title: PARP1-mediated necrosis is dependent on parallel JNK and Ca²⁺/calpain pathways.
abstract: Poly(ADP-ribose) polymerase-1 (PARP1) is a nuclear enzyme that can trigger caspase-independent necrosis. Two main mechanisms for this have been proposed: one involving RIP1 and JNK kinases and mitochondrial permeability transition (MPT), the other involving calpain-mediated activation of Bax and mitochondrial release of apoptosis-inducing factor (AIF). However, whether these two mechanisms represent distinct pathways for PARP1-induced necrosis, or whether they are simply different components of the same pathway has yet to be tested. Mouse embryonic fibroblasts (MEFs) were treated with either N-methyl-N'-nitro-N-nitrosoguanidine (MNNG) or β-Lapachone, resulting in PARP1-dependent necrosis. This was associated with increases in calpain activity, JNK activation and AIF translocation. JNK inhibition significantly reduced MNNG- and β-Lapachone-induced JNK activation, AIF translocation, and necrosis, but not calpain activation. In contrast, inhibition of calpain either by Ca(2+) chelation or knockdown attenuated necrosis, but did not affect JNK activation or AIF translocation. To our surprise, genetic and/or pharmacological inhibition of RIP1, AIF, Bax and the MPT pore failed to abrogate MNNG- and β-Lapachone-induced necrosis. In conclusion, although JNK and calpain both contribute to PARP1-induced necrosis, they do so via parallel mechanisms.
authors: Dalton Cardiovascular Research Center, University of Missouri-Columbia, Columbia, Missouri, 65211, USA.
authors: Diana L
authors: DL
authors: Douglas
authors: Dalton Cardiovascular Research Center, University of Missouri-Columbia, Columbia, Missouri, 65211, USA Department of Biomedical Sciences, University of Missouri-Columbia, Columbia, Missouri, 65211, USA Department of Medical Pharmacology and Physiology, University of Missouri-Columbia, Columbia, Missouri, 65211, USA bainesc@missouri.edu.
authors: Christopher P
authors: CP
authors: Baines
mesh_terms: D016475:3T3 Cells; D000818:Animals; D017209:Apoptosis / Q000502:physiology; D002154:Calpain / Q000378:metabolism*; D018929:Cell Culture Techniques; D016923:Cell Death; D020935:MAP Kinase Signaling System; D051379:Mice; D008928:Mitochondria / Q000378:metabolism; D009336:Necrosis / Q000378:metabolism; D000071137:Poly (ADP-Ribose) Polymerase-1; D011065:Poly(ADP-ribose) Polymerases / Q000378:metabolism*; D034741:RNA, Small Interfering / Q000378:metabolism; D015398:Signal Transduction
chemical_list: D034741:RNA, Small Interfering; C499321:Parp1 protein, mouse; D000071137:Poly (ADP-Ribose) Polymerase-1; D011065:Poly(ADP-ribose) Polymerases; D002154:Calpain
keywords: AIF; Calpain; Cell death; JNK; Mitochondria; Necrosis; PARP1