Multiphoton Imaging of Synaptic Processes in Neuron-Glia Networks with Novel Transgenic Fluorescent Protein Probes

点击翻译按钮获取中文摘要

Proteins serve many functions in living cells. Recently, naturally glowing (fluorescent) jellyfish proteins were engineered to visualize cellular biochemical processes. This enhanced greatly the importance of live cell imaging as recognized with the 2008 Nobel Prize in Chemistry. At the University of Alberta, the NSERC-supported group of Dr. Robert E. Campbell is highly productive in developing such fluorescent protein based genetically encoded biosensors. Their latest tools will be used by my group to image electrical activity by which brain cells talk to each other. Specifically, we will use calcium and voltage sensor proteins to image how electrical brain activity transiently increases cellular calcium. This is important to study because activity-related calcium increases trigger the release of chemical neurotransmitter that is pivotal for communication of the nerve cells, called neurons. The structure at which that happens is the synapse. Here, an active presynaptic neuron releases neurotransmitter which then binds to receptors on the postsynaptic neuron to evoke electrical activity in that cell. The synaptically released neurotransmitter can also raise calcium in another brain cell type called astrocyte. Consequently, the astrocyte may release its own transmitter which then influences the interaction between both neurons. Studying these interactions at synapses is of utmost importance for understanding the fundamental processes of how brain cells function as reflected by the 2013 Nobel Prize in Medicine. **My group will image synaptic processes in neuron-astrocyte networks from newborn rodents after the fluorescent protein sensors are genetically inserted into the target cells. Such imaging is performed with our state-of-the-art multiphoton microscopes. The short-term objective of our research is to implement the novel fluorescent protein sensors for imaging biochemical processes in brain cell communication. As the long-term objective, we will insert several of the genetic sensors at the same time into brain cells for a multi-parameter analysis of how various cellular biochemical processes interact to give rise to complex nervous functions. This research will likely be published in leading scientific journals and will thus put Canadian neuroscience further on the international neuroscience stage. Although this research focuses on a fundamental neurobiological phenomenon, successful implementation of our innovative approaches will be applicable to live imaging in cells of other organs. This paves way to study also mechanisms of pathological perturbation of organ function. For the brain, this will likely have a major impact on developing novel therapeutic approaches for treatment of nervous diseases. Examples for this are neuropathic pain, Alzheimer's or spontaneous depression of breathing in preterm infants that affect many Canadians. These brain diseases are among the research topics that we study with our collaborators.