Abstract
Presentation Description :
Among retinal photoreceptors, gap junction coupling occurs between photoreceptors of the same type (homologous coupling: cone-cone, rod-rod) and of different types (heterologous coupling: rod-cone). Distinct functional roles have been elucidated for photoreceptor homologous and heterologous coupling, and the gap junction expressed in cones has been identified as connexin35 (Cx35) in cold-blooded vertebrates and its ortholog Cx36 in mammals. However, despite decades of research on the molecular basis and function of photoreceptor coupling, some of its fundamental aspects remain unknown, in particular, if Cx36 is the rod connexin in mammals and the plasticity of coupling suggested by indirect measures but not yet demonstrated by direct measurements of the junctional conductance. Through a recent technical advance, we have developed the capability to record from pairs of adjacent photoreceptors in the mouse retina using a perforated-patch clamp technique. This permits direct measurement of the gap junction conductance between two coupled cells. We have also developed several mouse models that are deficient for Cx36, specifically in rods or cones. In this presentation, I will review recent research in the field and present our findings in the conditional knock out models. As a whole, current research in this area supports the view that 1) Cx36 is the rod connexin; and 2) photoreceptor coupling is not static but tuned with precision according to the time of day and/or environmental lighting conditions.
This is an abstract that was submitted for the 2016 ARVO Annual Meeting, held in Seattle, Wash., May 1-5, 2016.