PT  - JOURNAL ARTICLE
AU  - Antoine Fruleux
AU  - Arezki Boudaoud
TI  - Modulation of tissue growth heterogeneity by responses to mechanical stress
AID  - 10.1101/425355
DP  - 2018 Jan 01
TA  - bioRxiv
PG  - 425355
4099  - http://biorxiv.org/content/early/2018/09/24/425355.short
4100  - http://biorxiv.org/content/early/2018/09/24/425355.full
AB  - Morphogenesis often yields organs with robust size and shapes, whereas cell growth and deformation feature significant spatio-temporal variability. Here, we investigate whether tissue responses to mechanical signals contribute to resolve this apparent paradox. We built a model of growing tissues made of fiber-like material, corresponding to the cytoskeleton or the extracellular matrix of animals, or to the cell wall of plants, taking into account the synthesis and remodeling of this fiber-like material, as well as the modulation of synthesis by isotropic and anisotropic response to mechanical stress. Formally, our model describes an expanding, mechanoresponsive, nematic, and active fluid. We show that mechanical responses buffer localized perturbations, with two possible regimes - overdamped relaxation and underdamped relaxation, and the transition between the two corresponds to a minimum value of the relaxation time. Whereas robustness of shapes suggests that growth fluctuations are confined to small scales, our model yields growth fluctuations that have long-range correlations. This indicates that growth fluctuations are a source of heterogeneity in development. Nevertheless, we find that mechanical responses may dampen such fluctuations, with a magnitude of anisotropic response that minimizes heterogeneity of tissue contours. We finally discuss how our predictions might apply to the development of plants and animals. Altogether, our results call for the systematic quantification of fluctuations in growing tissues.