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Published on: May 6, 2022
Spatiotemporal dynamics of NF-κB/Dorsal inhibitor IκBα/Cactus in Drosophila blastoderm embryos
Allison E Schloop1, Sharva Vijayakumar Hiremath2,3, Razeen Shaikh4
1Graduate Program in Genetics, North Carolina State University, Raleigh, NC 27606, USA.
Insights
Cactus protein dynamics in Drosophila embryos were visualized using advanced imaging. This revealed how Cactus enhances the Dorsal gradient, improving developmental patterning precision.
Area of Science:
- Developmental biology
- Cellular signaling
- Molecular imaging
Background:
- The NF-κB/IκBα pathway is crucial for cellular processes like immunity and development.
- In Drosophila, the Dorsal/Cactus system governs embryonic dorsoventral axis patterning.
- Visualizing Cactus dynamics is difficult due to its rapid turnover.
Purpose of the Study:
- To overcome visualization challenges of Cactus.
- To quantitatively image Cactus distribution in live Drosophila embryos.
- To understand Cactus's role in regulating the Dorsal gradient.
Main Methods:
- Endogenous tagging of Cactus with a nanobody against GFP.
- Quantitative imaging of Cactus distribution in live embryos.
- Mathematical modeling to estimate Cactus concentrations.
Main Results:
- Cactus exhibits nuclear-cycle driven dynamics and nucleocytoplasmic shuttling, similar to Dorsal.
- Estimated Cactus nuclear and cytoplasmic concentrations were determined.
- The uniform nuclear presence of Cactus enhances Dorsal gradient range, robustness, and precision.
Conclusions:
- Cactus plays a significant role in refining the Dorsal gradient during Drosophila embryogenesis.
- This study provides quantitative insights into NF-κB pathway regulation in vivo.
- Highlights the importance of quantitative imaging for studying rapidly turning-over proteins.
Abstract:
The NF-κB/IκBα pathway regulates key cellular processes, including development, immunity, and inflammation. In Drosophila, the homologous Dorsal/Cactus system patterns the dorsoventral axis of the blastoderm embryo. While the inhibitor Cactus has been suggested to play multiple roles in regulating Dorsal, direct visualization of Cactus is challenging due to its rapid turnover. To overcome this challenge, we endogenously tagged Cactus with a nanobody against GFP and quantitatively imaged Cactus distribution in live embryos. We found that, like Dorsal, Cactus undergoes nuclear-cycle driven dynamics and nucleocytoplasmic shuttling. Using a mathematical model constrained by our data, we estimated Cactus nuclear and cytoplasmic concentration. Our results imply that the Dorsal gradient has increased spatial range, robustness, and precision due to the presence of Cactus in the nucleus uniformly throughout the embryo. This study provides insights into NF-κB regulation in Drosophila embryos and highlights the need for similar quantitative studies in other biological systems.
