Gap junction and purinergic P2 receptor proteins as a functional unit: insights from transcriptomics. Mus musculus

Gap junctions and purinergic P2 receptors (P2Rs) can be regarded as belonging to a common functional unit, given that they are involved in the transmission of calcium signals between cells. We have previously shown that deletion of the Gja1 gene alters expression levels of numerous genes encoding proteins with diverse functions, including purinergic, P2Rs, and have found that genes synergistically or antagonistically expressed in wildtype tissues are more prone to be similarly or oppositely regulated in Cx43-nulls. We have now explored the use of coordination analysis of gene expression as a strategy to identify interlinked genes encoding functionally related proteins and used pull-downs to evaluate their interlinkage. Our findings indicate that, in brain and in cultured astrocytes, several of these co-expressed genes encode proteins that are components of P2R signal transduction pathways and/or directly interact with these receptors, including the gap junction protein connexin43 (Cx43) and connexin45 (Cx45), as well as pannexins. It is proposed that coordination analysis of gene expression may provide a novel unbiased strategy for the identification of proteins belonging to supramolecular complexes. Keywords: genetic modification Overall design: The transcriptomes of cultured cortical astrocytes and whole brain of neonatal Cx43 null mice were compared to the transcriptomes of cortical astrocytes and whole brain of wildtype C57Bl/6 mice. 4 biological replicas were used for each sample type but wildtype cortical astrocytes were 6 replicas were used. Brain transcriptomes were compared using the sample reference method while for the astrocytes we have used the "multiple yellow" design described in Iacobas DA, Fan C, Iacobas S et al., Transcriptomic changes in developing kidney exposed to chronic hypoxia. Biochem Biophys Res Commun. 2006 349(1):329-38.