scholarly journals Hypoxia-inducible factor 1-alpha target protein up-regulation in Hypoxic cochlear neurons is associate with aged-related hearing loss in C57BL/6 mice

2012 ◽  
Vol 3 (1) ◽  
pp. 1 ◽  
Author(s):  
Emilie Donadieu ◽  
Catherine M. Riva
Keyword(s):  
Transcription Factor ◽  
Hearing Loss ◽  
Molecular Mechanisms ◽  
Caspase 3 ◽  
Target Genes ◽  
Stria Vascularis ◽  
Spiral Ganglion ◽  
Protein Accumulation ◽  
Spiral Ligament ◽  
Cochlear Neurons

Molecular mechanisms underlining hypoxia- induced aged-hearing loss were studied. 3- months C57BL/6 mice were subjected to four weeks of hypoxia (10% 02), whereas, controls were kept under normoxic condition for up to six months. Auditory function was explored by CAP and Preyer’s reflex measurements and correlated with histological analysis of the cochlea. The presence of oxidative damage, HIF-1 responsive target genes regulation involved in cell death, inflammation and neovascularization were assessed by immunofluorescence analysis. Hypoxia was associated to severe hearing loss at 4-8 and 16 KHz and degeneration of the cochlea, with significant cell loss (30%) in the spiral ganglion, the lateral wall, and the hair cells with a basal-apical alteration gradient. This was correlated with ROS formation and HIF-1a overexpression. Cochlear degeneration was due to apoptosis via activated caspase-3, P53, Bax and Bcl-2 protein differential expression in spiral ganglion, modiolus and spiral ligament. On the other hand, Hsp70, NF-kB transcription factor pathway and inflammatory mediators (caspase-1 and TNF-a) were induced in the stria vascularis. Furthermore, a phenomenon of neovascularization was observed with significant thickening of stria vascularis and increased expression of VEGF. In total, we demonstrated that the tandem-HIF-ROS is responsible for the caspase-3 and Bax–mediated apoptosis via P53 protein accumulation in the cochlear neurons, while inflammatory response mediated by Hsp70 stress protein and NF-kB transcription factor generating a neovascularization phenomenon occurred in stria vascularis.

Mechanisms of hearing loss and cell death in the cochlea of connexin mutant mice

2020 ◽  
Vol 319 (3) ◽  
pp. C569-C578
Author(s):  
Bei Chen ◽  
Hongen Xu ◽  
Yanfang Mi ◽  
Wei Jiang ◽  
Dan Guo ◽  
...  
Keyword(s):  
Oxidative Stress ◽  
Hearing Loss ◽  
Hair Cell ◽  
Stria Vascularis ◽  
Reactive Oxygen Species Generation ◽  
Cell Loss ◽  
Outer Hair Cells ◽  
Spiral Ligament ◽  
Hair Cell Loss ◽  
Auditory Brain Stem Response

Mutations in connexin 30 (Cx30) are known to cause severe congenital hearing impairment; however, the mechanism by which Cx30 mediates homeostasis of endocochlear gap junctions is unclear. We used a gene deletion mouse model to explore the mechanisms of Cx30 in preventing hearing loss. Our results suggest that despite severe loss of the auditory brain-stem response and endocochlear potential at postnatal day 18, Cx30−/− mice only show sporadic loss of the outer hair cells. This inconsistency in the time course and severity of hearing and hair cell losses in Cx30−/− mice might be explained, in part, by an increase in reactive oxygen species generation beginning at postnatal day 10. The expression of oxidative stress genes was increased in Cx30−/− mice in the stria vascularis, spiral ligament, and organ of Corti. Furthermore, Cx30 deficiency caused mitochondrial dysfunction at postnatal day 18, as assessed by decreased ATP levels and decreased expression of mitochondrial complex I proteins, especially in the stria vascularis. Proteomic analysis further identified 444 proteins that were dysregulated in Cx30−/− mice, including several that are involved in mitochondria electron transport, ATP synthesis, or ion transport. Additionally, proapoptotic proteins, including Bax, Bad, and caspase-3, were upregulated at postnatal day 18, providing a molecular basis to explain the loss of hearing that occurs before hair cell loss. Therefore, our results are consistent with an environment of oxidative stress and mitochondrial damage in the cochlea of Cx30−/− mice that is coincident with hearing loss but precedes hair cell loss.

scholarly journals Caffeine Induces Autophagy and Apoptosis in Auditory Hair Cells via the SGK1/HIF-1α Pathway

2021 ◽  
Vol 9 ◽  
Author(s):  
Xiaomin Tang ◽  
Yuxuan Sun ◽  
Chenyu Xu ◽  
Xiaotao Guo ◽  
Jiaqiang Sun ◽  
...  
Keyword(s):  
Hearing Loss ◽  
Hair Cells ◽  
Stria Vascularis ◽  
Spiral Ganglion ◽  
Organ Of Corti ◽  
Spiral Ganglion Neurons ◽  
Auditory Hair Cells ◽  
Qrt Pcr ◽  
Ganglion Neurons

Caffeine is being increasingly used in daily life, such as in drinks, cosmetics, and medicine. Caffeine is known as a mild stimulant of the central nervous system, which is also closely related to neurologic disease. However, it is unknown whether caffeine causes hearing loss, and there is great interest in determining the effect of caffeine in cochlear hair cells. First, we explored the difference in auditory brainstem response (ABR), organ of Corti, stria vascularis, and spiral ganglion neurons between the control and caffeine-treated groups of C57BL/6 mice. RNA sequencing was conducted to profile mRNA expression differences in the cochlea of control and caffeine-treated mice. A CCK-8 assay was used to evaluate the approximate concentration of caffeine. Flow cytometry, TUNEL assay, immunocytochemistry, qRT-PCR, and Western blotting were performed to detect the effects of SGK1 in HEI-OC1 cells and basilar membranes. In vivo research showed that 120 mg/ kg caffeine injection caused hearing loss by damaging the organ of Corti, stria vascularis, and spiral ganglion neurons. RNA-seq results suggested that SGK1 might play a vital role in ototoxicity. To confirm our observations in vitro, we used the HEI-OC1 cell line, a cochlear hair cell-like cell line, to investigate the role of caffeine in hearing loss. The results of flow cytometry, TUNEL assay, immunocytochemistry, qRT-PCR, and Western blotting showed that caffeine caused autophagy and apoptosis via SGK1 pathway. We verified the interaction between SGK1 and HIF-1α by co-IP. To confirm the role of SGK1 and HIF-1α, GSK650394 was used as an inhibitor of SGK1 and CoCl2 was used as an inducer of HIF-1α. Western blot analysis suggested that GSK650394 and CoCl2 relieved the caffeine-induced apoptosis and autophagy. Together, these results indicated that caffeine induces autophagy and apoptosis in auditory hair cells via the SGK1/HIF-1α pathway, suggesting that caffeine may cause hearing loss. Additionally, our findings provided new insights into ototoxic drugs, demonstrating that SGK1 and its downstream pathways may be potential therapeutic targets for hearing research at the molecular level.

scholarly journals Role of Oxidative Stress in the Senescence Pattern of Auditory Cells in Age-Related Hearing Loss

Antioxidants ◽  
2021 ◽  
Vol 10 (9) ◽  
pp. 1497
Author(s):  
Luz del Mar Rivas-Chacón ◽  
Sofía Martínez-Rodríguez ◽  
Raquel Madrid-García ◽  
Joaquín Yanes-Díaz ◽  
Juan Ignacio Riestra-Ayora ◽  
...  
Keyword(s):  
Oxidative Stress ◽  
Hearing Loss ◽  
Molecular Mechanisms ◽  
Morphological Changes ◽  
Cell Damage ◽  
Stria Vascularis ◽  
Organ Of Corti ◽  
Age Related ◽  
Age Related Hearing Loss

Age-related hearing loss (ARHL) is an increasing and gradual sensorineural hearing dysfunction. Oxidative stress is an essential factor in developing ARHL; additionally, premature senescence of auditory cells induced by oxidative stress can produce hearing loss. Hydrogen peroxide (H2O2) represents a method commonly used to generate cellular senescence in vitro. The objective of the present paper is to study H2O2-induced senescence patterns in three auditory cell lines (House Ear Institute-Organ of Corti 1, HEI-OC1; organ of Corti, OC-k3, and stria vascularis, SV-k1 cells) to elucidate the intrinsic mechanisms responsible for ARHL. The auditory cells were exposed to H2O2 at different concentrations and times. The results obtained show different responses of the hearing cells concerning cell growth, β-galactosidase activity, morphological changes, mitochondrial activation, levels of oxidative stress, and other markers of cell damage (Forkhead box O3a, FoxO3a, and 8-oxoguanine, 8-oxoG). Comparison between the responses of these auditory cells to H2O2 is a helpful method to evaluate the molecular mechanisms responsible for these auditory cells’ senescence. Furthermore, this in vitro model could help develop anti-senescent therapeutic strategies for the treatment of AHRL.

Fine Structure Histopathology of Labyrinthitis Ossificans in the Gerbil Model

2005 ◽  
Vol 114 (2) ◽  
pp. 161-166 ◽  
Author(s):  
Steven P. Tinling ◽  
Vishad Nabili ◽  
Hilary A. Brodie
Keyword(s):  
Connective Tissue ◽  
Ganglion Cells ◽  
Stria Vascularis ◽  
Spiral Ganglion ◽  
Organ Of Corti ◽  
Spiral Ligament ◽  
Otic Capsule ◽  
Dense Connective Tissue ◽  
Labyrinthitis Ossificans ◽  
End Stage

Labyrinthitis ossificans (LO) is the pathological deposition of new bone within the lumen of the cochlea and labyrinth. This process occurs most commonly as a result of infection or inflammation affecting the otic capsule. Trauma and vascular compromise can also lead to neo-ossification within the otic capsule. The mechanism that regulates this process remains unestablished. This study details the end-stage histopathology in high-resolution plastic thin sections. Twenty Mongolian gerbils were infected by intrathecal injection of Streptococcus pneumoniae type 3 followed by subcutaneous penicillin G procaine (8 days) and were painlessly sacrificed 3 months later. The cochleas were serially divided and sectioned for light and electron microscopy. Sixteen of 20 animals (27 of 40 cochleas) demonstrated LO. Cochlear damage was most extensive in the vestibule and basal turn and decreased toward the apex, which often appeared normal. The histopathologic findings consisted of 1) new bone, calcospherites, osteoid, and fibrosis without dense connective tissue or osteoblasts extending from the endosteal wall into the lumen of the vestibule and scala tympani; 2) areas of dense connective tissue and osteoid enclosed by epithelial cells conjoined with the organ of Corti, stria vascularis, spiral ligament, and vestibular (Reissner's) membrane; and 3) partial to complete loss of the organ of Corti, spiral ligament cell bodies, stria vascularis, and spiral ganglion cells. Osteoblastic activity was not demonstrated in end-stage ossification in LO in the gerbil model. Neoossification appears to occur by calcospherite deposition along collagen-like fibrils within osteoid. The destruction of the organ of Corti, spiral ganglion cells, stria vascularis, and cells of Reissner's membrane and the spiral ligament occurs even in the absence of ossification of the cochlear duct.

Detection and functional characterization of a novel MEF2A variation responsible for familial dilated cardiomyopathy

2020 ◽  
Vol 0 (0) ◽  
Author(s):  
Qi Qiao ◽  
Cui-Mei Zhao ◽  
Chen-Xi Yang ◽  
Jia-Ning Gu ◽  
Yu-Han Guo ◽  
...  
Keyword(s):  
Transcription Factor ◽  
Dilated Cardiomyopathy ◽  
Sanger Sequencing ◽  
Molecular Mechanisms ◽  
Target Genes ◽  
Functional Characterization ◽  
Luciferase Assay ◽  
Chinese Family ◽  
Sequencing Analysis ◽  
Loss Of Function

AbstractObjectivesDilated cardiomyopathy (DCM) represents the most frequent form of cardiomyopathy, leading to heart failure, cardiac arrhythmias and death. Accumulating evidence convincingly demonstrates the crucial role of genetic defects in the pathogenesis of DCM, and over 100 culprit genes have been implicated with DCM. However, DCM is of substantial genetic heterogeneity, and the genetic determinants underpinning DCM remain largely elusive.MethodsWhole-exome sequencing and bioinformatical analyses were implemented in a consanguineous Chinese family with DCM. A total of 380 clinically annotated control individuals and 166 more DCM index cases then underwent Sanger sequencing analysis for the identified genetic variation. The functional characteristics of the variant were delineated by utilizing a dual-luciferase assay system.ResultsA heterozygous variation in the MEF2A gene (encoding myocyte enhancer factor 2A, a transcription factor pivotal for embryonic cardiogenesis and postnatal cardiac adaptation), NM_001365204.1: c.718G>T; p. (Gly240*), was identified, and verified by Sanger sequencing to segregate with autosome-dominant DCM in the family with complete penetrance. The nonsense variation was neither detected in 760 control chromosomes nor found in 166 more DCM probands. Functional analyses revealed that the variant lost transactivation on the validated target genes MYH6 and FHL2, both causally linked to DCM. Furthermore, the variation nullified the synergistic activation between MEF2A and GATA4, another key transcription factor involved in DCM.ConclusionsThe findings firstly indicate that MEF2A loss-of-function variation predisposes to DCM in humans, providing novel insight into the molecular mechanisms of DCM and suggesting potential implications for genetic testing and prognostic evaluation of DCM patients.

scholarly journals Oxidative Stresses and Mitochondrial Dysfunction in Age-Related Hearing Loss

2014 ◽  
Vol 2014 ◽  
pp. 1-6 ◽  
Author(s):  
Chisato Fujimoto ◽  
Tatsuya Yamasoba
Keyword(s):  
Hearing Loss ◽  
Mitochondrial Dysfunction ◽  
Stria Vascularis ◽  
Spiral Ganglion ◽  
Organ Of Corti ◽  
The Elderly ◽  
Laboratory Animals ◽  
Age Related ◽  
Ganglion Neurons ◽  
Age Related Hearing Loss

Age-related hearing loss (ARHL), the progressive loss of hearing associated with aging, is the most common sensory disorder in the elderly population. The pathology of ARHL includes the hair cells of the organ of Corti, stria vascularis, and afferent spiral ganglion neurons as well as the central auditory pathways. Many studies have suggested that the accumulation of mitochondrial DNA damage, the production of reactive oxygen species, and decreased antioxidant function are associated with subsequent cochlear senescence in response to aging stress. Mitochondria play a crucial role in the induction of intrinsic apoptosis in cochlear cells. ARHL can be prevented in laboratory animals by certain interventions, such as caloric restriction and supplementation with antioxidants. In this review, we will focus on previous research concerning the role of the oxidative stress and mitochondrial dysfunction in the pathology of ARHL in both animal models and humans and introduce concepts that have recently emerged regarding the mechanisms of the development of ARHL.

scholarly journals Identification of key microRNAs and the underlying molecular mechanism in spinal cord ischemia-reperfusion injury in rats

PeerJ ◽  
2021 ◽  
Vol 9 ◽  
pp. e11454
Author(s):  
Fengshou Chen ◽  
Jie Han ◽  
Dan Wang
Keyword(s):  
Spinal Cord ◽  
Transcription Factor ◽  
Mirna Expression ◽  
Caspase 3 ◽  
Target Genes ◽  
Ischemia Reperfusion Injury ◽  
Ischemia Reperfusion ◽  
Spinal Cord Ischemia ◽  
Enrichment Analysis ◽  
Biological Processes

Spinal cord ischemia-reperfusion injury (SCII) is a pathological process with severe complications such as paraplegia and paralysis. Aberrant miRNA expression is involved in the development of SCII. Differences in the experimenters, filtering conditions, control selection, and sequencing platform may lead to different miRNA expression results. This study systematically analyzes the available SCII miRNA expression data to explore the key differently expressed miRNAs (DEmiRNAs) and the underlying molecular mechanism in SCII. A systematic bioinformatics analysis was performed on 23 representative rat SCII miRNA datasets from PubMed. The target genes of key DEmiRNAs were predicted on miRDB. The DAVID and TFactS databases were utilized for functional enrichment and transcription factor binding analyses. In this study, 19 key DEmiRNAs involved in SCII were identified, 9 of which were upregulated (miR-144-3p, miR-3568, miR-204, miR-30c, miR-34c-3p, miR-155-3p, miR-200b, miR-463, and miR-760-5p) and 10 downregulated (miR-28-5p, miR-21-5p, miR-702-3p, miR-291a-3p, miR-199a-3p, miR-352, miR-743b-3p, miR-125b-2-3p, miR-129-1-3p, and miR-136). KEGG enrichment analysis on the target genes of the upregulated DEmiRNAs revealed that the involved pathways were mainly the cGMP-PKG and cAMP signaling pathways. KEGG enrichment analysis on the target genes of the downregulated DEmiRNAs revealed that the involved pathways were mainly the Chemokine and MAPK signaling pathways. GO enrichment analysis indicated that the target genes of the upregulated DEmiRNAs were markedly enriched in biological processes such as brain development and the positive regulation of transcription from RNA polymerase II promoter. Target genes of the downregulated DEmiRNAs were mainly enriched in biological processes such as intracellular signal transduction and negative regulation of cell proliferation. According to the transcription factor analysis, the four transcription factors, including SP1, GLI1, GLI2, and FOXO3, had important regulatory effects on the target genes of the key DEmiRNAs. Among the upregulated DEmiRNAs, miR-3568 was especially interesting. While SCII causes severe neurological deficits of lower extremities, the anti-miRNA oligonucleotides (AMOs) of miR-3568 improve neurological function. Cleaved caspase-3 and Bax was markedly upregulated in SCII comparing to the sham group, and miR-3568 AMO reduced the upregulation. Bcl-2 expression levels showed a opposite trend as cleaved caspase-3. The expression of GATA6, GATA4, and RBPJ decreased after SCII and miR-3568 AMO attenuated this upregulation. In conclusion, 19 significant DEmiRNAs in the pathogenesis of SCII were identified, and the underlying molecular mechanisms were validated. The DEmiRNAs could serve as potential intervention targets for SCII. Moreover, inhibition of miR-3568 preserved hind limb function after SCII by reducing apoptosis, possibly through regulating GATA6, GATA4, and RBPJ in SCII.

scholarly journals Control of mitotic chromosome condensation by the fission yeast transcription factor Zas1

2018 ◽  
Vol 217 (7) ◽  
pp. 2383-2401 ◽  
Author(s):  
Christoph Schiklenk ◽  
Boryana Petrova ◽  
Marc Kschonsak ◽  
Markus Hassler ◽  
Carlo Klein ◽  
...  
Keyword(s):  
Transcription Factor ◽  
Fission Yeast ◽  
Molecular Mechanisms ◽  
Target Genes ◽  
Chromosome Condensation ◽  
Condensation Process ◽  
Transactivation Domain ◽  
Promoter Regions ◽  
Live Cell Microscopy ◽  
Mitotic Chromosome Condensation

Although the formation of rod-shaped chromosomes is vital for the correct segregation of eukaryotic genomes during cell divisions, the molecular mechanisms that control the chromosome condensation process have remained largely unknown. Here, we identify the C2H2 zinc-finger transcription factor Zas1 as a key regulator of mitotic condensation dynamics in a quantitative live-cell microscopy screen of the fission yeast Schizosaccharomyces pombe. By binding to specific DNA target sequences in their promoter regions, Zas1 controls expression of the Cnd1 subunit of the condensin protein complex and several other target genes, whose combined misregulation in zas1 mutants results in defects in chromosome condensation and segregation. Genetic and biochemical analysis reveals an evolutionarily conserved transactivation domain motif in Zas1 that is pivotal to its function in gene regulation. Our results suggest that this motif, together with the Zas1 C-terminal helical domain to which it binds, creates a cis/trans switch module for transcriptional regulation of genes that control chromosome condensation.

scholarly journals Cleidocranial dysplasia. A molecular and clinical review.

2018 ◽  
Vol 8 (1) ◽  
pp. 35-38
Author(s):  
Andrea Avendaño ◽  
Francisco Cammarata-Scalisi ◽  
Mochamad Fahlevi Rizal ◽  
Sarworini Bagio Budiardjo ◽  
Margaretha Suharsini ◽  
...  
Keyword(s):  
Transcription Factor ◽  
Molecular Mechanisms ◽  
Target Genes ◽  
Autosomal Dominant ◽  
Cleidocranial Dysplasia ◽  
Supernumerary Teeth ◽  
Phenotypic Characteristics ◽  
Autosomal Dominant Disorder ◽  
Dental Abnormalities ◽  
Related Transcription Factor

Cleidocranial dysplasia (CCD) is a rare autosomal dominant disorder characterized by skeletal and dental abnormalities primarily, short stature, aplasia or hypoplasia of clavicles, open fontanelles and supernumerary teeth. Heterozygous mutations of the runt related transcription factor 2 (RUNX2) gene have been found in approximately 60-70% of cases leaving a large number of cases with no defined genetic cause which led us to delve into molecular mechanisms underlying CCD and thus to detect potential target genes to be explored in these patients. In this review we also highlight very broadly the phenotypic characteristics of previously reported patients with CCD.

scholarly journals Heterogeneity in the transcriptional response of the human pathogen Aspergillus fumigatus to the antifungal agent caspofungin

Genetics ◽  
2021 ◽  
Author(s):  
Ana Cristina Colabardini ◽  
Fang Wang ◽  
Zhiqiang Dong ◽  
Lakhansing Pardeshi ◽  
Marina Campos Rocha ◽  
...  
Keyword(s):  
Cell Wall ◽  
Transcription Factor ◽  
Aspergillus Fumigatus ◽  
Antifungal Agent ◽  
Iron Homeostasis ◽  
Molecular Mechanisms ◽  
Target Genes ◽  
Invasive Pulmonary Aspergillosis ◽  
Transcriptional Response ◽  
Cell Wall Remodeling

Abstract Aspergillus fumigatus is the main causative agent of invasive pulmonary aspergillosis (IPA), a severe disease that affects immunosuppressed patients worldwide. The fungistatic drug caspofungin is the second line of therapy against IPA but has increasingly been used against clinical strains that are resistant to azoles, the first line antifungal therapy. In high concentrations, caspofungin induces a tolerance phenotype with partial reestablishment of fungal growth called caspofungin paradoxical effect (CPE), resulting from a change in the composition of the cell wall. An increasing number of studies has shown that different isolates of A. fumigatus exhibit phenotypic heterogeneity, including heterogeneity in their CPE response. To gain insights into the underlying molecular mechanisms of CPE response heterogeneity, we analyzed the transcriptomes of two A. fumigatus reference strains, Af293 and CEA17, exposed to low and high caspofungin concentrations. We found that there is a core transcriptional response that involves genes related to cell wall remodeling processes, mitochondrial function, transmembrane transport, and amino acid and ergosterol metabolism, and a variable response related to secondary metabolite (SM) biosynthesis and iron homeostasis. Specifically, we show here that the overexpression of a SM pathway that works as an iron chelator extinguishes the CPE in both backgrounds, whereas iron depletion is detrimental for the CPE in Af293 but not in CEA17. We next investigated the function of the transcription factor CrzA, whose deletion was previously shown to result in heterogeneity in the CPE response of the Af293 and CEA17 strains. We found that CrzA constitutively binds to and modulates the expression of several genes related to processes involved in caspofungin tolerance, and that crzA deletion differentially impacts the SM production and growth of Af293 and CEA17. As opposed to the ΔcrzACEA17 mutant, the ΔcrzA Af293 mutant fails to activate cell wall remodeling genes upon caspofungin exposure, which most likely severely affects its macrostructure and extinguishes its CPE. This work describes how heterogeneity in the response to an antifungal agent between A. fumigatus strains stems from heterogeneity in the function of a transcription factor and its downstream target genes.

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