Dissecting the Roles of the Nuclear and Mitochondrial Genomes in a Mouse Model of Autoimmune Diabetes.

Mitochondria, the organelles responsible for generating ATP in eukaryotic cells, have been previously implicated as a contributor to diabetes. However, mitochondrial proteins are encoded by both nuclear DNA (nDNA) and mtDNA. In order to better understand the relative contribution of each of these genomes to diabetes, a chimeric mitochondrial-nuclear exchange (MNX) mouse was created via pronuclear transfer carrying nDNA from a strain susceptible to type 1 diabetes (NOD/ShiLtJ) and mtDNA from nondiabetic C57BL/6J mice. Inheritance of the resulting heteroplasmic mtDNA mixture was then tracked across multiple generations, showing that offspring heteroplasmy generally followed that of the mother, with occasional large shifts consistent with an mtDNA bottleneck in the germ line. In addition, survival and incidence of diabetes in MNX mice were tracked and compared with those in unaltered NOD/ShiLtJ control mice. The results indicated improved survival and a delay in diabetes onset in the MNX mice, demonstrating that mtDNA has a critical influence on disease phenotype. Finally, enzyme activity assays showed that the NOD/ShiLtJ mice had significant hyperactivity of complex I of the electron transport chain relative to MNX mice, suggesting that a particular mtDNA variant (m.9461T>C) may be responsible for disease causation in the original NOD/ShiLtJ strain. ARTICLE HIGHLIGHTS: Mitochondria have been previously implicated in diabetes, but the specific genetic factors remain unclear. To better understand the contributions of mitochondrial genes in nuclear DNA (nDNA) versus mtDNA, we created mitochondrial-nuclear exchange (MNX) mice carrying nDNA from a diabetic strain and mtDNA from nondiabetic mice. Long-term tracking of MNX mice showed occasional large shifts in heteroplasmy consistent with an mtDNA bottleneck in the germ line. In addition, the MNX mice showed improved survival and delayed incidence of diabetes relative to the unaltered diabetic mice, which appeared to be linked to the activity of respiratory complex I.

Application of super-resolution microscopy in mitochondria-dynamic diseases.

Limited by spatial and temporal resolution, traditional optical microscopy cannot image the delicate ultra-structure organelles and sub-organelles. The emergence of super-resolution microscopy makes it possible. In this review, we focus on mitochondria. We summarize the process of mitochondrial dynamics, the primary proteins that regulate mitochondrial morphology, the diseases related to mitochondrial dynamics. The purpose is to apply super-resolution microscopy developed during recent years to the mitochondrial research. By providing the right research tools, we will help to promote the application of this technique to the in-depth elucidation of the pathogenesis of diseases related to mitochondrial dynamics, assistdiagnosis and develop the therapeutic treatment.

2D MoS2 and BN Nanosheets Damage Mitochondria through Membrane Penetration.

With the progression of nanotechnology, a growing number of nanomaterials have been created and incorporated into organisms and ecosystems, which raises significant concern about potential hazards of these materials on human health, wildlife, and the environment. Two-dimensional (2D) nanomaterials are one type of nanomaterials with thicknesses ranging from that of a single atom or of several atoms and have been proposed for a variety of biomedical applications such as drug delivery and gene therapy, but the toxicity thereof on subcellular organelles remains to be studied. In this work, we studied the impact of two typical 2D nanomaterials, MoS2 and BN nanosheets, on mitochondria, which are a type of membranous subcellular organelle that provides energy to cells. While 2D nanomaterials at a low dose exhibited a negligible cell mortality rate, significant mitochondrial fragmentation and partially reduced mitochondrial functions occurred; cells initiate mitophagy in response to mitochondrial damages, which cleans damaged mitochondria to avoid damage accumulation. Moreover, the molecular dynamics simulation results revealed that both MoS2 and BN nanosheets can spontaneously penetrate the mitochondrial lipid membrane through the hydrophobic interaction. The membrane penetration induced heterogeneous lipid packing resulting in damages. Our results demonstrate that even at a low dose 2D nanomaterials can physically damage mitochondria by penetrating the membrane, which draws attention to carefully evaluating the cytotoxicity of 2D nanomaterials for the potential biomedical application.

Infantile-onset Pompe disease with neutropenia: Treatment decisions in the face of a unique phenotype.

Infantile-onset Pompe disease manifests with early signs of cardiomyopathy during the first few days to weeks of life. We present the case of a newborn born via emergency cesarean section with atrial flutter and moderate biventricular hypertrophy who was diagnosed with Pompe disease on New York State newborn screen. Diagnosis was confirmed with repeat leukocyte acid alpha-glucosidase (GAA) enzyme activity, GAA gene sequencing, urine Hex4, and evaluation of Cross-Reactive Immunological Material (CRIM) status. The patient was also found to be persistently neutropenic which to our knowledge has not been previously reported in the literature in association with Pompe disease. This report highlights the impact that newborn screening had on time to diagnosis and initiation of treatment with enzyme replacement therapy. We also discuss how our patient's concurrent neutropenia impacted decision making related to immune tolerance induction prior to starting enzyme replacement therapy.

Use of a 3D-printed body surface percutaneous puncture guide plate in vertebroplasty for osteoporotic vertebral compression fractures.

BACKGROUND: Percutaneous vertebroplasty (PVP) has been used widely to treat osteoporotic vertebral compression fractures (OVCFs). However, it has many disadvantages, such as excessive radiation exposure, long operation times, and high cement leakage rates. This study was conducted to explore the clinical effects and safety of the use of a three-dimensional (3D)-printed body-surface guide plate to aid PVP for the treatment of OVCFs. METHODS: This prospective cohort study was conducted with patients with OVCFs presenting between October 2020 and June 2021. Fifty patients underwent traditional PVP (group T) and 47 patients underwent PVP aided by 3D-printed body-surface guide plates (3D group). The following clinical and adverse events were compared between groups: the puncture positioning, puncture, fluoroscopy exposure and total operation times; changes in vertebral height and the Cobb angle after surgery relative to baseline; preoperative and postoperative visual analog scale and Oswestry disability index scores; and perioperative complications (bone cement leakage, neurological impairment, vertebral infection, and cardiopulmonary complications. RESULTS: The puncture, adjustment, fluoroscopy, and total operation times were shorter in the 3D group than in group T. Visual analog scale and Oswestry disability index scores improved significantly after surgery, with significant differences between groups (both p < 0.05). At the last follow-up examination, the vertebral midline height and Cobb angle did not differ between groups. The incidence of complications was significantly lower in the 3D group than in group T (p < 0.05). CONCLUSION: The use of 3D-printed body-surface guide plates can simplify and optimize PVP, shortening the operative time, improving the success rate, reducing surgical complications, and overall improving the safety of PVP.

Mitochondrial Genome Variants as a Cause of Mitochondrial Cardiomyopathy.

Mitochondria are small double-membraned organelles responsible for the generation of energy used in the body in the form of ATP. Mitochondria are unique in that they contain their own circular mitochondrial genome termed mtDNA. mtDNA codes for 37 genes, and together with the nuclear genome (nDNA), dictate mitochondrial structure and function. Not surprisingly, pathogenic variants in the mtDNA or nDNA can result in mitochondrial disease. Mitochondrial disease primarily impacts tissues with high energy demands, including the heart. Mitochondrial cardiomyopathy is characterized by the abnormal structure or function of the myocardium secondary to genetic defects in either the nDNA or mtDNA. Mitochondrial cardiomyopathy can be isolated or part of a syndromic mitochondrial disease. Common manifestations of mitochondrial cardiomyopathy are a phenocopy of hypertrophic cardiomyopathy, dilated cardiomyopathy, and cardiac conduction defects. The underlying pathophysiology of mitochondrial cardiomyopathy is complex and likely involves multiple abnormal processes in the cell, stemming from deficient oxidative phosphorylation and ATP depletion. Possible pathophysiology includes the activation of alternative metabolic pathways, the accumulation of reactive oxygen species, dysfunctional mitochondrial dynamics, abnormal calcium homeostasis, and mitochondrial iron overload. Here, we highlight the clinical assessment of mtDNA-related mitochondrial cardiomyopathy and offer a novel hypothesis of a possible integrated, multivariable pathophysiology of disease.

Premature aging is associated with higher levels of 8-oxoguanine and increased DNA damage in the Polg mutator mouse.

Mitochondrial dysfunction plays an important role in the aging process. However, the mechanism by which this dysfunction causes aging is not fully understood. The accumulation of mutations in the mitochondrial genome (or "mtDNA") has been proposed as a contributor. One compelling piece of evidence in support of this hypothesis comes from the PolgD257A/D257A mutator mouse (Polgmut/mut ). These mice express an error-prone mitochondrial DNA polymerase that results in the accumulation of mtDNA mutations, accelerated aging, and premature death. In this paper, we have used the Polgmut/mut model to investigate whether the age-related biological effects observed in these mice are triggered by oxidative damage to the DNA that compromises the integrity of the genome. Our results show that mutator mouse has significantly higher levels of 8-oxoguanine (8-oxoGua) that are correlated with increased nuclear DNA (nDNA) strand breakage and oxidative nDNA damage, shorter average telomere length, and reduced mtDNA integrity. Based on these results, we propose a model whereby the increased level of reactive oxygen species (ROS) associated with the accumulation of mtDNA mutations in Polgmut/mut mice results in higher levels of 8-oxoGua, which in turn lead to compromised DNA integrity and accelerated aging via increased DNA fragmentation and telomere shortening. These results suggest that mitochondrial play a central role in aging and may guide future research to develop potential therapeutics for mitigating aging process.

Development of a diagnostic assay by three-tube multiplex real-time PCR for simultaneous detection of nine microorganisms causing acute respiratory infections.

Acute respiratory infections are widespread in vulnerable populations of all ages and are characterized by a variety of symptoms. The underlying infection can be caused by a multitude of microorganisms, including viruses and bacteria. Early detection of respiratory infections through rapid pathogen screening is vital in averting infectious respiratory disease epidemics. This study utilized a multiplex real-time PCR system to develop a three-tube reverse transcription-PCR (RT-PCR) assay, enabling simultaneously detect nine respiratory pathogens, including: influenza A and B, adenovirus, respiratory syncytial virus (RSV), Streptococcus pneumoniae, Legionella pneumophila, Haemophilus influenzae, Chlamydia pneumoniae, and Mycoplasma pneumoniae. This technique utilizes a one-step assay, with specifically designed TaqMan primer-probe sets combined in the same tube. This assay provided rapid and simplified detection of the nine prevalent pathogens, as well as increased sensitivity and reduced cross-contamination. This assay was evaluated using 25 related viral/bacterial strains as positive references, the other 25 irrelevant strains as negative controls, and clinical specimens from 179 patients. All positive strains were detected with no amplification of the non-target microorganism mixtures and the assay's detection limits ranged between 250-500 copies/ml (1.25-2.5 copies/reaction). A total of 167 (93.3%) samples tested positive for at least one of the pathogens identified; 109 of these samples were from patients confirmed to have RSV infections. The diagnostic accuracy of our assay was further confirmed by matching results from classical direct immunofluorescence assay and nucleotide sequencing. These data demonstrate the innovative multiplex real-time PCR assay as a promising alternative to the current approaches used for early screening of acute respiratory infections.

Super-resolution analyzing spatial organization of lysosomes with an organic fluorescent probe.

Lysosomes are multifunctional organelles involved in macromolecule degradation, nutrient sensing and autophagy. Live imaging has revealed lysosome subpopulations with dynamics and characteristic cellular localization. An as-yet unanswered question is whether lysosomes are spatially organized to coordinate and integrate their functions. Combined with super-resolution microscopy, we designed a small organic fluorescent probe, TPAE, that targeted lysosomes with a large Stokes shift. When we analyzed the spatial organization of lysosomes against mitochondria in different cell lines with this probe, we discovered different distance distribution patterns between lysosomes and mitochondria during increased autophagy flux. By using SLC25A46 mutation fibroblasts derived from patients containing highly fused mitochondria with low oxidative phosphorylation, we concluded that unhealthy mitochondria redistributed the subcellular localization of lysosomes, which implies a strong connection between mitochondria and lysosomes.

Light-activated mitochondrial fission through optogenetic control of mitochondria-lysosome contacts.

Mitochondria are highly dynamic organelles whose fragmentation by fission is critical to their functional integrity and cellular homeostasis. Here, we develop a method via optogenetic control of mitochondria-lysosome contacts (MLCs) to induce mitochondrial fission with spatiotemporal accuracy. MLCs can be achieved by blue-light-induced association of mitochondria and lysosomes through various photoactivatable dimerizers. Real-time optogenetic induction of mitochondrial fission is tracked in living cells to measure the fission rate. The optogenetic method partially restores the mitochondrial functions of SLC25A46-/- cells, which display defects in mitochondrial fission and hyperfused mitochondria. The optogenetic MLCs system thus provides a platform for studying mitochondrial fission and treating mitochondrial diseases.

Next-Generation Sequencing to Characterize Mitochondrial Genomic DNA Heteroplasmy.

Mitochondria play a very important role in many crucial cellular functions. Each eukaryotic cell contains hundreds of mitochondria with hundreds of mitochondrial genomes. Mutant and wild-type mitochondrial DNA (mtDNA) may co-exist as heteroplasmy and cause human disease. The purpose of the protocols in this article is to simultaneously determine the mtDNA sequence and quantify the heteroplasmy level using parallel sequencing. The protocols include mitochondrial genomic DNA PCR amplification of two full-length products using two distinct sets of PCR primers. The PCR products are mixed at an equimolar ratio, and the samples are then barcoded and sequenced with high-throughput next-generation sequencing technology. This technology is highly sensitive, specific, and accurate in determining mtDNA mutations and the degree/level of heteroplasmy. © 2022 Wiley Periodicals LLC. Basic Protocol 1: PCR amplification of mitochondrial DNA Basic Protocol 2: Analysis of next-generation sequencing of mitochondrial DNA Basic Protocol 3: Mutect2 pipeline for automated sample processing and large-scale data analysis.

PINK1-mediated Drp1S616 phosphorylation modulates synaptic development and plasticity via promoting mitochondrial fission.

Dynamic change of mitochondrial morphology and distribution along neuronal branches are essential for neural circuitry formation and synaptic efficacy. However, the underlying mechanism remains elusive. We show here that Pink1 knockout (KO) mice display defective dendritic spine maturation, reduced axonal synaptic vesicles, abnormal synaptic connection, and attenuated long-term synaptic potentiation (LTP). Drp1 activation via S616 phosphorylation rescues deficits of spine maturation in Pink1 KO neurons. Notably, mice harboring a knockin (KI) phosphor-null Drp1S616A recapitulate spine immaturity and synaptic abnormality identified in Pink1 KO mice. Chemical LTP (cLTP) induces Drp1S616 phosphorylation in a PINK1-dependent manner. Moreover, phosphor-mimetic Drp1S616D restores reduced dendritic spine localization of mitochondria in Pink1 KO neurons. Together, this study provides the first in vivo evidence of functional regulation of Drp1 by phosphorylation and suggests that PINK1-Drp1S616 phosphorylation coupling is essential for convergence between mitochondrial dynamics and neural circuitry formation and refinement.

Creating Cell Model 2.0 Using Patient Samples Carrying a Pathogenic Mitochondrial DNA Mutation: iPSC Approach for LHON.

Leber's Hereditary Optic Neuropathy is the most prevalent mitochondrial neurological disease caused by mutations in mitochondrial DNA encoded respiratory complex I subunits. Although the genetic origin for Leber's hereditary optic neuropathy was identified about 30 years ago, the underlying pathogenesis is still unclear primarily due to the lack of a relevant system or cell model. Current models are limited to lymphoblasts, fibroblasts, or cybrid cell lines. As the disease phenotype is limited to retinal ganglion cells, induced pluripotent stem cells will serve as an excellent model for studying this tissue-specific disease, elucidating its underlying molecular mechanisms, and identifying novel therapeutic targets. Here, we describe a detailed protocol for the generation of retinal ganglion cells, and also cardiomyocytes for proof of iPSC pluripotency.

A Novel Variant of ATP5MC3 Associated with Both Dystonia and Spastic Paraplegia.

BACKGROUND: In a large pedigree with an unusual phenotype of spastic paraplegia or dystonia and autosomal dominant inheritance, linkage analysis previously mapped the disease to chromosome 2q24-2q31. OBJECTIVE: The aim of this study is to identify the genetic cause and molecular basis of an unusual autosomal dominant spastic paraplegia and dystonia. METHODS: Whole exome sequencing following linkage analysis was used to identify the genetic cause in a large family. Cosegregation analysis was also performed. An additional 384 individuals with spastic paraplegia or dystonia were screened for pathogenic sequence variants in the adenosine triphosphate (ATP) synthase membrane subunit C locus 3 gene (ATP5MC3). The identified variant was submitted to the "GeneMatcher" program for recruitment of additional subjects. Mitochondrial functions were analyzed in patient-derived fibroblast cell lines. Transgenic Drosophila carrying mutants were studied for movement behavior and mitochondrial function. RESULTS: Exome analysis revealed a variant (c.318C > G; p.Asn106Lys) (NM_001689.4) in ATP5MC3 in a large family with autosomal dominant spastic paraplegia and dystonia that cosegregated with affected individuals. No variants were identified in an additional 384 individuals with spastic paraplegia or dystonia. GeneMatcher identified an individual with the same genetic change, acquired de novo, who manifested upper-limb dystonia. Patient fibroblast studies showed impaired complex V activity, ATP generation, and oxygen consumption. Drosophila carrying orthologous mutations also exhibited impaired mitochondrial function and displayed reduced mobility. CONCLUSION: A unique form of familial spastic paraplegia and dystonia is associated with a heterozygous ATP5MC3 variant that also reduces mitochondrial complex V activity.

SOAT1 is a new prognostic factor of colorectal cancer.

Colorectal cancer (CRC) is one of the most common malignant gastrointestinal cancers. Metastasis is the major leading cause of death in patients with CRC, and many patients treated with radical surgery were diagnosed with metastasis during follow-up. However, the underlying molecular mechanisms regulating CRC metastasis are still elusive. Sterol o-acyltransferase 1 (SOAT1) is a critical participant in maintaining intracellular cholesterol balance. Here, by analyzing the clinical specimens and in vitro cell line experiments, we evaluated the clinical relevance and role of SOAT1 in regulating CRC metastasis. The results revealed that SOAT1 was overexpressed in colon cancer tissues compared to peritumor tissues at mRNA and protein levels. High intratumor SOAT1 expression correlates to lymph node metastasis and indicates poor patient disease-free survival and overall survival. The silencing of SOAT1 strongly inhibited the migration and invasion ability of CRC tumor cells. These results demonstrated that SOAT1 was upregulated in colon cancer. Upregulation of SOAT1 expression may promote CRC progression by enhancing the migration and invasion ability of CRC. Our results indicate that targeting SOAT1 activity may be applied as a promising therapeutic strategy for preventing the metastasis of CRC after radical surgical treatment.

Validation of low-coverage whole-genome sequencing for mitochondrial DNA variants suggests mitochondrial DNA as a genetic cause of preterm birth.

Preterm birth (PTB), or birth that occurs earlier than 37 weeks of gestational age, is a major contributor to infant mortality and neonatal hospitalization. Mutations in the mitochondrial genome (mtDNA) have been linked to various rare mitochondrial disorders and may be a contributing factor in PTB given that maternal genetic factors have been strongly linked to PTB. However, to date, no study has found a conclusive connection between a particular mtDNA variant and PTB. Given the high mtDNA copy number per cell, an automated pipeline was developed for detecting mtDNA variants using low-coverage whole-genome sequencing (lcWGS) data. The pipeline was first validated against samples of known heteroplasmy, and then applied to 929 samples from a PTB cohort from diverse ethnic backgrounds with an average gestational age of 27.18 weeks (range: 21-30). Our new pipeline successfully identified haplogroups and a large number of mtDNA variants in this large PTB cohort, including 8 samples carrying known pathogenic variants and 47 samples carrying rare mtDNA variants. These results confirm that lcWGS can be utilized to reliably identify mtDNA variants. These mtDNA variants may make a contribution toward preterm birth in a small proportion of live births.

Nanoscopic quantification of sub-mitochondrial morphology, mitophagy and mitochondrial dynamics in living cells derived from patients with mitochondrial diseases.

SLC25A46 mutations have been found to lead to mitochondrial hyper-fusion and reduced mitochondrial respiratory function, which results in optic atrophy, cerebellar atrophy, and other clinical symptoms of mitochondrial disease. However, it is generally believed that mitochondrial fusion is attributable to increased mitochondrial oxidative phosphorylation (OXPHOS), which is inconsistent with the decreased OXPHOS of highly-fused mitochondria observed in previous studies. In this paper, we have used the live-cell nanoscope to observe and quantify the structure of mitochondrial cristae, and the behavior of mitochondria and lysosomes in patient-derived SLC25A46 mutant fibroblasts. The results show that the cristae have been markedly damaged in the mutant fibroblasts, but there is no corresponding increase in mitophagy. This study suggests that severely damaged mitochondrial cristae might be the predominant cause of reduced OXPHOS in SLC25A46 mutant fibroblasts. This study demonstrates the utility of nanoscope-based imaging for realizing the sub-mitochondrial morphology, mitophagy and mitochondrial dynamics in living cells, which may be particularly valuable for the quick evaluation of pathogenesis of mitochondrial morphological abnormalities.

Systemic immune-inflammation index changes predict outcome in stage III non-small-cell lung cancer patients treated with concurrent chemoradiotherapy.

Background: Although the systemic immune-inflammation index (SII) has been used to predict recurrence and survival in non-small-cell lung cancer (NSCLC) patients, the prognostic significance of change in SII (ΔSII) is unclear for stage III NSCLC patients treated with concurrent chemoradiotherapy (CCRT). In the present study we aimed to explore the association between ΔSII and the clinical outcomes of 142 patients with stage III NSCLC treated with CCRT. Methods: A total of 142 patients were included in this retrospective study. The SII values were calculated based on laboratory data regarding platelet, neutrophil and lymphocyte counts, and ΔSII was calculated using data acquired before and approximately 2 weeks after CCRT. The receiver operating characteristic curve was used to determine the optimal cut-off value for the peripheral blood inflammation index. Kaplan-Meier analysis and Cox proportional regression were used to analyze the prognostic value of ΔSII for overall survival (OS) and progression-free survival (PFS). Results: The area under the receiver operating characteristic curve for ΔSII (0.708) was larger than those for pre-CCRT SII (0.578) and post-CCRT SII (0.610). The optimal cut-off point for ΔSII was defined as 43. OS and PFS were better in patients with low ΔSII and in multivariate analysis, the ΔSII was an independent predictor of OS and PFS (p = 0.006 and p = 0.017, respectively). Conclusions: ΔSII is related to progression and death in patients with stage III NSCLC. The ΔSII can provide a detailed prognostic prediction for stage III NSCLC.

Mitochondrial replacement therapy: Genetic counselors' experiences, knowledge, and opinions.

Mitochondrial disorders affect at least 1 in 5,000 individuals worldwide and are often incurable and fatal. Mitochondrial replacement therapy (MRT) is an in vitro fertilization technique used to prevent the transmission of mitochondrial disorders. Currently, MRT is the only approach that provides mothers who carry a pathogenic variant in their mitochondrial DNA (mtDNA), the opportunity to have a biological child without a mitochondrial disease. MRT involves the combination of nuclear DNA from the egg of the carrier mother and the cytoplasm from an oocyte donor, which contains healthy mitochondria. While MRT was approved for use in the UK in 2015, the ban on congressional funding for research on 'heritable genetic modification' has made MRT unavailable within the US borders. This survey-based study aimed to describe genetic counselors' experience, knowledge, and opinions about MRT. Additionally, we also assessed whether genetic counselors' comfort discussing MRT with patients, and feelings about clinical use of MRT in the United States changed after providing information about MRT compared with baseline. Responses were received from 139 genetic counselors in North America. Findings indicate low awareness and knowledge about MRT among participants. However, more participants expressed comfort with discussing MRT with patients and more participants were able to form opinions about statements about MRT after they were provided with information about MRT. This study is the first to assess genetic counselors' opinions toward MRT and suggests the need for more education about novel technologies such as MRT among genetic counselors.