Molecular Medicine最新文献

Background: While nuclear DNA (nDNA) damage and alterations in nDNA repair are known to play a role in colon cancer (CC), there is insufficient research investigating these processes in mitochondrial DNA (mtDNA).

Methods: This study investigates mtDNA changes in CC, focusing on mitochondrial DNA copy number (mtDNA-CN) variations, mtDNA damage, and the expression and mutation status of DNA repair genes. Three cohorts were analyzed: healthy controls, colon adenoma patients, and CC patients, divided into a pilot and a validation set.

Results: Our findings revealed that mtDNA-CN was elevated in colon adenomas compared to adenoma-adjacent mucosa (FDR = 0.04), healthy mucosa (FDR = 0.005), and tumor-adjacent mucosa (FDR = 0.005). Moreover, mtDNA-CN was elevated in adenoma-adjacent mucosa compared to healthy mucosa (FDR = 0.04). MtDNA damage was greater in tumor-adjacent mucosa compared to tumor tissue in both the pilot and validation sets (FDR = 0.031 and FDR = 2.06e-05, respectively). Additionally, we identified novel DNA repair genes associated with mtDNA damage, predominantly upregulated in adenoma and tumor tissues compared to healthy colon tissues.

Conclusions: To conclude, this study highlights the importance of mtDNA alterations in CC development and identifies potential mtDNA biomarkers.

Respiratory Syncytial Virus (RSV) is a common cause of severe respiratory tract disease in infants, the elderly and immunocompromised patients. However, there is uncertainty as to how sample handling practices affect performance of tests to detect RSV. The aim of this study was to determine whether RSV RNA remains reliably detectable in nasopharyngeal/oropharyngeal (NP/OP) samples, saliva, and sputum samples over time.Respiratory samples were collected as part of a prospective observational study of acute lower respiratory tract disease (aLRTD) hospitalisations in adults in Bristol (UK). Samples that tested positive by PCR on receipt (0 h), were re-tested at 24 h having been stored at room temperature. We found that all but one of the samples PCR-positive for RSV at 0 h remained positive at 24 h, across all sample types and RSV strains. Ct values for NP/OP and saliva samples were significantly lower at 24 h than at 0 h, suggesting potential low-level viral replication in the samples. These results suggest that RSV tests can provide consistent results after a delay of up to 24 h following sample collection.

Background: Follistatin is a potent regulator of various TGF-β superfamily members, including myostatin (MSTN) and activin A. Previous studies have shown that follistatin is crucial in enhancing myogenesis during acute muscle injury. The mechanism by which fibro-adipogenic progenitors (FAPs)-specific follistatin influences muscle homeostasis in obese mice remains unknown. Therefore, we investigated the physiological role of follistatin in PDGFRα-positive FAPs in the regulation of muscle homeostasis and exercise in obese mice.

Methods: A PDGFRα-specific follistatin knockout (follistatin KO) mouse model was generated using PDGFRα-GFP-CreER^T2 (PDGFRα-GCE) and follistatin^flox/flox mice. These mice were fed a 60% high-fat diet (HFD) for 20 weeks, followed by a series of analyses, including exercise tolerance test, grip strength test, glucose and insulin tolerance assays, gene expression analysis, histology, western blotting, and immunohistochemistry.

Results: We showed that follistatin KO mice had reduced expression of Fst in skeletal muscle and white adipose tissue. We also showed that follistatin KO mice exhibited decreased exercise performance and altered skeletal homeostasis during obesity. Deletion of follistatin in FAPs activated the MSTN: Activin A/SMADs signaling pathways, which negatively impacted muscle homeostasis. Furthermore, follistatin KO mice showed reduced muscle mass, increased muscle degradation, and atrophic myofibers. Mitochondrial biogenesis, oxidative phosphorylation, and fatty acid oxidation were also altered in the skeletal muscles of follistatin KO mice.

Conclusion: Follistatin plays a protective role in mice by maintaining the metabolic health of skeletal muscles; it restores muscle function during HFD challenge, thereby reducing diet-induced obesity-related complications.

Background: Endothelial-to-mesenchymal transition (EndMT) in endothelial dysfunction exacerbates hypertension. However, the regulatory mechanisms underlying EndMT in hypertension are yet to be elucidated.

Methods: The N-acetyltransferase 10 (NAT10) and N4-acetylcytidine (ac4C) levels were determined in hypertensive mice, spontaneously hypertensive rats (SHRs), and angiotensin II (Ang II)-treated human umbilical vein endothelial cells (HUVECs). Biological functional assays were performed with lentiviral vectors to induce the overexpression or knockdown of NAT10 in vivo and in vitro. The detailed mechanisms underlying the role of ac4C-mediated posttranscriptional regulation in hypertension were investigated by combining ac4C-RIP-seq with RNA-seq, RIP-qRCR, mRNA stability, and dual-luciferase assays. Mitochondrial biogenesis and function were assessed via reactive oxygen species (ROS) and mitochondrial ROS (mtROS) staining; estimation of ATP levels, the mitochondrial membrane potential (MMP), and the mtDNA content; and evaluation of mitochondrial respiratory chain complex activities.

Results: The results revealed that NAT10 and ac4C levels are higher in the hypertensive mice descending thoracic aorta tissues, SHRs descending thoracic aorta samples, and Ang II-treated HUVECs compared to the control groups. NAT10 overexpression inhibits EndMT in hypertension, which is partly due to the inhibition of endothelial dysfunction, whereas NAT10 inhibition has the opposite effect. Mechanistically, NAT10 inhibited endothelial dysfunction in hypertension through increased AdipoR1 mRNA ac4C acetylation. Moreover, NAT10 induced AdipoR1 expression, leading to increased mitochondrial biogenesis and function in Ang II-treated ECs via p38 MAPK/PGC-1α signaling.

Conclusions: The current data highlighted the molecular mechanisms of NAT10-induced ac4C acetylation and implied that the NAT10-AdipoR1 axis might be the therapeutic target to inhibit endothelial dysfunction and EndMT in hypertension.

Background: Giant cell arteritis (GCA) is a chronic granulomatous inflammatory disease involving large- and medium-sized arteries. The disease spectrum comprises cranial (C-GCA), extracranial (EC-GCA) and mixed phenotypes. Toll-like receptors (TLRs) in the affected arteries may play an important role in GCA pathogenesis. However, data on TLR and TLR-ligands expression pattern in GCA arteries are lacking.

Objective: To investigate the expression of TLRs and putative ligands in temporal artery biopsies (TAB) from C-GCA, EC-GCA and isolated polymyalgia rheumatica (PMR) patients to establish a link between TLRs, antigen expression, and disease stage. To correlate the plasma levels of identified TLR-ligands with standard inflammatory markers (IL-6, CRP, ESR) in these patients.

Methods: Immunofluorescence staining of TLR2/4/7/8, HMGB-1, SAA, fibrinogen, and p-glycoprotein was performed with TABs of six biopsy proven C-GCA, six EC-GCA, five PMR patients and seven age-matched controls. Association studies among plasma inflammatory markers were done with 139 PMR and 40 GCA patients.

Results: The levels of TLR2/4/7/8 and the alarmins HMGB-1, SAA, and fibrinogen were highly increased in C-GCA TABs in the sites of inflammation and less in EC-GCA TABs. P-glycoprotein was overexpressed in C-GCA TABs. Glucocorticoids or TAK1-inhibitor treatment decreased the fibrinogen- and SAA-mediated IL-6 production in control PBMCs. Plasma levels of SAA and fibrinogen associated strongly with CRP and ESR levels.

Conclusion: TLRs are overexpressed at the site of vascular inflammation in C-GCA and at a lower level in EC-GCA and PMR with negative TAB. Moreover, HMGB-1, SAA, and fibrinogen may serve as disease biomarkers of patients with C-GCA.

Parkinson's disease (PD) is a progressive neurodegenerative disorder characterized by the pathological accumulation of α-synuclein aggregates and the selective degeneration of dopaminergic neurons in the substantia nigra. Growing evidence implicates dysfunction of the ubiquitin-proteasome system (UPS), a critical regulator of protein homeostasis, in the pathogenesis of PD through impaired clearance of toxic protein species. As key components of the UPS, deubiquitinating enzymes (DUBs) counterbalance ubiquitin ligase activity by cleaving ubiquitin chains from substrate proteins, thereby playing pivotal roles in maintaining protein turnover and regulating cellular signaling pathways. Notably, emerging research has demonstrated that specific DUBs are intimately involved in modulating multiple PD-related pathological processes, including α-synuclein aggregation, mitochondrial oxidative stress, iron homeostasis, and neuronal survival. These findings suggest DUBs as promising therapeutic targets for PD intervention. This review comprehensively summarize the pathophysiological roles of PD-associated DUBs, their molecular mechanisms in disease progression, and recent advances in the development of DUB inhibitors as potential disease-modifying therapies for PD.

Background: The neuromuscular junction (NMJ) is the synapse between motor neurons and skeletal muscle and controlls movement. Impaired synaptic transmission and NMJ degeneration has been observed during healthy ageing and is also implicated in several neuromuscular diseases. On account of the high energy demands of being distally located and large sized, NMJs are enriched with mitochondria. This enrichment is dependent on transport of mitochondria across the axon to the NMJ.

Methods: We first established a human 3D neuromuscular assembloid model to study in-vitro NMJs, by fusing human stem cell derived spinal cord organoids and primary skeletal muscle organoids. To determine whether enhancing axonal mitochondrial transport modulates NMJ formation and maintenance, we generated a CRISPR-Cas9 meditated knock-out of syntaphilin in human stem cells.

Results: Firstly, we characterised the neuromuscular assembloid model which showed functional innervated NMJs as measured by juxtaposed neurofilament⁺ axons and α-bungarotoxin⁺ acetylcholine receptors. Secondly, we showed that spinal cord selective genetic ablation of syntaphilin - an axonally localised mitochondrial anchor protein - resulted in increased mitochondrial motility in motor neurons, and consequently increased axonal density and NMJ formation.

Conclusion: This proof-of-concept study demonstrated that enhancing mitochondrial mobility could provide a therapeutic target to prevent NMJ degeneration.