An investigation of the endosomal trafficking of the ClC-2 chloride channel
By: by Sonja Urmilla Dhani.
Published: 2006
Language: eng
Number of pages: 213
ISBN-13: 9780494159286
Description: The voltage-gated ClC-2 chloride channel has been functionally implicated in several physiological processes. First, ClC-2 knock-out mice are blind, and the males, infertile. Furthermore, a role for modulating neuronal ionic homeostasis has been proposed as mutations in ClC-2 are associated with epilepsy, and ClC-2 has been localized to the GABAergic synaptic locale in hippocampal neurons. Although the functional properties of ClC-2 have been extensively studied, less is known about the proteins and mechanisms that serve to regulate its function. The work presented here has made significant progress towards achieving a better understanding of how the vesicular trafficking of ClC-2 contributes to the modulation of its function. Using a combination of biochemical, physiological and cell biology techniques, we demonstrate that manipulations known to modulate ClC-2 channel function do so, in part, by altering its endosomal trafficking routes. Specifically, Calyculin A, which promotes protein phosphorylation, facilitates the internalization of ClC-2 in a dynamin-dependent manner, and ultimately leads to its proteasomal degradation. This retrograde pathway involves the dynein motor complex, which participates in a functional interaction with ClC-2. Conversely ATP depletion, a condition that promotes protein dephosphorylation, recruits intracellular ClC-2 to the cell surface in a Rab11-dependent pathway. Finally, we have found that ClC-2 is physically associated with the GABA A receptor in vivo. Our investigations suggest an extrasynaptic and possibly intracellular localization for this interaction, and provide the biochemical evidence to support a functional interaction between these two channels. We therefore propose that the endosomal trafficking of ClC-2 may play a significant role in the functional regulation of the GABA A receptor. Collectively, our findings underscore the physiological significance of the endosomal trafficking of ClC-2, and provide the structural framework for future studies aimed to determine the role of ClC-2 in endosomal function.
Notes: Source: Dissertation Abstracts International, Volume: 67-07, Section: B, page: 3540.

Thesis (Ph.D.)--University of Toronto, 2006.

Includes bibliographic references.

Electronic version licensed for access by U. of T. users.