Assessment of gap junctional intercellular communication.

Gap junctions are important plasma membrane organelles through which most cells in normal tissues communicate with each other. They exist in two neighboring cells and each cell contributes half of the structure. One gap junction consists of two hexameric connexons that dock with each other to create a channel. Six of the basic subunits referred to as connexins form a connexon. Less than one hundred to several thousand gap junction channels cluster together in the plane of the membrane. The gap junction channels serve as a regulated conduit for the intercellular exchange of small molecules. Maintenance of the integrity of gap junctional intercellular communication (GJIC) is important and required for normal electrical coupling, homeostasis, and embryogenesis. Aberrations of gap junctions have been related to human diseases such as cancer, cardiac arrhythmia, Charcot-Marie-tooth disease, and visceroatrial heterotaxia syndrome. This unit describes methods for measuring gap junctional intercellular communication using primary mouse hepatocytes as a model. Focus is only on functional evaluation based on dye coupling. Other methods, such as intracellular calcium waves and dual patch clamp, have been used to measure gap junctional communication, but these are not described in this unit.