Mutations In Mitochondrial Genes Research Articles

Mitochondrial tRNAGlu 14693A>G Mutation, an "Enhancer" to the Phenotypic Expression of Leber's Hereditary Optic Neuropathy.

Leber's hereditary optic neuropathy (LHON), a maternally inherited ocular disease, is predominantly caused by mitochondrial DNA (mtDNA) mutations. Mitochondrial tRNA variants are hypothesized to amplify the pathogenic impact of three primary mutations. However, the exact mechanisms remained unclear. In the present study, the synergistic effect of the tRNAGlu 14693A>G and ND6 14484T>C mutations in three Chinese families affected by LHON is investigated. The m.14693A>G mutation nearly abolishes the pseudouridinylation at position 55 of tRNAGlu, leading to structural abnormalities, decreased stability, aberrant mitochondrial protein synthesis, and increased autophagy. In contrast, the ND6 14484T>C mutation predominantly impairs complex I function, resulting in heightened apoptosis and virtually no induction of mitochondrial autophagy compared to control cell lines. The presence of dual mutations in the same cell lines exhibited a coexistence of both upregulated cellular stress responses to mitochondrial damage, indicating a scenario of autophagy and mutation dysregulation within these dual-mutant cell lines. The data proposes a novel hypothesis that mitochondrial tRNA gene mutations generally lead to increased mitochondrial autophagy, while mutations in genes encoding mitochondrial proteins typically induce apoptosis, shedding light on the intricate interplay between different genetic factors in the manifestation of LHON.

Cannabidiol ameliorates mitochondrial disease via PPARγ activation in preclinical models

Mutations in mitochondrial energy-producing genes lead to a heterogeneous group of untreatable disorders known as primary mitochondrial diseases (MD). Leigh syndrome (LS) is the most common pediatric MD and is characterized by progressive neuromuscular affectation and premature death. Here, we show that daily cannabidiol (CBD) administration significantly extends lifespan and ameliorates pathology in two LS mouse models, and improves cellular function in fibroblasts from LS patients. CBD delays motor decline and neurodegenerative signs, improves social deficits and breathing abnormalities, decreases thermally induced seizures, and improves neuropathology in affected brain regions. Mechanistically, we identify peroxisome proliferator-activated receptor gamma (PPARγ) as a key nuclear receptor mediating CBD’s beneficial effects, while also providing proof of dysregulated PPARγ expression and activity as a common feature in both mouse neurons and fibroblasts from LS patients. Taken together, our results provide the first evidence for CBD as a potential treatment for LS.

Microbial genotoxin-elicited host DNA mutations related to mitochondrial dysfunction, a momentous contributor for colorectal carcinogenesis.

Gut microbe dysbiosis increases repetitive inflammatory responses, leading to an increase in the incidence of colorectal cancer. Recent studies have revealed that specific microbial species directly instigate mutations in the host nucleus DNA, thereby accelerating the progression of colorectal cancer. Given the well-established role of mitochondrial dysfunction in promoting colorectal cancer, it is reasonable to postulate that gut microbes may induce mitochondrial gene mutations, thereby inducing mitochondrial dysfunction. In this review, we focus on gut microbial genotoxins and their known and potential targets in mitochondrial genes. Consequently, we propose that targeted disruption of genotoxin transport pathways may effectively reduce the rate of mitochondrial gene mutations and yield substantial benefits for the prevention of colorectal carcinogenesis.

IARS2 mutations lead to Leigh syndrome with a combined oxidative phosphorylation deficiency

BackgroundLeigh syndrome (LS) is a common mitochondrial disease caused by mutations in both mitochondrial and nuclear genes. Isoleucyl-tRNA synthetase 2 (IARS2) encodes mitochondrial isoleucine-tRNA synthetase, and variants in IARS2 have been reported to cause LS. However, the pathogenic mechanism of IARS2 variants is still unclear.MethodsTwo unrelated patients, a 4-year-old boy and a 5-year-old boy diagnosed with LS, were recruited, and detailed clinical data were collected. The DNA of the patients and their parents was isolated from the peripheral blood for the identification of pathogenic variants using next-generation sequencing and Sanger sequencing. The ClustalW program, allele frequency analysis databases (gnomAD and ExAc), and pathogenicity prediction databases (Clinvar, Mutation Taster and PolyPhen2) were used to predict the conservation and pathogenicity of the variants. The gene expression level, oxygen consumption rate (OCR), respiratory chain complex activity, cellular adenosine triphosphate (ATP) production, mitochondrial membrane potential (MMP) and mitochondrial reactive oxygen species (ROS) levels were measured in patient-derived lymphocytes and IARS2-knockdown HEK293T cells to evaluate the pathogenicity of the variants.ResultsWe reported 2 unrelated Chinese patients manifested with LS who carried biallelic IARS2 variants (c.1_390del and c.2450G > A from a 4-year-old boy, and c.2090G > A and c.2122G > A from a 5-year-old boy), of which c.1_390del and c.2090G > A were novel. Functional studies revealed that the patient-derived lymphocytes carrying c.1_390del and c.2450G > A variants exhibited impaired mitochondrial function due to severe mitochondrial complexes I and III deficiencies, which was also found in IARS2-knockdown HEK293T cells. The compensatory experiments in vitro cell models confirmed the pathogenicity of IARS2 variants since re-expression of wild-type IARS2 rather than mutant IARS2 could rescue complexes I and III deficiency, oxygen consumption, and cellular ATP content in IARS2 knockdown cells.ConclusionOur results not only expand the gene mutation spectrum of LS, but also reveal for the first time the pathogenic mechanism of IARS2 variants due to a combined deficiency of mitochondrial complexes I and III, which is helpful for the clinical diagnosis of IARS2 mutation-related diseases.

Newborn concurrent hearing and genetic screening for hearing impairment: A systematic review and meta‑analysis.

Hearing loss is the most prevalent neurosensory disorder in humans, with significant implications for language, social and cognitive development if not diagnosed and treated early. The present systematic review and meta-analysis aimed to determine the rate of hearing screening pass and genetic screening failure [universal newborn hearing screening (UNHS) pass/genetic failure] and to investigate the advantages of combining newborn hearing and genetic screening for newborn hearing impairment. The PubMed, Embase and Cochrane databases were searched from inception to September 2023 to identify studies reporting the combination of neonatal hearing screening with genetic screening. Duplicate literature, unpublished literature, studies with incomplete data, animal experiments, literature reviews and systematic studies were excluded. All the data were processed by STATA15.1 statistical software. A total of nine cross-sectional studies were included in this meta-analysis. The sample sizes ranged from 1,716 to 180,469, and there were a total of 377,688 participants. The pooled results revealed that the prevalence of passing the UNHS while failing genetic screening was 0.31% (95% CI, 0.22-0.41%). The prevalence of UNHS pass and gap junction protein beta 2 and solute carrier family 26 member 4 variant screen failure was 0.01% (95% CI, 0.00-0.02%) and 0.00% (95% CI, 0.00%), respectively, while the prevalence of mitochondrially encoded 12S RRNA variant screening failure and UNHS pass was 0.21% (95% CI, 0.18-0.26%). Combined screening has a significant advantage over pure hearing screening, especially in terms of identifying newborns with mitochondrial gene mutations that render them sensitive to certain medications. In clinical practice, decision-makers can consider practical circumstances and leverage the benefits of combined newborn hearing and genetic screening for early diagnosis, early counseling, and early intervention in patients with hearing loss.

Leber hereditary optic neuropathy: A case report of concurrent rare mitochondrial mutations and ABCA4 nuclear gene mutation

Leber hereditary optic neuropathy: A case report of concurrent rare mitochondrial mutations and ABCA4 nuclear gene mutation

Mutation spectrum of hearing loss patients in Northwest China: Identification of 20 novel variants.

Hearing loss (HL) is the most frequent sensory deficit in humans, with strong genetic heterogeneity. The genetic diagnosis of HL is very important to aid treatment decisions and to provide prognostic information and genetic counselling for the patient's family. We detected and analysed 362 Chinese non-syndromic HL patients by screening of variants in 15 hot spot mutations. Subsequently, 40 patients underwent further whole-exome sequencing (WES) to determine genetic aetiology. The candidate variants were verified using Sanger sequencing. Twenty-three carrier couples with pathogenic variants or likely pathogenic variants chose to proceed with prenatal diagnosis using Sanger sequencing. Among the 362 HL patients, 102 were assigned a molecular diagnosis with 52 different variants in 22 deafness genes. A total of 41 (11.33%) cases with the biallelic GJB2 (OMIM # 220290) gene mutations were detected, and 21 (5.80%) had biallelic SLC26A4 (OMIM # 605646) mutations. Mitochondrial gene (OMIM # 561000) mutations were detected in seven (1.93%) patients. Twenty of the variants in 15 deafness genes were novel. SOX10 (OMIM # 602229), MYO15A (OMIM # 602666) and WFS1 (OMIM # 606201) were each detected in two patients. Meanwhile, OSBPL2 (OMIM # 606731), RRM2B (OMIM # 604712), OTOG (OMIM # 604487), STRC (OMIM # 606440), PCDH15 (OMIM # 605514), LOXHD1 (OMIM # 613072), CDH23 (OMIM # 605516), TMC1 (OMIM # 606706), CHD7 (OMIM # 608892), DIAPH3 (OMIM # 614567), TBC1D24 (OMIM # 613577), TIMM8A (OMIM # 300356), PTPRQ (OMIM # 603317), SALL1 (OMIM # 602218), and GSDME (OMIM # 608798) were each detected in one patient. In addition, as regards one couple with a heterozygous variant of CDH23 and PCDH15, respectively, prenatal diagnosis results suggest that the foetus had double heterozygous (DH) variants of CDH23 and PCDH15, which has a high risk to cause ID/F type Usher syndrome. Our study expanded the spectrum of deafness gene variation, which will contribute to the genetic diagnosis, prenatal diagnosis and the procreation guidance of deaf couple. In addition, the deafness caused by two genes should be paid attention to in the prenatal diagnosis of families with both deaf patients.

Transport activity regulates mitochondrial bioenergetics and biogenesis in renal tubules.

Renal tubules are featured with copious mitochondria and robust transport activity. Mutations in mitochondrial genes cause congenital renal tubulopathies, and changes in transport activity affect mitochondrial morphology, suggesting mitochondrial function and transport activity are tightly coupled. Current methods of using bulk kidney tissues or cultured cells to study mitochondrial bioenergetics are limited. Here, we optimized an extracellular flux analysis (EFA) to study mitochondrial respiration and energy metabolism using microdissected mouse renal tubule segments. EFA detects mitochondrial respiration and glycolysis by measuring oxygen consumption and extracellular acidification rates, respectively. We show that both measurements positively correlate with sample sizes of a few centimeter-length renal tubules. The thick ascending limbs (TALs) and distal convoluted tubules (DCTs) critically utilize glucose/pyruvate as energy substrates, whereas proximal tubules (PTs) are significantly much less so. Acute inhibition of TALs' transport activity by ouabain treatment reduces basal and ATP-linked mitochondrial respiration. Chronic inhibition of transport activity by 2-week furosemide treatment or deletion of with-no-lysine kinase 4 (Wnk4) decreases maximal mitochondrial capacity. In addition, chronic inhibition downregulates mitochondrial DNA mass and mitochondrial length/density in TALs and DCTs. Conversely, gain-of-function Wnk4 mutation increases maximal mitochondrial capacity and mitochondrial length/density without increasing mitochondrial DNA mass. In conclusion, EFA is a sensitive and reliable method to investigate mitochondrial functions in isolated renal tubules. Transport activity tightly regulates mitochondrial bioenergetics and biogenesis to meet the energy demand in renal tubules. The system allows future investigation into whether and how mitochondria contribute to tubular remodeling adapted to changes in transport activity.

Galactose-replacement unmasks the biochemical consequences of the G11778A mitochondrial DNA mutation of LHON in patient-derived fibroblasts

Leber's hereditary optic neuropathy (LHON) is a visual impairment associated with mutations of mitochondrial genes encoding elements of the electron transport chain. While much is known about the genetics of LHON, the cellular pathophysiology leading to retinal ganglion cell degeneration and subsequent vision loss is poorly understood. The impacts of the G11778A mutation of LHON on bioenergetics, redox balance and cell proliferation were examined in patient-derived fibroblasts. Replacement of glucose with galactose in the culture media reveals a deficit in the proliferation of G11778A fibroblasts, imparts a reduction in ATP biosynthesis, and a reduction in capacity to accommodate exogenous oxidative stress. While steady-state ROS levels were unaffected by the LHON mutation, cell survival was diminished in response to exogenous H2O2.

Understand the connection between oxidative stress levels and mitochondrial gene mutations in Parkinson’s disease patients

Understand the connection between oxidative stress levels and mitochondrial gene mutations in Parkinson’s disease patients

Cochlear implantation in patients with Charcot-Marie-Tooth disease: two cases with a review of the literature.

To report two cases of bilateral cochlear implantation (CI) in Charcot-Marie-Tooth disease (CMT) patients with novel mutations. Furthermore, we conducted a detailed literature review on the profile and outcomes of CI in this uncommon clinical circumstance. Case 1 involved a 25-year-old woman who was referred for sudden hearing loss (HL) in her left ear and had a 7-year history of HL in her right ear. She was diagnosed with CMT type 1 with a thymidine phosphorylase gene mutation. CI was performed on her left side because her hearing gradually worsened to deafness in both ears. At 3months post-operation, her speech discrimination score without lip-reading improved from 0 to 100%. She underwent a second CI on her right ear 6months after her first CI. Two years from her first operation, the speech discrimination score was 100%. Case 2 received her first CI on her right ear at the age of nine for her bilateral HL. She was diagnosed with CMT type 2 with a Twinkle mitochondrial DNA helicase gene mutation. Preoperatively, the speech discrimination score in both ear-aided conditions was 70%. At the 7-year post-operation follow-up, the speech discrimination score was 76%. A second CI was performed due to decreasing hearing ability in her left ear. The speech discrimination score showed 100% at 7months after the second CI. CI is an effective hearing rehabilitation option for CMT patients with severe-to-profound SNHL. Neuro-otologists should consider CI as a treatment option, even though hearing loss in CMT is associated with auditory neuropathy spectrum disease (ANSD).

A Two-Genome Portrayal of Mitochondrial Disorders: A Review with Clinical Presentations.

Disorders of mitochondrial function are responsible for many inherited neuromuscular and metabolic diseases. Their combination of high mortality, multi-systemic involvement, and economic burden cause devastating effects on patients and their families. Molecular diagnostic tools are becoming increasingly important in providing earlier diagnoses and guiding more precise therapeutic treatments for patients suffering from mitochondrial disorders. This review addresses fundamental molecular concepts relating to the pathogenesis of mitochondrial dysfunction and disorders. A series of short cases highlights the various clinical presentations, inheritance patterns, and pathogenic mutations in nuclear and mitochondrial genes that cause mitochondrial diseases. Graphical and tabular representations of the results are presented to guide the understanding of the important concepts related to mitochondrial molecular genetics and pathology. Emerging technology is incorporating preimplantation genetic testing for mtDNA disorders, while mitochondrial replacement shows promise in significantly decreasing the transfer of diseased mitochondrial DNA (mtDNA) to embryos. Medical professionals must maintain an in-depth understanding of the gene mutations and molecular mechanisms underlying mitochondrial disorders. Continued diagnostic advances and comprehensive management of patients with mitochondrial disorders are essential to achieve robust clinical impacts from comprehensive genomic testing. This is especially true when supported by non-genetic tests such as biochemical analysis, histochemical stains, and imaging studies. Such a multi-pronged investigation should improve the management of mitochondrial disorders by providing accurate and timely diagnoses to reduce disease burden and improve the lives of patients and their families.

The Optic Nerve at Stake: Update on Environmental Factors Modulating Expression of Leber's Hereditary Optic Neuropathy.

Optic neuropathies are characterized by the degeneration of the optic nerves and represent a considerable individual and societal burden. Notably, Leber's hereditary optic neuropathy (LHON) is a devastating vision disease caused by mitochondrial gene mutations that hinder oxidative phosphorylation and increase oxidative stress, leading to the loss of retinal ganglion neurons and axons. Loss of vision is rapid and severe, predominantly in young adults. Penetrance is incomplete, and the time of onset is unpredictable. Recent findings revealed that the incidence of genetic LHON susceptibility is around 1 in 1000, much higher than believed till now. Environmental factors are critical in LHON triggering or severity. Families at risk have a very strong demand for how to prevent the onset or limit the severity of the disease. Here, we review recent knowledge of the extrinsic determinants of LHON expression, including lifestyle, dietary supplements, common chemicals, and drugs.

Mitochondrial DNA mutations in extremely preterm infants with bronchopulmonary dysplasia

AbstractBronchopulmonary dysplasia (BPD) is a serious chronic lung disease affecting extremely preterm infants. While mitochondrial dysfunction has been investigated in various medical conditions, limited research has explored mitochondrial DNA (mtDNA) gene mutations, specifically in BPD. This study aimed to evaluate mitochondrial mtDNA gene mutations in extremely preterm infants with BPD. In this prospective observational study, we enrolled a cohort of extremely preterm infants diagnosed with BPD. Clinical data were collected to provide comprehensive patient profiles. Peripheral blood mononuclear cells were isolated from whole-blood samples obtained within a defined timeframe. Subsequently, mtDNA extraction and sequencing using next-generation sequencing technology were performed to identify mtDNA gene mutations. Among the cohort of ten extremely preterm infants with BPD, mtDNA sequencing revealed the presence of mutations in seven patients, resulting in a total of twenty-one point mutations. Notably, many of these mutations were identified in loci associated with critical components of the respiratory chain complexes, vital for proper mitochondrial function and cellular energy production. This pilot study provides evidence of mtDNA point mutations in a subset of extremely preterm infants with BPD. These findings suggest a potential association between mitochondrial dysfunction and the pathogenesis of BPD. Further extensive investigations are warranted to unravel the mechanisms underlying mtDNA mutations in BPD.

One-pot, degradable, silica nanocarriers with encapsulated oligonucleotides for mitochondrial specific targeting

Mutations in nuclear and mitochondrial genes are responsible for severe chronic disorders such as mitochondrial myopathies. Gene therapy using antisense oligonucleotides is a promising strategy to treat mitochondrial DNA (mtDNA) diseases by blocking the replication of the mutated mtDNA. However, transport vehicles are needed for intracellular, mitochondria-specific transport of oligonucleotides. Nanoparticle (NP) based vectors such as large pore mesoporous silica nanoparticles (LP) often rely on surface complexation of oligonucleotides exposing them to nucleases and limiting mitochondria targeting and controlled release ability. In this work, stable, fluorescent, hollow silica nanoparticles (HSN) that encapsulate and protect oligonucleotides in the hollow core were synthesized by a facile one-pot procedure. Both rhodamine B isothiocyanate and bis[3-(triethoxysilyl)propyl]tetrasulfide were incorporated in the HSN matrix by co-condensation to enable cell tracing, intracellular-specific degradation and controlled oligonucleotide release. We also synthesized LP as a benchmark to compare the oligonucleotide loading and release efficacy of our HSN. Mitochondria targeting was enabled by NP functionalization with cationic, lipophilic Triphenylphosphine (TPP) and, for the first time a fusogenic liposome based carrier, previously reported under the name MITO-Porter. HSN exhibited high oligonucleotide incorporation ratios and release dependent on intracellular degradation. Further, MITO-Porter capping of our NP enabled delayed, glutathione (GSH) responsive oligonucleotide release and mitochondria targeting at the same efficiency as TPP functionalized NP. Overall, our NP are promising vectors for anti-gene therapy of mtDNA disease as well as many other monogenic disorders worldwide.Graphical

STAT3 protects dopaminergic neurons against degeneration in animal model of Parkinson's disease

IntroductionParkinson's disease (PD) is the most prevalent disorder of the basal ganglia, propagated by the degeneration of axon terminals within the striatum and subsequent loss of dopaminergic neurons in the substantia nigra (SN). Exposure of environmental neurotoxins and mutations of several mitochondrial and proteasomal genes are primarily responsible. MethodsTo determine whether signal transducer and activator of transcription 3 (STAT3) could protect dopaminergic neurons against degeneration, we first screened it in the in vitro capacity using immortalized rat dopaminergic N27 cells under 6-OHDA neurotoxicity. We then evaluated the effectiveness of constitutively active (ca) STAT3 as a neuroprotective agent on N27 cells in a 6-hydroxydopamine (6-OHDA) induced rat model of PD and compared it to control animals or animals where AAV/caRheb was expressed in SN. Behavioral outcomes were assessed using rotational and cylinder assays and mitochondrial function using reactive oxygen species (ROS) levels. ResultsUsing flow cytometry, the in vitro analysis determined caSTAT3 significantly decreased dopaminergic neuronal death under 6-OHDA treatment conditions. Importantly, in vivo overexpression of caSTAT3 in SN dopaminergic neurons using AAV-mediated expression demonstrated significant neuroprotection of dopaminergic neurons following 6-OHDA. Both caSTAT3 and caRheb + caSTAT3 co-injection into substantia nigra reduced D-amphetamine-induced rotational behavior and increased ipsilateral forelimb function when compared to control animals. In addition, caSTAT3 decreased mitochondrial ROS production following 6-OHDA induced neurotoxicity. ConclusioncaSTAT3 confers resistance against ROS production in mitochondria of susceptible SN dopaminergic neurons potentially offering a new avenue for treatment against PD.

Abstract 18721: Increased Predisposition to Hypertrophic Cardiomyopathy in Mitochondria Gene CYP2E1 Rare Variant Carriers

Introduction: With a prevalence of up to 1 in 200, hypertrophic cardiomyopathy (HCM) is the most common monogenic hereditary cardiovascular disease. Previous studies have observed that mitochondrial dysfunction and mitochondria-associated metabolic remodeling are major metabolic features in HCM. However, the impact of mitochondrial gene mutations on HCM were poorly understood. Methods and Results: We selected 2272 mitochondrial genes from the Mitocarta database 3.0 and screened rare variants from the whole-exome sequencing data in 985 HCM patients (excluding patients with HCM phenotypes, including mitochondrial myopathy) and 759 non-HCM controls. We found that CYP2E1 rare variants were significantly enriched in HCM patients (OR = 9.56, Bonferroni corrected P = 0.001). Patients with or without CYP2E1 rare variants shared similar demographic and echocardiographic variables at baseline. With a median follow-up time of 5.31 years in 735 HCM patients, we revealed that HCM patients with CYP2E1 rare variants were more likely to experience myocardial infarction (HR 14.1, P < 0.001). Conclusion: We demonstrated that rare variants in the mitochondrial gene CYP2E1 might increase the risk of HCM onset and may be associated with the occurrence of myocardial infarction endpoints in HCM. We hypothesize that the mechanism is related to the extensive and complex mitochondrial metabolic processes in which CYP2E1 is involved. Our findings provided new evidence for the association between mitochondrial gene variants and HCM, and more multi-center evidence is needed to confirm this association in the future.

Successful transcatheter mitral valve repair for functional mitral regurgitation in a patient with mitochondrial cardiomyopathy: a case report

Abstract Background Mitochondrial diseases are a group of genetic disorders caused by nuclear or mitochondrial DNA gene mutations and characterized by multiorgan disorders, including cardiomyopathy. Mitochondrial cardiomyopathy is occasionally complicated by hypertrophic cardiomyopathy with/without left ventricular systolic dysfunction, dilated cardiomyopathy, and left ventricular non-compaction. In such cases, the dilated left ventricle impairs coaptation of the mitral leaflets and leads to functional mitral regurgitation. To date, valvular interventions in patients with mitochondrial cardiopathy have not been investigated. Case summary A 64-year-old woman with mitochondrial cardiopathy was referred to our hospital owing to dyspnoea. She experienced her first admission with heart failure at age 60 years. At 62 years old, she was diagnosed with maternally inherited diabetes and deafness with mitochondrial cardiomyopathy based on mitochondrial DNA sequencing. Despite administration of guideline-directed medical therapy and high-dose taurine supplementation, she was repeatedly hospitalized for heart failure. At admission, transthoracic echocardiography revealed severe functional mitral regurgitation due to left ventricular dilatation. Surgical risk was considered high (Society of Thoracic Surgeons score of 12.6%); therefore, transcatheter edge-to-edge repair with the MitraClip system was performed. Two devices deployed at the middle segment of the anterior and posterior leaflet successfully reduced mitral regurgitation. The patient was free from cardiovascular events during the 2-year follow-up period. Discussion Transcatheter edge-to-edge repair is a less invasive and effective treatment for severe drug-refractory mitral regurgitation in patients with mitochondrial disease. Given the limited therapeutic options for mitochondrial cardiopathy, further studies are required to uncover the mechanism underlying mitochondrial diseases and establish disease-specific treatments.

Pharmacological Effects of Astragaloside IV: A Review.

Astragaloside IV (AS-IV) is one of the main active components extracted from the Chinese medicinal herb Astragali and serves as a marker for assessing the herb's quality. AS-IV is a tetracyclic triterpenoid saponin in the form of lanolin ester alcohol and exhibits various biological activities. This review article summarizes the chemical structure of AS-IV, its pharmacological effects, mechanism of action, applications, future prospects, potential weaknesses, and other unexplored biological activities, aiming at an overall analysis. Papers were retrieved from online electronic databases, such as PubMed, Web of Science, and CNKI, and data from studies conducted over the last 10 years on the pharmacological effects of AS-IV as well as its impact were collated. This review focuses on the pharmacological action of AS-IV, such as its anti-inflammatory effect, including suppressing inflammatory factors, increasing T and B lymphocyte proliferation, and inhibiting neutrophil adhesion-associated molecules; antioxidative stress, including scavenging reactive oxygen species, cellular scorching, and regulating mitochondrial gene mutations; neuroprotective effects, antifibrotic effects, and antitumor effects.

Maternally inherited non-syndromic hearing loss is linked with a novel mitochondrial ND6 gene mutation.

Maternally inherited non-syndromic hearing loss is linked with mitochondrial DNA mutations. This investigation demonstrates the features of a Chinese pedigree suffering from maternally inherited non-syndromic hearing loss. Biochemical characterizations included the measurements ofprotein synthesis levels, membrane potential, and the synthesis of reactive oxygen species (ROS) and adenosine triphosphate (ATP) using cybrid cell lines derived from an affected matrilineal subject and control subject. Non-congenital early or late-onset/development hearing impairment has been observed in 4 of 9 in a family (matrilineal), with different degrees of hearing impairment, ranging from normal to severe. A pedigree's whole mitochondrial genome sequence analysis revealed the homoplasmic m.14502T > C (I58V) mutation at ND6's isoleucine location-58, and specific mitocchondrial DNA polymorphisms set haplogroups M10 were highly conserved. In vitro models indicated that m.14502T > C mutation-derived respiratory deficiency decreases ND6 protein synthesis, mitochondrial membrane potential, and ATP synthesis. These mitochondrial dysregulations enhance the generation of ROS in the mutant cells. Identifying nuclear modifiers is essential for elucidating hearing loss's pathogenesis and furnishing novel therapeutic interventions. The m.14502T > C mutation should be considered an inherited risk factor that can help diagnose. The data of this investigation help counsel families of individuals with hearing loss.