<table class="infobox infobox-gene">
<tr>
<th class="infobox-header" colspan="2">AIF Gene</th>
</tr>
<tr>
<td class="label">Symbol</td>
<td><strong>AIF</strong></td>
</tr>
<tr>
<td class="label">Full Name</td>
<td>AIF</td>
</tr>
<tr>
<td class="label">Type</td>
<td>Gene</td>
</tr>
<tr>
<td class="label">NCBI</td>
<td><a href="https://www.ncbi.nlm.nih.gov/gene/?term=AIF" target="_blank">Search NCBI</a></td>
</tr>
<tr>
<td class="label">Associated Diseases</td>
<td><a href="/wiki/als" style="color:#ef9a9a">Als</a>, <a href="/wiki/alzheimer" style="color:#ef9a9a">Alzheimer</a>, <a href="/wiki/amyotrophic-lateral-sclerosis" style="color:#ef9a9a">Amyotrophic Lateral Sclerosis</a>, <a href="/wiki/huntington" style="color:#ef9a9a">Huntington</a>, <a href="/wiki/inflammation" style="color:#ef9a9a">Inflammation</a></td>
</tr>
<tr>
<td class="label">KG Connections</td>
<td><a href="/atlas" style="color:#4fc3f7">126 edges</a></td>
</tr>
</table>
AIF ([Apoptosis](/entities/apoptosis) Factor), officially designated AIFM1 (Apoptosis-Inducing Factor Mitochondria-Associated 1), encodes a 67 kDa flavoprotein that serves dual roles as a mitochondrial oxidoreductase essential for oxidative phosphorylation and as a caspase-independent death effector.[@mate2002][@susin1999] Located on chromosome Xq26.1, AIFM1 is X-linked and its loss-of-function mutations cause a spectrum of mitochondrial diseases including severe encephalomyopathy, spondylo-epiphyseal dysplasia, and [Charcot-Marie-Tooth disease](/diseases/charcot-marie-tooth-disease) type 4.[@ghezzi2010] AIF's translocation from mitochondria to the nucleus during cell death mediates large-scale DNA fragmentation and chromatin condensation — a pathway termed parthanatos — that is implicated in neuronal loss after [stroke](/diseases/stroke), excitotoxicity, and in [Parkinson's Disease](/diseases/parkinsons-disease) and [Huntington's Disease](/diseases/huntington-disease).[@susin1999][@culmsee2005]
AIF is synthesized as a 613-amino-acid precursor with an N-terminal mitochondrial targeting sequence (MTS, aa 1–54) that is cleaved upon import into the intermembrane space (IMS).[@mate2002] The mature 57 kDa form is anchored to the inner mitochondrial membrane via a single transmembrane helix (aa 55–77). The soluble portion folds into three domains:
AIF's primary housekeeping function is maintaining mitochondrial respiratory chain integrity. AIF is required for the proper assembly and stability of [Complex I](/mechanisms/mitochondrial-complex-i), the largest enzyme complex in the electron transport chain.[@ghezzi2010][@klein2002] AIF-deficient cells show 50–70% reduction in Complex I activity, impaired oxidative phosphorylation, and a compensatory shift toward glycolytic metabolism.[@ghezzi2010] This bioenergetic function is independent of AIF's apoptotic role and is mediated by its oxidoreductase activity in the mitochondrial intermembrane space.
AIF functions as a NAD(P)H oxidase that helps regulate cellular redox state. It interacts with the thioredoxin/glutathione antioxidant systems and contributes to mitochondrial [ROS](/entities/reactive-oxygen-species) homeostasis.[@mate2002] Loss of AIF increases mitochondrial superoxide production, creating oxidative stress that further damages respiratory chain components.
AIF plays a role in hematopoietic and neural stem cell function. AIF-deficient (Harlequin) mice develop progressive cerebellar degeneration due to granule cell loss, demonstrating AIF's essential role in post-mitotic neuronal survival.[@klein2002]
The most well-characterized neurodegenerative pathway involving AIF is parthanatos — a cell death mechanism triggered by excessive activation of [PARP-1](/entities/parp1) (poly-ADP-ribose polymerase 1).[@culmsee2005][@wang2011] The signaling cascade proceeds:
Parthanatos is distinct from apoptosis (caspase-dependent) and [necroptosis](/entities/necroptosis) (RIPK-dependent), and PARP inhibitors or AIF knockdown protect [neurons](/entities/neurons) from excitotoxic death in vitro and in vivo.[@culmsee2005][@wang2011]
AIF nuclear translocation is a major mediator of neuronal death after ischemic stroke.[@culmsee2005] In mouse models of middle cerebral artery occlusion (MCAO), AIF translocates to the nucleus within 2–4 hours of reperfusion. The Harlequin mouse (with ~80% AIF reduction) shows significantly smaller infarct volumes after MCAO, confirming AIF's causal role in ischemic neuronal death.[@culmsee2005][@klein2002]
In dopaminergic neurons exposed to [MPTP](/entities/mptp)/MPP+ or 6-OHDA, PARP-1 hyperactivation triggers AIF-mediated parthanatos.[@wang2011] PARP-1 knockout mice are protected from MPTP-induced dopaminergic neurodegeneration. AIF nuclear translocation has been detected in substantia nigra neurons of PD patient post-mortem tissue, suggesting this pathway is active in human disease.[@wang2011]
[Mutant huntingtin](/proteins/huntingtin-protein) protein causes oxidative DNA damage that activates PARP-1, leading to AIF release and nuclear translocation in striatal medium spiny neurons.[@wang2004] PARP inhibition rescues neurodegeneration in Huntington's mouse models (R6/2, YAC128), and AIF pathway activation correlates with disease progression.[@wang2004]
Loss-of-function mutations in AIFM1 cause a spectrum of X-linked mitochondrial disorders characterized by Complex I deficiency, progressive neurodegeneration, and muscle weakness.[@ghezzi2010] Clinical presentations include Cowchock syndrome (X-linked CMT4), infantile-onset encephalomyopathy, and auditory neuropathy. These monogenic disorders demonstrate that AIF's bioenergetic function is essential for neuronal survival independent of its death effector role.
The following diagram shows the key molecular relationships involving AIF Gene discovered through SciDEX knowledge graph analysis: