Scaling morphogen gradients during tissue growth by a cell division rule

Area of Science:

• Developmental Biology
• Mathematical Modeling
• Cell Signaling

Background:

• Morphogen gradients are crucial for tissue patterning and growth in multicellular organisms.
• The interplay between morphogen signaling, tissue growth, and patterning remains incompletely understood.
• Dpp signaling in Drosophila wing imaginal discs influences both patterning and growth, with cell division correlating to increased Dpp signaling.

Purpose of the Study:

• To mathematically model morphogen gradient formation in a growing tissue, incorporating advection and dilution.
• To define and analyze a novel scaling mechanism, the morphogen-dependent division rule (MDDR).
• To investigate the role of MDDR in tissue growth, gradient scaling, and finite size attainment.

Main Methods:

• Development of a mathematical model for morphogen gradient dynamics in a growing tissue.
• Inclusion of morphogen advection and dilution within the model.
• Analysis of the proposed morphogen-dependent division rule (MDDR) and its implications.

Main Results:

• The MDDR model demonstrates that cell division dependent on temporal increases in morphogen signaling leads to gradient scaling with tissue size.
• This mechanism promotes spatially uniform tissue growth and natural attainment of a finite tissue size.
• The MDDR model aligns with many observed properties of the Drosophila wing imaginal disc.

Conclusions:

• The MDDR provides a local coupling mechanism for cell division and morphogen signaling, enabling gradient scaling and uniform growth without global feedbacks.
• The model's inconsistency with scaling-defective mutants suggests temporal Dpp signaling increase may not drive late-stage cell division in Drosophila wing discs.
• The MDDR mechanism is potentially advantageous for rapid proliferation phases where global feedback implementation is challenging.