title: Purinergic receptors are part of a signaling system for keratinocyte proliferation, differentiation, and apoptosis in human fetal epidermis.
abstract: We have investigated the expression of P2X5, P2X7, P2Y1, and P2Y2 receptor subtypes in 8- to 11-wk-old human fetal epidermis in relation to markers of proliferation (proliferating cell nuclear antigen (PCNA) and Ki-67), keratinocyte differentiation (cytokeratin K10 and involucrin), and markers of apoptosis (TdT-mediated dUTP nick end labeling (TUNEL) and anti-caspase-3). Immunohistochemistry showed that each of the four receptors was expressed in spatially distinct zones of the developing epidermis: P2Y1 receptors were found in the basal layer, P2X5 receptors were predominantly in the basal and intermediate layers, and both P2Y2 and P2X7 receptors were in the periderm. Colocalization experiments suggested different functional roles for these receptors. P2Y1 receptors were found in fetal keratinocytes positive for PCNA and Ki-67, suggesting a role in proliferation. P2X5 receptors double labeled with differentiated fetal keratinocytes that were positive for cytokeratin K10, suggesting a role in differentiation. P2X7 receptors colocalized with anti-caspase-3 antibody and were also expressed in periderm cells positive for TUNEL, suggesting a role in periderm cell apoptosis. P2Y2 receptors were found only in periderm cells and may have a role in chloride and fluid secretion into the amniotic fluid.
authors.affiliation: Autonomic Neuroscience Institute, Royal Free and University College Medical School, London, UK.
authors.forename: Aina V H
authors.initials: AV
authors.lastname: Greig
authors.forename: Claire
authors.initials: C
authors.lastname: Linge
authors.forename: Alison
authors.initials: A
authors.lastname: Cambrey
authors.forename: Geoffrey
authors.initials: G
authors.lastname: Burnstock
mesh_terms: D017209:Apoptosis; D002454:Cell Differentiation; D002455:Cell Division; D000078404:Epidermal Cells; D004817:Epidermis / Q000196:embryology*; D005333:Fetus / Q000166:cytology; D006801:Humans; D007150:Immunohistochemistry; D015603:Keratinocytes / Q000502:physiology*; D018048:Receptors, Purinergic P2 / Q000032:analysis / Q000502:physiology*; D058485:Receptors, Purinergic P2X5; D058486:Receptors, Purinergic P2X7; D058472:Receptors, Purinergic P2Y1; D058473:Receptors, Purinergic P2Y2; D015398:Signal Transduction / Q000502:physiology*
chemical_list: C546465:P2RX5 protein, human; C546468:P2RX7 protein, human; C546382:P2RY1 protein, human; C546385:P2RY2 protein, human; D018048:Receptors, Purinergic P2; D058485:Receptors, Purinergic P2X5; D058486:Receptors, Purinergic P2X7; D058472:Receptors, Purinergic P2Y1; D058473:Receptors, Purinergic P2Y2