Overview   Lab & Research     Rane Lab     My Research       -Neurons       -Ion Channels       -Patch Clamp       -Growth Factors       -PC12 Cells       -Summary   Pseudoscience   Evolution &   Creationism	Just what do you do, anyway? A long while back, my answer to that was "I'm researching intracellular signaling pathways underlying acute and long-term growth factor regulation of neuronal ion channels." In other words, I was studying how growth factors induce both long-term and acute effects on ion channels. Specifically, I was attempting to understand the signaling pathways that underlie these phenomena. How, exactly, did I accomplish all of this? First, as I said before, I used the PC12 cell line as a model for sympathetic neurons. The individual cell lines I used express either normal (wild-type) or mutated growth factor receptors (in my case, receptors that bind to PDGF). I could then use whole cell patch clamp recording to determine what effects, if any, growth factors have on ion channels in cells expressing these various receptors. For example, recall that PC12 cells respond to a long-term exposure of certain growth factors by transforming into a neuronal-like cell. This transformation includes a doubling, or upregulation, of the number of calcium channels inserted into the membrane, something that can be measured with the patch clamp. When I applied PDGF to PC12 cells expressing normal PDGF receptors, the cells underwent a similar transformation, including this upregulation of calcium channels. Therefore, if I observed this upregulation in cells expressing a mutant receptor that can not activate a specific signaling pathway, it was a good bet that the signaling pathway was involved in the normal response. What about acute effects of growth factors? To measure this, I simply applied growth factors to PC12 cells while I was recording from them. Note that these cells had already undergone their transformation into a neuronal-like cell. Within less than a minute, a small application of growth factor, such as PDGF, inhibited sodium channel currents. Once again, if PDGF was applied to cells expressing certain mutant PDGF receptors, I no longer observed this inhibition. Coupled with some other experiments, my advisor and I arrived at the conclusion that two signaling pathways, the Src and Ras pathways, appear to be involved in this inhibition. So, there it is in a nutshell. My research. I hope you found it understandable and if not, well, feel better that it took me three years of arduous work to arrive at my basic understanding of things. But let's address one last question before the final wrap-up: How conclusive were these results? Were we certain that this was truly going on inside our nervous system? We thought, and still think so, but remember the tenant of good science is replication and expansion. I hope that other labs will confirm my results with experiments of their own, and in doing so, demonstrate that what I saw can be applied to functioning nervous systems. If not, then I must admit to error and discard years of work. It's not a particularly happy thought, but that's the way it goes. That's why science has brought us this far.
Mind 'Scapes, its pages and contents are © 1998 by Michael D. Hilborn, President of the Biggles 2000 Time-Dimensional Corporation. You are free to copy and use the original artwork on these pages, although I would appreciate it if you ask me first.