| Description |
Different cell types have unique combinations of ion channels and receptors that define their physiological function. Combinations of ion channel and receptor isoforms may change in a cell-specific manner with disease progression. Thus, it is essential to design a general platform to investigate the descriptive properties of cell types and understand their role in health and disease. In this dissertation, I contributed to constellation pharmacology, a platform to assess phenotypic properties of individual cell types based on the combinations (constellations) of ion channels and receptors expressed in the plasma membrane. To validate the platform, major cell types were identified in the pacemaking circuit of mice ventral respiratory column (VRC), a region that generates and maintains respiratory rhythm. The cell-specific constellations of three major cell types were characterized and the properties of putative inspiratory neurons were examined in intact brainstem slice preparations by electrophysiological recordings. This work revealed new neuromodulators of the respiratory pacemaking circuit that were validated using intact slice preparations. To test the application of constellation pharmacology in identifying molecular changes in disease states, the molecular correlates of neuropathic pain were investigated. Concerted multivalent molecular changes were observed in the sensory neurons of rat dorsal root ganglia following chronic constriction injury and sciatic nerve ligation injury that resulted in the appearance of aberrant neuronal phenotypes, which upregulated with the progression of pain states. This work demonstrated the strength of constellation pharmacology in monitoring neuronal phenotypes with the progression of disease states. Constellation pharmacology requires the use of target selective pharmacological tools to uncover the combinations of ion channels and receptors in cell membrane. The ion channels and receptors exist in complex heteromeric isoforms for which selective pharmacological tools are not well explored. The applicability of this platform to screen for novel bioactive marine natural products with potential for targeting these ion channel isoforms was demonstrated by identifying novel neuroactive peptides from a new superfamily of snails, Crassispiridae. Thus, in this dissertation, I establish the application of constellation pharmacology to 1) describe different cellular phenotypes based on the membrane constellations, 2) investigate changes to cellular phenotypes in pathological conditions and 3) discover bioactive marine natural products. |
