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ACS Nano Jun 2024This study investigates transfer ribonucleic acid (tRNA) conformational dynamics in the context of MELAS (mitochondrial encephalomyopathy, lactic acidosis, and...
This study investigates transfer ribonucleic acid (tRNA) conformational dynamics in the context of MELAS (mitochondrial encephalomyopathy, lactic acidosis, and stroke-like episodes) using solid-state silicon nitride (SiN) nanopore technology. SiN nanopores in thin membranes with specific dimensions exhibit high signal resolution, enabling real-time and single-molecule electronic detection of tRNA conformational changes. We focus on human mitochondrial tRNALeu(UAA) (mt-Leu(UAA)) that decodes Leu codons UUA/UUG (UUR) during protein synthesis on the mt-ribosome. The single A14G substitution in mt-Leu(UAA) is the major cause of MELAS disease. Measurements of current blockades and dwell times reveal distinct conformational dynamics of the wild-type (WT) and the A14G variant of mt-Leu(UAA) in response to the conserved post-transcriptional mG9 methylation. While the mG9-modified WT transcript adopts a more stable structure relative to the unmodified transcript, the mG9-modified MELAS transcript adopts a less stable structure relative to the unmodified transcript. Notably, these differential features were observed at 0.4 M KCl, but not at 3 M KCl, highlighting the importance of experimental settings that are closer to physiological conditions. This work demonstrates the feasibility of the nanopore platform to discern tRNA molecules that differ by a single-nucleotide substitution or by a single methylation event, providing an important step forward to explore changes in the conformational dynamics of other RNA molecules in human diseases.
PubMed: 38906834
DOI: 10.1021/acsnano.4c04625 -
Frontiers in Genetics 2024Patients with mitochondrial encephalomyopathy, lactic acidosis, and stroke-like episodes (MELAS) usually present with multisystemic dysfunction with a wide range of...
BACKGROUND
Patients with mitochondrial encephalomyopathy, lactic acidosis, and stroke-like episodes (MELAS) usually present with multisystemic dysfunction with a wide range of clinical manifestations. When the tests for common mitochondrial DNA (mtDNA) point mutations are negative and the mtDNA defects hypothesis remains, urine epithelial cells can be used to screen the mitochondrial genome for unknown mutations to confirm the diagnosis.
CASE PRESENTATION
A 66-year-old Chinese woman presented with symptoms of MELAS and was initially misdiagnosed with acute encephalitis at another institution. Although genetic analysis of blood lymphocyte DNA was negative, brain imaging, including magnetic resonance imaging, magnetic resonance spectroscopy, and clinical and laboratory findings, were all suggestive of MELAS. Finally, the patient was eventually diagnosed with MELAS with the mtDNA 5783G>A mutation in the MT-TC gene with a urinary sediment genetic test.
CONCLUSION
This case report expands the genetic repertoire associated with MELAS syndrome and highlights the importance that full mtDNA sequencing should be warranted beside the analysis of classical variants when a mitochondrial disorder is highly suspected. Furthermore, urine sediment genetic testing has played a crucial role in the diagnosis of MELAS.
PubMed: 38881794
DOI: 10.3389/fgene.2024.1367716 -
FASEB Journal : Official Publication of... Jun 2024Mitochondrial disease is a devastating genetic disorder, with mitochondrial myopathy, encephalopathy, lactic acidosis, and stroke-like episodes (MELAS) and m.3243A>G...
Mitochondrial disease is a devastating genetic disorder, with mitochondrial myopathy, encephalopathy, lactic acidosis, and stroke-like episodes (MELAS) and m.3243A>G being the most common phenotype and genotype, respectively. The treatment for MELAS patients is still less effective. Here, we performed transcriptomic and proteomic analysis in muscle tissue of MELAS patients, and discovered that the expression of molecules involved in serine catabolism were significantly upregulated, and serine hydroxymethyltransferase 2 (SHMT2) increased significantly in both the mRNA and protein levels. The SHMT2 protein level was also increased in myoblasts with m.3243A>G mutation, which was transdifferentiated from patients derived fibroblasts, accompanying with the decreased nicotinamide adenine dinucleotide (NAD)/reduced NAD (NADH) ratio and cell viability. After treating with SHMT2 inhibitor (SHIN1), the NAD/NADH ratio and cell viability in MELAS myoblasts increased significantly. Taken together, our study indicates that enhanced serine catabolism plays an important role in the pathogenesis of MELAS and that SHIN1 can be a potential small molecule for the treatment of this disease.
Topics: Humans; MELAS Syndrome; Glycine Hydroxymethyltransferase; Serine; Myoblasts; NAD; Male; Proteomics; Female; Transcriptome; Multiomics
PubMed: 38865203
DOI: 10.1096/fj.202302286RRR -
American Journal of Ophthalmology Case... Jun 2024To describe examination and findings in a case of mitochondrial encephalomyopathy, lactic acidosis, and stroke-like episodes (MELAS) with particular focus on the ocular...
PURPOSE
To describe examination and findings in a case of mitochondrial encephalomyopathy, lactic acidosis, and stroke-like episodes (MELAS) with particular focus on the ocular sequelae from diabetes.
OBSERVATIONS
Neovascular glaucoma is not a common manifestation of MELAS.
CONCLUSIONS AND IMPORTANCE
We present a rare case of neovascular glaucoma in a patient with MELAS with a history of diabetes, hearing loss, and macular dystrophy. MELAS should be suspected in patients with this constellation of symptoms.
PubMed: 38707951
DOI: 10.1016/j.ajoc.2024.102064 -
Cureus Mar 2024This case report presents a description of a hypertrophic left ventricle with reduced ejection fraction in a man in his mid-twenties with clinical, radiologic, and...
This case report presents a description of a hypertrophic left ventricle with reduced ejection fraction in a man in his mid-twenties with clinical, radiologic, and biochemical features of a rare syndrome called mitochondrial encephalomyopathy, lactic acidosis, and stroke-like episodes (MELAS). A literature review of this uncommon syndrome and MELAS cardiomyopathy has been conducted.
PubMed: 38665734
DOI: 10.7759/cureus.56980 -
European Journal of Clinical... Jul 2024Primary mitochondrial diseases (PMDs) are rare genetic disorders resulting from mutations in genes crucial for effective oxidative phosphorylation (OXPHOS) that can... (Review)
Review
OBJECTIVES AND SCOPE
Primary mitochondrial diseases (PMDs) are rare genetic disorders resulting from mutations in genes crucial for effective oxidative phosphorylation (OXPHOS) that can affect mitochondrial function. In this review, we examine the bioenergetic alterations and oxidative stress observed in cellular models of primary mitochondrial diseases (PMDs), shedding light on the intricate complexity between mitochondrial dysfunction and cellular pathology. We explore the diverse cellular models utilized to study PMDs, including patient-derived fibroblasts, induced pluripotent stem cells (iPSCs) and cybrids. Moreover, we also emphasize the connection between oxidative stress and neuroinflammation.
INSIGHTS
The central nervous system (CNS) is particularly vulnerable to mitochondrial dysfunction due to its dependence on aerobic metabolism and the correct functioning of OXPHOS. Similar to other neurodegenerative diseases affecting the CNS, individuals with PMDs exhibit several neuroinflammatory hallmarks alongside neurodegeneration, a pattern also extensively observed in mouse models of mitochondrial diseases. Based on histopathological analysis of postmortem human brain tissue and findings in mouse models of PMDs, we posit that neuroinflammation is not merely a consequence of neurodegeneration but a potential pathogenic mechanism for disease progression that deserves further investigation. This recognition may pave the way for novel therapeutic strategies for this group of devastating diseases that currently lack effective treatments.
SUMMARY
In summary, this review provides a comprehensive overview of bioenergetic alterations and redox imbalance in cellular models of PMDs while underscoring the significance of neuroinflammation as a potential driver in disease progression.
Topics: Humans; Oxidative Stress; Mitochondrial Diseases; Neuroinflammatory Diseases; Animals; Energy Metabolism; Oxidative Phosphorylation; Mice; Mitochondria; Fibroblasts; Induced Pluripotent Stem Cells; Leigh Disease; MELAS Syndrome; Disease Models, Animal
PubMed: 38644687
DOI: 10.1111/eci.14217 -
International Journal of Molecular... Mar 2024MELAS syndrome, characterized by mitochondrial myopathy, encephalopathy, lactic acidosis and stroke-like episodes, represents a devastating mitochondrial disease, with... (Review)
Review
MELAS syndrome, characterized by mitochondrial myopathy, encephalopathy, lactic acidosis and stroke-like episodes, represents a devastating mitochondrial disease, with the stroke-like episodes being its primary manifestation. Arginine supplementation has been used and recommended as a treatment for these acute attacks; however, insufficient evidence exists to support this treatment for MELAS. The mechanisms underlying the effect of arginine on MELAS pathophysiology remain unclear, although it is hypothesized that arginine could increase nitric oxide availability and, consequently, enhance blood supply to the brain. A more comprehensive understanding of these mechanisms is necessary to improve treatment strategies, such as dose and regimen adjustments; identify which patients could benefit the most; and establish potential markers for follow-up. This review aims to analyze the existing evidence concerning the mechanisms through which arginine supplementation impacts MELAS pathophysiology and provide the current scenario and perspectives for future investigations.
Topics: Humans; MELAS Syndrome; Acidosis, Lactic; Arginine; Stroke; Dietary Supplements
PubMed: 38612442
DOI: 10.3390/ijms25073629 -
European Journal of Case Reports in... 2024
PubMed: 38584895
DOI: 10.12890/2024_004388 -
Clinical Case Reports Mar 2024MELAS is a disorder with clinical variability that also responsible for a significant portion of unexplained hereditary or childhood-onset hearing loss. Although...
KEY CLINICAL MESSAGE
MELAS is a disorder with clinical variability that also responsible for a significant portion of unexplained hereditary or childhood-onset hearing loss. Although patients typically present in childhood, the first stroke-like episode can occur later in life in some patients, potentially related to a lower heteroplasmy level. It is crucial to consider MELAS as a potential cause of stroke-like events if age at presentation and symptoms are atypical, especially among middle-aged patients without vascular risk factors.
ABSTRACT
MELAS syndrome (mitochondrial encephalopathy with lactic acidosis and stroke-like episodes) is a rare genetic condition that most patients develop stroke-like episodes before the age of 40. We report a 52-year-old female with a documented 40-year history of progressive sensorineural hearing loss, developed a visual field deficit and stroke-like events in her middle age who finally diagnosed was MELAS. The patient was started on vitamin E, l-carnitine, l-arginine, and coenzyme Q10 that gradually improved before dismissal from the hospital. This case highlights the importance of considering MELAS as a potential cause of stroke-like events if imaging findings are atypical for cerebral infarction, especially among middle-aged patients without vascular risk factors and an unusual cause of progressive sensorineural hearing loss.
PubMed: 38487642
DOI: 10.1002/ccr3.8438 -
Neurological Sciences : Official... Jul 2024
Topics: Humans; Metformin; MELAS Syndrome; Stroke; Hypoglycemic Agents
PubMed: 38448790
DOI: 10.1007/s10072-024-07444-5