Expression Of Mitochondria-related Genes Research Articles

Cross-species analysis uncovers the mitochondrial stress response in the hippocampus as a shared mechanism in mouse early life stress and human depression

Depression, or major depressive disorder, poses a significant burden for both individuals and society, affecting approximately 10.8% of the general population. This psychiatric disorder leads to approximately 800,000 deaths per year. A combination of genetic and environmental factors such as early life stress (ELS) increase the risk for development of depression in humans, and a clear role for the hippocampus in the pathophysiology of depression has been shown. Nevertheless, the underlying mechanisms of depression remain poorly understood, resulting in a lack of effective treatments. To better understand the core mechanisms underlying the development of depression, we used a cross-species design to investigate shared hippocampal pathophysiological mechanisms in mouse ELS and human depression. Mice were subjected to ELS by a maternal separation paradigm, followed by RNA sequencing analysis of the adult hippocampal tissue. This identified persistent transcriptional changes linked to mitochondrial stress response pathways, with oxidative phosphorylation and protein folding emerging as the main mechanisms affected by maternal separation. Remarkably, there was a significant overlap between the pathways involved in mitochondrial stress response we observed and publicly available RNAseq data from hippocampal tissue of depressive patients. This cross-species conservation of changes in gene expression of mitochondria-related genes suggests that mitochondrial stress may play a pivotal role in the development of depression. Our findings highlight the potential significance of the hippocampal mitochondrial stress response as a core mechanism underlying the development of depression. Further experimental investigations are required to expand our understanding of these mechanisms.

Transcriptomic analysis reveals extensive modulation of mitochondrial gene expressions after volumetric muscle loss injury

Volumetric muscle loss (VML) is characterized by the unrecoverable loss of muscle tissue and function. Therapeutic modalities remain elusive in part because the etiology of the pathology remains unclear. Past RNA-sequencing analyses shed light on transcriptional regulation, but differential gene expression and gene set enrichment analysis (GSEA) results are often dominated by the robust inflammatory and fibrotic response to the injury. The primary objective of this study was to leverage past datasets and interrogate transcriptional regulation of cellular metabolism because our group has previously reported that VML injury disrupts mitochondrial function in the remaining muscle after VML injury. We hypothesized that a metabolic GSEA analysis will identify several differentially expressed mitochondrial gene sets. Utilizing a publicly-available rat species RNAseq dataset, we transformed that data from transcripts per million (TPM) to a Z-score with respect to the uninjured group. Since TPM is not compatible with cross-sample comparisons, we opted for a single-sample GSEA that permits phenotype comparisons. Visualizing the normalized enrichment scores (NES) into heatmaps allowed us to select the top-25 enriched gene sets. The majority of the top-25 could be split into three groups: electron transport chain (ETC, n=8), substrate metabolism (SM, n=5), and mitochondrial maintenance (MM, n=2). The NES at each day post-VML injury (dpi) was compared to its respective uninjured group using a two-tailed t-test. We found that all ETC-related pathways were significantly enriched and downregulated at 7-, 14-, and 28-dpi (p ≤ 0.039). For example, the percent change in NES of ‘complex 1’ was- 436%, -419%, and -816%, respectively (p≤0.002). SM-related pathways followed a similar downward trend (p≤0.044). For example, ‘TCA’ -149%, -303%, and -697%, respectively (p≤0.028). Interestingly, within the MM-related gene sets, mitochondrial ‘fusion’ was significant down at 7- and 28-dpi (-319%, -414%, p≤0.009) while ‘fission’ was significantly down at 3-, 7-, and 14-dpi (-157%, -319%, and -797%, p≤0.030). We next analyzed a publicly-available mouse species scRNAseq data set. To examine the muscle-specific transcriptional response we combined the counts for myonuclei and satellite cells. GSEA revealed six significantly enriched gene sets, notably ‘all metabolism genes’ (NES = 1.33, FDR q = 0.050), and the remaining four were related to the ETC (NES ≥ 1.81, FDR q ≤ 0.050). This retrospective, comprehensive analysis confirms dynamic changes in the expression of mitochondrial-related genes in response to VML injury in both rats and mice. The modulation of genes related to the electron transport chain, mitochondrial maintenance, and substrate metabolism agree with physiological outcomes of impaired mitochondrial carbohydrate metabolism, hyperpolarized mitochondria, and slowed electron conductance from previous mouse studies. R01AR078903 to SG and JC. This is the full abstract presented at the American Physiology Summit 2024 meeting and is only available in HTML format. There are no additional versions or additional content available for this abstract. Physiology was not involved in the peer review process.

Maternal Ezh1/2 deficiency impairs the function of mitochondria in mouse oocytes and early embryos.

Maternal histone methyltransferase is critical for epigenetic regulation and development of mammalian embryos by regulating histone and DNA modifications. Here, we reported a novel mechanism by revealing the critical effects of maternal Ezh1/2 deletion on mitochondria in MIIoocytes and early embryos in mice. We found that Ezh1/2 knockout in mouse MIIoocytes impaired the structure of mitochondria and decreased its number, but membrane potential and respiratory function of mitochondrion were increased. The similar effects of Ezh1/2 deletion have been observed in 2-cell and morula embryos, indicating that the effects of maternal Ezh1/2 deficiency on mitochondrion extend to early embryos. However, the loss of maternal Ezh1/2 resulted in a severe defect of morula: the number, membrane potential, respiratory function, and ATP production of mitochondrion dropped significantly. Content of reactive oxygen specieswas raised in both MIIoocytes and early embryos, suggesting maternal Ezh1/2 knockout induced oxidative stress. In addition, maternal Ezh1/2 ablation interfered the autophagy in morula and blastocyst embryos. Finally, maternal Ezh1/2 deletion led to cell apoptosis in blastocyst embryos in mice. By analyzing the gene expression profile, we revealed that maternal Ezh1/2 knockout affected the expression of mitochondrial related genes in MIIoocytes and early embryos. Thechromatin immunoprecipitation-polymerase chain reaction assay demonstrated that Ezh1/2 directly regulated the expression of genes Fxyd6, Adpgk, Aurkb, Zfp521, Ehd3, Sgms2, Pygl, Slc1a1, and Chst12 by H3K27me3 modification. In conclusion, our study revealed the critical effect of maternal Ezh1/2 on the structure and function of mitochondria in oocytes and early embryos, and suggested a novel mechanism underlying maternal epigenetic regulation on early embryonic development through the modulation of mitochondrial status.

Chronic kidney disease and left ventricular diastolic dysfunction (CKD-LVDD) alter cardiac expression of mitochondria-related genes in swine

Cardiovascular disease and heart failure doubles in patients with chronic kidney disease (CKD), but the underlying mechanisms remain obscure. Mitochondria are central to maintaining cellular respiration and modulating cardiomyocyte function. We took advantage of our novel swine model of CKD and left ventricular diastolic dysfunction (CKD-LVDD) to investigate the expression of mitochondria-related genes and potential mechanisms regulating their expression. CKD-LVDD and normal control pigs (n=6/group, 3 males/3 females) were studied for 14 weeks. Renal and cardiac hemodynamics were quantified by multidetector-CT, echocardiography, and pressure-volume loop studies, respectively. Mitochondrial morphology (electron microscopy) and function (Oroboros) were assessed ex vivo. In randomly selected pigs (n=3/group), cardiac mRNA-, MeDIP-, and miRNA-sequencing (seq) were performed to identify mitochondria-related genes and study their pre- and post -transcriptional regulation. CKD-LVDD exhibited cardiac mitochondrial structural abnormalities and elevated mitochondrial H2O2 emission but preserved mitochondrial function. Cardiac mRNA-seq identified 862 mitochondria-related genes, of which 69 were upregulated and 33 downregulated (fold-change ≥2, false discovery rate≤0.05). Functional analysis showed that upregulated genes were primarily implicated in processes associated with oxidative stress, whereas those downregulated mainly participated in respiration and ATP synthesis. Integrated mRNA/miRNA/MeDIP-seq analysis showed that upregulated genes were modulated predominantly by miRNAs, whereas those downregulated were by miRNA and epigenetic mechanisms. CKD-LVDD alters cardiac expression of mitochondria-related genes, associated with mitochondrial structural damage but preserved respiratory function, possibly reflecting intrinsic compensatory mechanisms. Our findings may guide the development of early interventions at stages of cardiac dysfunction in which mitochondrial injury could be prevented, and the development of LVDD ameliorated.

Guanidinoacetic acid ameliorates hepatic steatosis and inflammation and promotes white adipose tissue browning in middle-aged mice with high-fat-diet-induced obesity.

Guanidinoacetic acid (GAA) is a naturally occurring amino acid derivative that plays a critical role in energy metabolism. In recent years, a growing body of evidence has emerged supporting the importance of GAA in metabolic dysfunction. Hence, we aimed to investigate the effects of GAA on hepatic and adipose tissue metabolism, as well as systemic inflammatory responses in obese middle-aged mice models and attempted to explore the underlying mechanism. We found that dietary supplementation of GAA inhibited inguinal white adipose tissue (iWAT) hypertrophy in high-fat diet (HFD)-fed mice. In addition, GAA supplementation observably decreased the levels of some systemic inflammatory factors, including IL-4, TNF-α, IL-1β, and IL-6. Intriguingly, GAA supplementation ameliorated hepatic steatosis and lipid deposition in HFD-fed mice, which was revealed by decreased levels of TG, TC, LDL-C, PPARγ, SREBP-1c, FASN, ACC, FABP1, and APOB and increased levels of HDL-C in the liver. Moreover, GAA supplementation increased the expression of browning markers and mitochondrial-related genes in the iWAT. Further investigation showed that dietary GAA promoted the browning of the iWAT via activating the AMPK/Sirt1 signaling pathway and might be associated with futile creatine cycling in obese mice. These results indicate that GAA has the potential to be used as an effective ingredient in dietary interventions and thus may play an important role in ameliorating and preventing HFD-induced obesity and related metabolic diseases.

Different impact of vitamin D on mitochondrial activity and morphology in normal and malignant keratinocytes, the role of genomic pathway

Deregulation of mitochondria activity is one of the hallmarks of cancerogenesis and an important target for cancer therapy. Therefore, we compared the impact of an active form of vitamin D3 (1,25(OH)2D3) on mitochondrial morphology and bioenergetics in human squamous cell carcinoma (A431) and immortalized HaCaT keratinocytes. It was shown that mitochondria of cancerous A431 cells differ from that observed in HaCaT keratinocytes in terms of network, morphology, bioenergetics, glycolysis, and mitochondrial DNA copy number, while treatment of A431 with 1,25(OH)2D3 partially eliminates these differences. Furthermore, mitochondrial membrane potential, basal respiration, and mitochondrial reactive oxygen species production were decreased in A431 cells treated with 1,25(OH)2D3. Additionally, the expression and protein level of mitophagy marker PINK1 was significantly increased in A431 1,25(OH)2D3 treated cells, but not observed in treated HaCaT cells. Knockout of VDR (vitamin D receptor) or RXRA (binding partner retinoid X receptor) partially altered mitochondrial morphology and function as well as mitochondrial response to 1,25(OH)2D3. Transcriptomic analysis on A431 cells treated with 1,25(OH)2D3 revealed modulation of expression of several mitochondrial-related genes involved in mitochondrial depolarization, mitochondrial protein translation (i.e. LYRM9, MARS2), and fusion-fission (OPA1, FIS1, MFN1 and 2), however, none of the genes coded by mitochondrial DNA was affected. Interestingly, in silico analyses of nuclear-encoded mitochondrial genes revealed that they are rather activated by the secondary genomic response to 1,25(OH)2D3. Taken together, 1,25(OH)2D3 remodels mitochondrial architecture and bioenergetics through VDR-dependent and only partially RXRA-dependent activation of the genomic pathway, thus outlining a new perspective for anticancer properties of vitamin D3 in relation to mitochondria in squamous cell carcinoma.

Different Mutations in SF3B1 Gene Have Specific Transcriptomic Characteristics in Myelodysplastic Neoplasms

Myelodysplastic neoplasms (MDS) are hematopoietic stem cell (HSC) disorders characterized by ineffective hematopoiesis, peripheral cytopenia, and increased tendency to leukemic transformation. Somatic mutations in spliceosome machinery occur in approx. 50% of MDS patients. Among these, up to 30% of MDS patients carry a mutation in SF3B1. According to the 2022 classification system, MDS-SF3B1 is now considered as separate MDS subtype. Mutated SF3B1 perturbs mitochondrial function, resulting in apoptosis and ineffective erythropoiesis. The most common mutation of SF3B1, K700E, accounts for 50% of the variants, with additional codons (such as 666 and 662) acting as hotspot sites. Different mutations seem to be associated with distinct clinicopathological features. However, the prognostic implication of different SF3B1 mutations in MDS remains controversial and needs further clarification. This study investigated differences in clinical and molecular features of MDS-SF3B1 with different types of SF3B1 mutations. To investigate a direct impact of different point mutations in SF3B1, the study was based on four isogenic NALM6 cell lines, the wildtype (wt) and three cell lines, each with different SF3B1 mutation (CRISPR/Cas9-edited K700E, K666N, and H662Q). To understand phenotypic manifestations of the mutations in the disease, we also analyzed clinical and transcriptional characteristics of 146 lower-risk MDS patients. Using RNA-seq in the cell lines and CD34+ BM patient cells (17 patients with no mutation, 11 patients with K700E SF3B1 mutation, 5 patients with K666N/E SF3B1 mutation), we investigated effects of different SF3B1 mutations on RNA splicing events and gene expression levels. Initially, outcome analysis confirmed the previously described observation that patients with a SF3B1 mutation have favorable outcomes compared to those with other splicing factor mutations. Further, the analysis showed that specific mutations in SF3B1 tend to lead to different prognoses; patients with K700E had longer survival compared to those with other SF3B1 mutations (mean progression-free survival was 64.8 vs. 29.1 months). Analysis of RNA splicing in NALM6 showed that K666N and H662Q mutations share similar characteristics whereas K700E mutation is more similar to wt-cells. Most significant changes were found in retained introns (RI); increased RI inclusion levels were detected in K666N/H662Q cells compared to K700E/wt cells. In patients, RI events were also strongly increased in K666N/E compared to K700E samples (Fig. 1). A significant overlap was identified between cell line and patient data; out of 173 genes with higher RI inclusion level in K666N-NALM6 cells, 77 genes had higher RI inclusion also in patients. Interestingly, 12 out of these 77 genes were related to mitochondrial functions (e.g., CREBZF, DDX1, MRPL23, MUTYH, and RAF1). RNA-seq data further showed significant alternations in gene expression levels in the four isogenic cell lines and also in patient samples with different mutations. Surprisingly, a more pronounced difference was detected in gene expression between patients with different SF3B1 mutations than between patients with no mutation and with any SF3B1 mutation (irrespective of its type), suggesting that specific SF3B1 mutations result in different phenotypes. Pathway analyses showed that deregulated genes in samples with K700E vs. other hotspot mutations were significantly enriched in electron transport, cell cycle, proliferation, quiescence, and HSC differentiation. Importantly, expression of multiple mitochondria-related genes was altered between K700E and K666N/H662Q NALM6 cells (334 genes, FDR < 0.01; Fig. 2), indicating different metabolic characteristics of the cells with non-K700E mutations. For example, several subunits of mitochondrial respiratory complexes I and IV were upregulated in K700E cells, pointing to differences in energetic metabolism. Altogether, our data support the hypothesis that only K700E mutation of SF3B1 may have a positive prognostic value and that other SF3B1 mutations may influence cells differently, specifically affecting their mitochondrial functions. Based on our results, we conclude that prognostic implication of different SF3B1 mutations in MDS will need additional refinements in future. Supported by AZV CR (NU20-03-00412), GA CR (20-19162S), and MH CZ-DRO (00023736).

Transcriptomic analysis reveals mitochondrial pathways associated with distinct adolescent behavioral phenotypes and stress response

Adolescent individuals exhibit great variability in cortical dynamics and behavioral outcomes. The developing adolescent brain is highly sensitive to social experiences and environmental insults, influencing how personality traits emerge. A distinct pattern of mitochondrial gene expression in the prefrontal cortex (PFC) during adolescence underscores the essential role of mitochondria in brain maturation and the development of mental illnesses. Mitochondrial features in certain brain regions account for behavioral differences in adulthood. However, it remains unclear whether distinct adolescent behavioral phenotypes and the behavioral consequences of early adolescent stress exposure in rats are accompanied by changes in PFC mitochondria-related genes and mitochondria respiratory chain capacity. We performed a behavioral characterization during late adolescence (postnatal day, PND 47–50), including naïve animals and a group exposed to stress from PND 31–40 (10 days of footshock and 3 restraint sessions) by z-normalized data from three behavioral domains: anxiety (light–dark box tests), sociability (social interaction test) and cognition (novel-object recognition test). Employing principal component analysis, we identified three clusters: naïve with higher-behavioral z-score (HBZ), naïve with lower-behavioral z-score (LBZ), and stressed animals. Genome-wide transcriptional profiling unveiled differences in the expression of mitochondria-related genes in both naïve LBZ and stressed animals compared to naïve HBZ. Genes encoding subunits of oxidative phosphorylation complexes were significantly down-regulated in both naïve LBZ and stressed animals and positively correlated with behavioral z-score of phenotypes. Our network topology analysis of mitochondria-associated genes found Ndufa10 and Cox6a1 genes as central identifiers for naïve LBZ and stressed animals, respectively. Through high-resolution respirometry analysis, we found that both naïve LBZ and stressed animals exhibited a reduced prefrontal phosphorylation capacity and redox dysregulation. Our findings identify an association between mitochondrial features and distinct adolescent behavioral phenotypes while also underscoring the detrimental functional consequences of adolescent stress on the PFC.

GADD45A regulates subcutaneous fat deposition and lipid metabolism by interacting with Stat1

BackgroundObesity, characterized by excessive white adipose tissue expansion, is associated with several metabolic complications. Identifying new adipogenesis regulators may lead to effective therapies for obesity-induced metabolic disorders.ResultsHere, we identified the growth arrest and DNA damage-inducible A (GADD45A), a stress-inducible histone-folding protein, as a novel regulator of subcutaneous adipose metabolism. We found that GADD45A expression was positively correlated with subcutaneous fat deposition and obesity in humans and fatty animals. In vitro, the gain or loss function of GADD45A promoted or inhibited subcutaneous adipogenic differentiation and lipid accumulation, respectively. Using a Gadd45a-/- mouse model, we showed that compared to wild-type (WT) mice, knockout (KO) mice exhibited subcutaneous fat browning and resistance to high-fat diet (HFD)-induced obesity. GADD45A deletion also upregulated the expression of mitochondria-related genes. Importantly, we further revealed that the interaction of GADD45A with Stat1 prevented phosphorylation of Stat1, resulting in the impaired expression of Lkb1, thereby regulating subcutaneous adipogenesis and lipid metabolism.ConclusionsOverall, our results reveal the critical regulatory roles of GADD45A in subcutaneous fat deposition and lipid metabolism. We demonstrate that GADD45A deficiency induces the inguinal white adipose tissue (iWAT) browning and protects mice against HFD-induced obesity. Our findings provide new potential targets for combating obesity-related metabolic diseases and improving human health.

Expressions of mitochondria-related genes in pregnant women with subclinical hypothyroidism, and expressions of miRNAs in maternal and cord blood

BackgroundSubclinical hypothyroidism in pregnancy and definition by upper thyrotropin (TSH) cutoff are controversial. As mitochondria are influenced by thyroid hormones, the purpose in this study was to measure expression of mitochondria-related genes in euthyroid and subclinical hypothyroid pregnant women to obtain more knowledge of potential metabolic consequences of maternal subclinical hypothyroidism. In addition, we wished to test if applied TSH-cutoff significantly changed our results of expressed gene-levels. Moreover, we aimed to identify potential microRNA-biomarkers for subclinical hypothyroidism – markers that could be traced to offspring as well.MethodsFrom a cohort of at-term pregnant women undergoing planned cesarean section, 77 women had expression levels of the mitochondria-related genes Peroxisome Proliferator-activated Receptor-γ coactivator-1β (PGC-1β), mitochondrial Transcription Factor A (TFAM), Superoxide Dismutase 2 (SOD2) and Nuclear Respiratory Factor 2 (NRF-2) determined by qPCR from blood sampled in prior to delivery. Two TSH-cutoff levels defining subclinical hypothyroidism (> 3.0 and > 3.7 mIU/L) were applied for the procession of results, generating two data analyses of the same cohort. In 22 pairwise maternal-cord samples (subclinical hypothyroid/euthyroid-rate 0.5, TSH-cutoff > 3.0 mIU/L), microRNA-expressions (miRNA) were analyzed.ResultsAll gene expressions were lower in the subclinical hypothyroid group regardless of applied TSH-cutoff, but insignificant except for PGC-1β at TSH cutoff > 3.0 mIU/L. Two miRNAs (hsa-let-7d-3p and hsa-miR-345-5p) were upregulated in blood from women and offspring (cord blood) with subclinical hypothyroidism.ConclusionsA trend towards decreased mitochondrial gene expressions in subclinical hypothyroidism were demonstrated. The miRNAs hsa-let-7d-3p and hsa-miR-345-5p might be potential markers of maternal subclinical hypothyroidism. However, larger studies are needed to verify the findings.

Abstract 052: Vascular Endothelin-1 Mediates Hyperoxia-induced Cellular Stress In Kidney Vessels

Despite its common use in the clinic, therapeutic oxygen supplementation can result in organdamage. We recently reported in a mouse model that hyperoxia leads to elevated levels ofendothelin-1 (ET-1) in plasma and kidney, as well as exaggerated extracellular matrixdeposition, cell death and expression of mitochondria-related genes in the kidney. ET-1 is avasoactive peptide that is linked to various forms of cell stress pathways and kidney damage;however, the specific role that vasculature-derived ET-1 may play in hyperoxia-induced cellularstress in this organ is unknown. We hypothesized that, during hyperoxia, the lack ofvasculature-derived ET-1 results in ameliorated activation of endoplasmic reticulum andmitochondrial stress in kidney vessels. Male and female floxed ET-1 and vascular endothelialcell ET-1 knockout (VEET KO) mice were exposed to >95% O2 for 72 hours. After this time,mice were sacrificed, and renal vessels were isolated. Expression of genes involved inendoplasmic reticulum (ER) and mitochondrial stress was assessed by RT-PCR. Absence ofET-1 in the vasculature led to a significantly decreased expression of the ER stress marker ATF-4 after hyperoxia (floxed ET-1 vs. VEET KO: 1 ± 0.1 vs. 0.58 ± 0.08, n=8-12/group,p=0.0036). In response to high oxygen, VEET KO mice also presented with reduced expressionof mitochondrial genes FIS1 (1 ± 0.14 vs. 0.67 ± 0.15, p=0.0036), MFN2 (1 ± 0.16 vs. 0.58 ±0.12, p=0.0495), and PINK1 (1 ± 0.18 vs. 0.73 ± 0.28, p=0.048). No sex differences weredetected. Our data demonstrate that vascular ET-1 stimulates ER stress and mitochondrialstress pathways in the kidney vessels during hyperoxia, possibly inducing downstream kidneydamage. Our findings may provide new insights into novel therapeutic targets to preventhyperoxia-induced organ damage.

Expression of expanded GGC repeats within NOTCH2NLC causes cardiac dysfunction in mouse models

BackgroundNeuronal intranuclear inclusion disease (NIID) is a rare neurodegenerative disorder characterized by widespread intranuclear inclusions in the nervous system as well as multiple visceral organs. In 2019, expanded GGC repeats within the 5′ untranslated region of the NOTCH2NLC gene was identified as the causative factor. NIID is a heterogeneous disorder with variable clinical manifestations including cognitive impairment, cerebellar ataxia, parkinsonism, paroxysmal symptoms, autonomic dysfunction, and muscle weakness. Although NIID primarily affects the central and peripheral nervous systems, growing evidence suggests potential cardiac abnormalities in NIID. However, the link between expanded GGC repeats within NOTCH2NLC and cardiac dysfunction remains uncertain.ResultsIn this study, we utilized two transgenic mouse models, expressing NOTCH2NLC-(GGC)98 ubiquitously or specifically in cardiomyocytes, and identified p62 (also known as sequestosome 1, SQSTM1)-positive intranuclear NOTCH2NLC-polyG inclusions in cardiomyocytes in two mouse models. We observed that both models exhibited cardiac-related pathological and echocardiographic changes, albeit exhibiting varying degrees of severity. Transcriptomic analysis revealed shared downregulation of genes related to ion channels and mitochondria in both models, with the cardiomyocyte-specific mice showing a more pronounced downregulation of mitochondria and energy metabolism-related pathways. Further investigations revealed decreased expression of mitochondria-related genes and electron transport chain activity. At last, we conducted a retrospective review of cardiac-related examination results from NIID patients at our hospital and also identified some cardiac abnormalities in NIID patients.ConclusionsOur study provided the first in vivo evidence linking GGC repeat expansions within NOTCH2NLC to cardiac abnormalities and highlighted the contribution of mitochondrial dysfunction in the development of cardiac abnormalities.

A link between mitochondrial damage and the immune microenvironment of delayed onset muscle soreness

BackgroundDelayed onset muscle soreness (DOMS) is a self-healing muscle pain disorder. Inflammatory pain is the main feature of DOMS. More and more researchers have realized that changes in mitochondrial morphology are related to pain. However, the role of mitochondria in the pathogenesis of DOMS and the abnormal immune microenvironment is still unknown.MethodsMitochondria-related genes and gene expression data were obtained from MitoCarta3.0 and NCBI GEO databases. The network of mitochondrial function and the immune microenvironment of DOMS was constructed by computer algorithm. Subsequently, the skeletal muscle of DOMS rats was subjected to qPCR to verify the bioinformatics results. DOMS and non-DOMS histological samples were further studied by staining and transmission electron microscopy.ResultsBioinformatics results showed that expression of mitochondria-related genes was changed in DOMS. The results of qPCR showed that four hub genes (AMPK, PGC1-α, SLC25A25, and ARMCX1) were differentially expressed in DOMS. These hub genes are related to the degree of skeletal muscle immune cell infiltration, mitochondrial respiratory chain complex, DAMPs, the TCA cycle, and mitochondrial metabolism. Bayesian network inference showed that IL-6 and PGC1-α may be the main regulatory genes of mitochondrial damage in DOMS. Transmission electron microscopy revealed swelling of skeletal muscle mitochondria and disorganization of myofilaments.ConclusionsOur study found that skeletal muscle mitochondrial damage is one of the causes of inflammatory factor accumulation in DOMS. According to the screened-out hub genes, this study provides a reference for follow-up clinical application.

Inhibitory Neurons in Nucleus Tractus Solitarius Are Involved in Decrease of Heart Rate Variability and Development of Depression-Like Behaviors in Temporal Lobe Epilepsy.

Diminished heart rate variability (HRV) has been observed in epilepsy, especially in epilepsy with depressive disorders. However, the underlying mechanism remains elusive. We studied HRV, spontaneous recurrent seizures, and depression-like behaviors in different phases of pilocarpine-induced temporal lobe epilepsy (TLE) in mice. Single-cell RNA sequencing analysis was used to identify various nerve cell subsets in TLE mice with and without depression. Differentially expressed gene (DEG) analysis was performed in epilepsy, depression, and HRV central control-related brain areas. We found decreased HRV parameters in TLE mice, and alterations were positively correlated with the severity of depression-like behaviors. The severity of depression-like behaviors was correlated with the frequency of spontaneous recurrent seizure. Characteristic expression of mitochondria-related genes was significantly elevated in mice with depression in glial cells, and the enrichment analysis of those DEGs showed an enriched GABAergic synapse pathway in the HRV central control-related brain area. Furthermore, inhibitory neurons in the nucleus tractus solitarius, which is an HRV central control-related brain area, were specifically expressed in TLE mice combined with depression compared with those in mice without depression. A significantly enriched long-term depression pathway in DEGs from inhibitory neurons was found. Our study reported correlations between HRV and epilepsy-depression comorbidity in different phases of TLE. More importantly, we found that HRV central control-related inhibitory neurons are involved in the development of depression in TLE, providing new insights into epilepsy comorbid with depression.

Depot-specific adaption of adipose tissue for different exercise approaches in high-fat diet/streptozocin-induced diabetic mice.

Background: Adipose tissue pathology plays a crucial role in the pathogenesis of type 2 diabetes mellitus. Understanding the impact of exercise training on adipose tissue adaptation is of paramount importance in enhancing metabolic health. In this study, we aimed to investigate the effects of various exercise modalities on three distinct adipose tissue depots, namely, interscapular brown adipose tissue (iBAT), subcutaneous white adipose tissue (sWAT), and epididymal white adipose tissue (eWAT), in a murine model of diabetes. Methods: Male C57BL/6J mice received a 12-week high-fat diet and a single injection of streptozotocin, followed by an 8-week exercise intervention. The exercise intervention included swimming, resistance training, aerobic exercise, and high-intensity interval training (HIIT). Results: We found that exercise training reduced body weight and body fat percentage, diminished adipocyte size and increased the expression of mitochondria-related genes (PGC1, COX4, and COX8B) in three adipose tissue depots. The effects of exercise on inflammatory status include a reduction in crown-like structures and the expression of inflammatory factors, mainly in eWAT. Besides, exercise only induces the browning of sWAT, which may be related to the expression of the sympathetic marker tyrosine hydroxylase. Among the four forms of exercise, HIIT was the most effective in reducing body fat percentage, increasing muscle mass and reducing eWAT adipocyte size. The expression of oxidative phosphorylation and thermogenesis-related genes in sWAT and eWAT was highest in the HIIT group. Conclusion: When targeting adipose tissue to improve diabetes, HIIT may offer superior benefits and thus represents a more advantageous choice.

Preclinical characterization of WB737, a potent and selective STAT3 inhibitor, in natural killer/T-cell lymphoma.

Natural killer/T-cell lymphoma (NKTL) is an uncommon malignancy with poor prognosis and limited therapeutic options. Activating mutations of signal transducer and activator of transcription 3 (STAT3) are frequently found in patients with NKTL, suggesting that targeted inhibition of STAT3 is a potential therapeutic option for this disease. Here, we have developed a small molecule drug WB737 as a novel and potent STAT3 inhibitor that directly binds to the STAT3-Src homology 2 domain with high affinity. In addition, the binding affinity of WB737 to STAT3 is 250-fold higher than STAT1 and STAT2. Interestingly, WB737 is more selective for NKTL with STAT3-activating mutations in terms of growth inhibition and apoptotic induction when compared with Stattic. Mechanistically, WB737 inhibits both canonical and noncanonical STAT3 signaling via suppression of STAT3 phosphorylation at Tyr705 and Ser727, respectively, thereby inhibiting the expression of c-Myc and mitochondria-related genes. Moreover, WB737 inhibited STAT3 more potently than Stattic, resulting in a significant antitumor effect with undetectable toxicity, followed by almost complete tumor regression in an NKTL xenograft model harboring a STAT3-activating mutation. Taken together, these findings provide preclinical proof-of-concept for WB737 as a novel therapeutic strategy for the treatment of NKTL patients with STAT3-activating mutations.

Dysregulation of Immune Cell Subpopulations in Atypical Hemolytic Uremic Syndrome.

Atypical hemolytic uremic syndrome (aHUS) is a rare, life-threatening thrombotic microangiopathy. Definitive biomarkers for disease diagnosis and activity remain elusive, making the exploration of molecular markers paramount. We conducted single-cell sequencing on peripheral blood mononuclear cells from 13 aHUS patients, 3 unaffected family members of aHUS patients, and 4 healthy controls. We identified 32 distinct subpopulations encompassing 5 B-cell types, 16 T- and natural killer (NK) cell types, 7 monocyte types, and 4 other cell types. Notably, we observed a significant increase in intermediate monocytes in unstable aHUS patients. Subclustering analysis revealed seven elevated expression genes, including NEAT1, MT-ATP6, MT-CYB, VIM, ACTG1, RPL13, and KLRB1, in unstable aHUS patients, and four heightened expression genes, including RPS27, RPS4X, RPL23, and GZMH genes, in stable aHUS patients. Additionally, an increase in the expression of mitochondria-related genes suggested a potential influence of cell metabolism on the clinical progression of the disease. Pseudotime trajectory analysis revealed a unique immune cell differentiation pattern, while cell-cell interaction profiling highlighted distinctive signaling pathways among patients, family members, and controls. This single-cell sequencing study is the first to confirm immune cell dysregulation in aHUS pathogenesis, offering valuable insights into molecular mechanisms and potential new diagnostic and disease activity markers.

Connecting Dots between Mitochondrial Dysfunction and Depression.

Mitochondria are the prime source of cellular energy, and are also responsible for important processes such as oxidative stress, apoptosis and Ca2+ homeostasis. Depression is a psychiatric disease characterized by alteration in the metabolism, neurotransmission and neuroplasticity. In this manuscript, we summarize the recent evidence linking mitochondrial dysfunction to the pathophysiology of depression. Impaired expression of mitochondria-related genes, damage to mitochondrial membrane proteins and lipids, disruption of the electron transport chain, higher oxidative stress, neuroinflammation and apoptosis are all observed in preclinical models of depression and most of these parameters can be altered in the brain of patients with depression. A deeper knowledge of the depression pathophysiology and the identification of phenotypes and biomarkers with respect to mitochondrial dysfunction are needed to help early diagnosis and the development of new treatment strategies for this devastating disorder.

Constructing a novel mitochondrial-related gene signature for evaluating the tumor immune microenvironment and predicting survival in stomach adenocarcinoma

BackgroundThe incidence and mortality of gastric cancer ranks fifth and fourth worldwide among all malignancies, respectively. Accumulating evidences have revealed the close relationship between mitochondrial dysfunction and the initiation and progression of stomach cancer. However, rare prognostic models for mitochondrial-related gene risk have been built up in stomach cancer.MethodsIn current study, the expression and prognostic value of mitochondrial-related genes in stomach adenocarcinoma (STAD) patients were systematically analyzed to establish a mitochondrial-related risk model based on available TCGA and GEO databases. The tumor microenvironment (TME), immune cell infiltration, tumor mutation burden, and drug sensitivity of gastric adenocarcinoma patients were also investigated using R language, GraphPad Prism 8 and online databases.ResultsWe established a mitochondrial-related risk prognostic model including NOX4, ALDH3A2, FKBP10 and MAOA and validated its predictive power. This risk model indicated that the immune cell infiltration in high-risk group was significantly different from that in the low-risk group. Besides, the risk score was closely related to TME signature genes and immune checkpoint molecules, suggesting that the immunosuppressive tumor microenvironment might lead to poor prognosis in high-risk groups. Moreover, TIDE analysis demonstrated that combined analysis of risk score and immune score, or stromal score, or microsatellite status could more effectively predict the benefit of immunotherapy in STAD patients with different stratifications. Finally, rapamycin, PD-0325901 and dasatinib were found to be more effective for patients in the high-risk group, whereas AZD7762, CEP-701 and methotrexate were predicted to be more effective for patients in the low-risk group.ConclusionsOur results suggest that the mitochondrial-related risk model could be a reliable prognostic biomarker for personalized treatment of STAD patients.

Choroid plexus imaging to track neuroinflammation - a translational model for mouse and human studies.

Choroid plexus imaging to track neuroinflammation - a translational model for mouse and human studies.