and developmental robustness regulate teleost skin morphogenesis.

Area of Science:

• Developmental biology
• Cell biology
• Zebrafish models

Background:

• Vertebrate embryonic axis elongation requires epidermal expansion.
• The periderm, the epidermis's outer layer, must grow to accommodate underlying tissue development.

Purpose of the Study:

• To develop tools for visualizing and quantifying signaling in the zebrafish periderm.
• To investigate the mechanisms of periderm growth during embryonic development.
• To understand the role of Extracellular signal-regulated kinase (ERK) signaling in periderm development.

Main Methods:

• Generation of a toolkit for live imaging and signaling quantification in the zebrafish periderm.
• Utilizing a live biosensor to measure ERK activity.
• Employing optogenetics to manipulate ERK activity.
• Genetic manipulation to block cell division.

Main Results:

• Periderm growth during early axial elongation is primarily driven by oriented cell divisions, not basal cell addition.
• ERK activity, measured by a biosensor, correlates with cell cycle entry.
• Optogenetic activation of ERK influences cell cycling.
• Later in development, ERK signaling shifts from promoting proliferation to hypertrophic growth.
• Blocking cell division results in enlarged periderm cells without impairing adult development.

Conclusions:

• Zebrafish periderm growth is regulated by stage-dependent ERK signaling.
• Oriented cell divisions are key to early periderm expansion.
• ERK signaling dynamically controls cell proliferation and hypertrophic growth.
• Teleost skin exhibits significant developmental robustness, tolerating disruptions in cell division.