Pathogens commonly disrupt the intestinal epithelial barrier; however, how the epithelial immune system senses the loss of intestinal barrier as a danger signal to activate self-defense is unclear. ...Through an unbiased approach in the model nematode Caenorhabditis elegans, we found that the EGL-44/TEAD transcription factor and its transcriptional activator YAP-1/YAP (Yes-associated protein) were activated when the intestinal barrier was disrupted by infections with the pathogenic bacterium Pseudomonas aeruginosa PA14. Gene Ontology enrichment analysis of the genes containing the TEAD-binding sites revealed that "innate immune response" and "defense response to Gram-negative bacterium" were two top significantly overrepresented terms. Genetic inactivation of yap-1 and egl-44 significantly reduced the survival rate and promoted bacterial accumulation in worms after bacterial infections. Furthermore, we found that disturbance of the E-cadherin-based adherens junction triggered the nuclear translocation and activation of YAP-1/YAP in the gut of worms. Although YAP is a major downstream effector of the Hippo signaling, our study revealed that the activation of YAP-1/YAP was independent of the Hippo pathway during disruption of intestinal barrier. After screening 10 serine/threonine phosphatases, we identified that PP2A phosphatase was involved in the activation of YAP-1/YAP after intestinal barrier loss induced by bacterial infections. Additionally, our study demonstrated that the function of YAP was evolutionarily conserved in mice. Our study highlights how the intestinal epithelium recognizes the loss of the epithelial barrier as a danger signal to deploy defenses against pathogens, uncovering an immune surveillance program in the intestinal epithelium.
Metabolic disorders, such as obesity and type 2 diabetes, are associated with an increased risk of cardiomyopathy. To date, microRNA (miRNAs) functions in cardiac remodeling induced by obesity remain ...to be elucidated. We found that rats fed a high fat diet (HFD) manifested cardiac fibrosis and LV dysfunction. In the heart of rats fed HFD, the phosphorylation levels of Smad 2 and the expression of fibrotic genes, such as connective tissue growth factor, collagen-1α1 (Col1α1), Col3α1, and Col4α1, were up-regulated, which accompanied by an increase in Smad 7 protein levels, but not its mRNA levels. Using miRNA microarray analysis, we showed that the miRNA miR-410-5p inhibited the protein expression of Smad 7, thus increasing the phosphorylation levels of Smad 2. Overexpression of miR-410-5p promoted cardiac fibrosis in rats fed normal diet, whereas inhibition of miR-410-5p by way of miR-410-5p antimiR suppressed cardiac fibrosis in rats fed HFD. Finally, our data revealed that miR-410-5p from the kidney and adipose tissues was probably transferred to heart to induce cardiac fibrosis. Taken together, our study characterizes an endocrine mechanism in which adipose- or kidney-derived circulating miR-410-5p regulates metabolic disorders-mediated cardiac remodeling by activating the TGFβ/Smad signaling in heart.
Metabolism is intimately linked to aging. There is a growing number of studies showing that endogenous metabolites may delay aging and improve healthspan. Through the analysis of existing ...transcriptome data, we discover a link between activation of the transsulfuration pathway and a transcriptional program involved in peroxisome function and biogenesis in long-lived glp-1(e2141ts) mutant Caenorhabditis elegans worms. Subsequently, we show that supplementation with α-ketobutyrate, an intermediate of the transsulfuration pathway, extends lifespan in wild-type worms. Alpha-ketobutyrate augments the production of NAD
via the lactate dehydrogenase LDH-1, leading to SIR-2.1/SIRT1-mediated enhanced peroxisome function and biogenesis, along with a concomitant increase in the expression of acox-1.2/ACOX1 in the peroxisomal fatty acid β-oxidation pathway. ACOX-1.2/ACOX1 promotes H
O
formation, thereby resulting in activation of SKN-1/NRF2. This transcription factor in turn extends the lifespan of worms by driving expression of autophagic and lysosomal genes. Finally, we show that α-ketobutyrate also delays the cellular senescence in fibroblast cells through the SIRT1-ACOX1-H
O
-NRF2 pathway. This finding uncovers a previously unknown role for α-ketobutyrate in organismal lifespan and healthspan by coordinating the NAD
-SIRT1 signaling and peroxisomal function.
Background & Aims
Insulin resistance is strongly associated with non‐alcoholic fatty liver disease, a chronic, obesity–related liver disease. Increased endoplasmic reticulum (ER) stress plays an ...important role in the development of insulin resistance. In this study, we investigated the roles of miRNAs in regulating ER stress in the liver of rats with obesity.
Methods
We used miRNA microarray to determine the miRNA expression profiles in the liver of rats fed with a high fat diet (HFD). We used prediction algorithms and luciferase reporter assay to identify the target gene of miRNAs. To overexpress the miRNA miR‐30b or inhibit miR‐30b rats were injected with lentivirus particles containing PGLV3‐miR‐30b or PGLV3‐miR‐30b antimiR through tail vein. Hepatic steatosis was measured using transient elastography in human subjects.
Results
Our data showed that miR‐30b was markedly up‐regulated in the liver of HFD–treated rats. Bioinformatic and in vitro and in vivo studies led us to identify sarco(endo)plasmic reticulum Ca2+‐ATPase 2b (SERCA2b), as a novel target of miR‐30b. Overexpression of miR‐30b induced ER stress and insulin resistance in rats fed with normal diet, whereas inhibition of miR‐30b by miR‐30b antimiR suppressed ER stress and insulin resistance in HFD–treated rats. Finally, our data demonstrated that there was a positive correlation between serum miR‐30b levels and hepatic steatosis or homoeostasis model assessment of insulin resistance (HOMA‐IR) in human subjects.
Conclusions
Our findings suggest that miR‐30b represents not only a potential target for the treatment of insulin resistance, but also a non‐invasive disease biomarker of NAFLD.
Background
Although the adiponectin signalling exerts exercise‐mimicking effects, whether this pathway contributes to the anti‐ageing benefits of physical exercise has not been established yet.
...Methods
Swim exercise training and wheel running were used to measure lifespan in the nematode Caenorhabditis elegans and skeletal muscle quality in mice, respectively. Muscle weight, muscle fibre cross‐sectional area (CSA) and myonuclei number were used to evaluate muscle mass. RNA sequencing (RNA‐Seq) analysis of skeletal muscle in exercised mice was used to study the underlying mechanisms. Western blot and immunofluorescence were performed to explore autophagy‐ and senescence‐related markers.
Results
The C. elegans adiponectin receptor PAQR‐1/AdipoR1, but not PAQR‐2/AdipoR2, was activated (3.55‐fold and 3.48‐fold increases in p‐AMPK on Days 1 and 6, respectively, P < 0.001), which was involved in lifespan extension in exercised worms. Exercise training increased skeletal muscle mass index (1.29‐fold, P < 0.01), muscle weight (1.75‐fold, P < 0.001), myonuclei number (1.33‐fold, P < 0.05), muscle fibre CSA (1.39‐fold, P < 0.05) and capillary abundance (2.19‐fold, P < 0.001 for capillary density; 1.58‐fold, P < 0.01 for capillary number) in aged mice. Physical exercise reduced protein (2.94‐fold, P < 0.001) and mRNA levels (1.70‐fold, P < 0.001) of p16INK4a, a marker for cellular senescence, in skeletal muscle of aged mice. These beneficial effects of exercise on skeletal muscle of mice were dependent on AdipoR1. Kyoto Encyclopedia of Genes and Genomes (KEGG) analysis for differentially expressed genes in skeletal muscle between exercised mice with and without AdipoR1 knockdown by RNA‐Seq analysis revealed that several KEGG pathways, such as ‘AMPK signalling pathway’ (P < 0.001), ‘FOXO signalling pathway’ (P < 0.001) and ‘autophagy’ (P < 0.001) were overrepresented. Knockdown of FoxO3a inhibited exercise‐mediated beneficial effects on skeletal muscle quality of mice by inhibiting autophagy/mitophagy (3.81‐fold reduction in LC3‐II protein, P < 0.001; 1.53‐fold reduction in BNIP3 protein, P < 0.05). Knockdown of daf‐16, the FoxO homologue in C. elegans, reduced autophagy (2.77‐fold and 2.06‐fold reduction in GFP::LGG‐1 puncta in seam cells and the intestine, respectively, P < 0.05) and blocked lifespan extension by exercise in worms.
Conclusions
Our findings provide insights into how the AdipoR1 pathway has an impact on the anti‐ageing benefits of exercise and implicate that activation of the AdipoR1 signalling may represent a potential therapeutic strategy for reducing age‐related loss of skeletal muscle.
An imbalance of the gut microbiota, termed dysbiosis, has a substantial impact on host physiology. However, the mechanism by which host deals with gut dysbiosis to maintain fitness remains largely ...unknown. In Caenorhabditis elegans, Escherichia coli, which is its bacterial diet, proliferates in its intestinal lumen during aging. Here, we demonstrate that progressive intestinal proliferation of E. coli activates the transcription factor DAF-16, which is required for maintenance of longevity and organismal fitness in worms with age. DAF-16 up-regulates two lysozymes lys-7 and lys-8, thus limiting the bacterial accumulation in the gut of worms during aging. During dysbiosis, the levels of indole produced by E. coli are increased in worms. Indole is involved in the activation of DAF-16 by TRPA-1 in neurons of worms. Our finding demonstrates that indole functions as a microbial signal of gut dysbiosis to promote fitness of the host.
Angiotensin-converting enzyme 2 (ACE2) is a major cell entry receptor for severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). The induction of ACE2 expression may serve as a strategy by ...SARS-CoV-2 to facilitate its propagation. However, the regulatory mechanisms of ACE2 expression after viral infection remain largely unknown. Using 45 different luciferase reporters, the transcription factors SP1 and HNF4α were found to positively and negatively regulate ACE2 expression, respectively, at the transcriptional level in human lung epithelial cells (HPAEpiCs). SARS-CoV-2 infection increased the transcriptional activity of SP1 while inhibiting that of HNF4α. The PI3K/AKT signaling pathway, activated by SARS-CoV-2 infection, served as a crucial regulatory node, inducing ACE2 expression by enhancing SP1 phosphorylation-a marker of its activity-and reducing the nuclear localization of HNF4α. However, colchicine treatment inhibited the PI3K/AKT signaling pathway, thereby suppressing ACE2 expression. In Syrian hamsters (
) infected with SARS-CoV-2, inhibition of SP1 by either mithramycin A or colchicine resulted in reduced viral replication and tissue injury. In summary, our study uncovers a novel function of SP1 in the regulation of ACE2 expression and identifies SP1 as a potential target to reduce SARS-CoV-2 infection.
Background
As a biomarker of alveolar-capillary basement membrane injury, Krebs von den Lungen-6 (KL-6) is involved in the occurrence and development of pulmonary diseases. However, the role of the ...KL-6 in patients with acute exacerbation of chronic obstructive pulmonary disease (AECOPD) has yet to be elucidated. This prospective study was designed to clarify the associations of the serum KL-6 with the severity and prognosis in patients with AECOPD.
Methods
This study enrolled 199 eligible AECOPD patients. Demographic data and clinical characteristics were recorded. Follow-up was tracked to evaluate acute exacerbation and death. The serum KL-6 concentration was measured via an enzyme-linked immunosorbent assay.
Results
Serum KL-6 level at admission was higher in AECOPD patients than in control subjects. The serum KL-6 concentration gradually elevated with increasing severity of AECOPD. Pearson and Spearman analyses revealed that the serum KL-6 concentration was positively correlated with the severity score, monocyte count and concentrations of C-reactive protein, interleukin-6, uric acid, and lactate dehydrogenase in AECOPD patients during hospitalization. A statistical analysis of long-term follow-up data showed that elevated KL-6 level at admission was associated with longer hospital stays, an increased risk of future frequent acute exacerbations, and increased severity of exacerbation in COPD patients.
Conclusion
Serum KL-6 level at admission is positively correlated with increased disease severity, prolonged hospital stay and increased risk of future acute exacerbations in COPD patients. There are positive dose–response associations of elevated serum KL-6 with severity and poor prognosis in COPD patients. The serum KL-6 concentration could be a novel diagnostic and prognostic biomarker in AECOPD patients.
Autophagy, a conserved pathway that delivers intracellular materials into lysosomes for degradation, is involved in development, aging, and a variety of diseases. Accumulating evidence demonstrates ...that autophagy plays a protective role against infectious diseases by diminishing intracellular pathogens, including bacteria, viruses, and parasites. However, the mechanism by which autophagy regulates innate immunity remains largely unknown. Here, we show that autophagy is involved in host defense against a pathogenic bacterium Pseudomonas aeruginosa in the metazoan Caenorhabditis elegans . P. aeruginosa infection induces autophagy via a conserved extracellular signal-regulated kinase (ERK). Intriguingly, impairment of autophagy does not influence the intestinal accumulation of P. aeruginosa , but instead induces intestinal necrosis. Inhibition of necrosis results in the survival of autophagy-deficient worms after P. aeruginosa infection. These findings reveal a previously unidentified role for autophagy in protection against necrosis triggered by pathogenic bacteria in C. elegans and implicate that such a function of autophagy may be conserved through the inflammatory response in diverse organisms.
The unfolded protein response (UPR), which is activated by perturbations of the endoplasmic reticulum homeostasis, has been shown to play an important role in innate immunity and inflammation. ...However, little is known about the molecular mechanisms underlying activation of the UPR during immune responses. Using small RNA deep sequencing and reverse genetic analysis, we show that the microRNA mir-233 is required for activation of the UPR in Caenorhabditis elegans exposed to Pseudomonas aeruginosa PA14. P. aeruginosa infection up-regulates the expression of mir-233 in a p38 MAPK-dependent manner. Quantitative proteomic analysis identifies SCA-1, a C. elegans homologue of the sarco/endoplasmic reticulum Ca2+-ATPase, as a target of mir-233. During P. aeruginosa PA14 infection, mir-233 represses the protein levels of SCA-1, which in turn leads to activation of the UPR. Whereas mir-233 mutants are more sensitive to P. aeruginosa infection, knockdown of sca-1 leads to enhanced resistance to the killing by P. aeruginosa. Our study indicates that microRNA-dependent pathways may have an impact on innate immunity by activating the UPR.
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