Cx36 preferentially connects beta-cells within pancreatic islets

Previous studies have provided evidence for the transcripts of Cx43 and Cx4 5 within pancreatic islets. As of yet, however, it has proven difficult to unambiguously demonstrate the expression of these proteins by islet cells. me have investigated whether Cx36, a new connexin species recently identifi ed in mammalian brain and retina, may also be expressed in pancreatic islet s. Using probes that permitted the original identification of Cx36 in the c entral nervous system, we show that a transcript for Cx36 is clearly detect able in rat pancreatic islets. Using novel and affinity-purified polyclonal antibodies, we have found that Cx36 is actually expressed in pancreatic is lets. Both in situ hybridization and immunolabeling indicated that this con nexin is abundant in the centrally located insulin-producing beta-cells and is expressed much less, if at all, by the other endocrine cell types. This differential expression was further confirmed on fluorescence-activated ce ll sorter-purified preparations enriched in either beta- or non-beta-cells. The finding of a differential distribution of Cx36 within distinct regions of pancreatic islets creates the possibility that this connexin may provid e the establishment of selective pathways of communication between the diff erent types of endocrine cells comprising the pancreatic islet.