Sam50 Regulates PINK1-Parkin-Mediated Mitophagy by Controlling PINK1 Stability and Mitochondrial Morphology

PINK1 and Parkin mediate mitophagy, the cellular process that clears dysfunctional mitochondria. Mitophagy is regulated by mitochondrial dynamics, but the molecules linking these two processes remain poorly understood. Here, we show that Sam50, the core component of the sorting and assembly machinery (SAM), is a critical regulator of mitochondrial dynamics and PINK1-Parkin-mediated mitophagy. In response to Sam50 depletion, normal tubular mitochondria are first fragmented and subsequently merged into large spheres. Sam50 interacts with PINK1 to facilitate its processing and degradation. Depletion of Sam50 results in PINK1 accumulation, Parkin recruitment, and mitophagy. Interestingly, Sam50 deficiency induces a piecemeal mode of mitophagy that eliminates mitochondria “bit by bit” but spares mtDNA. In C. elegans, the Sam50 homolog gop-3 is required for the maintenance of mitochondrial morphology and mass. Our findings reveal that Sam50 directly links mitochondrial dynamics and mitophagy and that Sam50 depletion induces elimination of mitochondria without affecting mtDNA content

Single-cell RNA sequencing shows the immune cell landscape in the kidneys of patients with idiopathic membranous nephropathy

Idiopathic membranous nephropathy (IMN) is a leading pathological type of the adult primary nephrotic syndrome. Some patients develop end-stage renal disease due to poor response to treatment with steroid and immunosuppressive agents. In order to explore the molecular mechanism of IMN, we collected renal tissue samples from IMN patients and healthy controls and performed analysis by single-cell RNA sequencing (scRNA-seq). A total of 11 kidney cell clusters were identified, including multiple myeloid cell clusters, NK/T cell clusters, and B cell clusters. Most kidney parenchymal and immune cells were enriched in the regulation of immune response, inflammation, fibrosis and endoplasmic reticulum stress. The macrophage population in the IMN group showed a highly activated profile with up-regulated genes related to chemotaxis, inflammation, phagocytosis and fibrosis. CD8+ T cells continued to be cytotoxic in IMN; however, a transition to “inflammageing” GZMK+ CD8+ T cells was observed. The proportion of activated B cells in renal tissues of IMN patients was much higher than that of normal controls, indicating that B cells in IMN might be activated by constant antigenic stimulation. Moreover, the cell-cell interaction analysis revealed the potential communication between renal glomerular cells and immune cells in IMN. Overall, scRNA-seq was applied to IMN to unravel the characteristics of immune cells and elucidate possible underlying mechanisms involved in the pathogenesis of IMN

Fatty acid metabolites of Dendrobium nobile were positively correlated with representative endophytic fungi at altitude

IntroductionAltitude, as a comprehensive ecological factor, regulates the growth and development of plants and microbial distribution. Dendrobium nobile (D. nobile) planted in habitats at different elevations in Chishui city, also shows metabolic differences and endophytes diversity. What is the triangular relationship between altitude, endophytes, and metabolites?MethodsIn this study, the diversity and species of endophytic fungi were tested by ITS sequencing and metabolic differences in plants were tested by UPLC–ESI–MS/MS. Elevation regulated the colonization of plant endophytic fungal species and fatty acid metabolites in D. nobile.ResultsThe results indicate that and high altitude was better for the accumulation of fatty acid metabolites. Therefore, the high-altitude characteristic endophytic floras were screened, and the correlation with fatty acid metabolites of plants was built. The colonization of T. rubrigenum, P. Incertae sedis unclassified, Phoma. cf. nebulosa JZG 2008 and Basidiomycota unclassified showed a significantly positive correlation with fatty acid metabolites, especially 18-carbon-chain fatty acids, such as (6Z,9Z,12Z)-octadeca-6,9,12-trienoic acid, 3,7,11,15-tetramethyl-12-oxohexadeca-2,4-dienoic acid and Octadec-9-en-12-ynoic acid. What is more fascinating is these fatty acids are the essential substrates of plant hormones.DiscussionConsequently, it was speculated that the D. nobile- colonizing endophytic fungi stimulated or upregulated the synthesis of fatty acid metabolites and even some plant hormones, thus affecting the metabolism and development of D. nobile

Experimental and Theoretical Investigations of the Constitutive Relations of Artificial Frozen Silty Clay

The strength and deformation characteristics of artificial frozen soils are quite sensitive to temperature, confining pressure, and water content. To investigate these effects, a series of triaxial compressive tests on frozen Harbin silty clay were conducted at temperatures of −5 °C, −10 °C, and −15 °C under different confining pressures and water contents. From the stress–strain curves under lower water content and confining pressure, strain–softening behavior was observed. The modified Duncan–Chang (MDC) model was employed to describe the constitutive relations of artificial frozen silty clay while considering the strain–softening effects. After introducing statistical damage (SD) theory, an SD constitutive model with the failure strain as a random variable was proposed, which is able to overcome the drawbacks of the MDC model. The predicted SD model results are found to be consistent with the experimental results

The role of circulating microRNAs in the diagnosis of Takotsubo cardiomyopathy

Takotsubo cardiomyopathy (TTC), also known as Stress cardiomyopathy, is a primary cardiomyopathy characterized by reversible ventricular wall motion abnormality. Its clinical manifestations are similar to acute myocardial infarction (AMI). So, it could be difficult to differentiate TTC from AMI in the early phases. The use of cardiac biomarkers in the diagnosis of TTC might be of considerable value. Until now, many scholars have discussed some novel cardiac biomarkers. These discussed markers, such as B-type natriuretic peptide (BNP), troponin I (TnI) and creatine kinase MB fraction (CKMB) provide a desirable diagnostic and prognostic value for TTC. However, the above related markers also have their limitations and it may take some time to apply them in routine clinical practice. In view of this, we need to find better biomarkers for use with TTC. MicroRNAs (miRNAs) are a class of high abundance, evolutionarily conserved, non-coding, small single-stranded RNAs that negatively regulate gene expression through binding on the 3’ untranslated region (UTR) of target mRNAs. Recently, some discovered miRNAs in body fluids seem promising to be utilized as biomarkers to monitor cardiovascular diseases’ initiation and progression. It is believed that expression of circulating miRNAs may reflect disease pathology

MicroRNA-24 Attenuates Neointimal Hyperplasia in the Diabetic Rat Carotid Artery Injury Model by Inhibiting Wnt4 Signaling Pathway

The long-term stimulation of hyperglycemia greatly increases the incidence of vascular restenosis (RS) after angioplasty. Neointimal hyperplasia after vascular injury is the pathological cause of RS, but its mechanism has not been elucidated. MicroRNA-24 (miR-24) has low expression in the injured carotid arteries of diabetic rats. However, the role of miR-24 in the vascular system is unknown. In this study, we explore whether over-expression of miR-24 could attenuate neointimal formation in streptozotocin (STZ)-induced diabetic rats. Adenovirus (Ad-miR-24-GFP) was used to deliver the miR-24 gene to injured carotid arteries in diabetic rats. The level of neointimal hyperplasia was examined by hematoxylin-eosin (HE) staining. Vascular smooth muscle cell (VSMC) proliferation in the neointima was evaluated by immunostaining for proliferating cell nuclear antigen (PCNA). The mRNA levels of miR-24, PCNA, wingless-type MMTV integration site family member 4 (Wnt4), disheveled-1 (Dvl-1), β-catenin and cell cycle-associated molecules (Cyclin D1, p21) were determined by Quantitative Real-Time PCR (qRT-PCR). PCNA, Wnt4, Dvl-1, β-catenin, Cyclin D1 and p21 protein levels were measured by Western blotting analysis. STZ administration decreased plasma insulin and increased fasting blood glucose in Sprague-Dawley (SD) rats. The expression of miR-24 was decreased in the carotid artery after a balloon injury in diabetic rats, and adenoviral transfection (Ad-miR-24-GFP) increased the expression of miR-24. Over-expression of miR-24 suppressed VSMC proliferation and neointimal hyperplasia in diabetic rats at 14 days. Furthermore, compared with Sham group, the mRNA and protein levels of PCNA, Wnt4, Dvl-1, β-catenin, and Cyclin D1 were strikingly up-regulated in the carotid arteries of diabetic rats after a balloon injury. Interestingly, up-regulation of miR-24 significantly reduced the mRNA and protein levels of these above molecules. In contrast, the change trend in p21 mRNA and protein levels was opposite after a balloon injury. However, over-expression of miR-24 after gene delivery increased the mRNA and protein levels of p21. We conclude that over-expression of miR-24 could attenuate VSMC proliferation and neointimal hyperplasia after vascular injuries in diabetic rats. This result is possibly related to the regulation of the expression of Cyclin D1 and p21 through the Wnt4/Dvl-1/β-catenin signaling pathway

Negative Correlation between Serum NLRP3 and the Ratio of Treg/Th17 in Patients with Obstructive Coronary Artery Disease

Background: Regulatory T (Treg) cells are a class of anti-inflammatory lymphocyte subpopulations with a potential protective effect against atherosclerosis, whereas T helper 17 (Th17) cells have been reported to possess proatherogenic activity. It was believed that disturbed circulating Treg/Th17 balance was associated with the onset and progression of atherosclerosis. This study is designed to probe the regulative action of serum Nod-like receptor protein 3 (NLRP3) on the Treg/Th17 balance in patients with atherosclerosis. Methods: Fifty-two patients with coronary atherosclerosis and stenosis degrees of more than 50% were assigned to the coronary artery disease (CAD) group, and an equal number of people without coronary atherosclerosis were assigned to the control group (assessed by coronary angiography). Peripheral blood mononuclear cells (PBMCs) from two group patients were extracted and cultivated. The calculation of the Treg/Th17 ratio and quantitative analysis of the Treg and Th17 cell frequencies were performed through flow cytometry. Real-time fluorescence quantitative polymerase chain reaction (RT-PCR) was executed for the quantitative mRNA detection of the fork head-winged helix transcription factor (Foxp3) and the retinoic acid-related orphan nuclear receptor C (RORC) in PBMCs. Enzyme-linked immunosorbent assays were applied to measure the serum level of NLRP3, interleukin (IL)-10, IL-1β, IL-17A, IL-23, and transforming growth factor (TGF)-β1. Additionally, the connection between serum Treg/Th17 ratio and NLRP3 levels was analyzed using the Pearson correlation coefficient. Results: The baseline parameters, including sex, age, or blood biochemical indices had no difference in both groups (p > 0.05). The CAD group showed higher Th17 cell frequency, lower Treg cell frequency, and a lower Treg/Th17 ratio when compared to the control (p < 0.05). Consistent with the variation in the T-cell subset ratio, in patients with atherosclerosis, the Th17-cell-related transcription factor RORC showed a markedly higher mRNA level (p < 0.05), conversely, the mRNA expression of the Treg cell-related transcription factor Foxp3 was notably reduced (p < 0.05). Similarly, the serum levels of NLRP3, IL-17A, IL-1, and IL-23 were significantly enhanced in CAD group but IL-10 and TGF-β1 were reduced (p < 0.05). Additionally, a negative correlation was found between NLRP3 and the Treg/Th17 ratio (r = –0.69, p < 0.001). Conclusions: Due to the potential impact on the serum Treg/Th17 ratio, NLRP3 may act as an aggravator in the onset and progression of atherosclerotic disease

Comparison of dexmedetomidine vs. remifentanil combined with sevoflurane during radiofrequency ablation of hepatocellular carcinoma: a randomized controlled trial

Abstract Background Remifentanil is widely used for ultrasound-guided percutaneous radiofrequency ablation (RFA) of small hepatocellular carcinoma (HCC). We determined whether dexmedetomidine could be an alternative to remifentanil for RFA of HCC under general anesthesia with sevoflurane. Methods We prospectively randomized patients scheduled to undergo RFA for HCC to a dexmedetomidine (DEX) group or remifentanil (REMI) group (47 patients each). In the DEX group, a bolus infusion (0.4 μg kg− 1) was started 15 min before anesthesia induction and continued at 0.2 μg kg− 1 h− 1 until 10 min before the end of surgery. In the REMI group, 3 μg kg− 1 h− 1 of remifentanil was administered from 15 min before anesthesia induction to the end of the surgery. The primary endpoint was postoperative pain intensity. Secondary endpoints included analgesic requirement, postoperative liver function, patient comfort, and hemodynamic changes. Group allocation was concealed from patients and data analysts but not from anesthesiologists. Results Postoperative pain intensity, analgesic consumption, comfort, liver function, and time to emergence and extubation did not differ between the two groups. Heart rate, but not mean arterial pressure, was significantly lower in the DEX group than in the REMI group, at 1 min after intubation and from 30 min after the start of the surgery until anesthesia recovery. Sevoflurane concentration and dosage were significantly lower in the DEX group than in the REMI group. Conclusion During RFA for HCC, low-dose dexmedetomidine reduced the heart rate and need for inhalational anesthetics, without exacerbating postoperative discomfort or liver dysfunction. Although it did not exhibit outstanding advantages over remifentanil in terms of pain management, dexmedetomidine could be a safe alternative adjuvant for RFA under sevoflurane anesthesia. Trial registration Chinese Clinical Trial Registry, ChiCTR-OPC-15006613. Registered on 16 June 2015