Search Results (246)

Chemotherapy remains a cornerstone in the treatment of esophageal cancer (EC), yet chemoresistance remains a critical challenge, leading to poor outcomes and limited therapeutic success. Mitochondrial DNA (mtDNA) has emerged as a pivotal player in mediating these responses, influencing cellular metabolism, oxidative stress regulation, and apoptotic pathways. This review provides a comprehensive overview of the mechanisms by which mtDNA alterations, including mutations and copy number variations, drive chemoresistance in EC. Specific focus is given to the role of mtDNA in metabolic reprogramming, including its contribution to the Warburg effect and lipid metabolism, as well as its impact on epithelial–mesenchymal transition (EMT) and mitochondrial bioenergetics. Recent advances in targeting mitochondrial pathways through novel therapeutic agents, such as metformin and mitoquinone, and innovative approaches like CRISPR/Cas9 gene editing, are also discussed. These interventions highlight the potential for overcoming chemoresistance and improving patient outcomes. By integrating mitochondrial diagnostics with personalized treatment strategies, we propose a roadmap for future research that bridges basic mitochondrial biology with translational applications in oncology. The insights offered in this review emphasize the critical need for continued exploration of mtDNA-targeted therapies to address the unmet needs in EC management and other diseases associated with mitochondria. Full article

Insulin resistance is a fundamental pathophysiological mechanism contributing to the development of type 2 diabetes and metabolic syndrome. Recently, attention has focused on mitochondria’s role in glucose and lipid metabolism. Mitochondrial dysfunction is strongly associated with impaired energy metabolism and elevated oxidative stress. We investigated the mitochondrial DNA (mtDNA) copy number in subcutaneous adipose tissue (SAT) and visceral adipose tissue (VAT) in insulin-sensitive (IS) and insulin-resistant (IR) individuals. Twenty-seven paired adipose tissue biopsies were obtained during elective abdominal surgery. DNA and RNA were extracted, and mtDNA copy number was quantified using Real-Time PCR. We found that mtDNA content in VAT was approximately two-fold lower than in SAT. Furthermore, in IR individuals, mtDNA copy number was significantly reduced in both SAT and VAT compared to IS subjects. A strong positive correlation was observed between mtDNA content in VAT and body mass index (BMI), and a negative correlation was found with the QUICKI index. Additionally, mtDNA copy number in VAT positively correlated with the expression of several genes involved in insulin signalling, lipid metabolism, and other metabolic pathways. These findings underscore the central role of mitochondrial function in VAT in the context of metabolic disorders and suggest that targeting mitochondrial regulation in this tissue may represent a promising therapeutic approach. Full article

In this study, we investigated the mitochondrial defects resulting from the deletion of GCN5, a lysine-acetyltransferase, in the yeast Saccharomyces cerevisiae. Gcn5 serves as the catalytic subunit of the SAGA acetylation complex and functions as an epigenetic regulator, primarily acetylating N-terminal lysine residues on histones H2B and H3 to modulate gene expression. The loss of GCN5 leads to mitochondrial abnormalities, including defects in mitochondrial morphology, a reduced mitochondrial DNA copy number, and defective mitochondrial inheritance due to the depolarization of actin filaments. These defects collectively trigger the activation of the mitophagy pathway. Interestingly, deleting CSN5, which encodes to Csn5/Rri1 (Csn5), the catalytic subunit of the COP9 signalosome complex, rescues the mitochondrial phenotypes observed in the gcn5Δ strain. Furthermore, these defects are suppressed by exogenous ergosterol supplementation, suggesting a link between the rescue effect mediated by CSN5 deletion and the regulatory role of Csn5 in the ergosterol biosynthetic pathway. Full article

Maternal obesity programs the fetus for increased risk of chronic disease development in early life and adulthood. We hypothesized that maternal nutrient excess leads to fetal inflammation and impairs offspring skeletal muscle mitochondrial biogenesis in non-human primates. At least 12 months before pregnancy, female baboons were fed a normal chow (CTR, 12% energy fat) or a maternal nutrient excess (MNE, 45% energy fat, and ad libitum fructose sodas) diet, with the latter to induce obesity. After 165 days of gestation (0.9 G), offspring baboons were delivered by cesarean section, and the soleus muscle was collected (CTR n = 16, MNE n = 5). At conception, MNE mothers presented increased body fat and weighed more than controls. The soleus muscle of MNE fetuses exhibited increased levels of stress signaling associated with inflammation (TLR4, TNFα, NF-kB p65, and p38), concomitant with reduced expression of key regulators of mitochondrial biogenesis, including PGC1α, both at the protein and transcript levels, as well as downregulation of PPARGC1B, PPARA, PPARB, CREB1, NOS3, SIRT1, SIRT3. Decreased transcript levels of NRF1 were observed alongside diminished mitochondrial DNA copy number, mitochondrial fusion elements (MFN1, MFN2), cytochrome C protein levels, and cytochrome C oxidase subunits I and II transcripts (cox1 and cox2). MNE coupled to MO-induced stress signaling in fetal baboon soleus muscle is associated with impaired mitochondrial biogenesis and lower mitochondrial content, resembling the changes observed in metabolic dysfunctions, such as diabetes. The observed fetal alterations may have important implications for postnatal development and metabolism, potentially increasing the risk of early-onset metabolic disorders and other non-communicable diseases. Full article

LC continues to be the leading cause of cancer mortality globally, among both males and females, representing a major public health challenge. The impact of mitochondria on human health and disease is a rapidly growing focus in scientific research, due to their critical roles in cellular survival and death. Mitochondria play an important role in controlling imperative cellular parameters, and alterations in mtDNAcn might be crucial for LC development. MtDNAcn has been studied as a possible marker for LC risk, but its role in prevention is still unclear. This review and meta-analysis aims to summarize the current evidence and provide an overall estimate of the relationship between the mtDNA copy number in human samples like blood and sputum. PubMed, Web of Science, and Scopus databases were used for studies published up to February 2024, following PRISMA and MOOSE guidelines. Studies were combined using a random-effects model, and we assessed the heterogeneity between studies with the chi-square-based Cochran’s Q statistic and the I² statistic. Publication bias was checked using Begg’s and Egger’s tests. Five studies, including a total of 3.748 participants, met the eligibility criteria. The MtDNA copy number was measured in blood or sputum samples and compared across different quantiles. The pooled analysis did not find a significant association between the mtDNA copy number and LC risk (OR = 0.94; 95% CI: 0.49–1.78). Moreover, when looking at different study designs, no significant results were found, due to the small number of studies available. No significant publication bias was detected. Further studies are needed to better understand the connection between the mtDNA copy number and LC risk and to better understand the role of potential confounders. Full article

Background: Ischemia–reperfusion injury (IRI) is a key contributor to graft dysfunction in kidney transplantation. Cell-free mitochondrial DNA (mtDNA) is increasingly recognized as a damage-associated molecular pattern (DAMP) and biomarker in IRI, but its prognostic role in living donor kidney transplantation (LDKT) remains unclear. Methods: This post hoc analysis of the VAPOR-1 study evaluated urinary mtDNA (UmtDNA) in 57 LDKT recipients. MtDNA levels (ND1, ND6, and D-loop) were measured at five early timepoints post-transplantation using qPCR. Associations between early UmtDNA and long-term graft function, defined by estimated glomerular filtration rate (eGFR) at 1, 12, and 24 months, were analyzed. Results: Higher UmtDNA levels in the first urine after reperfusion were significantly associated with improved eGFR at 12 months and a positive change in eGFR between month 1 and 24. These associations were not attributable to urine creatinine levels or mitochondrial copy number. Conclusions: In this LDKT cohort, elevated early UmtDNA may reflect a well-functioning graft capable of clearing systemic mtDNA rather than ongoing tubular injury. These findings suggest that the biological interpretation of mtDNA as a biomarker is context-dependent and call for careful reconsideration of its role in early transplant monitoring. Full article

Patients with chronic kidney disease (CKD) face an increased risk of early vascular aging, progressive vascular calcification, and premature death. With increasing age, mitochondrial function and mitochondrial DNA copy number (mtDNA-cn) decline. This has been identified as an independent predictor of frailty and mortality in cardiovascular diseases (CVDs) and cancer. However, the relationship between mtDNA-cn and vascular calcification in the context of a uremic milieu remains ambiguous. We hypothesize that a lower mtDNA-cn is associated with medial calcification, as both are linked to impaired vascular health and accelerated aging. mtDNA-cn was analyzed in 211 CKD5 patients undergoing renal transplantation (RTx) and 196 healthy controls using quantitative PCR (qPCR) for three mtDNA genes (mtND1, mtND4, and mtCOX1) and single-locus nuclear gene hemoglobin beta (HbB). In 32 patients, mtDNA-cn was also quantified one year after RTx. The association between mtDNA-cn and vascular calcification scores, circulatory cell-free (ccf) mtDNA in plasma, and the surrogate marker of biological aging (skin autofluorescence) and CVD risk was assessed. mtDNA-cn was significantly lower in CKD5 patients than in controls and correlated with biological age, vascular calcification, and CVD risk. One year after RTx there was a significant recovery of mtDNA-cn in male patients compared to baseline levels. mtDNA-cn and ccf-mtDNA were inversely correlated. This prospective study provides novel insights into the link between low mtDNA-cn and vascular aging. It demonstrates that RTx restores mtDNA levels and may improve oxidative phosphorylation capacity in CKD. Further investigation is warranted to evaluate mtDNA as a biologically relevant biomarker and a potential therapeutic target for early vascular aging in the uremic environment. Full article

Background/Objectives: Triple-negative breast cancer (TNBC) is a highly aggressive subtype with limited therapeutic options, and identifying reliable biomarkers for diagnosis and prognosis is crucial for improving patient outcomes. Mitochondrial DNA (mtDNA) copy number has been linked to an increased risk of developing various types of cancer, including breast cancer. However, there is a lack of understanding regarding how mtDNA copy number variations may influence the development and progression of TNBC. Methods: This study investigated mtDNA copy number in TNBC tumors and corresponding normal breast tissues from 23 TNBC patients who received neoadjuvant chemotherapy. The relative mtDNA copy number was estimated using quantitative PCR for the NADH dehydrogenase subunit 1 (ND1) and subunit 5 (ND5) regions. Results: The results showed a significant decrease in mtDNA copy number in TNBC tumor tissues compared to corresponding normal breast tissue. However, no significant correlation was found between mtDNA content and clinical parameters such as age, tumor size, or chemotherapy response. Conclusions: These results suggest that while mtDNA content decreases in TNBC tumors, it may not directly influence these clinical characteristics. Despite some inconsistencies in the literature regarding mtDNA dynamics in cancer, this study supports the potential of mtDNA as a biomarker for TNBC. Larger cohort studies are needed to further validate these results and explore the role of mtDNA in guiding personalized treatment strategies for TNBC patients. Full article

Background: Mitochondria are essential for placental function as they regulate energy metabolism, oxidative balance, and apoptotic signaling. Increasing evidence suggests that placental mitochondrial dysfunction may play a role in the development of many poor perinatal outcomes, including preeclampsia, intrauterine growth restriction (IUGR), premature birth, and stillbirth. Nonetheless, no systematic review has thoroughly investigated this connection across human research. This study aims to consolidate evidence from human research concerning the link between placental mitochondrial dysfunction and negative birth outcomes. Methods: A systematic search of PubMed, Scopus, and Web of Science identified human research examining placental mitochondrial features (e.g., mtDNA copy number, ATP production, oxidative stress indicators) in connection with adverse pregnancy outcomes. Methodological variety resulted in narrative data extraction and synthesis. Results: Twenty-nine studies met the inclusion criteria. Mitochondrial dysfunction was consistently associated with PE, IUGR, FGR, and PTB. The most often observed outcomes included diminished mtDNA copy number, decreased ATP production, elevated reactive oxygen species (ROS), and disrupted mitochondrial dynamics, characterized by increased DRP1 and decreased MFN2. Early-onset preeclampsia and symmetric fetal growth restriction exhibited particularly severe mitochondrial abnormalities, indicating a primary placental origin of the condition. Conclusions: A significant factor contributing to adverse pregnancy outcomes is the dysfunction of placental mitochondria. The analogous molecular signatures across many disorders suggest promising avenues for developing targeted therapies aimed at improving maternal–fetal health and predictive biomarkers. Full article

Malnutrition and aging are major factors that inhibit myoblast differentiation, leading to a decline in muscle function and contributing to sarcopenia development. This study aimed to elucidate the role of nutrients in myoblast differentiation by establishing a culture system at physiological glucose levels and investigating the effects of ketone bodies and oxaloacetate. We successfully cultured myoblasts at physiological glucose concentrations in a hydrophobic membrane filter-equipped culture flask. Under these conditions, ketone bodies and oxaloacetate synergistically upregulated myogenic differentiation markers (Lmod2 and Ckm), indicating enhanced differentiation. Additionally, oxaloacetate upregulated mitochondrial biogenesis markers (mitochondrial DNA copy number and Cs), whereas ketone bodies promoted Akt phosphorylation, a key regulator of differentiation, via the PI3K/Akt/mTOR pathway. These results suggest that the intake of ketone bodies and oxaloacetate effectively prevents sarcopenia by synergistically promoting myoblast differentiation via distinct molecular mechanisms, suggesting a potential new nutritional strategy. Full article

Diabetic kidney disease (DKD) displays a high prevalence of cardiovascular and cerebrovascular disease. Both the kidney and the brain share common pathogenic mechanisms, such as inflammation, endothelial dysfunction, oxidative stress, and mitochondrial dysfunction. The aim of this study was to establish a potential association of cerebral vessel remodeling and its related functional impairment with biomarkers of inflammation, oxidative stress, and mitochondrial dysfunction in the early stages of DKD in type 2 diabetes mellitus (DM) patients. A cohort of 184 patients and 39 healthy controls was assessed concerning serum and urinary stromal cell-derived factor-1 (SDF-1), P-selectin, advanced oxidation protein products (AOPPs), urinary synaptopodin, podocalyxin, kidney injury molecule-1 (KIM-1), and N-acetyl-β-(D)-glucosaminidase (NAG). The quantification of the mitochondrial DNA copy number (mtDNA-CN) and nuclear DNA (nDNA) in urine and peripheral blood was conducted using quantitative reverse transcription polymerase chain reaction (qRT-PCR). Using TaqMan tests, the beta-2 microglobulin nuclear gene (B2M) and the cytochrome b (CYTB) gene, which encodes subunit 2 of NADH dehydrogenase (ND2), were evaluated. The MtDNA-CN is the ratio of mitochondrial DNA to nuclear DNA copies, ascertained through the examination of the CYTB/B2M and ND2/B2M ratios. The intima-media thickness (IMT) measurements of the common carotid arteries (CCAs), along with the pulsatility index (PI) and resistivity index (RI) of the internal carotid arteries (ICAs) and middle cerebral arteries (MCAs), were obtained through cerebral Doppler ultrasonography (US). Additionally, the breath-holding index (BHI) was also measured by cerebral Doppler US. PI-ICAs, PI-MCAs, CCAs-IMT, RI-MCAs, and RI-ICAs demonstrated direct relationships with SDF-1, P-selectin, AOPPs, urine mtDNA, podocalyxin, synaptopodin, NAG, and KIM-1 while showing indirect correlations with serum mtDNA and the eGFR. In contrast, the BHI had negative correlations with SDF-1, P-selectin, AOPPs, urine mtDNA, synaptopodin, podocalyxin, KIM-1, and NAG while showing direct associations with serum mtDNA and the eGFR. In conclusion, a causative association exists among SDF-1, P-selectin, and AOPPs, as well as mitochondrial dysfunction, in early diabetic kidney disease (DKD) and significant cerebrovascular alterations in patients with type 2 diabetes mellitus and normoalbuminuric DKD, with no neurological symptoms. Full article

This study aimed to evaluate the effects of dietary 5-aminolevulinic acid (ALA) on laying hens to alleviate chronic heat stress-induced renal damage, resulting in improved egg productivity and eggshell quality. A total of 57 white-leghorn laying hens (46 weeks old) were randomly assigned to three groups and fed three experimental diets with different levels of ALA (0, 10, and 100 ppm) for 1 week. The birds in each group were then divided into two subgroups; one of the two subgroups was subjected to heat stress (33 °C for 3 weeks), whereas the other group was maintained at 24 °C. Heat exposure significantly decreased the laying rate and eggshell strength and caused renal damage, whereas ALA supplementation alleviated heat-induced poor productivity and renal damage. ALA increased the renal mitochondrial DNA copy number and downregulated the expression of the cGAS-STING pathway-related genes in the kidneys of heat-stressed hens. Furthermore, ALA upregulated the renal expression levels of NRF2 and HO-1, whereas it downregulated those of NF-κB and tended to decrease the content of TBARS in the kidney (p = 0.07). Dietary ALA confers a renal protective effect by reducing heat-induced mitochondrial damage and enhancing antioxidant activity, which may contribute to improved productivity under chronic heat stress. Full article

Mercury, a prevalent heavy metal, negatively impacts oocyte maturation. However, the exact mechanism by which methylmercury chloride (MMC) affects this process remains elusive. The present study found that MMC administration triggered meiotic failure in oocytes by disrupting cumulus cell expansion, leading to compromised spindle apparatus and altered chromosomal architecture, which are crucial for oocyte development. This disruption is characterized by abnormal microtubule organization and defective chromosome alignment. Additionally, MMC exposure caused oxidative stress-induced apoptosis due to mitochondrial dysfunction, as indicated by decreased mitochondrial membrane potential, mitochondrial content, mitochondrial DNA copy number, and adenosine triphosphate levels. Proteomic analysis identified 97 differentially expressed proteins, including P62, an autophagy marker. Our results confirmed that MMC induced autophagy, particularly through the hyperactivation of the mitochondrial autophagy to remove damaged and normal mitochondria. The mitochondrial reactive oxygen species (ROS) scavenger Mito-TEMPO alleviated oxidative stress and mitochondrial autophagy levels, suggesting that mitochondrial ROS initiates this autophagic response. Notably, MMC activates mitochondrial autophagy via the monophosphate-activated protein kinase (AMPK)/mammalian target of rapamycin (mTOR) signal pathway due to mitochondrial dysfunction. In vivo studies in mice revealed that MMC exposure decreased reproductive performance, attributed to excessive mitochondrial autophagy leading to reduced oocyte quality. Overall, these findings demonstrate that MMC exposure impairs oocyte maturation via the hyperactivation of mitochondrial autophagy induced by mitochondrial dysfunction. Full article

Hydrogen sulfide (H₂S) is a critical gasotransmitter that plays a dual role in physiological and pathological processes, particularly in the gastrointestinal tract. While physiological levels of H₂S exert cytoprotective effects, excessive concentrations can lead to toxicity, oxidative stress, and inflammation. The aim of this study was to investigate the dose-dependent effects of exogenous H₂S on mitochondrial functions and biogenesis in intestinal epithelial cells under non-stressed conditions. Using a Caco-2 monolayer model, we evaluated the impact of sodium hydrosulfide (NaHS) at concentrations ranging from 1 × 10⁻⁷ M to 5 × 10⁻³ M on mitochondrial metabolism, redox balance, antioxidant defense, inflammatory responses, autophagy/mitophagy, and apoptosis. Our results demonstrated a biphasic response: low-to-moderate H₂S concentrations (1 × 10⁻⁷ M–1.5 × 10⁻³ M) enhance mitochondrial biogenesis through PGC-1α activation, upregulating TFAM and COX-4 expression, and increasing the mtDNA copy number. In contrast, higher concentrations (2 × 10⁻³–5 × 10⁻³ M) impair mitochondrial function, induce oxidative stress, and promote apoptosis. These effects are associated with elevated reactive oxygen species (ROS) production, dysregulation of antioxidant enzymes, and COX-2-mediated inflammation. H₂S-induced autophagy/mitophagy is a protective mechanism at intermediate concentrations but fails to mitigate mitochondrial damage at toxic levels. This study underscores the delicate balance between the cytoprotective and cytotoxic effects of exogenous H₂S in intestinal cells, helping to develop new therapeutic approaches for gastrointestinal disorders. Full article

Traumatic brain injuries (TBIs) are a serious problem affecting individuals of all ages. Mitochondrial dysfunctions represent a significant form of secondary injury and may serve as a promising target for therapeutic intervention. Our research demonstrated that craniotomy, which precedes the experimental induction of trauma in mice, can cause considerable damage to mitochondrial DNA (mtDNA), disrupt the regulatory expression of angiogenesis, and increase inflammation. However, the reduction in the mtDNA copy number and glial activation occur only after a direct impact to the brain. We explored two potential therapeutic agents: the dietary supplement L-carnitine—a potential reserve source of ATP for the brain—and the cardiac drug mildronate, which inhibits L-carnitine but activates alternative compensatory pathways for the brain to adapt to metabolic disturbances. We found that L-carnitine injections could protect against mtDNA depletion by promoting mitochondrial biogenesis. However, they also appeared to aggravate inflammatory responses, likely due to changes in the composition of the gut microbiome. On the other hand, mildronate enhanced the expression of genes related to angiogenesis while also reducing local and systemic inflammation. Therefore, both compounds, despite their opposing metabolic effects, have the potential to be used in the treatment of secondary injuries caused by TBI. Full article