Gravity sensing by cells: mechanisms and theoretical grounds

Spaceflight technologies have disclosed amazing opportunities to outreach human knowledge and control over the natural world. However, the actual experience of microgravity has become a relevant threat that significantly limits the extent of man permanence in space. Since then, gravity effects on living organisms became a critical field of investigation. Gravity has been proven to affect a wide array of biological functions, interacting at different levels of complexity, from molecules to cells, tissue and the organisms as a whole. However, it is still a matter of investigation if gravity induces direct or indirect effects on cells. The non-equilibrium theory has been proven to explain how biological dissipative structures, like the cytoskeleton, may be sensitive enough to sense gravity change, then transferring the mechano-signal into biochemical pathways. Within that framework, gravity represents an ‘inescapable’ constraint that obliges living beings to adopt only a few configurations among many others. By removing the gravitational field, living structures will be free to recover more degrees of freedom, thus acquiring new phenotypes and new properties. Discoveries on that field are thought to advance our knowledge, providing amazing insights into the biological mechanism underlying physiology as well as many relevant diseases.