Rabbit Anti-Human AIFM1 (C-terminal) Polyclonal antibody

We investigated two male infant patients who were given a diagnosis of progressive mitochondrial encephalomyopathy on the basis of clinical, biochemical, and morphological features. These patients were born from monozygotic twin sisters and unrelated fathers, suggesting an X-linked trait. Fibroblasts from both showed reduction of respiratory chain (RC) cIII and cIV, but not of cl activities. We found a disease-segregating mutation in the X-linked AIFM1 gene, encoding the Apoptosis-Inducing Factor (AIF) mitochondrion-associated 1 precursor that deletes arginine 201 (R201 del). Under normal conditions, mature AIF is a FAD-dependent NADH oxidase of unknown function and is targeted to the mitochondrial intermembrane space (this form is called AIF(mit)). Upon apoptogenic stimuli, a soluble form (AIF(sol)) is released by proteolytic cleavage and migrates to the nucleus, where it induces "parthanatos," i.e., caspase-independent fragmentation of chromosomal DNA. In vitro, the AIF(R201) (del) mutation decreases stability of both AIF(mit), and AIF(sol) and increases the AIF(sol) DNA binding affinity, a prerequisite for nuclear apoptosis. In AIF(R201) (del) fibroblasts, staurosporine-induced parthanatos was markedly increased, whereas re-expression of AIF(wt) induced recovery of RC activities. Numerous TUNEL-positive, caspase 3-negative nuclei were visualized in patient #1's muscle, again indicating markedly increased parthanatos in the AIF(R201 del) critical tissues. We conclude that AIF(R201) (del) is an unstable mutant variant associated with increased parthanatos-linked cell death. Our data suggest a role for AIF in RC integrity and mtDNA maintenance, at least in some tissues. Interestingly, riboflavin supplementation was associated with prolonged improvement of patient #1's neurological conditions, as well as correction of RC defects in mutant fibroblasts, suggesting that stabilization of the FAD binding in AIF(mit) is beneficial.

Histone deacetylase (HDAC) proteins are overexpressed in multiple diseases, including cancer, and have emerged as anticancer drug targets. HDAC proteins regulate cellular processes, such as the cell cycle, apoptosis, and cell proliferation, by deacetylating histone and non-histone substrates. Although a plethora of acetylated proteins have been identified using large-scale proteomic approaches, the HDAC proteins responsible for their dynamic deacetylation have been poorly studied. For example, few substrates of HDAC1 have been identified, which is mainly due to the scarcity of substrate identification tools. We recently developed a mutant trapping strategy to identify novel substrates of HDAC1. Herein, we introduce an improved version of the trapping method that uses mass spectrometry (MS)-based proteomics to identify multiple substrates simultaneously. Among the substrate hits, CDK1, AIFM1, MSH6, and RuvB-like 1 were identified as likely HDAC1 substrates. These newly discovered HDAC1 substrates are involved in various biological processes, suggesting novel functions of HDAC1 apart from epigenetics. Substrate trapping combined with MS-based proteomics provides an efficient approach to HDAC1 substrate identification and contributes to the full characterization of HDAC function in normal and disease states.