The nucleus acts as a ruler tailoring cell responses to spatial constraints

The microscopic environment inside a metazoan organism is highly
crowded. Whether individual cells can tailor their behavior to the limited
space remains unclear. In this study, we found that cells measure the degree
of spatial confinement by using their largest and stiffest organelle, the
nucleus. Cell confinement below a resting nucleus size deforms the nucleus,
which expands and stretches its envelope. This activates signaling to the
actomyosin cortex via nuclear envelope stretch-sensitive proteins,
up-regulating cell contractility. We established that the tailored
contractile response constitutes a nuclear ruler–based signaling pathway
involved in migratory cell behaviors. Cells rely on the nuclear ruler to
modulate the motive force that enables their passage through restrictive
pores in complex three-dimensional environments, a process relevant to
cancer cell invasion, immune responses, and embryonic development.