Stress propagation through membranes

Central to the perception of tactile or acoustic stimuli is the conversion of mechanical stimuli into electrical signals that can be processed by the nervous system. Responsible for the conversion are so- called mechanosensitive channels in the membrane of specialized cells. When open, these channels conduct ions, i.e., they generate an electrical signal. It is currently unclear whether the channel opening is mediated by contact with other proteins, more precisely with proteins of the cytoskeleton. According to an alternative hypothesis, the mechanical stimulus could also be transmitted directly by the surrounding membrane to the channel. We will test this hypothesis by isolating such channels from their natural environment and incorporating them into simple lipid bilayers. To generate mechanical stimuli, we use photo-switchable lipids. If the stimuli were to be conducted by the membrane, we would detect channel opening utilizing current measurements even if the area containing the light-switched lipids was located at some distance from the mechanosensitive channels. Contrary results would indicate that direct contact between cytoskeleton and channel is required.

This project demonstrated that light-much like flipping a switch-can be converted into an electrical signal in cells that are not naturally light-sensitive. This is achieved using specially designed light-sensitive lipids ("photolipids") that change their shape upon illumination. This structural change modulates the activity of natural ion channels in the membrane-without the need for genetic modification. By introducing light responsiveness externally, the approach offers new strategies for controlling biological processes and holds potential for biomedical research, such as investigating signal transmission or developing novel therapies.