title: Role of P2z purinergic receptors in ATP-mediated killing of tumor necrosis factor (TNF)-sensitive and TNF-resistant L929 fibroblasts.
abstract: Two closely related cell lines were characterized in their responses to extracellular ATP (ATPo): the fibroblast cell line L929 and a TNF-resistant variant L929/R. Both lines showed ATPo-activated increases in intracellular Ca2+, inward current, and sustained depolarization of the plasma membrane, cell responses compatible with activation of purinergic receptors of the P2y, P2x, or P2z subtype; however, only the L929/R variant was susceptible to ATPo-dependent early permeabilization of the plasma membrane to hydrophilic solutes of M(r) below 900, a response uniquely caused by the activation of P2z receptors. Both cell types were susceptible to the cytotoxic effect of ATPo, but killing of the L929/R variant required much shorter incubations in the presence of this nucleotide. Morphologic examination of ATPo-challenged L929 and L929/R cells showed that cell death occurred by two alternative mechanisms: colloido-osmotic lysis or apoptosis. Occurrence of apoptosis was confirmed by agarose gel analysis of cellular DNA. Although ATPo caused a fast mobilization of intracellular Ca2+, neither colloido-osmotic lysis nor apoptosis were Ca2+ dependent. Our results show that the L929/R variant, but not the L929 parental fibroblast cell line, expresses functional purinergic receptors of the P2z subtype. The presence of P2z receptors confers to L929/R cells enhanced susceptibility to ATPo-mediated cytotoxicity.
authors.affiliation: National Research Council Center for the Study of the Physiology of Mitochondria, University of Padova, Italy.
authors.forename: P
authors.initials: P
authors.lastname: Pizzo
authors.forename: M
authors.initials: M
authors.lastname: Murgia
authors.forename: A
authors.initials: A
authors.lastname: Zambon
authors.forename: P
authors.initials: P
authors.lastname: Zanovello
authors.forename: V
authors.initials: V
authors.lastname: Bronte
authors.forename: D
authors.initials: D
authors.lastname: Pietrobon
authors.forename: F
authors.initials: F
authors.lastname: Di Virgilio
mesh_terms: D000255:Adenosine Triphosphate / Q000494:pharmacology*; D000818:Animals; D017209:Apoptosis / Q000187:drug effects; D002118:Calcium / Q000378:metabolism; D002460:Cell Line; D002463:Cell Membrane Permeability; D004351:Drug Resistance; D005347:Fibroblasts / Q000187:drug effects; D051379:Mice; D011983:Receptors, Purinergic / Q000187:drug effects / Q000502:physiology*; D014409:Tumor Necrosis Factor-alpha / Q000494:pharmacology*
chemical_list: D011983:Receptors, Purinergic; D014409:Tumor Necrosis Factor-alpha; D000255:Adenosine Triphosphate; D002118:Calcium