Over the years, everything in the body gets stiffer: skin, joints, blood vessels. The intestine too. Its wall accumulates collagen and loses elasticity. For a long time this was thought to be simply the result of wear and tear, but now it is clear: stiffness itself is a signal that makes the intestinal muscle cells stop contracting.
In the membrane of these cells there is a sensor protein, Piezo1. When the environment around the cell is stiff, the membrane stretches and the sensor opens. Calcium flows in, and through a chain of signals it reaches the nucleus: the cell stops making proteins for contraction and starts releasing building material. This makes the wall even stiffer, and the loop closes.
Scientists tested this in humans too. Older people have more of this sensor in the intestine, and in carriers of a particular gene variant that makes the sensor too sensitive, food moved more slowly even at a young age. So if we find a drug that blocks this sensor, we could preserve normal intestinal function well into old age.
In mice with Piezo1 deleted in intestinal smooth muscle, the gut kept working like that of young animals even at 24 months, which is equivalent to about 70 human years. Meanwhile, activating the channel in young mice slowed transit to the level of old animals in just two weeks.
In Liu Cixin's novel The Three-Body Problem, an alien civilization uses sophons to block fundamental physics. Here the mechanosensitive channel Piezo1 acts as a molecular sophon: it intercepts the physical signal of stiffness and rewrites the cell's program, making it forget its contractile function.
Not published on arXiv. Here are its page, the PDF and the formalization: you can check it yourself, not only read our account.