RESUMEN
Auditory neuropathy spectrum disorder (ANSD) represents a variety of sensorineural deafness conditions characterized by abnormal inner hair cells and/or auditory nerve function, but with the preservation of outer hair cell function. ANSD represents up to 15% of individuals with hearing impairments. Through mutation screening, bioinformatic analysis and expression studies, we have previously identified several apoptosis-inducing factor (AIF) mitochondria-associated 1 (AIFM1) variants in ANSD families and in some other sporadic cases. Here, to elucidate the pathogenic mechanisms underlying each AIFM1 variant, we generated AIF-null cells using the clustered regularly interspersed short palindromic repeats (CRISPR)/CRISPR-associated protein 9 (Cas9) system and constructed AIF-wild type (WT) and AIF-mutant (mut) (p.T260A, p.R422W, and p.R451Q) stable transfection cell lines. We then analyzed AIF structure, coenzyme-binding affinity, apoptosis, and other aspects. Results revealed that these variants resulted in impaired dimerization, compromising AIF function. The reduction reaction of AIF variants had proceeded slower than that of AIF-WT. The average levels of AIF dimerization in AIF variant cells were only 34.5%‒49.7% of that of AIF-WT cells, resulting in caspase-independent apoptosis. The average percentage of apoptotic cells in the variants was 12.3%‒17.9%, which was significantly higher than that (6.9%‒7.4%) in controls. However, nicotinamide adenine dinucleotide (NADH) treatment promoted the reduction of apoptosis by rescuing AIF dimerization in AIF variant cells. Our findings show that the impairment of AIF dimerization by AIFM1 variants causes apoptosis contributing to ANSD, and introduce NADH as a potential drug for ANSD treatment. Our results help elucidate the mechanisms of ANSD and may lead to the provision of novel therapies.
Asunto(s)
Humanos , Factor Inductor de la Apoptosis/metabolismo , NAD/metabolismo , Dimerización , ApoptosisRESUMEN
@#Parthanatos is a form of programmed cell death,which is also known as poly(ADP-ribose)polymerase 1(PARP1)-mediated apoptosis-inducing factor(AIF)and macrophage migration inhibitory factor(MIF)-dependent cell death according to its molecular mechanism. Parthanatos is the main cause of a variety of neurodegenerative diseases,such as Parkinson's disease(PD),Alzheimer's disease(AD),motor neuron disease,and is also involved in the pathogenesis of some tumors,such as lung cancer and breast cancer. Therefore,a thorough understanding of the molecular mechanism of Parthanatos is crucial for the therapeutic strategies of related diseases. In recent years,studies have found that effective regulation of the occurrence of Parthanatos by regulating the key proteins PARP1,AIF and MIF is expected to become a therapeutic target for many diseases. Based on the specific molecular mechanism of Parthanatos,this paper reviewed the research progress of therapeutic strategies for related diseases from the aspects of inhibiting and promoting Parthanatos.
RESUMEN
Objective The study aimed to explore the relationship between AIF related pathway and the inju-ring of cultured SGNs (spiral ganglion neurons)by glutamate toxicity,and to find AIF expression and distribution changes in SGNs.Methods SGNs of 40 newborn rats within 3 day were obtained and cultured in vitro.Cultured cells were divided into four groups:the normal control group,10 mM,20 mM and 40 mM glutamate injured group, separately.After 48 h hours culturing,optical microscopy,immune fluorescence staining and real-time fluores-cence quantitative PCR were used to observe the morphology,AIF distribution,and AIF,calpain,Caspase3 expres-sion changes in SGNs in vitro.TUNEL was used to verify the cell apoptosis.ResuIts Noticeable morphological chan-ges and cell apoptosis were occurred in 20 mM glutamate group,with AIF nuclear translocation.AIF gene expression was significantly higher than normal after glutamate administration (P0.05). ConcIusion In the process of cultured SGNs injured by glutamate,AIF participated in the cell apoptosis.Noticeable cell apoptosis were occurred in 20 mM glutamate group with AIF nuclear translocation.Calpain up-expression also contributed to excitatory neurotransmitter injury on SGNs,but Caspase 3 had no obvious effects.
RESUMEN
Apoptosis-inducing factor (AIF) is a mitochondrial flavoprotein that mediates both NADH-oxidizing and caspase-independent apoptosis. Further, the proapoptotic activity of AIF is located in the C-terminus of AIF, although the precise minimum sequence responsible for apoptosis induction remains to be investigated. In the present study, we generated two truncated AIFs, AIFΔ1-480-FLAG, which is a FLAG-tagged C-terminal peptide comprising amino acids from 481 to 613, and AIF360-480 containing amino acids from 360 to 480 of AIF. We used confocal microscopy to demonstrate that both the truncated proteins are expressed and located in the cytoplasm of transfected cells. AIFΔ1-480 but not AIF360-480 induces apoptosis in transfected cells. We also found that the expression of AIFΔ1-480 could initiate the release of cytochrome c from the mitochondria. The suppression of caspase-9 via siRNA blocked the proapoptotic activity of AIFΔ1-480. Therefore, AIFΔ 1-480 is sufficient for inducing caspase-9-dependent apoptotic signaling, probably by promoting the release of cytochrome c. At last, we generated a chimeric immuno-AIFΔ 1-480 protein, which comprised an HER2 antibody, a Pseudomonas exotoxin A translocation domain and AIFΔ 1-480. Human Jurkat cells transfected with the immuno-AIFΔl-480 gene could express and secrete the chimeric protein, which selectively recognize and kill HER2-overexpressing tumor cells. Our study demonstrates the feasibility of the immuno-AIFΔl-480 gene as a novel approach to treating HER2-overexpressing cancers.