ABSTRACT
Activation of brown adipose tissue (BAT) thermogenesis increases energy expenditure and alleviates obesity. Here we discover that histone methyltransferase suppressor of variegation 4-20 homolog 2 (Suv420h2) expression parallels that of Ucp1 in brown and beige adipocytes and that Suv420h2 knockdown significantly reduces - whereas Suv420h2 overexpression significantly increases - Ucp1 levels in brown adipocytes. Suv420h2 knockout (H2KO) mice exhibit impaired cold-induced thermogenesis and are prone to diet-induced obesity. In contrast, mice with specific overexpression of Suv420h2 in adipocytes display enhanced cold-induced thermogenesis and are resistant to diet-induced obesity. Further study shows that Suv420h2 catalyzes H4K20 trimethylation at eukaryotic translation initiation factor 4E-binding protein 1 (4e-bp1) promoter, leading to downregulated expression of 4e-bp1, a negative regulator of the translation initiation complex. This in turn upregulates PGC1α protein levels, and this upregulation is associated with increased expression of thermogenic program. We conclude that Suv420h2 is a key regulator of brown/beige adipocyte development and thermogenesis.
Subject(s)
Adipocytes, Beige , Adipose Tissue, Brown , Histone-Lysine N-Methyltransferase , Mice, Knockout , Obesity , Thermogenesis , Uncoupling Protein 1 , Animals , Thermogenesis/genetics , Mice , Adipocytes, Beige/metabolism , Histone-Lysine N-Methyltransferase/metabolism , Histone-Lysine N-Methyltransferase/genetics , Obesity/metabolism , Obesity/genetics , Uncoupling Protein 1/metabolism , Uncoupling Protein 1/genetics , Adipose Tissue, Brown/metabolism , Peroxisome Proliferator-Activated Receptor Gamma Coactivator 1-alpha/metabolism , Peroxisome Proliferator-Activated Receptor Gamma Coactivator 1-alpha/genetics , Adipocytes, Brown/metabolism , Male , Cell Cycle Proteins/metabolism , Cell Cycle Proteins/genetics , Energy Metabolism , Mice, Inbred C57BLABSTRACT
Cancer metastasis is the primary cause of cancer deaths. Metastasis involves the spread of cancer cells from the primary tumors to other body parts, commonly through lymphatic and vascular pathways. Key aspects include the high mutation rate and the capability of metastatic cells to form invasive tumors even without a large initial tumor mass. Particular emphasis is given to early metastasis, occurring in initial cancer stages and often leading to misdiagnosis, which adversely affects survival and prognosis. The present review highlighted the need for improved understanding and detection methods for early metastasis, which has not been effectively identified clinically. The present review demonstrated the clinicopathological and molecular characteristics of earlyonset metastatic types of cancer, noting factors such as age, race, tumor size and location as well as the histological and pathological grade as significant predictors. In conclusion, the present review underscored the importance of early detection and management of metastatic types of cancer and called for improved predictive models, including advanced techniques such as nomograms and machine learning, so as to enhance patient outcomes, acknowledging the challenges and limitations of the current research as well as the necessity for further studies.
Subject(s)
Neoplasms , Nomograms , Humans , Neoplasm Staging , Prognosis , Neoplasms/diagnosis , Neoplasms/geneticsABSTRACT
The paper summarizes the clinical experience of professor ZHANG Ren in the staging treatment with characteristic acupuncture techniques for oculomotor paralysis. According to the symptoms of oculomotor paralysis, the staging treatment is given, in which acupuncture is dominant and the needling techniques are optioned in compliance with the symptoms. In the early, middle and late stages of illness, three different acupuncture therapies are delivered accordingly, i.e. the combination of the point-toward-point needling at the four acupoints located on the forehead and the electroacupuncture with disperse-dense wave, the surrounding needling and the triple needling at the acupoints around the eyeball, as well as the perpendicular needle insertion at the three acupoints within the orbit. Professor ZHANG Ren lays the stress on identifying the etiology and differentiating the symptoms, as well as the early intervention for the disease. For the intractable cases, the comprehensive regimen such as acupoint injection, dermal needling and auricular point sticking is supplemented. During treatment, the spirit harmonization is greatly considered to ensure the effectiveness. On the basis of the staging acupuncture therapy, the acupuncture technique for harmonizing the spirit and regulating qi is combined to obtain the favorable clinical effect on oculomotor paralysis.
Subject(s)
Acupuncture Therapy , Acupuncture , Electroacupuncture , Ophthalmoplegia , Humans , Acupuncture Therapy/methods , Acupuncture PointsABSTRACT
BACKGROUND: The practical application of moisture sensitive metal organic frameworks (MOFs) in extraction technology faces challenges related to competitive adsorption and water stability. The target analytes cannot be effectively extracted under humid conditions due to the competitive moisture adsorption and/or framework structure collapse of MOFs. In this study, the microporous organic networks (MONs) were synthesized through Sonogashira coupling reaction to use for hydrophobic modification on the surface of MOF-199. RESULTS: The MOF-199@MON as coating was deposited on stainless steel wires for solid-phase microextraction (SPME) of benzene series (BTEX) in aqueous environments. Under the optimal extraction conditions, the MOF-199@MON coated fiber for SPME coupled with GC-MS for the determination of BTEX gave the linear range of 0.5-500 µg L-1, the limit of detections (LODs, S/N = 3) of 0.01-0.04 µg L-1, the limit of quantifications (LOQs, S/N = 10) of 0.04-0.12 µg L-1, the enhancement factors of 3567-4878, and the intra-day, inter-day and fiber-to-fiber precisions (relative standard deviations, RSDs) of 1.0-9.8, 1.9-7.9 and 4.5-9.5 %, respectively. The developed method was successfully applied to the analysis of BTEX in water samples with the recoveries of 71.0 %-113 %. SIGNIFICANCE: This work reveals the home-made SPME fibers have a long service life (the extraction efficiency of fiber decreased by only 7.26 %-13.14 % after 100 cycles). The potential of MON functionalized MOFs as effective adsorbents for the SPME of pollutants in the water environment.
ABSTRACT
Non-small cell lung cancer (NSCLC) remains one of the leading causes of cancer-related deaths worldwide. Different treatment approaches are typically employed based on the stage of NSCLC. Common clinical treatment methods include surgical resection, drug therapy, and radiation therapy. However, with the introduction and utilization of immune checkpoint inhibitors, cancer treatment has entered a new era, completely revolutionizing the treatment landscape for various cancers and significantly improving overall patient survival. Concurrently, treatment resistance often poses a critical challenge, with many patients experiencing disease progression following an initial response due to treatment resistance. Increasing evidence suggests that the tumor microenvironment (TME) plays a pivotal role in treatment resistance. Tumor-associated macrophages (TAMs) within the TME can promote treatment resistance in NSCLC by secreting various cytokines activating signaling pathways, and interacting with other immune cells. Therefore, this article will focus on elucidating the key mechanisms of TAMs in treatment resistance and analyze how targeting TAMs can reduce the levels of treatment resistance in NSCLC, providing a comprehensive understanding of the principles and approaches to overcome treatment resistance in NSCLC.
Subject(s)
Carcinoma, Non-Small-Cell Lung , Lung Neoplasms , Humans , Carcinoma, Non-Small-Cell Lung/drug therapy , Carcinoma, Non-Small-Cell Lung/metabolism , Lung Neoplasms/drug therapy , Lung Neoplasms/metabolism , Tumor-Associated Macrophages/metabolism , Tumor-Associated Macrophages/pathology , Cytokines , Signal Transduction , Tumor MicroenvironmentABSTRACT
Genetic and biochemical evidence has established DDHD-domain containing 2 (DDHD2) as the principal triacylglycerol (TAG) hydrolase in neuronal lipolysis of cytosolic lipid droplets. In this issue of Journal of Lipid Research, Hofer et al. report that DDHD2 cooperates with adipose triglyceride lipase, the principal TAG hydrolase in adipose lipolysis, contributing to cytosolic hydrolysis of both TAG and diacylglycerols in murine neuroblastoma cells and primary cortical neurons via different configurations of the lipases. This finding highlights the complexity of cytosolic acylglycerol hydrolysis and raises many new questions in the field of lipid metabolism.
Subject(s)
Glycerides , Lipolysis , Animals , Mice , Lipolysis/physiology , Triglycerides/metabolism , Lipase/metabolism , Neurons/metabolismABSTRACT
BACKGROUND & AIMS: Autophagy-related 14 (ATG14) is a key regulator of autophagy. ATG14 is also localized to lipid droplet; however, the function of ATG14 on lipid droplet remains unclear. In this study, we aimed to elucidate the role of ATG14 in lipid droplet homeostasis. METHODS: ATG14 loss-of-function and gain-of-function in lipid droplet metabolism were analyzed by fluorescence imaging in ATG14 knockdown or overexpression hepatocytes. Specific domains involved in the ATG14 targeting to lipid droplets were analyzed by deletion or site-specific mutagenesis. ATG14-interacting proteins were analyzed by co-immunoprecipitation. The effect of ATG14 on lipolysis was analyzed in human hepatocytes and mouse livers that were deficient in ATG14, comparative gene identification-58 (CGI-58), or both. RESULTS: Our data show that ATG14 is enriched on lipid droplets in hepatocytes. Mutagenesis analysis reveals that the Barkor/ATG14 autophagosome targeting sequence (BATS) domain of ATG14 is responsible for the ATG14 localization to lipid droplets. Co-immunoprecipitation analysis illustrates that ATG14 interacts with adipose triglyceride lipase (ATGL) and CGI-58. Moreover, ATG14 also enhances the interaction between ATGL and CGI-58. In vitro lipolysis analysis demonstrates that ATG14 deficiency remarkably decreases triglyceride hydrolysis. CONCLUSIONS: Our data suggest that ATG14 can directly enhance lipid droplet breakdown through interactions with ATGL and CGI-58.
Subject(s)
Lipase , Lipid Droplets , Mice , Animals , Humans , Lipase/metabolism , Lipid Droplets/metabolism , 1-Acylglycerol-3-Phosphate O-Acyltransferase/genetics , 1-Acylglycerol-3-Phosphate O-Acyltransferase/metabolism , Lipolysis , Lipid Metabolism/genetics , Liver/metabolism , Homeostasis , Autophagy-Related Proteins/genetics , Autophagy-Related Proteins/metabolism , Adaptor Proteins, Vesicular Transport/genetics , Adaptor Proteins, Vesicular Transport/metabolismABSTRACT
A circular RNA (circRNA) is a non-coding RNA (ncRNA) derived from reverse splicing from pre-mRNA and is characterized by the absence of a cap structure at the 5' end and a poly-adenylated tail at the 3' end. Owing to the development of RNA sequencing and bioinformatics approaches in recent years, the important clinical value of circRNAs has been increasingly revealed. Circ_0067934 is an RNA molecule of 170 nucleotides located on chromosome 3q26.2. Circ_0067934 is formed via the reverse splicing of exons 15 and 16 in PRKCI (protein kinase C Iota). Recent studies revealed the upregulation or downregulation of circ_0067934 in various tumors. The expression of circ_0067934 was found to be correlated with tumor size, TNM stage, and poor prognosis. Based on experiments with cancer cells, circ_0067934 promotes cancer cell proliferation, migratory activity, and invasion when overexpressed or downregulated. The potential mechanism involves the binding of circ_0067934 to microRNAs (miRNAs; miR-545, miR-1304, miR-1301-3p, miR-1182, miR-7, and miR-1324) to regulate the post-transcriptional expression of genes. Other mechanisms include inhibition of the Wnt/ß-catenin and PI3K/AKT signaling pathways. Here, we summarized the biological functions and possible mechanisms of circ_0067934 in different tumors to enable further exploration of its translational applications in clinical diagnosis, therapy, and prognostic assessments.
ABSTRACT
While extensive investigations have been devoted to the study of genetic pathways related to fatty liver diseases, much less is known about epigenetic mechanisms underlying these disorders. DNA methylation is an epigenetic link between environmental factors (e.g., diets) and complex diseases (e.g., non-alcoholic fatty liver disease). Here, it is aimed to study the role of DNA methylation in the regulation of hepatic lipid metabolism. A dynamic change in the DNA methylome in the liver of high-fat diet (HFD)-fed mice is discovered, including a marked increase in DNA methylation at the promoter of Beta-klotho (Klb), a co-receptor for the biological functions of fibroblast growth factor (FGF)15/19 and FGF21. DNA methyltransferases (DNMT) 1 and 3A mediate HFD-induced methylation at the Klb promoter. Notably, HFD enhances DNMT1 protein stability via a ubiquitination-mediated mechanism. Liver-specific deletion of Dnmt1 or 3a increases Klb expression and ameliorates HFD-induced hepatic steatosis. Single-nucleus RNA sequencing analysis reveals pathways involved in fatty acid oxidation in Dnmt1-deficient hepatocytes. Targeted demethylation at the Klb promoter increases Klb expression and fatty acid oxidation, resulting in decreased hepatic lipid accumulation. Up-regulation of methyltransferases by HFD may induce hypermethylation of the Klb promoter and subsequent down-regulation of Klb expression, resulting in the development of hepatic steatosis.
Subject(s)
Fatty Liver , Lipid Metabolism , Mice , Animals , Lipid Metabolism/genetics , DNA Methylation/genetics , Epigenesis, Genetic/genetics , Fatty Liver/metabolism , Fatty AcidsABSTRACT
BACKGROUND AND AIMS: Alcohol-associated liver disease (ALD) and NAFLD often coexist in Western societies that consume energy-rich and cholesterol-containing Western diets. Increased rates of ALD mortality in young people in these societies are likely attributable to binge drinking. It is largely unknown how alcohol binge causes liver damage in the setting of Western diets. APPROACH AND RESULTS: In this study, we showed that a single ethanol binge (5 g/kg body weight) induced severe liver injury as shown by marked increases in serum activities of the 2 aminotransferases AST and ALT in C57BL/6J mice that have been fed a Western diet for 3 weeks. The Western diet plus binge ethanol-fed mice also displayed severe lipid droplet deposition and high contents of triglycerides and cholesterol in the liver, which were associated with increased lipogenic and reduced fatty acid oxidative gene expression. These animals had the highest Cxcl1 mRNA expression and myeloperoxidase (MPO)-positive neutrophils in the liver. Their hepatic ROS and lipid peroxidation were the highest, but their hepatic levels of mitochondrial oxidative phosphorylation proteins remained largely unaltered. Hepatic levels of several ER stress markers, including mRNAs for CHOP, ERO1A, ERO1B, BIM, and BIP, as well as Xbp1 splicing and proteins for BIP/GRP78 and IRE-α were also the highest in these animals. Interestingly, Western diet feeding for 3 weeks or ethanol binge dramatically increased hepatic caspase 3 cleavage, and the combination of the 2 did not further increase it. Thus, we successfully established a murine model of acute liver injury by mimicking human diets and binge drinking. CONCLUSIONS: This simple Western diet plus single ethanol binge model recapitulates major hepatic phenotypes of ALD, including steatosis and steatohepatitis characterized by neutrophil infiltration, oxidative stress, and ER stress.
Subject(s)
Binge Drinking , Liver Diseases, Alcoholic , Non-alcoholic Fatty Liver Disease , Humans , Animals , Mice , Adolescent , Mice, Inbred C57BL , Ethanol/toxicity , Diet, Western/adverse effects , Binge Drinking/complications , Non-alcoholic Fatty Liver Disease/etiologyABSTRACT
BACKGROUND: Organ failure (OF) and death are considered the most significant adverse outcomes in necrotizing pancreatitis (NP). However, there are few NP-related studies describing the clinical traits of OF and aggravated outcomes. PURPOSE: An improved insight into the details of OF and death will be helpful to the management of NP. Thus, in our research, we addressed the risk factors of OF and death in NP patients. METHODS: We performed a study of 432 NP patients from May 2017 to December 2021. All patients with NP were followed up for 36 months. The primary end-points were risk factors of OF and death in NP patients. The risk factors were evaluated by logistic regression analysis. RESULTS: NP patients with OF or death patients were generally older, had a higher APACHE II score, longer hospital stay, longer ICU stay, as well as a higher incidence of severe acute pancreatitis (SAP), shock and pancreatic necrosis. Independent risk factors related to OF included BMI, APACHE II score and SAP (P < 0.05). Age, shock and APACHE II score (P < 0.05) were the most significant factors correlated with the risk of death in NP patients. Notably, increased mortality was linked to the number of failed organs. CONCLUSIONS: NP is a potentially fatal disease with a long hospital or ICU stay. Our study indicated that the incidence of OF and death in NP patients was 69.9% and 10.2%, respectively. BMI, SAP, APACHE II score, age and shock are potential risk factors of OF and death in NP patients. Clinicians should focus on these factors for early diagnosis and appropriate therapy.
Subject(s)
Pancreatitis, Acute Necrotizing , Humans , Acute Disease , APACHE , Prognosis , Risk Factors , Retrospective StudiesABSTRACT
This study set out to investigate the clinical significance of serum tumor necrosis factor receptor-associated protein 1 (TRAP1) in diagnosing small cell lung cancer (SCLC) with different clinical stages, and to compare the diagnostic efficiency with neuron-specific enolase (NSE), carcinoembryonic antigen (CEA) and carbohydrate antigen 19-9 (CA19-9). Besides, to analyze the role of serum TRAP1 in tumor immunity. A total of 91 patients with SCLC, 99 patients with non-small cell lung cancer (NSCLC), 102 patients with pulmonary nodules (PN), and 75 healthy people were included. The concentrations of serum TRAP1 was detected by enzyme-linked immunosorbent assay (ELISA). NSE, CEA, and CA19-9 were detected by chemiluminescence. The results showed that level of TRAP1 in Group SCLC was lower than other three groups (P < 0.01), whereas NSE in SCLC was significantly higher than the others (P < 0.01), and the levels of CEA and CA19-9 were higher than healthy people and PN patients (P < 0.01). There was a significant difference in TRAP1 levels between patients with limited-stage disease SCLC (LD-SCLC) and extensive-stage disease SCLC (ED-SCLC) (P < 0.0001). The sensitivity and specificity of TRAP1 in diagnosing LD-SCLC were 0.964 and 0.560, respectively, and the area under the curve (AUC) was 0.819. The sensitivity and specificity in diagnosing ED-SCLC were 0.810 and 0.868, respectively, and the AUC was 0.933, which showed high diagnostic value. The AUC of these two groups can be increased to 0.946 and 0.947 in combination of four biomarkers, effectively improving the diagnosis rate of SCLC. Our findings have revealed that serum TRAP1 has high diagnostic value for SCLC and high diagnostic sensitivity for LD-SCLC. It is a potential biomarker for SCLC. Combined detection can effectively improve the diagnosis rate of SCLC. TRAP1 may be secreted into the circulation by mature immune cells and participates in tumor immunity as a carrier of tumor antigens.
Subject(s)
Carcinoma, Non-Small-Cell Lung , Lung Neoplasms , Humans , Carcinoembryonic Antigen , Carcinoma, Non-Small-Cell Lung/pathology , Lung Neoplasms/pathology , CA-19-9 Antigen , Biomarkers, Tumor/analysis , HSP90 Heat-Shock ProteinsABSTRACT
Here, two-dimensional (2D) nitrogen-doped carbon nanosheets (CNSs) were prepared through carbonizing MOFs (ZIF-8) in-situ grown using graphitic carbon nitride (g-C3N4) as a template. The developed ZIF-8 CNS was then used as solid-phase microextraction (SPME) fiber coating for beneficiation of five biomarkers in exhalation of patients with esophageal cancer and in gas chromatography-mass spectrometry (GC-MS) for determination. The ZIF-8 CNS fiber exhibits satisfactory enrichment factors (3490-5631), wide linearity (5-1000 µg L-1), and low detection limits (0.26-0.96 µg L-1). The relative standard deviations (RSDs) for six replicate extractions of the same ZIF-8 CNS fiber were between 2.0-3.9% (intra-day) and 2.8-5.2% (inter-day). The reproducibility of three fibers prepared by the same approach was in the range 6.8-12.3% (RSD). The developed ZIF-8 CNS fiber can persist in 120 SPME cycles with no prominent loss of extraction efficiency and precision. The high enrichment factors of the 2D ZIF-8 CNS coatings are attributed to the high specific surface area, ultrathin thickness, and nano-pore or interlayer channels; moreover, nitrogen doping also endows the π system with a strong electron absorption ability, which will enhance the π-π interaction between the ZIF-8 CNS and the aromatic ring. Ultimately, the self-made ZIF-8 CNS-coated SPME fiber was applied to the analysis of exhaled breath samples. The recoveries of spiked analytes are between 84 and 105%.
Subject(s)
Carbon , Esophageal Neoplasms , Humans , Carbon/chemistry , Nitrogen , Solid Phase Microextraction/methods , Exhalation , Reproducibility of ResultsABSTRACT
BACKGROUND AND AIMS: Alcohol-associated liver disease (ALD) pathologies include steatosis, inflammation, and injury, which may progress to fibrosis, cirrhosis, and cancer. The liver receives ~60% of fatty acids from adipose tissue triglyceride hydrolysis, but the role of this lipolytic pathway in ALD development has not been directly examined in any genetic animal models with selective inactivation of adipose lipolysis. APPROACH AND RESULTS: Using adipose-specific comparative gene identification-58 (CGI-58) knockout (FAT-KO) mice, a model of impaired adipose lipolysis, we show that mice deficient in adipose lipolysis are almost completely protected against ethanol-induced hepatic steatosis and lipid peroxidation when subjected to the National Institute on Alcohol Abuse and Alcoholism chronic and binge ethanol feeding model. This is unlikely due to reduced lipid synthesis because this regimen of ethanol feeding down-regulated hepatic expression of lipogenic genes similarly in both genotypes. In the pair-fed group, FAT-KO relative to control mice displayed increased hepatocyte injury, neutrophil infiltration, and activation of the transcription factor signal transducer and activator of transcription 3 (STAT3) in the liver; and none of these were exacerbated by ethanol feeding. Activation of STAT3 is associated with a marked increase in hepatic leptin receptor mRNA expression and adipose inflammatory cell infiltration. CONCLUSIONS: Our findings establish a critical role of adipose lipolysis in driving hepatic steatosis and oxidative stress during ALD development.
Subject(s)
Fatty Liver , Liver Diseases, Alcoholic , United States , Mice , Animals , Ethanol/pharmacology , Lipolysis , Disease Models, Animal , National Institute on Alcohol Abuse and Alcoholism (U.S.) , Fatty Liver/metabolism , Liver/pathology , Liver Diseases, Alcoholic/metabolism , Mice, Inbred C57BLABSTRACT
BACKGROUND & AIMS: Binge drinking in patients with metabolic syndrome accelerates the development of alcohol-associated liver disease. However, the underlying mechanisms remain elusive. We investigated if oxidative and nonoxidative alcohol metabolism pathways, diet-induced obesity, and adipose tissues influenced the development of acute liver injury in a single ethanol binge model. METHODS: A single ethanol binge was administered to chow-fed or high-fat diet (HFD)-fed wild-type and genetically modified mice. RESULTS: Oral administration of a single dose of ethanol induced acute liver injury and hepatic endoplasmic reticulum (ER) stress in chow- or HFD-fed mice. Disruption of the Adh1 gene increased blood ethanol concentration and exacerbated acute ethanol-induced ER stress and liver injury in both chow-fed and HFD-fed mice, while disruption of the Aldh2 gene did not affect such hepatic injury despite high blood acetaldehyde levels. Mechanistic studies showed that alcohol, not acetaldehyde, promoted hepatic ER stress, fatty acid synthesis, and increased adipocyte death and lipolysis, contributing to acute liver injury. Increased serum fatty acid ethyl esters (FAEEs), which are formed by an enzyme-mediated esterification of ethanol with fatty acids, were detected in mice after ethanol gavage, with higher levels in Adh1 knockout mice than in wild-type mice. Deletion of the Ces1d gene in mice markedly reduced the acute ethanol-induced increase of blood FAEE levels with a slight but significant reduction of serum aminotransferase levels. CONCLUSIONS: Ethanol and its nonoxidative metabolites, FAEEs, not acetaldehyde, promoted acute alcohol-induced liver injury by inducing ER stress, adipocyte death, and lipolysis.
Subject(s)
Chemical and Drug Induced Liver Injury , Endoplasmic Reticulum Stress , Ethanol , Lipolysis , Animals , Mice , Acetaldehyde/metabolism , Adipocytes/metabolism , Esters/metabolism , Ethanol/toxicity , Fatty Acids/metabolism , Liver/metabolismABSTRACT
Comparative gene identification-58 (CGI-58), also known as α/ß hydrolase domain containing 5, is the co-activator of adipose triglyceride lipase that hydrolyzes triglycerides stored in the cytosolic lipid droplets. Mutations in CGI-58 gene cause Chanarin-Dorfman syndrome (CDS), an autosomal recessive neutral lipid storage disease with ichthyosis. The liver pathology of CDS manifests as steatosis and steatohepatitis, which currently has no effective treatments. Perilipin-3 (Plin3) is a member of the Perilipin-ADRP-TIP47 protein family that is essential for lipid droplet biogenesis. The objective of this study was to test a hypothesis that deletion of a major lipid droplet protein alleviates fatty liver pathogenesis caused by CGI-58 deficiency in hepatocytes. Adult CGI-58-floxed mice were injected with adeno-associated vectors simultaneously expressing the Cre recombinase and microRNA against Plin3 under the control of a hepatocyte-specific promoter, followed by high-fat diet feeding for 6 weeks. Liver and blood samples were then collected from these animals for histological and biochemical analysis. Plin3 knockdown in hepatocytes prevented steatosis, steatohepatitis, and necroptosis caused by hepatocyte CGI-58 deficiency. Our work is the first to show that inhibiting Plin3 in hepatocytes is sufficient to mitigate hepatocyte CGI-58 deficiency-induced hepatic steatosis and steatohepatitis in mice.
Subject(s)
1-Acylglycerol-3-Phosphate O-Acyltransferase , Fatty Liver , Mice , Animals , Perilipin-3 , 1-Acylglycerol-3-Phosphate O-Acyltransferase/genetics , 1-Acylglycerol-3-Phosphate O-Acyltransferase/metabolism , Fatty Liver/genetics , Fatty Liver/metabolism , Hepatocytes/metabolism , Triglycerides/metabolismABSTRACT
Knockout of the transcription factor X-box binding protein (XBP1) is known to decrease liver glucose production and lipogenesis. However, whether insulin can regulate gluconeogenesis and lipogenesis through XBP1 and how insulin activates the inositol-requiring enzyme-XBP1 ER stress pathway remains unexplored. Here, we report that in the fed state, insulin-activated kinase AKT directly phosphorylates inositol-requiring enzyme 1 at S724, which in turn mediates the splicing of XBP1u mRNA, thus favoring the generation of the spliced form, XBP1s, in the liver of mice. Subsequently, XBP1s stimulate the expression of lipogenic genes and upregulates liver lipogenesis as previously reported. Intriguingly, we find that fasting leads to an increase in XBP1u along with a drastic decrease in XBP1s in the liver of mice, and XBP1u, not XBP1s, significantly increases PKA-stimulated CRE reporter activity in cultured hepatocytes. Furthermore, we demonstrate that overexpression of XBP1u significantly increases cAMP-stimulated expression of rate-limiting gluconeogenic genes, G6pc and Pck1, and glucose production in primary hepatocytes. Reexpression of XBP1u in the liver of mice with XBP1 depletion significantly increases fasting blood glucose levels and gluconeogenic gene expression. These data support an important role of XBP1u in upregulating gluconeogenesis in the fasted state. Taken together, we reveal that insulin signaling via AKT controls the expression of XBP1 isoforms and that XBP1u and XBP1s function in different nutritional states to regulate liver gluconeogenesis and lipogenesis, respectively.