Acute and chronic effects of a light-activated FGF receptor in keratinocytes in vitro and in mice

Area of Science:

• Cell Biology
• Molecular Biology
• Biotechnology

Background:

• Fibroblast Growth Factors (FGFs) and their receptors (FGFRs) are crucial for cellular processes like development and repair.
• Overlapping ligand binding of FGFRs complicates studying individual receptor functions.
• Optogenetics offers a potential solution for precise temporal control of signaling pathways.

Purpose of the Study:

• To develop a light-activated FGFR2 (OptoR2) for selective and temporally controlled activation of FGFR signaling in keratinocytes.
• To investigate the functional consequences of OptoR2 activation on cell migration, proliferation, and gene expression.
• To assess the long-term efficacy and potential limitations of optogenetic FGFR activation in relevant cellular and in vivo models.

Main Methods:

• Generation of a light-activated FGFR2 variant (OptoR2).
• Expression of OptoR2 in HEK 293T cells, murine, and human keratinocytes.
• Stimulation via light illumination to activate OptoR2 and subsequent analysis of signaling pathways, gene expression, cell migration, and proliferation.
• In vitro and in vivo studies in transgenic mice to evaluate long-term effects.

Main Results:

• OptoR2 activation in HEK 293T cells demonstrated precise temporal control of FGFR signaling, promoting cell migration and proliferation.
• OptoR2 activation in keratinocytes rapidly induced canonical FGFR signaling pathways and FGF target gene expression.
• Unexpected multi-level counter-regulation was observed, including OptoR2 down-regulation and loss of light responsiveness in long-term in vitro and in vivo settings.

Conclusions:

• OptoR2 provides a powerful tool for precise, light-inducible FGFR signaling control with high temporal resolution.
• Cell type-specific limitations and counter-regulatory mechanisms can impact the long-term effectiveness of optogenetic tools in relevant biological contexts.
• These findings highlight the complexity of translating optogenetic tools into physiological settings and emphasize the need for careful evaluation of their long-term behavior.