Dataset Information

Endocytosis is required for Toll signaling and shaping of the Dorsal/NF-kappaB morphogen gradient during Drosophila embryogenesis.

ABSTRACT: Dorsoventral cell fate in the Drosophila embryo is specified by activation of the Toll receptor, leading to a ventral-to-dorsal gradient across nuclei of the NF-?B transcription factor Dorsal. Toll receptor has been investigated genetically, molecularly, and immunohistologically, but much less is known about its dynamics in living embryos. Using live imaging of fluorescent protein chimeras, we find that Toll is recruited from the plasma membrane to Rab5(+) early endosomes. The distribution of a constitutively active form of Toll, Toll(10b), is shifted from the plasma membrane to early endosomes. Inhibition of endocytosis on the ventral side of the embryo attenuates Toll signaling ventrally and causes Dorsal to accumulate on the dorsal side of the embryo, essentially inverting the dorsal/ventral axis. Conversely, enhancing endocytosis laterally greatly potentiates Toll signaling locally, altering the shape of the Dorsal gradient. Photoactivation and fluorescence recovery after photobleaching studies reveal that Toll exhibits extremely limited lateral diffusion within the plasma membrane, whereas Toll is highly compartmentalized in endosomes. When endocytosis is blocked ventrally, creating an ectopic dorsal signaling center, Toll is preferentially endocytosed at the ectopic signaling center. We propose that Toll signals from an endocytic compartment rather than the plasma membrane. Our studies reveal that endocytosis plays a pivotal role in the spatial regulation of Toll receptor activation and signaling and in the correct shaping of the nuclear Dorsal concentration gradient.

SUBMITTER: Lund VK

PROVIDER: S-EPMC2964194 | biostudies-other | 2010 Oct

REPOSITORIES: biostudies-other

ACCESS DATA

Publications

Endocytosis is required for Toll signaling and shaping of the Dorsal/NF-kappaB morphogen gradient during Drosophila embryogenesis.

Lund Viktor K VK DeLotto Yvonne Y DeLotto Robert R

Proceedings of the National Academy of Sciences of the United States of America 20101004 42

Dorsoventral cell fate in the Drosophila embryo is specified by activation of the Toll receptor, leading to a ventral-to-dorsal gradient across nuclei of the NF-κB transcription factor Dorsal. Toll receptor has been investigated genetically, molecularly, and immunohistologically, but much less is known about its dynamics in living embryos. Using live imaging of fluorescent protein chimeras, we find that Toll is recruited from the plasma membrane to Rab5(+) early endosomes. The distribution of a ...[more]

PMID: 20921412

Similar Datasets

Project description:In multicellular organisms, the timing and placement of gene expression in a developing tissue assigns the fate of each cell in the embryo in order for a uniform field of cells to differentiate into a reproducible pattern of organs and tissues. This positional information is often achieved through the action of spatial gradients of morphogens. Spatial patterns of gene expression are paradoxically robust to variations in morphogen dosage, given that, by definition, gene expression must be sensitive to morphogen concentration. In this work we investigate the robustness of the Dorsal/NF-κB signaling module with respect to perturbations to the dosage of maternally-expressed dorsal mRNA. The Dorsal morphogen gradient patterns the dorsal-ventral axis of the early Drosophila embryo, and we found that an empirical description of the Dorsal gradient is highly sensitive to maternal dorsal dosage. In contrast, we found experimentally that gene expression patterns are highly robust. Although the components of this signaling module have been characterized in detail, how their function is integrated to produce robust gene expression patterns to variations in the dorsal maternal dosage is still unclear. Therefore, we analyzed a mechanistic model of the Dorsal signaling module and found that Cactus, a cytoplasmic inhibitor for Dorsal, must be present in the nucleus for the system to be robust. Furthermore, active Toll, the receptor that dissociates Cactus from Dorsal, must be saturated. Finally, the vast majority of robust descriptions of the system require facilitated diffusion of Dorsal by Cactus. Each of these three recently-discovered mechanisms of the Dorsal module are critical for robustness. These mechanisms synergistically contribute to changing the amplitude and shape of the active Dorsal gradient, which is required for robust gene expression. Our work highlights the need for quantitative understanding of biophysical mechanisms of morphogen gradients in order to understand emergent phenotypes, such as robustness.

Dataset Information

Endocytosis is required for Toll signaling and shaping of the Dorsal/NF-kappaB morphogen gradient during Drosophila embryogenesis.

Publications

Endocytosis is required for Toll signaling and shaping of the Dorsal/NF-kappaB morphogen gradient during Drosophila embryogenesis.

Similar Datasets

OmicsDI is part of the ELIXIR infrastructure

Tweets