  In living matter, shape fluctuations induced by acto-myosin are usually
studied in vitro via reconstituted gels, whose properties are controlled by
changing the concentrations of actin, myosin and cross-linkers. Such an
approach deliberately avoids to consider the complexity of biochemical
signaling inherent to living systems. Acto-myosin activity inside living cells
is mainly regulated by the Rho signaling pathway which is composed of multiple
layers of coupled activators and inhibitors. We investigate how such a pathway
controls the dynamics of confluent epithelial tissues by tracking the
displacements of the junction points between cells. Using a phenomenological
model to analyze the vertex fluctuations, we rationalize the effects of
different Rho signaling targets on the emergent tissue activity by quantifying
the effective diffusion coefficient, the persistence time and persistence
length of the fluctuations. Our results reveal an unanticipated correlation
between layers of activation/inhibition and spatial fluctuations within
tissues. Overall, this work connects the regulation via biochemical signaling
with mesoscopic spatial fluctuations, with potential application to the study
of structural rearrangements in epithelial tissues.
