FETCH: A platform for high-throughput quantification of gap junction hemichannel docking

Gap junctions are membrane spanning channels that connect the cytoplasm of apposed cells, allowing for the passage of small molecules and ions. They are formed by the connexin (Cx) family of proteins which assemble into hexameric hemichannels on each cell and dock to create gap junctional channels between two cells. Despite importance of various Cx isoforms in human physiology and disease, available tools for screening and discriminating their interactions such as hemichannel compatibility, docking and permeability are limited. Here, we developed FETCH (flow enabled tracking of connexosomes in HEK cells), a method which utilizes the generation of annular gap junctions (connexosomes) as downstream indicators of hemichannel compatibility for intercellular docking. First, we show that fluorescent connexosomes create a cellular phenotype that is detectable by flow cytometry analysis. We then show that FETCH identifies homotypic and heterotypic docking of many single isoform connexin hemichannels. Finally, we demonstrate that FETCH captures the impact of disease-relevant connexin protein mutations on gap junction formation. Thus, we establish a new flow cytometry-based method that is amenable to the high-throughput classification of gap junction hemichannel docking.

Neuron-Glia Interactions in Neurodevelopmental Disorders

Recent studies have revealed synaptic dysfunction to be a hallmark of various psychiatric diseases, and that glial cells participate in synapse formation, development, and plasticity. Glial cells contribute to neuroinflammation and synaptic homeostasis, the latter being essential for maintaining the physiological function of the central nervous system (CNS). In particular, glial cells undergo gliotransmission and regulate neuronal activity in tripartite synapses via ion channels (gap junction hemichannel, volume regulated anion channel, and bestrophin-1), receptors (for neurotransmitters and cytokines), or transporters (GLT-1, GLAST, and GATs) that are expressed on glial cell membranes. In this review, we propose that dysfunction in neuron-glia interactions may contribute to the pathogenesis of neurodevelopmental disorders. Understanding the mechanisms of neuron-glia interaction for synapse formation and maturation will contribute to the development of novel therapeutic targets of neurodevelopmental disorders.