GSE65110
Identification of Macrophage Inhibitory Factor as the Parthanatos Dependent AIF Associate Nuclease
Inhibition or genetic deletion of poly(ADP-ribose) polymerase-1 (PARP-1) is profoundly protective against a number of toxic insults in many organ systems1,2. In the brain the molecular mechanisms underlying PARP-1-dependent cell death (parthanatos) involves mitochondrial apoptosis-inducing factor (AIF) release and translocation to the nucleus resulting in chromatinolysis3-5. However, it is not known how AIF induces chromatinolysis and neuronal death in parthanatos3. Here we show through an unbiased screen of a ~16K human protein microarray followed by a second siRNA-based screen for protection against PARP-1- dependent cell death, that macrophage migration inhibitory factor (MIF)6 is an AIF associated nuclease that is required for cell death following N-methyl-D-aspartate (NMDA) glutamate receptor excitotoxicity and N-methyl-N-nitroso-N- nitroguanidine (MNNG) toxicity in primary neuronal cultures and focal stroke in mice. MIF contains a central four stranded mixed ß-sheet flanked by two a- helices on both sides with an aßßßaß topology which is the structural core of many proteins belonging to the PD-D/E(X)K nuclease-like superfamily. MIF possesses previously unknown Mg2+/Ca2+-dependent nuclease activity, cleaving genomic DNA into large 20-50 kb fragments. AIF recruits MIF to the nucleus after NMDA treatment to induce DNA damage and cell death. Disruption of the AIF-MIF interaction prevents MIF recruitment to the nucleus and protects neurons from NMDA excitotoxicity and ischemic injury. Mutation of Glu22 to Gln in the catalytic nuclease domain completely blocks MIF’s nuclease activity, which almost completely inhibits DNA damage and cell death in vitro and in vivo. These findings reveal that MIF is recruited by AIF to the nucleus where it functions as a parthanatos dependent AIF associated nuclease that induces chromatinolysis and neuronal death, providing a new therapeutic target for stroke and other disorders involving parthanatos. Overall design: Examination of 2 different histone modifications in 2 cell types.