Glucose regulation of adipose tissue browning by CBP/p300- and HDAC3-mediated reversible acetylation of CREBZF

Glucose is required for generating heat during cold-induced nonshivering thermogenesis in adipose tissue, but the regulatory mechanism is largely unknown. CREBZF has emerged as a critical mechanism for metabolic dysfunction-associated steatotic liver disease (MASLD), formerly known as nonalcoholic fatty liver disease (NAFLD). We investigated the roles of CREBZF in the control of thermogenesis and energy metabolism. Glucose induces CREBZF in human white adipose tissue (WAT) and inguinal WAT (iWAT) in mice. Lys208 acetylation modulated by transacetylase CREB-binding protein/p300 and deacetylase HDAC3 is required for glucose-induced reduction of proteasomal degradation and augmentation of protein stability of CREBZF. Glucose induces rectal temperature and thermogenesis in white adipose of control mice, which is further potentiated in adipose-specific CREBZF knockout (CREBZF FKO) mice. During cold exposure, CREBZF FKO mice display enhanced thermogenic gene expression, browning of iWAT, and adaptive thermogenesis. CREBZF associates with PGC-1α to repress thermogenic gene expression. Expression levels of CREBZF are negatively correlated with UCP1 in human adipose tissues and increased in WAT of obese ob/ob mice, which may underscore the potential role of CREBZF in the development of compromised thermogenic capability under hyperglycemic conditions. Our results reveal an important mechanism of glucose sensing and thermogenic inactivation through reversible acetylation.

Macrophage CREBZF Orchestrates Inflammatory Response to Potentiate Insulin Resistance and Type 2 Diabetes

Chronic adipose tissue inflammation accompanied by macrophage accumulation and activation is implicated in the pathogenesis of insulin resistance and type 2 diabetes in humans. The transcriptional coregulator CREBZF is a key factor in hepatic metabolism, yet its role in modulating adipose tissue inflammation and type 2 diabetes remains elusive. The present study demonstrates that overnutrition-induced CREBZF links adipose tissue macrophage (ATM) proinflammatory activation to insulin resistance. CREBZF deficiency in macrophages, not in neutrophils, attenuates macrophage infiltration in adipose, proinflammatory activation, and hyperglycemia in diet-induced insulin-resistant mice. The coculture assays show that macrophage CREBZF deficiency improves insulin sensitivity in primary adipocytes and adipose tissue. Mechanistically, CREBZF competitively inhibits the binding of IκBα to p65, resulting in enhanced NF-κB activity. In addition, bromocriptine is identified as a small molecule inhibitor of CREBZF in macrophages, which suppresses the proinflammatory phenotype and improves metabolic dysfunction. Furthermore, CREBZF is highly expressed in ATM of obese humans and mice, which is positively correlated with proinflammatory genes and insulin resistance in humans. This study identifies a previously unknown role of CREBZF coupling ATM activation to systemic insulin resistance and type 2 diabetes.

Multi-channel synthetic aperture infrared imaging and experimental research

The synthetic aperture infrared radio imaging method based on laser local oscillator coherent detection has potential application value for astronomical observations. This paper studies the multi-channel synthetic aperture infrared imaging method and conducts experimental verification using a principle prototype. In the short-wave infrared band, five beam-expanding fiber collimators are used to build an observation structure of five laser local oscillator coherent detection channels at a near-field distance of 5 m to carry out physical experiments. The laser local oscillator wavelength is 1.55 µm, and the AD sampling rate is 4 GHz. For the infrared radiation source signal, the phase relationship of the infrared signals between channels acquired by the prototype principle is stable, and the five-channel synthetic aperture imaging results are consistent with the computer simulated results. The experiment verified the effectiveness of the laser local oscillator comprehensive aperture infrared radio imaging method.

Intergenerational relationship between parental famine exposure and offspring's obesity risks

BACKGROUND

The intergenerational relationship between parental famine exposure and the obesity risks of offspring has not been well studied.

METHODS

Using a cohort of 3654 respondents whose parents were born between 1950 and 1964 from the national data of the China Family Panel Studies, this study examines the associations between parental exposure to the 1959-1961 Chinese famine and offspring's body mass index (BMI). A cross-sectional difference-in-difference design was used to estimate the effects of parental famine exposures on offspring's BMI by exploiting temporal variations in the duration and period of famine across the parental birth cohorts between 1950 and 1964, and geographical variations in the famine severity at the province level.

RESULTS

After adjusting individual characteristics and province-level fixed effects, we found that parental famine exposures in the preschool and school-age stages were associated with an increased BMI of offspring while there was not a significant association between prenatal famine exposure and offspring's BMI. The stratified analyses further show that the effects of parental famine exposure did not follow the same trajectory in subgroups.

CONCLUSIONS

Famine experiences of parents were associated with increased BMI of offspring, suggesting an intergenerational impact of severe malnutrition on obesity risks.

Intrahepatic osteopontin signaling by CREBZF defines a checkpoint for steatosis-to-NASH progression

BACKGROUND AND AIMS

NASH has emerged as a leading cause of chronic liver disease. However, the mechanisms that govern NASH fibrosis remain largely unknown. CREBZF is a CREB/ATF bZIP transcription factor that causes hepatic steatosis and metabolic defects in obesity.

APPROACH AND RESULTS

Here, we show that CREBZF is a key mechanism of liver fibrosis checkpoint that promotes hepatocyte injury and exacerbates diet-induced NASH in mice. CREBZF deficiency attenuated liver injury, fibrosis, and inflammation in diet-induced mouse models of NASH. CREBZF increases HSC activation and fibrosis in a hepatocyte-autonomous manner by stimulating an extracellular matrix protein osteopontin, a key regulator of fibrosis. The inhibition of miR-6964-3p mediates CREBZF-induced production and secretion of osteopontin in hepatocytes. Adeno-associated virus -mediated rescue of osteopontin restored HSC activation, liver fibrosis, and NASH progression in CREBZF-deficient mice. Importantly, expression levels of CREBZF are increased in livers of diet-induced NASH mouse models and humans with NASH.

CONCLUSIONS

Osteopontin signaling by CREBZF represents a previously unrecognized intrahepatic mechanism that triggers liver fibrosis and contributes to the severity of NASH.

Proline hydroxylation of CREB-regulated transcriptional coactivator 2 controls hepatic glucose metabolism

Prolyl hydroxylase domain (PHD) enzymes change HIF activity according to oxygen signal; whether it is regulated by other physiological conditions remains largely unknown. Here, we report that PHD3 is induced by fasting and regulates hepatic gluconeogenesis through interaction and hydroxylation of CRTC2. Pro129 and Pro615 hydroxylation of CRTC2 following PHD3 activation is necessary for its association with cAMP-response element binding protein (CREB) and nuclear translocation, and enhanced binding to promoters of gluconeogenic genes by fasting or forskolin. CRTC2 hydroxylation-stimulated gluconeogenic gene expression is independent of SIK-mediated phosphorylation of CRTC2. Liver-specific knockout of PHD3 (PHD3 LKO) or prolyl hydroxylase-deficient knockin mice (PHD3 KI) show attenuated fasting gluconeogenic genes, glycemia, and hepatic capacity to produce glucose during fasting or fed with high-fat, high-sucrose diet. Importantly, Pro615 hydroxylation of CRTC2 by PHD3 is increased in livers of fasted mice, diet-induced insulin resistance or genetically obese ob/ob mice, and humans with diabetes. These findings increase our understanding of molecular mechanisms linking protein hydroxylation to gluconeogenesis and may offer therapeutic potential for treating excessive gluconeogenesis, hyperglycemia, and type 2 diabetes.

Aging exaggerates acute-on-chronic alcohol-induced liver injury in mice and humans by inhibiting neutrophilic sirtuin 1-C/EBPα-miRNA-223 axis

BACKGROUND AND AIMS

Aging exacerbates liver neutrophil infiltration and alcohol-associated liver disease (ALD) in mice and humans, but the underlying mechanisms remain obscure. This study aimed to examine the effect of aging and alcohol consumption on neutrophilic Sirtuin 1 (SIRT1) and microRNA-223 (miR-223), and their contribution to ALD pathogeneses.

APPROACH AND RESULTS

Young and aged myeloid-specific Sirt1 knockout mice were subjected to chronic-plus-binge ethanol feeding. Blood samples from healthy controls and patients with chronic alcohol drinking who presented with acute intoxication were analyzed. Neutrophilic Sirt1 and miR-223 expression were down-regulated in aged mice compared with young mice. Deletion of the Sirt1 gene in myeloid cells including neutrophils exacerbated chronic-plus-binge ethanol-induced liver injury and inflammation and down-regulated neutrophilic miR-223 expression. Immunoprecipitation experiments revealed that SIRT1 promoted C/EBPα deacetylation by directly interacting with C/EBPα, a key transcription factor that controls miR-223 biogenesis, and subsequently elevated miR-223 expression in neutrophils. Importantly, down-regulation of SIRT1 and miR-223 expression was also observed in circulating neutrophils from middle-aged and elderly subjects compared with those from young individuals. Chronic alcohol users with acute intoxication had a reduction in neutrophilic SIRT1 expression in young and middle-aged patients, with a greater reduction in the latter group. The neutrophilic SIRT1 expression correlated with neutrophilic miR-223 and serum alanine transaminase levels in those patients.

CONCLUSIONS

Aging increases the susceptibility of alcohol-induced liver injury in mice and humans through the down-regulation of the neutrophilic SIRT1-C/EBPα-miR-223 axis, which could be a therapeutic target for the prevention and/or treatment of ALD.

POS0298 UNDERSERVED POPULATIONS IDENTIFY BARRIERS AND PROPOSE SOLUTIONS FOR SELF-MANAGING ARTHRITIS AND CHRONIC CONDITIONS

Background:

Underserved populations, such as ethnic minorities, low-income adults, and Indigenous people living with arthritis are more likely to have lower health literacy, higher rates of multi-morbidity, and face challenges in accessing care1-3. Self-management support (SMS) can help to mitigate the impacts of living with arthritis4. However, we require a more in-depth understanding of the daily barriers underserved communities face in living with arthritis in order to develop effective SMS that can meaningfully improve well-being and quality of life.

Objectives:

The study objective was to bring together underserved people living with arthritis to identify common barriers they face in taking care of their conditions in daily life, and to identify their solutions to the identified challenges.

Methods:

A team of researchers from several universities, nurse practitioners, physicians, policy makers, an arthritis consumer-patient leader and our community partners (Multi-lingual Orientation Service Association for Immigrant Communities and the Portland Hotel Society Community Services Society) engaged in a Community-based Participatory and Concept Mapping (CM) study5-7 where participants from underserved communities identified major barriers they face in managing arthritis, agreed on key themes that emerged, and determined priorities for actions. This involved three key CM activities: 1) brainstorming ideas; 2) sorting and rating ideas; and 3) analyzing and interpreting concept maps8. Data was collected through face-to-face interviews and prioritized and interpreted in workshop settings.

Results:

Sixty-three individuals who were ethnic minorities, immigrants, refugees, low-income, over 65, and/or housing insecure and living with arthritis identified 35 common barriers and made recommendations in the areas of financial difficulties, social services, access to health services, quality of health services, lack of knowledge, and mental health. Additional funding has been sought through Community-University Engagement Support Funding to enable our community partners to prioritize the recommendations in their communities, and to develop mechanisms for implementation using already existing community structures, processes, and services.

Conclusion:

Persons living with arthritis in diverse underserved communities face significant health and social inequities, including lack of access to basic life necessities such as food, housing, employment, and safety, which creates barriers to self-managing arthritis and other chronic conditions in daily life. SMS for these communities needs to address these social and environmental barriers shaping capacity for self-management, and ultimately, quality of life and well-being.

References:

[1]Ackerman I, Busija L. Access to self-management education, conservative treatment and surgery for arthritis according to socioeconomic status. Best Pr Res Clin Rheumatol. 2012;26(5):561–83.

[2]Shadmi E. Multimorbidity and equity in health. Int J Equity Heal. 2013;12(59):59.

[3]Foster M, Kendall E, Dickson P, Chaboyer W, Hunter B, Gee T. Participation and chronic disease self-management: are we risking inequitable resource allocation? Aust J Prim Health. 2003;9(3):132–40.

[4]Brady T, Anderson L, Kobau R. Chronic disease self-management support: public health perspectives. Front Public Heal. 2015;2(234).

[5]Trochim W. An introduction to concept mapping for planning and evaluation. Eval Progr Plann. 1989;12(1):1–16.

[6]Anderson L, Day K, Vandenberg A. Using a concept map as a tool for strategic planning: the healthy brain initiative. Prev Chronic Dis. 2011;8(5):A117.

[7]Petrucci C, Quinlan K. Bridging the research practice gap: concept mapping as a mixed methods strategy in practice-based research and evaluation. J Soc Serv Res. 2007;34(2):25–42.

[8]Kane M, Trochim W. Concept mapping for planning and evaluation. Thousand Oaks (CA): SAGE Publications; 2007.

Disclosure of Interests:

None declared

Sodium Butyrate Supplementation Inhibits Hepatic Steatosis by Stimulating Liver Kinase B1 and Insulin-Induced Gene

BACKGROUND AND AIMS

Butyric acid is an intestinal microbiota-produced short-chain fatty acid, which exerts salutary effects on alleviating nonalcoholic fatty liver disease (NAFLD). However, the underlying mechanism of butyrate on regulating hepatic lipid metabolism is largely unexplored.

METHODS

A mouse model of NAFLD was induced with high-fat diet feeding, and sodium butyrate (NaB) intervention was initiated at the eighth week and lasted for 8 weeks. Hepatic steatosis was evaluated and metabolic pathways concerning lipid homeostasis were analyzed.

RESULTS

Here, we report that administration of NaB by gavage once daily for 8 weeks causes an augmentation of insulin-induced gene (Insig) activity and inhibition of lipogenic gene in mice fed with high-fat diet. Mechanistically, NaB is sufficient to enhance the interaction between Insig and its upstream kinase AMP-activated protein kinase (AMPK). The stimulatory effects of NaB on Insig-1 activity are abolished in AMPKα1/α2 double knockout (AMPK-/-) mouse primary hepatocytes. Moreover, AMPK activation by NaB is mediated by LKB1, as evidenced by the observations showing NaB-mediated induction of phosphorylation of AMPK, and its downstream target acetyl-CoA carboxylase is diminished in LKB1-/- mouse embryonic fibroblasts.

CONCLUSIONS

These studies indicate that NaB serves as a negative regulator of hepatic lipogenesis in NAFLD and that NaB attenuates hepatic steatosis and improves lipid profile and liver function largely through the activation of LKB1-AMPK-Insig signaling pathway. Therefore, NaB has therapeutic potential for treating NAFLD and related metabolic diseases.

Regulation of Hepatic Metabolism and Cell Growth by the ATF/CREB Family of Transcription Factors

The liver is a major metabolic organ that regulates the whole-body metabolic homeostasis and controls hepatocyte proliferation and growth. The ATF/CREB family of transcription factors integrates nutritional and growth signals to the regulation of metabolism and cell growth in the liver, and deregulated ATF/CREB family signaling is implicated in the progression of type 2 diabetes, nonalcoholic fatty liver disease, and cancer. This article focuses on the roles of the ATF/CREB family in the regulation of glucose and lipid metabolism and cell growth and its importance in liver physiology. We also highlight how the disrupted ATF/CREB network contributes to human diseases and discuss the perspectives of therapeutically targeting ATF/CREB members in the clinic.

The precursor of PI(3,4,5)P3 alleviates aging by activating daf-18(Pten) and independent of daf-16

Aging is characterized by the loss of homeostasis and the general decline of physiological functions, accompanied by various degenerative diseases and increased rates of mortality. Aging targeting small molecule screens have been performed many times, however, few have focused on endogenous metabolic intermediates-metabolites. Here, using C. elegans lifespan assays, we conducted a worm metabolite screen and identified an eukaryotes conserved metabolite, myo-inositol (MI), to extend lifespan, increase mobility and reduce fat content. Genetic analysis of enzymes in MI metabolic pathway suggest that MI alleviates aging through its derivative PI(4,5)P2. MI and PI(4,5)P2 are precursors of PI(3,4,5)P3, which is negatively related to longevity. The longevity effect of MI is dependent on the tumor suppressor gene, daf-18 (homologous to mouse Pten), independent of its classical pathway downstream genes, akt or daf-16. Furthermore, we found MI effects on aging and lifespan act through mitophagy regulator PTEN induced kinase-1 (pink-1) and mitophagy. MI's anti-aging effect is also conserved in mouse, indicating a conserved mechanism in mammals.

[Transthoracic ultrasonographic features of typical high-resolution computed tomography signs of interstitial lung diseases]

Objective: To investigate the accuracy of bedside transthoracic lung ultrasonography (TLU) in different typical high resolution computed tomography (HRCT) signs of interstitial lung diseases (ILDs). Methods: Fifty patients first diagnosed with ILDs were enrolled from January 2016 to December 2018. There were 21 males and 29 females. The mean age was (56±14) years(rang 42-73 years). TLU was performed in inspiration for the characters of A-lines and B-lines as well as pleural at anterior, lateral and dorsal chest walls, respectively. HRCT was selected at three levels according to the upper, middle, and lower lung fields. The range of each level needing to be evaluated corresponded to the TLU scanning field one by one, and recording the signs of HRCT. Early change of ILDs was definite as the HRCT score was no more than 1 and no honeycomb was present. The correlation between A-lines, B-lines, pleural abnormal and HRCT signs was evaluted. Spearman's correlation coefficient was used to evaluate the relationship between B-lines and HRCT score. Results: The sensitivity and specificity of A-lines for HRCT normality were 83.9% and 84.9%, respectively. Coincidence rate was 84.6%. The sensitivity and specificity of B-lines for HRCT abnormality were 84.9% and 83.9%, respectively. Coincidence rate was 84.6%. Interlobular septal thickening shadow had fewer B-lines and narrower interval than other HRCT signs, while the other HRCT signs had no differences in B-lines. And the sensitivity and specificity of B-lines for detection the early change of HRCT in ILDs were 89.5% and 89.2%, respectively. Coincidence rate was 89.3%. A positive correlation was found between the number of B-lines and HRCT scores (R=0.827, P<0.001), and the width of B-lines and HRCT score (R=0.951, P<0.001). Meanwhile, a negative correlation was found between the interval of B-lines and HRCT score (R=-0.831, P<0.001). The sensitivity and specificity of TLU for HRCT pleural abnormality were 100.0% and 90.0%, respectively. Coincidence rate was 93.6%. Conclusions: TLU showed high sensitivity and specificity in finding interstitial changes of the lung. It gives a new view on the diagnostic possibilities of ILDs and may be used to evaluate the severity and the therapeutic effect of treatment. However, TLU could not differentiate HRCT signs of ILDs.

The Effects of B1344, a Novel Fibroblast Growth Factor 21 Analog, on Nonalcoholic Steatohepatitis in Nonhuman Primates

Nonalcoholic steatohepatitis has emerged as a major cause of liver diseases with no effective therapies. Here, we evaluate the efficacies and pharmacokinetics of B1344, a long-acting polyethylene glycolylated (PEGylated) fibroblast growth factor 21 analog, in a nongenetically modified nonhuman primate species that underwent liver biopsy and demonstrate the potential for efficacies in humans. B1344 is sufficient to selectively activate signaling from the βKlotho/FGFR1c receptor complex. In cynomolgus monkeys with nonalcoholic fatty liver disease (NAFLD), administration of B1344 via subcutaneous injection for 11 weeks caused a profound reduction of hepatic steatosis, inflammation, and fibrosis, along with amelioration of liver injury and hepatocyte death, as evidenced by liver biopsy specimen and biochemical analysis. Moreover, improvement of metabolic parameters was observed in the monkeys, including reduction of body weight and improvement of lipid profiles and glycemic control. To determine the role of B1344 in the progression of murine NAFLD independent of obesity, B1344 was administered to mice fed a methionine- and choline-deficient diet. Consistently, B1344 administration prevented the mice from lipotoxicity damage and nonalcoholic steatohepatitis in a dose-dependent manner. These results provide preclinical validation for an innovative therapeutic approach to NAFLD and support further clinical testing of B1344 for treating nonalcoholic steatohepatitis and other metabolic diseases in humans.

Thrombospondin 1 improves hepatic steatosis in diet-induced insulin-resistant mice and is associated with hepatic fat content in humans

BACKGROUND

Nonalcoholic fatty liver disease (NAFLD) is associated with altered production of secreted proteins. Increased understanding of secreted proteins could lead to improved prediction and treatment of NAFLD. Here, we aimed to discover novel secreted proteins in humans that are associated with hepatic fat content using unbiased proteomic profiling strategy, and how the identified Thbs1 modulates lipid metabolism and hepatic steatosis.

METHOD

NAFLD patients were enrolled and treated with lifestyle intervention. Patients who underwent liver biopsy were enrolled for analyzing the correlation between circulating Thbs1 and liver steatosis. Mice were fed on high-fat, high-sucrose diet and treated with recombinant Thbs1. Primary hepatocytes isolated from CD36 knockout (CD36-/-) mice and their wild-type littermates (controls) were treated with glucose plus insulin for 24 h together with or without recombinant Thbs1.

FINDING

Serum Thbs1 levels are increased in participants with NAFLD and positively associated with liver steatosis grades. Improvement of liver steatosis after lifestyle intervention was accompanied with significant reduction of serum Thbs1 levels. Pharmacological administration of recombinant human Thbs1 attenuates hepatic steatosis in diet-induced obese mice. Treatment with Thbs1 protein or stably overexpression of Thbs1 causes a significant reduction of lipid accumulation in primary hepatocytes or HepG2 cells exposed to high glucose plus insulin, suggesting that Thbs1 regulates lipid metabolism in a hepatocyte-autonomous manner. Mechanistically, Thbs1 inhibits cleavage and processing of SREBP-1, leading to a reduction of target lipogenic gene expression and hepatic steatosis. Inhibitory effects of Thbs1 on lipogenesis and triglyceride accumulation are abrogated in CD36 deficient primary hepatocytes exposed to high glucose plus insulin. Interestingly, beneficial effects of Thbs1 on lipid accumulation are observed in primary hepatocytes treated with a Thbs1 nonapeptide mimetic ABT-526.

INTERPRETATION

Thbs1 is a biomarker for NAFLD in humans, and pharmacological and genetic approaches for the modulation of Thbs1 activity may have the therapeutic potential for treating hepatic steatosis. FUND: A full list of funding bodies that contributed to this study can be found in the Funding Sources section.

CREBZF as a Key Regulator of STAT3 Pathway in the Control of Liver Regeneration in Mice

BACKGROUND AND AIMS

STAT3, a member of the signal transducer and activator of transcription (STAT) family, is strongly associated with liver injury, inflammation, regeneration, and hepatocellular carcinoma development. However, the signals that regulate STAT3 activity are not completely understood.

APPROACH AND RESULTS

Here we characterize CREB/ATF bZIP transcription factor CREBZF as a critical regulator of STAT3 in the hepatocyte to repress liver regeneration. We show that CREBZF deficiency stimulates the expression of the cyclin gene family and enhances liver regeneration after partial hepatectomy. Flow cytometry analysis reveals that CREBZF regulates cell cycle progression during liver regeneration in a hepatocyte-autonomous manner. Similar results were observed in another model of liver regeneration induced by intraperitoneal injection of carbon tetrachloride (CCl₄ ). Mechanistically, CREBZF potently associates with the linker domain of STAT3 and represses its dimerization and transcriptional activity in vivo and in vitro. Importantly, hepatectomy-induced hyperactivation of cyclin D1 and liver regeneration in CREBZF liver-specific knockout mice was reversed by selective STAT3 inhibitor cucurbitacin I. In contrast, adeno-associated virus-mediated overexpression of CREBZF in the liver inhibits the expression of the cyclin gene family and attenuates liver regeneration in CCl₄ -treated mice.

CONCLUSIONS

These results characterize CREBZF as a coregulator of STAT3 to inhibit regenerative capacity, which may represent an essential cellular signal to maintain liver mass homeostasis. Therapeutic approaches to inhibit CREBZF may benefit the compromised liver during liver transplantation.

Indole-3-propionic acid inhibits gut dysbiosis and endotoxin leakage to attenuate steatohepatitis in rats

Microbial metabolites have emerged as critical components that mediate the metabolic effects of the gut microbiota. Here, we show that indole-3-propionic acid (IPA), a tryptophan metabolite produced by gut bacteria, is a potent anti-non-alcoholic steatohepatitis (NASH) microbial metabolite. Here, we demonstrate that administration of IPA modulates the microbiota composition in the gut and inhibits microbial dysbiosis in rats fed a high-fat diet. IPA induces the expression of tight junction proteins, such as ZO-1 and Occludin, and maintains intestinal epithelium homeostasis, leading to a reduction in plasma endotoxin levels. Interestingly, IPA inhibits NF-κB signaling and reduces the levels of proinflammatory cytokines, such as TNFα, IL-1β, and IL-6, in response to endotoxin in macrophages to repress hepatic inflammation and liver injury. Moreover, IPA is sufficient to inhibit the expression of fibrogenic and collagen genes and attenuate diet-induced NASH phenotypes. The beneficial effects of IPA on the liver are likely mediated through inhibiting the production of endotoxin in the gut. These findings suggest a protective role of IPA in the control of metabolism and uncover the gut microbiome and liver cross-talk in regulating the intestinal microenvironment and liver pathology via a novel dietary nutrient metabolite. IPA may provide a new therapeutic strategy for treating NASH.

A molecule made by beneficial microbes in the gut helps protect against a severe form of fatty liver disease by preventing bacterial toxins from leaking out of the intestines into the bloodstream. A research team in China led by Yu Li from the Shanghai Institute of Nutrition and Health (CAS) and Jian-Gao Fan from Xinhua Hospital (SJTU) showed in a rat model of non-alcoholic steatohepatitis that indole-3-propionic acid (IPA), a metabolite produced by gut bacteria, helps maintain the integrity of the intestinal inner lining. The more robust intestinal barrier ensures that bacterial toxins do not enter the bloodstream and eventually reach the liver, where they can trigger injury-inducing inflammation. The findings reveal an interaction between the gut microbiome and the liver, and suggest a role for IPA in the treatment of fatty liver disease.

Post-translational regulation of lipogenesis via AMPK-dependent phosphorylation of insulin-induced gene

Insulin-induced gene (Insig) negatively regulates SREBP-mediated de novo fatty acid synthesis in the liver. However, the upstream regulation of Insig is incompletely understood. Here we report that AMPK interacts with and mediates phosphorylation of Insig. Thr222 phosphorylation following AMPK activation is required for protein stabilization of Insig-1, inhibition of cleavage and processing of SREBP-1, and lipogenic gene expression in response to metformin or A769662. AMPK-dependent phosphorylation ablates Insig’s interaction with E3 ubiquitin ligase gp78 and represses its ubiquitination and degradation, whereas AMPK deficiency shows opposite effects. Interestingly, activation of AMPK by metformin causes an augmentation of Insig stability and reduction of lipogenic gene expression, and leads to the attenuation of hepatic steatosis in HFHS diet-fed mice. Moreover, hepatic overexpression of Insig-1 rescues hepatic steatosis in liver-specific AMPKα2 knockout mice fed with HFHS diet. These findings uncover a novel effector of AMPK. Targeting Insig may have the therapeutic potential for treating fatty liver disease and related disorders.

Insulin-related gene (Insig) negatively regulates hepatic fatty acid synthesis, a process involved in development of non-alcoholic fatty liver disease (NAFLD). Here, the authors show that AMPK activation by metformin promotes Insig phosphorylation, stabilizing it and inhibiting lipogenic gene expression. This is protective against steatosis in diabetic mice.

Hepatic CREBZF couples insulin to lipogenesis by inhibiting insig activity and contributes to hepatic steatosis in diet-induced insulin-resistant mice

Insulin is critical for the regulation of de novo fatty acid synthesis, which converts glucose to lipid in the liver. However, how insulin signals are transduced into the cell and then regulate lipogenesis remains to be fully understood. Here, we identified CREB/ATF bZIP transcription factor (CREBZF) of the activating transcription factor/cAMP response element-binding protein (ATF/CREB) gene family as a key regulator for lipogenesis through insulin-Akt signaling. Insulin-induced gene 2a (Insig-2a) decreases during refeeding, allowing sterol regulatory element binding protein 1c to be processed to promote lipogenesis; but the mechanism of reduction is unknown. We show that Insig-2a inhibition is mediated by insulin-induced CREBZF. CREBZF directly inhibits transcription of Insig-2a through association with activating transcription factor 4. Liver-specific knockout of CREBZF causes an induction of Insig-2a and Insig-1 and resulted in repressed lipogenic program in the liver of mice during refeeding or upon treatment with streptozotocin and insulin. Moreover, hepatic CREBZF deficiency attenuates hepatic steatosis in high-fat, high-sucrose diet-fed mice. Importantly, expression levels of CREBZF are increased in livers of diet-induced insulin resistance or genetically obese ob/ob mice and humans with hepatic steatosis, which may underscore the potential role of CREBZF in the development of sustained lipogenesis in the liver under selective insulin resistance conditions.

CONCLUSION

These findings uncover an unexpected mechanism that couples changes in extracellular hormonal signals to hepatic lipid homeostasis; disrupting CREBZF function may have the therapeutic potential for treating fatty liver disease and insulin resistance. (Hepatology 2018).

Berberine attenuates hepatic steatosis and enhances energy expenditure in mice by inducing autophagy and fibroblast growth factor 21

BACKGROUND AND PURPOSE

Berberine, a compound from rhizome coptidis, is traditionally used to treat gastrointestinal infections, such as bacterial diarrhoea. Recently, berberine was shown to have hypoglycaemic and hypolipidaemic effects. We investigated the mechanisms by which berberine regulates hepatic lipid metabolism and energy expenditure in mice.

EXPERIMENTAL APPROACH

Liver-specific SIRT1 knockout mice and their wild-type littermates were fed a high-fat, high-sucrose (HFHS) diet and treated with berberine by i.p. injection for five weeks. Mouse primary hepatocytes and human HepG2 cells were treated with berberine and then subjected to immunoblotting analysis and Oil Red O staining.

KEY RESULTS

Berberine attenuated hepatic steatosis and controlled energy balance in mice by inducing autophagy and FGF21. These beneficial effects of berberine on autophagy and hepatic steatosis were abolished by a deficiency of the nutrient sensor SIRT1 in the liver of HFHS diet-fed obese mice and in mouse primary hepatocytes. SIRT1 is essential for berberine to potentiate autophagy and inhibit lipid storage in mouse livers in response to fasting. Mechanistically, the berberine stimulates SIRT1 deacetylation activity and induces autophagy in an autophagy protein 5-dependent manner. Moreover, the administration of berberine was shown to promote hepatic gene expression and circulating levels of FGF21 and ketone bodies in mice in a SIRT1-dependent manner.

CONCLUSIONS AND IMPLICATIONS

Berberine acts in the liver to regulate lipid utilization and maintain whole-body energy metabolism by mediating autophagy and FGF21 activation. Hence, it has therapeutic potential for treating metabolic defects under nutritional overload, such as fatty liver diseases, type 2 diabetes and obesity.

Adenosine A2A receptor and ERK-driven impulsivity potentiates hippocampal neuroblast proliferation

Dampened adenosine A_2A receptor (A_2AR) function has been implicated in addiction through enhancement of goal-directed behaviors. However, the contribution of the A_2AR to the control of impulsive reward seeking remains unknown. Using mice that were exposed to differential reward of low rate (DRL) schedules during Pavlovian-conditioning, second-order schedule discrimination, and the 5-choice serial reaction time task (5-CSRTT), we demonstrate that deficits of A_2AR function promote impulsive responses. Antagonism of the A_2AR lowered ERK1 and ERK2 phosphorylation in the dorsal hippocampus (dHip) and potentiated impulsivity during Pavlovian-conditioning and the 5-CSRTT. Remarkably, inhibition of ERK1 and ERK2 phosphorylation by U0126 in the dHip prior to Pavlovian-conditioning exacerbated impulsive reward seeking. Moreover, we found decreased A_2AR expression, and reduced ERK1 and ERK2 phosphorylation in the dHip of equilibrative nucleoside transporter type 1 (ENT1^-/-) null mice, which displayed exacerbated impulsivity. To determine whether impulsive response behavior is associated with hippocampal neuroblast development, we investigated expression of BrdU⁺ and doublecortin (DCX⁺) following 5-CSRTT testing. These studies revealed that impulsive behavior driven by inhibition of the A_2AR is accompanied by increased neuroblast proliferation in the hippocampus.

Optimized Analysis of In Vivo and In Vitro Hepatic Steatosis

Establishing a system of procedures to qualitatively and quantitatively characterize in vivo and in vitro hepatic steatosis is important for metabolic study in the liver. Here, numerous assays are described to comprehensively measure the phenotype and parameters of hepatic steatosis in mouse and hepatocyte models. Combining the physiological, histological, and biochemical methods, this system can be used to assess the progress of hepatic steatosis. In vivo, the measurements of body weight and nuclear magnetic resonance (NMR) provide a general understanding of mice in a non-invasive manner. Hematoxylin and Eosin (H&E) and Oil Red O staining determine the histological morphology and lipid deposition of liver tissue under nutrient overload conditions, such as high-fat diet feeding. Next, the total lipid contents are isolated by chloroform/methanol extraction, which are followed by a biochemical analysis for triglyceride and cholesterol. Moreover, mouse primary hepatocytes are treated with high glucose plus insulin to stimulate lipid accumulation, an efficient in vitro model to mimic diet-induced hyperglycemia and hyperinsulinemia in vivo. Then, the lipid deposition is measured by Oil Red O staining and chloroform/methanol extraction. Oil Red O staining determines intuitive hepatic steatotic phenotypes, while the lipid extraction analysis determines the parameters that can be analyzed statistically. The present protocols are of interest to scientists in the fields of fatty liver diseases, insulin resistance, and type 2 diabetes.

Fibroblast growth factor 21 improves hepatic insulin sensitivity by inhibiting mammalian target of rapamycin complex 1 in mice

Among the 22 fibroblast growth factors (FGFs), FGF21 has now emerged as a key metabolic regulator. However, the mechanism whereby FGF21 mediates its metabolic actions per se remains largely unknown. Here, we show that FGF21 represses mammalian target of rapamycin complex 1 (mTORC1) and improves insulin sensitivity and glycogen storage in a hepatocyte-autonomous manner. Administration of FGF21 in mice inhibits mTORC1 in the liver, whereas FGF21-deficient mice display pronounced insulin-stimulated mTORC1 activation and exacerbated hepatic insulin resistance (IR). FGF21 inhibits insulin- or nutrient-stimulated activation of mTORC1 to enhance phosphorylation of Akt in HepG2 cells at both normal and IR condition. TSC1 deficiency abrogates FGF21-mediated inhibition of mTORC1 and augmentation of insulin signaling and glycogen synthesis. Strikingly, hepatic βKlotho knockdown or hepatic hyperactivation of mTORC1/ribosomal protein S6 kinase 1 abrogates hepatic insulin-sensitizing and glycemic-control effects of FGF21 in diet-induced insulin-resistant mice. Moreover, FGF21 improves methionine- and choline-deficient diet-induced steatohepatitis.

CONCLUSIONS

FGF21 acts as an inhibitor of mTORC1 to control hepatic insulin action and maintain glucose homeostasis, and mTORC1 inhibition by FGF21 has the therapeutic potential for treating IR and type 2 diabetes. (Hepatology 2016;64:425-438).

Hepatic ATF6 Increases Fatty Acid Oxidation to Attenuate Hepatic Steatosis in Mice Through Peroxisome Proliferator-Activated Receptor α

The endoplasmic reticulum quality control protein activating transcription factor 6 (ATF6) has emerged as a novel metabolic regulator. Here, we show that adenovirus-mediated overexpression of the dominant-negative form of ATF6 (dnATF6) increases susceptibility to develop hepatic steatosis in diet-induced insulin-resistant mice and fasted mice. Overexpression of dnATF6 or small interfering RNA-mediated knockdown of ATF6 decreases the transcriptional activity of peroxisome proliferator-activated receptor α (PPARα)/retinoid X receptor complex, and inhibits oxygen consumption rates in hepatocytes, possibly through inhibition of the binding of PPARα to the promoter of its target gene. Intriguingly, ATF6 physically interacts with PPARα, enhances the transcriptional activity of PPARα, and triggers activation of PPARα downstream targets, such as CPT1α and MCAD, in hepatocytes. Furthermore, hepatic overexpression of the active form of ATF6 promotes hepatic fatty acid oxidation and protects against hepatic steatosis in diet-induced insulin-resistant mice. These data delineate the mechanism by which ATF6 controls the activity of PPARα and hepatic mitochondria fatty acid oxidation. Therefore, strategies to activate ATF6 could be used as an alternative avenue to improve liver function and treat hepatic steatosis in obesity.

Polymorphisms of the bovine MC3R gene and their associations with body measurement traits and meat quality traits in Qinchuan cattle

The melanocortin 3 receptor (MC3R) gene, which belongs to the rhodopsin-like family A of the G protein-coupled receptor family, plays a crucial role in feed efficiency and energy homeostasis. The aim of this study was to examine associations between bovine MC3R gene polymorphisms and body measurement traits (BMTs) and meat quality traits (MQTs). We identified three synonymous mutations (T429C, T537C, and T663C) in exon 1 of the MC3R gene in Chinese Qinchuan beef cattle (N = 271) by sequencing. D' and r(2) values revealed that these three SNPs were in strong linkage disequilibrium (LD) (r(2) > 0.33); the T429C and T537C SNPs were in complete LD (D' = 1 and r(2) = 1). Association analyses revealed that the SNPs were significantly associated with BMTs and MQTs in Qinchuan cattle. Individuals with the wild homozygotic genotypes g.TTTT and g.TT had significantly higher values of chest depth, heart girth, back fat thickness, intramuscular fat content, and loin muscle area than the mutant heterozygotic genotypes g.TCTC and g.TC. These results suggest that the MC3R gene affects MQTs in Qinchuan cattle, and that it may be a good candidate gene for marker-assisted selection.

Increased TEAD4 expression and nuclear localization in colorectal cancer promote epithelial-mesenchymal transition and metastasis in a YAP-independent manner

Dysregulation of the Hippo pathway occurs in a variety of cancers and often correlates with a poor prognosis. To further explore the potential role of Hippo pathway dysregulation in tumor development and progression, we investigated its downstream transcription factor TEAD4 in colorectal cancer (CRC). Increased expression and nuclear localization of TEAD4 were found in a significant portion of CRC tissues, in association with metastasis and a poor prognosis. In CRC cells, TEAD4 knockdown induced the mesenchymal-epithelial transition and decreased cell mobility in vitro and metastasis in vivo. Microarray analysis revealed that TEAD4 promoted cell adhesion and upregulated the epithelial-mesenchymal transition-related transcriptome in CRC cells. Vimentin was identified as a new direct target gene mediating TEAD4 function in CRC cells, whereby forced vimentin expression markedly reversed TEAD4-knockdown-induced cell morphological changes and decreased mobility. Interestingly, rescued expression of both WT TEAD4 and a Y429H mutant can reverse the mesenchymal-epithelial transition and increase vimentin expression, cell mobility and metastatic potential in TEAD4-knockdown CRC cells. The discrepant expression of YAP and TEAD4 in CRC tissues, the rescue ability of TEAD4 mutant defect in YAP binding and no effect on vimentin expression by YAP knockdown in CRC cells, all implicated a YAP-independent manner of TEAD4 function in CRC. Furthermore, vimentin positively correlated and CDH1 reversely correlated with the level of TEAD4 in CRC tissues and xenograft tumors. Our results suggest that TEAD4 nuclear expression can serve as a biomarker for CRC progression and poor prognosis. The transcription factor TEAD4 regulates a pro-metastasis transcription program in a YAP-independent manner in CRC, thus providing a novel mechanism of TEAD4 transcriptional regulation and its oncogenic role in CRC, independently of the Hippo pathway.

Tumour-infiltrating inflammation and prognosis in colorectal cancer: systematic review and meta-analysis

Background:

The role of tumour-infiltrating inflammation in the prognosis of patients with colorectal cancer (CRC) has not been fully evaluated. The primary objective of our meta-analysis was to determine the impact of tumour-infiltrating inflammation on survival outcomes.

Methods:

Ovid MEDLINE and EMBASE were searched to identify studies reporting the prognostic significance of tumour-infiltrating inflammation for patients with CRC. The primary outcome measures were overall survival (OS), cancer-specific survival (CS) and disease-free survival (DFS).

Results:

A total of 30 studies involving 2988 patients were identified. Studies were subdivided into those considering the associations between CRC survival and generalised tumour inflammatory infiltrate (n=12) and T lymphocyte subsets (n=18). Pooled analyses revealed that high generalised tumour inflammatory infiltrate was associated with good OS (HR, 0.59; 95% CI, 0.48–0.72), CS (HR, 0.40; 95% CI, 0.27–0.61) and DFS (HR, 0.72; 95% CI, 0.57–0.91). Stratification by location and T lymphocyte subset indicated that in the tumour centre, CD3⁺, CD8⁺ and FoxP3⁺ infiltrates were not statistically significant prognostic markers for OS or CS. In the tumour stroma, high CD8⁺, but not CD3⁺ or FoxP3⁺ cell infiltrates indicated increased OS. Furthermore, high CD3⁺ cell infiltrate was detected at the invasive tumour margin in patients with good OS and DFS; and high CCR7⁺ infiltrate was also indicated increased OS.

Conclusion:

Overall, high generalised tumour inflammatory infiltrate could be a good prognostic marker for CRC. However, significant heterogeneity and an insufficient number of studies underscore the need for further prospective studies on subsets of T lymphocytes to increase the robustness of the analyses.

Serum KL-6 as a novel disease marker in adolescent and adult cystic fibrosis

BACKGROUND

Cystic fibrosis (CF) is a chronic progressive disease leading to obstructive pulmonary impairment, fibrosis and shortened life expectancy. Serum levels of KL-6, high molecular weight human MUC1 mucin, are increased in the majority of patients with various interstitial lung disorders. Whether they are also elevated in CF has not been investigated before.

OBJECTIVE

To evaluate whether serum KL-6 levels are elevated and correlate with pulmonary function variables in CF.

DESIGN

Serum KL-6, lactate dehydrogenase (LDH) and C-reactive protein (CRP) levels were measured in 72 consecutive CF and 80 age- and sex-matched healthy control subjects. The relationship between serum KL-6 levels and pulmonary function variables was analyzed.

RESULTS

Serum KL-6 levels in CF patients were significantly increased compared to healthy subjects. Receiver operating characteristic curve analysis revealed that the diagnostic accuracy of KL-6 was better than that of LDH and CRP. Serum KL-6 levels showed an inverse relationship with vital capacity (VC) % predicted and forced expiratory volume in one second (FEV1) % predicted.

CONCLUSIONS

Serum KL-6 levels are elevated and appear to be correlated with pulmonary function variables in CF. These results suggest that KL-6 may be a useful noninvasive marker to monitor disease severity.

Plasma IL-6 level and survival of pancreatic cancer patients treated with a VEGFR inhibitor, vatalanib (PTK/ZK)

e15514

Background: Use of anti-angiogenesis drugs in pancreatic cancer has not yet resulted in significant clinical improvements and it is unknown if there are subsets of patients with pancreatic cancer that may benefit from this therapeutic approach. We have reported on a phase II trial of PTK/ZK (VEGFR inhibitor) in patients (n=65) who have failed or progressed on gemcitabine. The 6- month OS met the primary endpoint of 29 % and there were 2 partial responses. We investigated some of the plasma proteins relevant for angiogenesis in correlation with clinical outcomes on this trial. Methods: Plasma samples were obtained prior to and after 4 weeks of therapy with PTK/ZK, aliquoted and frozen until assayed. Patient plasma was assayed for: VEGFA, VEGFC, VEGFR1, VEGFR2, FGFb, PDGFBB, OPN, ANG2, IL-6, and sIL-6R (SearchLight, Pierce Biotechnology Multiplex ELISA and IL-6 and sIL-6R using R&D Systems).The Spearmen correlation was utilized to look for correlations and changes from baseline compared to post-treatment levels. The correlation of baseline levels with survival were analyzed using the Cox proportional hazard model. Results: Thirty eight paired patient samples were assayed. A significant correlation of baseline values was found between VEGF-C and VEGFR1 (p=0.0496), VEGF-C and VEGF (0.0092), PDGFB and ANG2 (p=0.0003), IL-6 and ANG2 (p=0.0089), and FGFb and OPN (p=0.0281). A correlation in post-treatment change was observed between VEGF-C and PDGFB (p=0.0008), FGFb and OPN (p=0.0374), PDGFB and ANG2 (p=0.0005), IL-6 and ANG-2 (p=0.0464), and VEGF and IL-6 (p=0.0546). Lower baseline IL-6 levels correlated with longer survival (p=0.0227). A post-treatment decrease in plasma IL-6 levels was significantly associated with improvement in survival (p=0.0457). IL-6 mediates multiple effects including angiogenic and pro-survival signaling and has been proposed as a potential prognostic factor in different malignancies. Conclusions: Of all angiogenesis markers analyzed only a post-treatment decrease in plasma IL-6 correlated with improved survival on study. IL-6 warrants further investigation as a potential marker of sensitivity to anti-angiogenesis therapy, especially in patients with pancreatic cancer. Supported by: 1P50 CA95060; 1PO1CA109552–01A1

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Real-time PCR and its application to mumps rapid diagnosis

A real-time polymerase chain reaction assay was initially developed in China to detect mumps genome. The primers and TaqMan-MGB probe were selected from regions of the hemagglutinin gene of mumps virus. The primers and probe for the real-time PCR were evaluated by both laboratories in China and in the UK using three different pieces of equipment, LightCycler (Roche), MJ DNA Engine Option 2 (BIO-RAD) and TaqMan (ABI Prism) on different samples. The reaction was performed with either a one-step (China) or two-step (UK) process. The sensitivity (10 copies) was estimated using a serial dilution of constructed mumps-plasmid DNA and a linear standard curve was obtained between 10 and 10(7) DNA copies/reaction, which can be used to quantify viral loads. The detection limit on cell culture-grown virus was approximately 2 pfu/ml with a two-step assay on TaqMan, which was equivalent to the sensitivity of the nested PCR routinely used in the UK. The specificity was proved by testing a range of respiratory viruses and several genotypes of mumps strains. The concentration of primers and probe is 22 pmol and 6.25 or 7 pmol respectively for a 25 microl reaction. The assay took 3 hr from viral RNA extraction to complete the detection using any of the three pieces of equipment. Three hundred forty-one (35 in China and 306 in the UK) clinical specimens were tested, the results showing that this real-time PCR assay is suitable for rapid and accurate detection of mumps virus RNA in various types of clinical specimens.