title: Trophic activity of a naturally occurring truncated isoform of the P2X7 receptor.
abstract: P2X7 is the largest member of the P2X subfamily of purinergic receptors. A typical feature is the carboxyl tail, which allows formation of a large pore. Recently a naturally occurring truncated P2X7 splice variant, isoform B (P2X7B), has been identified. Here we show that P2X7B expression in HEK293 cells, a cell type lacking endogenous P2X receptors, mediated ATP-stimulated channel activity but not plasma membrane permeabilization, raised endoplasmic reticulum Ca(2+) content, activated the transcription factor NFATc1, increased the cellular ATP content, and stimulated growth. In addition, P2X7B-transfected HEK293 cells (HEK293-P2X7B), like most tumor cells, showed strong soft agar-infiltrating ability. When coexpressed with full-length P2X7 (P2X7A), P2X7B coassembled with P2X7A into a heterotrimer and potentiated all known responses mediated by this latter receptor. P2X7B mRNA was found to be widely distributed in human tissues, especially in the immune and nervous systems, and to a much higher level than P2X7A. Finally, P2X7B expression was increased on mitogenic stimulation of peripheral blood lymphocyte. Altogether, these data show that P2X7B is widely expressed in several human tissues, modulates P2X7A functions, participates in the control of cell growth, and may help understand the role of the P2X7 receptor in the control of normal and cancer cell proliferation.
authors.affiliation: Department of Experimental and Diagnostic Medicine, Section of General Pathology, Interdisciplinary Center for the Study of Inflammation, University of Ferrara, via L. Borsari 46, 44100, Ferrara, Italy.
authors.forename: Elena
authors.initials: E
authors.lastname: Adinolfi
authors.forename: Maria
authors.initials: M
authors.lastname: Cirillo
authors.forename: Ronja
authors.initials: R
authors.lastname: Woltersdorf
authors.forename: Simonetta
authors.initials: S
authors.lastname: Falzoni
authors.forename: Paola
authors.initials: P
authors.lastname: Chiozzi
authors.forename: Patrizia
authors.initials: P
authors.lastname: Pellegatti
authors.forename: Maria Giulia
authors.initials: MG
authors.lastname: Callegari
authors.forename: Doriana
authors.initials: D
authors.lastname: Sandonà
authors.forename: Fritz
authors.initials: F
authors.lastname: Markwardt
authors.forename: Günther
authors.initials: G
authors.lastname: Schmalzing
authors.forename: Francesco
authors.initials: F
authors.lastname: Di Virgilio
mesh_terms: D000255:Adenosine Triphosphate / Q000378:metabolism; D000595:Amino Acid Sequence; D002460:Cell Line; D002462:Cell Membrane / Q000378:metabolism; D005455:Fluorescent Antibody Technique; D006801:Humans; D008564:Membrane Potentials / Q000235:genetics / Q000502:physiology; D008969:Molecular Sequence Data; D020033:Protein Isoforms / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D018048:Receptors, Purinergic P2 / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism*; D058486:Receptors, Purinergic P2X7; D020133:Reverse Transcriptase Polymerase Chain Reaction; D017386:Sequence Homology, Amino Acid
chemical_list: C546468:P2RX7 protein, human; D020033:Protein Isoforms; D018048:Receptors, Purinergic P2; D058486:Receptors, Purinergic P2X7; D000255:Adenosine Triphosphate