TRPV6 regulation by sensing PIP2 in the paralipidome

The TRPV6 ion channel belongs to a larger family of channels called TRP channels, which are responsible for detecting various stimuli in the body. TRPV6 stands for Transient Receptor Potential Vanilloid subfamily member 6. The TRPV6 ion channel is a protein in human cells that acts like a gate for ions. Ion channels in general are a set of proteins, which allow for controlled ion permeation through the otherwise impermeable cell membranes. TRPV6 is specifically selective for calcium ions to enter cells, which intracellularly serve as signalling molecules to regulate cellular function. TRPV6 is present in various tissues throughout the body, including skin, ovaries, kidneys, digestive tract, bones, and brain. Key roles of TPRV6 channels include calcium absorption in the intestine and maintenance the proper calcium levels in several organs as needed for normal functioning, but calcium also plays an vital role in many cellular processes, including muscle contraction, nerve signalling, and cell growth. Such a broad spectrum of important functions also requires precise regulation. The current knowledge on TRPV6 channel regulation is at its infancy, while the diseases associated with TRPV6 disfunction mandate its investigation to create the knowledge base for helping patients in the future. TRPV6 play a fundamental role in various human diseases, such as non-alcohol dependent pancreatitis, kidney stone formation, skeletal abnormalities with transient neonatal hyperparathyroidism, and cancer. The objectives of this research proposal is to uncover the elusive regulation of TRPV6 by the paralipidome, most importantly by the signalling lipid species PIP2. With paralipidome we describe the membrane lipid environment in close proximity to the TRPV6 channel. We could recently demonstrate that impaired TRPV6 function can be associated with altered regulatory lipid binding, as it resulted in altered channel activity and sensitivity, thereby suggesting a direct coupling between TRPV6 and the functional lipid. PIP2 is a rare lipid of the plasma membrane, as present only at a concentration of 1-2%, but is it of particular importance, because used by cells to regulate and tune TRPV6 function, among several other membrane proteins. How PIP2 binding regulates the function of the channel is unknown. We intend to uncover this mechanism by posing the following questions: Where does PIP2 bind? How is a signal created by PIP2 binding? Through which path is the signal propagated to the ion conducting pore to achieve channel regulation as needed for normal cellular function. To reach these goals, we will combine a number of methods that use theoretical approaches using simulation techniques and artificial intelligence (AI) and in parallel, use experimental techniques from electrophysiology and calcium imaging to quantify TRPV6 function.