Protein Interactions Regulate KCC2-mediated Chloride Homeostasis

KCC2 is the primary Cl- cotransporter which maintains a low [Cl-]i required for inhibitory neurotransmission. Despite intense investigation into the mechanisms governing KCC2 regulation, the underlying mechanisms remain poorly understood. In this thesis I have presented three novel pieces of evidence providing further insight into KCC2 regulation. First, KCC2 membrane expression, and therefore function, require the expression of the KAR-type subunit GluK2. Second, KCC2 membrane recycling can be increased in the presence of GluK2 or by PKC-mediated phosphorylation. Protein interaction with GluK2 and PKC-mediated phosphorylation synergistically increase KCC2 expression and function, demonstrating how this protein can be regulated by functional cross-talk of multiple protein modifications. Finally, KCC2 is dephosphorylated by a calcineurin-dependent mechanism in response to ionic shift plasticity induction. Elucidating the mechanisms which regulate KCC2 function are highly coveted as KCC2 down-regulation is commonly observed in neuropathophysiological conditions such as epilepsy and neuropathic pain. Taken together, my results present novel findings regarding the mechanisms which regulate KCC2 function and surface expression and critically regulate neuronal Cl- homeostasis.Ph.D.2018-02-12 00:00:0