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.
Humans ; Apoptosis Inducing Factor/metabolism* ; NAD/metabolism* ; Dimerization ; Apoptosis

Hypoxia is frequently observed in solid tumors and also one of the major obstacles for effective cancer therapies. Cancer cells take advantage of their ability to adapt hypoxia to initiate a special transcriptional program that renders them more aggressive biological behaviors. Hypoxia-inducible factors (HIFs) are the key factors that control hypoxia-inducible pathways by regulating the expression of a vast array of genes involved in cancer progression and treatment resistance. HIFs, mainly HIF-1 and -2, have become potential targets for developing novel cancer therapeutics. This article reviews the updated information in tumor HIF pathways, particularly recent advances in the development of HIF inhibitors. These inhibitors interfere with mRNA expression, protein synthesis, protein degradation and dimerization, DNA binding and transcriptional activity of HIF-1 and -2, or both. Despite efforts in the past two decades, no agents directly inhibiting HIFs have been approved for treating cancer patients. By analyzing results of the published reports, we put the perspectives at the end of the article. The therapeutic efficacy of HIF inhibitors may be improved if more efforts are devoted on developing agents that are able to simultaneously target HIF-1 and -2, increasing the penetrating capacity of HIF inhibitors, and selecting suitable patient subpopulations for clinical trials.
Anoxia ; Dimerization ; DNA ; Humans ; Hypoxia-Inducible Factor 1* ; Proteolysis ; RNA, Messenger

Base Pairing ; Dimerization ; Genome, Viral ; RNA, Viral ; chemistry ; genetics ; Retroviridae ; chemistry ; genetics

Nascent polypeptide associated complex (NAC) and its two isolated subunits, αNAC and βNAC, play important roles in nascent peptide targeting. We determined a 1.9 Å resolution crystal structure of the interaction core of NAC heterodimer and a 2.4 Å resolution crystal structure of αNAC NAC domain homodimer. These structures provide detailed information of NAC heterodimerization and αNAC homodimerization. We found that the NAC domains of αNAC and βNAC share very similar folding despite of their relative low identity of amino acid sequences. Furthermore, different electric charge distributions of the two subunits at the NAC interface provide an explanation to the observation that the heterodimer of NAC complex is more stable than the single subunit homodimer. In addition, we successfully built a βNAC NAC domain homodimer model based on homologous modeling, suggesting that NAC domain dimerization is a general property of the NAC family. These 3D structures allow further studies on structure-function relationship of NAC.
Amino Acid Sequence ; Dimerization ; Humans ; Molecular Chaperones ; chemistry ; Peptides ; metabolism ; Protein Multimerization

Allelic differences in A and B mating-type loci are a prerequisite for the progression of mating in the genus Pleurotus eryngii; thus, the crossing is hampered by this biological barrier in inbreeding. Molecular markers linked to mating types of P. eryngii KNR2312 were investigated with randomly amplified polymorphic DNA to enhance crossing efficiency. An A4-linked sequence was identified and used to find the adjacent genomic region with the entire motif of the A locus from a contig sequenced by PacBio. The sequence-characterized amplified region marker 7-2299 distinguished A4 mating-type monokaryons from KNR2312 and other strains. A BLAST search of flanked sequences revealed that the A4 locus had a general feature consisting of the putative HD1 and HD2 genes. Both putative HD transcription factors contain a homeodomain sequence and a nuclear localization sequence; however, valid dimerization motifs were found only in the HD1 protein. The ACAAT motif, which was reported to have relevance to sex determination, was found in the intergenic region. The SCAR marker could be applicable in the classification of mating types in the P. eryngii breeding program, and the A4 locus could be the basis for a multi-allele detection marker.
Breeding ; Cicatrix ; Classification ; Dimerization ; DNA ; DNA, Intergenic ; Inbreeding ; Pleurotus ; Transcription Factors

To study the chemical constituents from Zanthoxylum simulans and their anti-inflammatory activity. The constituents of Z. simulans were isolated and purified using various column chromatographies. Their chemical structures were elucidated using extensive spectroscopic methods. The compounds were assayed inhibitory activity against NO production in LPS stimulated RAW 264.7 cells. Four compounds were obtained from the ethanol extract of Z. simulans and determined to be isozanthpodocarpin B(1), kobusin (2), (+)-fargesin (3), and epieudesmin (4). Compound 1 exhibited NO production inhibitory effect with IC50 value of 14.49 µmol · L(-1). Compound 1 is a new dimeric lignan and may be serve as potential anti-inflammatory agent in the future.
Animals ; Anti-Inflammatory Agents ; pharmacology ; Cells, Cultured ; Dimerization ; Lignans ; chemistry ; isolation & purification ; pharmacology ; Mice ; Nitric Oxide ; antagonists & inhibitors ; Zanthoxylum ; chemistry

As a part of our search for bioactive material, the chemical investigation of the stems of Kadsura heteroclita led up to the isolation of a new lignan, heteroclitin R. The structure was elucidated on the basis of nuclear magnetic resonance spectroscopic data. Heteroclitin R was a new compound as a lignan dimer obtained from Schisandraceae family for the first time.
Dimerization ; Kadsura ; chemistry ; Lignans ; chemistry ; isolation & purification ; Molecular Structure ; Plant Extracts ; chemistry ; isolation & purification ; Plant Stems ; chemistry

Translationally controlled tumor protein (TCTP) is also known as histamine releasing factor as it has the ability to activate mast cells. To investigate the role of TCTP in the pathogenesis of chronic spontaneous urticaria (CSU), we evaluated serum level of TCTP and effect of TCTP on basophil and mast cell degranulation. TCTP levels in the sera from 116 CSU patients and 70 normal healthy controls (NCs) were measured by ELISA. CD203c expression on basophils from CSU patients and β-hexosaminidase release from Laboratory of Allergic Disease 2 mast cells were measured upon stimulation monomeric and dimeric TCTP. Non-reducing Western blot analysis was used for detecting dimeric TCTP. No difference was observed in serum TCTP levels between CSU patients and NCs (p=0.676). However, dimeric TCTP intensity on Western blot was stronger in CSU patients than in NCs. TCTP levels were higher in patients with severe CSU (p=0.049) and with IgG positivity to FcɛRIα (p=0.038). A significant positive correlation was observed between TCTP and eosinophil cationic protein levels (Spearman's rho=0.341; p=0.001). Both basophil and mast cell degranulation were significantly increased after stimulation with dimeric TCTP, but not with monomic TCTP. The ability of TCTP to activate basophil and mast cells is dependent on dimerization, suggesting that the inhibition of TCTP dimerization can be a therapeutic option for CSU. Association between TCTP levels and the presence of IgG to high affinity Fc epsilon receptor I alpha subunit in CSU patients indicates that autoimmune mechanisms may be involved in the dimerization of TCTP.
Basophils ; Blotting, Western ; Dimerization ; Enzyme-Linked Immunosorbent Assay ; Eosinophil Cationic Protein ; Histamine ; Humans ; Immunoglobulin G ; Mast Cells ; Urticaria

OBJECTIVES: Bok, Bcl-2-related ovarian killer, is a proapoptotic Bcl-2 family protein identified in the ovary based on its dimerization with the antiapoptotic protein Mcl-1. The present study examined the hormonal regulation and localization of Bok messenger RNA levels in the mouse ovary during the follicle development. METHODS: The animals were implanted subcutaneously with Silastic brand capsules containing the synthetic estrogen, DES at 21~23 days of age. Ovaries were collected 1~3 days after implantation for RNA analysis and in situ hybridization. Some mice were removed capsule for 1~2 days to induce ovarian follicle apoptosis. Ovaries were also collected from 26 day-old immature mice at various times after treatment with 10 iU PMSG. Some mice received a single intraperitoneal injection of 10 iU hCG to induce ovulation, and ovaries were obtained at different time intervals for Northern blot and in situ hybridization analysis, respectively. RESULTS: Treatment of immature mice with diethylstilbestrol (DES) for 24~48 h increased ovarian Bok mRNA levels. Bok mRNA was remained the same levels in mice removed DES for 24~48 h to induce apoptosis. High signals of Bok mRNA after DES treatment were detected in granulosa cells of early antral follicles. Treatment of immature mice with PMSG for 12 h increased markedly ovarian Bok mRNA expression which was detected mainly in preantral and atretic follicles. interestingly, low levels of Bok mRNA were also expressed in granulosa cells of preovulatory follicles. Treatment of PMSGprimed mice with hCG stimulated strongly ovarian Bok mRNA expression at 6~9 h. At that time, Bok mRNA was expressed in granulosa cells of atretic and small growing follicles. CONCLUSION: These results demonstrate that Bok is one of proapoptotic Bcl-2 members expressed in early growing and atretic follicles during the ovarian follicular development. Gonadotropins induce a transient increase of Bok gene expression in granulosa cells of preantral and preovulatory follicles indicating some role in the ovulatory process.
Animals ; Apoptosis ; Blotting, Northern ; Capsules ; Diethylstilbestrol ; Dimerization ; Estrogens ; Female ; Gene Expression ; Gonadotropins ; Granulosa Cells ; Humans ; In Situ Hybridization ; Injections, Intraperitoneal ; Mice* ; Ovarian Follicle ; Ovary* ; Ovulation ; RNA ; RNA, Messenger

OBJECTIVE: Bok, Bcl-2-related ovarian killer, is a proapoptotic Bcl-2 family protein identified in the ovary based on its dimerization with the antiapoptotic protein Mcl-1. The present study examined the hormonal regulation and localization of Bok messenger RNA levels in the rat ovary during the follicle development. METHODS: We used the female rats of SD strain. Bok mRNA levels in the ovary were determined by Northern blot analysis. In situ hybridization were performed to determine the specific ovarian cell type expressing Bok mRNA. RESULTS: Northern blot analysis of ovaries obtained from immature rats revealed increasing levels of Bok mRNA during postnatal development. The major cell types expressing Bok mRNA were the granulosa cells of preantral and atretic follicles. Treatment of immature rats with diethylstilbestrol (DES) for 24-48 h increased ovarian Bok mRNA levels. Bok mRNA was remained the same levels in rats removed DES for 24- 48 h to induce apoptosis. High signals of Bok mRNA after DES treatment were detected in granulosa cells of early antral follicles. Treatment of immature rats with pregnant mare's serum gonadotropin (PMSG) for 12 h increased markedly ovarian Bok mRNA expression which was detected mainly in preantral and atretic follicles. Interestingly, low levels of Bok mRNA were also expressed in granulosa cells of preovulatory follicles. Treatment of PMSG-primed rats with human chorionic gonadotropin (hCG) stimulated strongly ovarian Bok mRNA expression at 6-9 h. At that time, Bok mRNA was expressed in granulosa cells of atretic and small growing follicles. In adult estrus cyclic ovaries, Bok gene expression was higher on proestrus and estrus than metaestrus and diestrus. Moreover, the highly increased expression of Bok mRNA was found in rat ovaries at 48 h after hypophysectomy. CONCLUSION: These results demonstrate that Bok is one of proapoptotic Bcl-2 members expressed in early growing and atretic follicles during the ovarian follicular development. Gonadotropins induce a transient increase of Bok gene expression in granulosa cells of preantral and preovulatory follicles indicating some role in the ovulatory process.
Adult ; Animals ; Apoptosis* ; Blotting, Northern ; Chorionic Gonadotropin ; Diestrus ; Diethylstilbestrol ; Dimerization ; Estrus ; Female ; Gene Expression ; Gonadotropins ; Granulosa Cells ; Humans ; Hypophysectomy ; In Situ Hybridization ; Ovarian Follicle ; Ovary* ; Proestrus ; Rats* ; RNA, Messenger