Imbalance between the growth rate of different organs can amplify to large
deviations of their size proportions during development. I will present evidence
that, for the pharynx of C. elegans, such size divergence is prevented by
reciprocal coordination of pharyngeal growth with other tissues. We
characterize this mechanism by a combination of live imaging of hundreds of
individuals in micro chambers, and by tissue-selective perturbation of mTORC1
and insulin signaling. By mathematical modelling, we show that the conservation
of proportions requires a bi-directional ultra-sensitive coupling of body growth
and pharynx size. Robustness of size proportions can thus not be explained by a
reduction of food uptake due to reduced pharynx size alone. Instead, we show
that organ growth coordination requires regulation by the mechano-transducing
transcriptional co-activator YAP/yap-1. Knock-down of yap-1 by RNAi makes
animals sensitive to tissue-specific inhibition mTORC1 inhibition, causing a
disproportionate pharynx and developmental arrest. Our data suggests that
mechanotransduction tightly coordinates organ growth during C. elegans
development to ensure the uniformity of body plan proportions among
individuals.
Bibliography: Ultra-sensitive coupling between organ growth and size by YAP-1 ensures
uniform body plan proportions in C. elegans. K. Stojanovski, I. Gheorghe, A. Lanjuin, W. B.
Mair, B.D. Towbin. bioRxiv 2022.09. 05.506666