Structural and Biophysical Studies of Kinase-Ion Channel Interactions

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The transformation of electrical signals to biochemical ones requires the movement of ions from one compartment to another in excitable cells. Thus, having the right amount of these ions at the right time is critical for proper muscle and neuronal function. These ions must pass through special channel proteins that can open and close, thus determining the amount and timing of their release. Protein kinases are a group of regulatory proteins that modify ion channels by adding a little 'tag' to it, which in turn can alter the activity of the channel. This tagging, which is known as 'phosphorylation', is normally required for the activity of ion channels however, when the tagging is excessive, it can lead to disorders. Surprisingly, kinase involvement in ion channel regulation is poorly understood. Only a few studies show which protein kinase target which site, and fewer still have measured phosphorylation rates. Understanding the rate of phosphorylation toward each target site is physiologically important because this modification alters conditions of excitation, such as the "fight-or-flight" response, where timing of an ion channel opening is critical. My research program focuses on how protein kinases target mammalian ion channels and their associated proteins using biochemical and biophysical approaches. My long-term goal is to use an interdisciplinary approach to unravel how certain protein kinases regulate ion channels. While this ultimately this requires us to elucidate the cascade of signaling events involving numerous kinases and proteins, my short-term goal is to focus on two protein kinases PKA and CaMKII, and their regulation of the voltage gated sodium channels (NaVs). To this end, my lab seek to determine how their catalytic subunits bind and regulate proteins and ion channels involved in the formation of signaling junctions starting with peptide substrates derived from NaVs, and eventually including other ion channels, their different isoforms and ancillary subunits. There are only a handful of experimentally derived kinase-substrate complexes. Long-term, this program aims to study the affects of phosphorylation in context of fully folded channels as opposed to peptides and explore how kinases such as CaMKII and PKA are recruited to ion channels. This will bring concomitant insights into their inhibition and a better mechanistic understanding of these kinases. Finally, we seek to uncover how other regulatory proteins are affected by the activity and action of kinases, as these are known to regulate ion channels in a phosphorylation dependent manner. This work not only advance our knowledge of human physiology, but may eventually aid in design of drugs that alter specific kinase-ion channel interactions. Importantly, the proposed studies utilize cutting-edge biochemical and biophysical methods which provides a rich training environment for the next generation of scientific personnel and future research innovation in Canada.