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Download or read book Cyclic Guanosine Monophosphate in Caenorhabditis Elegans written by Oldham Scott Hamilton and published by . This book was released on 2012 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Cyclic guanosine monophosphate (cGMP) functions across all known living organisms as a second messenger that amplifies extracellular signals to downstream proteins in a multiplicity of signal-transduction cascades. In humans, cGMP-dependent pathways mediate cellular responses to contribute to a large number of important biological processes within the cardiovascular, neurological, immune, and metabolic systems. In Caenorhabditis elegans, cGMP is part of a complex series of protein networks that contribute to many critical functions including neuronal patterning, plasticity, chemosensation, thermosensation, phototransduction, metabolism, and life span. Here I examine the contribution of several key cGMP-dependent proteins and pathways including the G-protein kinase EGL-4, two guanylyl cyclases DAF-11 and ODR-1, and four phosphodiesterases PDE-1, PDE-2, PDE-3 and PDE-5 to the adaptation response of the chemosensory neuron AWC. Jin Lee, Damien O'Halloran, I, and others showed that there is a temporal correlation between the cGMP-dependent translocation of EGL-4 into the nucleus of the AWC and the adaptive behavioral change in C. elegans after long-term exposure to an attractive volatile odor in the absence of food. We showed that the nuclear localization of EGL-4 in the AWC neuron is both necessary and sufficient to induce long-term adaptation. Jin Lee and Damien O'Halloran demonstrated that the loss of function of the ODR-1 or the DAF-11 guanylyl cyclase results in constitutively nuclear EGL-4 in the AWC. Damien O'Halloran, I, and others also showed that loss of function in the four phosphodiesterases PDE-1, PDE-2, PDE-3 and PDE-5 block the movement of EGL-4 into the nucleus after prolonged odor exposure. Damien O'Halloran was also able to disrupt the EGL-4 translocation event with the treatment of animals with the phosphodiesterase inhibitor 3-isobutyl-1-methylxanthine. Through this line of evidence, we deduced that reducing cGMP levels in AWC is necessary for the translocation of EGL-4 into the nucleus thereby inducing an adaptive response. To obtain a direct readout of cGMP levels in a living animal I developed a genetically encoded single fluorescent protein cGMP biosensor called WincG that stably expresses in C. elegans. Chantal Brueggemann and I used the WincG biosensor in living C. elegans animals immobilized in microfluidic devices to measure the dynamic changes in cGMP levels in the ASER amphid sensory neuron when exposed to NaCl and in the PHB phasmid neurons when exposed to sodium dodecyl sulfate polyacrylamide and 8-bromo-cGMP. These experiments established that the WincG cGMP biosensor was fully functional and also uncovered a number of novel findings related to the timing of the changes in cGMP levels in the stimulated ASER and PHB neurons. It also brought to light patterns in the increase and decrease of cGMP levels that appear to correlate with memory acquisition and retrieval models.