title: Functional and structural alterations in the endoplasmic reticulum and mitochondria during apoptosis triggered by C2-ceramide and CD95/APO-1/FAS receptor stimulation.
abstract: C(2)-ceramide (C(2)-cer) and binding of the CD95/APO-1/FAS (aCD95) receptor are acknowledged inducers of apoptosis. In spite of that, their effects on the endoplasmic reticulum (ER) and mitochondria during early phases of apoptotic onset are poorly characterized. Here, by employing various approaches, we followed structural and functional modifications of these organelles at the beginning of cellular demise. In detail, we observed that C(2)-cer, but not CD95 activation, markedly modifies the morphology of the ER and promotes Ca(2+) release. Accordingly, mitochondria of C(2)-cer-treated, but not of CD95-stimulated, cells are fragmented, show reduced Ca(2+) uptake, and collapsed membrane potential (DeltaPsi(m)). Most notably, C(2)-cer-mediated morphological aberrations of the ER are prevented neither by the pan-caspase inhibitor Z-VADfmk nor by the cell cytoskeleton dissembler cytochalasin-D, while on the contrary they are reduced by incubation in the presence of the intracellular Ca(2+) chelator 1,2-bis(O-aminophenoxy)ethane-N,N,N',N'-tetraacetic acid (BAPTA). We conclude that initiation of apoptosis via the intrinsic (i.e. C(2)-cer mediated) pathway causes an early structural and functional alteration of both ER and mitochondria, thus underlying a final "non return" point in the apoptotic pathway.
authors: Department of Experimental and Diagnostic Medicine, Section of General Pathology, Interdisciplinary Center for the Study of Inflammation and Emilia Romagna Laboratory BioPharmaNet, University of Ferrara, Ferrara, Italy.
authors: Davide
authors: D
authors: Ferrari
authors: Paolo
authors: P
authors: Pinton
authors: Michelangelo
authors: M
authors: Campanella
authors: Maria Giulia
authors: MG
authors: Callegari
authors: Cinzia
authors: C
authors: Pizzirani
authors: Alessandro
authors: A
authors: Rimessi
authors: Francesco
authors: F
authors: Di Virgilio
authors: Tullio
authors: T
authors: Pozzan
authors: Rosario
authors: R
authors: Rizzuto
mesh_terms: D000590:Amino Acid Chloromethyl Ketones / Q000494:pharmacology; D017209:Apoptosis; D002118:Calcium / Q000378:metabolism; D061945:Caspase Inhibitors; D002614:Chelating Agents / Q000494:pharmacology; D015853:Cysteine Proteinase Inhibitors / Q000494:pharmacology; D004533:Egtazic Acid / Q000031:analogs & derivatives / Q000494:pharmacology; D004721:Endoplasmic Reticulum / Q000378:metabolism / Q000648:ultrastructure*; D006367:HeLa Cells; D006801:Humans; D053078:Membrane Potential, Mitochondrial; D008928:Mitochondria / Q000378:metabolism / Q000648:ultrastructure*; D013110:Sphingosine / Q000031:analogs & derivatives* / Q000378:metabolism; D019014:fas Receptor / Q000819:agonists* / Q000378:metabolism
chemical_list: D000590:Amino Acid Chloromethyl Ketones; D061945:Caspase Inhibitors; D002614:Chelating Agents; D015853:Cysteine Proteinase Inhibitors; C064769:N-acetylsphingosine; C096713:benzyloxycarbonylvalyl-alanyl-aspartyl fluoromethyl ketone; D019014:fas Receptor; D004533:Egtazic Acid; C025603:1,2-bis(2-aminophenoxy)ethane-N,N,N',N'-tetraacetic acid; D013110:Sphingosine; D002118:Calcium