Gravity constraints drive biological systems toward specific organization patterns. Commitment of cell specification is constrained by physical cues
Different cell lineages growing in microgravity undergo a spontaneous
transition leading to the emergence of two distinct phenotypes. By returning
these populations in a normal gravitational field, the two phenotypes
collapse, recovering their original configuration. In this review, we hypothesize
that, once the gravitational constraint is removed, the system freely
explores its phenotypic space, while, when in a gravitational field, cells are
“constrained” to adopt only one favored configuration. We suggest that the
genome allows for a wide range of “possibilities” but it is unable per se to
choose among them: the emergence of a specific phenotype is enabled by
physical constraints that drive the system toward a preferred solution. These
findings may help in understanding how cells and tissues behave in both
development and cancer.