title: Acute downregulation of Cx43 alters P2Y receptor expression levels in mouse spinal cord astrocytes.
abstract: Propagation of intercellular calcium waves (ICW) between astrocytes depends on the diffusion of signaling molecules through gap junction channels and diffusion through the extracellular space of neuroactive substances acting on plasmalemmal receptors. The relative contributions of these two pathways vary in different brain regions and under certain pathological conditions. We have previously shown that in wild-type spinal cord astrocytes, ICW are primarily gap junction-dependent, but that deletion of the main gap junction protein (Cx43) by homologous recombination results in a switch in mode of ICW propagation to a purinoceptor-dependent mechanism. Such a compensatory mechanism for ICW propagation was related to changes in the pharmacological profile of P2Y receptors, from an adenine-sensitive P2Y(1), in wild-type, to a uridine-sensitive P2U receptor subtype, in Cx43 knockout (KO) astrocytes. Using oligonucleotide antisense to Cx43 mRNA for acute downregulation of connexin43 expression levels, we provide evidence for the molecular nature of such compensatory mechanism. Pharmacological studies and Western blot analysis indicate that there is a reciprocal regulation of P2Y(1) and P2Y(4) expression levels, such that downregulation of Cx43 leads to decreased expression of the adenine-sensitive P2Y(1) receptor and increased expression of the uridine-sensitive P2Y(4) receptor. This change in functional expression of the P2Y receptor subtype population in acutely downregulated Cx43 was paralleled by changes in the mode of ICW propagation, similar to that previously observed for Cx43 KO spinal cord astrocytes. On the basis of these results, we propose that Cx43 regulates both modes of ICW by altering P2Y receptor subtype expression in addition to providing intercellular coupling.
authors.affiliation: Department of Neuroscience, Albert Einstein College of Medicine, Bronx, New York, USA.
authors.forename: Sylvia O
authors.initials: SO
authors.lastname: Suadicani
authors.forename: Mara Helena
authors.initials: MH
authors.lastname: De Pina-Benabou
authors.forename: Marcia
authors.initials: M
authors.lastname: Urban-Maldonado
authors.forename: David C
authors.initials: DC
authors.lastname: Spray
authors.forename: Eliana
authors.initials: E
authors.lastname: Scemes
mesh_terms: D000225:Adenine / Q000494:pharmacology; D000255:Adenosine Triphosphate / Q000031:analogs & derivatives / Q000494:pharmacology; D000818:Animals; D000831:Animals, Newborn; D016375:Antisense Elements (Genetics); D001253:Astrocytes / Q000166:cytology / Q000187:drug effects / Q000378:metabolism*; D020013:Calcium Signaling / Q000187:drug effects / Q000235:genetics; D002450:Cell Communication / Q000187:drug effects / Q000235:genetics; D002478:Cells, Cultured; D018031:Connexin 43 / Q000172:deficiency* / Q000235:genetics; D004305:Dose-Response Relationship, Drug; D015536:Down-Regulation / Q000187:drug effects / Q000235:genetics*; D016257:Fura-2; D017629:Gap Junctions / Q000187:drug effects / Q000235:genetics / Q000378:metabolism*; D005786:Gene Expression Regulation / Q000187:drug effects / Q000235:genetics; D007546:Isoquinolines; D051379:Mice; D018345:Mice, Knockout; D018048:Receptors, Purinergic P2 / Q000187:drug effects / Q000235:genetics / Q000378:metabolism*; D058472:Receptors, Purinergic P2Y1; D013116:Spinal Cord / Q000166:cytology / Q000378:metabolism*; D015854:Up-Regulation / Q000187:drug effects / Q000235:genetics; D014529:Uridine / Q000494:pharmacology; D014544:Uridine Triphosphate / Q000494:pharmacology
chemical_list: D016375:Antisense Elements (Genetics); D018031:Connexin 43; D007546:Isoquinolines; C546383:P2ry1 protein, mouse; D018048:Receptors, Purinergic P2; D058472:Receptors, Purinergic P2Y1; C104749:purinoceptor P2Y4; D000255:Adenosine Triphosphate; C017475:lucifer yellow; D000225:Adenine; D016257:Fura-2; D014544:Uridine Triphosphate; D014529:Uridine