Physical interaction of apoptosis-inducing factor with DNA and RNA

Abstract

Apoptosis-inducing factor (AIF) is a mitochondrial flavoprotein, which upon apoptosis induction translocates to the nucleus where it interacts with DNA by virtue of positive charges clustered on the AIF surface. Here we show that the AIF interactome, as determined by mass spectroscopy, contains a large panel of ribonucleoproteins, which apparently bind to AIF through the RNA moiety. However, AIF is devoid of any detectable RNAse activity both in vitro and in vivo. Recombinant AIF can directly bind to DNA as well as to RNA. This binding can be visualized by electron microscopy, revealing that AIF can condense DNA, showing a preferential binding to singlestranded over double-stranded DNA. AIF also binds and aggregates single-stranded and structured RNA in vitro. Single-stranded poly A, poly G and poly C, as well doublestranded A/T and G/C RNA competed with DNA for AIF binding with a similar efficiency, thus corroborating a computer-calculated molecular model in which the binding site within AIF is the same for distinct nucleic acid species, without a clear sequence specificity. Among the preferred electron donors and acceptors of AIF, nicotine adenine dinucleotide phosphate (NADP) was particularly efficient in enhancing the generation of higher-order AIF/ DNA and AIF/RNA complexes. Altogether, these data support a model in which a direct interaction of AIF contributes to the compaction of nucleic acids within apoptotic cells.

Huntingtin protein interactions altered by polyglutamine expansion as determined by quantitative proteomic analysis

“…[49][50][51] Our biochemical apoptosis results in the translocation of AIFM1 to the nucleus, where it binds DNA and affects chromosome condensation and fragmentation, although the precise mechanism of AIFM1 nuclear function is unknown. 48,[52][53][54][55] We showed that AIFM1 knockdown in striatal cells attenuated toxicity of expanded Htt-N585-82Q fragment (Fig. 3D).…”

Mitochondria as therapeutic targets for cancer chemotherapy

“…Upon apoptosis induction, AIF translocates to the nucleus where it contributes to chromatin condensation via a direct interaction with DNA (Ye et al, 2002;Vahsen et al, 2006) and recruits other proteins into the 'degradosome', which mediates chromatinolysis Cande et al, 2004a). Microinjection of recombinant AIF is sufficient to induce hallmarks of apoptosis (chromatin condensation, rounding up of cells, phosphatidyl serine exposure) .…”

Methods for the assessment of mitochondrial membrane permeabilization in apoptosis

“…the inhibitor of apoptosis proteins (IAPs). AIF and EndoG translocate to the nucleus where they mediate chromatin condensation and large-scale DNA fragmentation, independently from caspases [16,17,19,20].…”