Arachidonic acid metabolism in liver glucose and lipid homeostasis / 生理学报

Arachidonic acid (AA) is an ω-6 polyunsaturated fatty acid, which mainly exists in the cell membrane in the form of phospholipid. Three major enzymatic pathways including the cyclooxygenase (COX), lipoxygenase (LOX) and cytochrome P450 monooxygenase (CYP450) pathways are involved in AA metabolism leading to the generation of a variety of lipid mediators such as prostaglandins, leukotrienes, hydroxyeicosatetraenoic acids (HETEs) and epoxyeicoastrienoic acids (EETs). These bioactive AA metabolites play an important role in the regulation of many physiological processes including the maintenance of liver glucose and lipid homeostasis. As the central metabolic organ, the liver is essential in metabolism of carbohydrates, lipids and proteins, and its dysfunction is associated with the pathogenesis of many metabolic diseases such as type 2 diabetes mellitus, dyslipidemia and nonalcoholic fatty liver disease (NAFLD). This article aims to provide an overview of the enzymatic pathways of AA and discuss the role of AA-derived lipid mediators in the regulation of hepatic glucose and lipid metabolism and their associations with the pathogenesis of major metabolic disorders.

Farnesoid X receptor (FXR) inhibits coagulation process via inducing hepatic antithrombin III expression in mice / 生理学报

Farnesoid X receptor (FXR) has been identified as an inhibitor of platelet function and an inducer of fibrinogen protein complex. However, the regulatory mechanism of FXR in hemostatic system remains incompletely understood. In this study, we aimed to investigate the functions of FXR in regulating antithrombin III (AT III). C57BL/6 mice and FXR knockout (FXR KO) mice were treated with or without GW4064 (30 mg/kg per day). FXR activation significantly prolonged prothrombin time (PT) and activated partial thromboplastin time (APTT), lowered activity of activated factor X (FXa) and concentrations of thrombin-antithrombin complex (TAT) and activated factor II (FIIa), and increased level of AT III, whereas all of these effects were markedly reversed in FXR KO mice. In vivo, hepatic AT III mRNA and protein expression levels were up-regulated in wild-type mice after FXR activation, but down-regulated in FXR KO mice. In vitro study showed that FXR activation induced, while FXR knockdown inhibited, AT III expression in mouse primary hepatocytes. The luciferase assay and ChIP assay revealed that FXR can bind to the promoter region of AT III gene where FXR activation increased AT III transcription. These results suggest FXR activation inhibits coagulation process via inducing hepatic AT III expression in mice. The present study reveals a new role of FXR in hemostatic homeostasis and indicates that FXR might act as a potential therapeutic target for diseases related to hypercoagulation.

Role of systematic integration teaching reform at the basic medicine teaching stage in Chinese medical education system / 生理学报

Systematic integration teaching is a curriculum system focusing on organs and systems, which is an important direction of medical education reform in China. Based on the practice of integrated curriculum teaching in Dalian Medical University for more than 10 years, combined with the experience in 15 medical colleges and universities in China, this paper analyzed the modes of systematic integrated teaching at the basic medicine teaching stage for medical higher education, and specified the purpose and significance of this teaching reform. The results showed that: (1) The systematic integrated teaching is a well-accepted and widely used teaching mode in domestic medical colleges and universities, which mainly includes three types of methodologies, i.e., integration of basic medicine courses, integration of clinical medicine courses and integration of basic and clinical medicine courses. The systematic integrated teaching is carried out by reforming various teaching methods including problem-based learning (PBL), case-based learning (CBL) and team-based learning (TBL). (2) The systematic integration teaching at the basic medicine teaching stage can significantly optimize the transition between basic and clinical courses, promote the cooperation and exchange between basic and clinical teachers, and improve the medical students' knowledge construction and critical thinking, and teachers' teaching ability as well. (3) The systematic integration teaching concept of "Six focuses" and "Five combinations" effectively guides the design and implementation of the integrated curriculum at the basic medical teaching stage of Dalian Medical University. With the deepening and development of medical education system reform in China, giving full play to the respective advantages of the systematic integrated teaching and traditional single-subject teaching at the basic medicine stage, and strengthening the integration of basic and clinical courses will play an important role in optimizing medical education curriculum system with Chinese characteristics.

Role of pregnane X receptor (PXR) in endobiotic metabolism / 生理学报

As a member of the nuclear receptor superfamily, the pregnane X receptor (PXR) is a ligand-activated transcription factor. PXR is highly expressed in liver and intestinal tissues, and also found in other tissues and organs, such as stomach and kidney. After heterodimerization with retinoid X receptor (RXR), PXR recruits numerous co-activating factors, and binds to specific DNA response elements to perform transcriptional regulation of the downstream target genes. As an acknowledged receptor for xenobiotics, PXR was initially considered as a nuclear receptor regulating drug metabolizing enzymes and transporters. However, nowadays, PXR has also been recognized as an important endobiotic receptor. Recent studies have shown that PXR activation can regulate glucose metabolism, lipid metabolism, steroid endocrine homeostasis, detoxification of cholic acid and bilirubin, bone mineral balance, and immune inflammation in vivo. This review focuses on the role of PXR in metabolism of endogenous substances.

Role of prostaglandin E2 receptor 4 in cardiovascular diseases / 生理学报

Prostaglandin E2 (PGE2) is a cyclooxygenase metabolite of arachidonic acid. It acts as a bioactive lipid and plays an important role in regulating many biological processes. PGE2 binds to 4 different G protein-coupled receptors including prostaglandin E2 receptor subtypes EP1, EP2, EP3 and EP4. The EP4 receptor is widely expressed in most of human organs and tissues. Increasing evidence demonstrates that EP4 is essential for cardiovascular homeostasis and participates in the pathogenesis of many cardiovascular diseases. Here we summarize the role of EP4 in the regulation of cardiovascular function and discuss potential mechanisms by which EP4 is involved in the development of cardiovascular disorders with a focus on its effect on inflammation.

Role of prostaglandin E receptor EP4 in the regulation of adipogenesis and adipose metabolism / 生理学报

Adipose tissue is the energy storage organ of the body, and excess energy is stored in adipocytes in the form of lipid droplets. The homeostasis of adipose tissue is the basis for the body to maintain normal metabolic activity. Prostaglandin E (PGE) is an important lipid mediator in the body. It is synthesized in almost all tissues and participates in the regulation of many physiological processes such as blood pressure, glucose and lipid metabolism, and inflammation. PGE is abundant in white adipose tissue, where it is involved in the regulation of fat metabolism. PGE plays its biological role through binding to four G protein coupled receptors (prostaglandin E receptors), including EP-1, -2, -3, and -4. The EP4 subtype has been proved to play an important role in adipogenesis and adipose metabolism: it could inhibit adipogenesis while it was activated, whereas its knockout could promote lipolysis. This review summarized the relationship between EP4 and adipose metabolism, hoping to identify new targets of drug development for metabolic disorders.

Hyperhomocysteinemia and kidney diseases / 生理学报

Homocysteine (Hcy) is an intermediate metabolite of methionine metabolism. Hyperhomocysteinemia (HHcy) is defined as a condition characterized by plasma Hcy level above 16 μmol/L which can result from abnormal Hcy metabolism. HHcy has been confirmed to be related to cardio-cerebrovascular disease, peripheral vascular disorders, neurodegenerative diseases, diabetes, pregnancy-induced hypertension syndrome, liver cirrhosis and kidney diseases. In this review, we summarize the correlation between HHcy and kidney diseases. Elucidating the role of HHcy in kidney diseases may provide a new strategy to prevent and treat kidney diseases.

Construction of the skeletal muscle-specific TbetaR II knockout mice / 中国应用生理学杂志

<p><b>OBJECTIVE</b>To generate the skeletal muscle-specific transforming growth factor beta receptor II (TbetaR II) gene knockout mice for the research on the function of the TbetaR II gene in skeletal muscles.</p><p><b>METHODS</b>TbetaR II (flox/flox) mice were generated using embryonic stem cell technology. The MCK-Cre mice were engineered containing Cre recombinase under the control of creatine kinase (MCK) muscle-specific promoter. TbetaR II (flox/flox) mice were crossed with MCK-Cre mice generating TbetaR II (flox/flox)/MCK-Cre double Tg mice. And then, TbetaR II (flox/wt) /MCK-Cre(+) double Tg mice were crossed with TbetaR II (flox/flox) mice to generate TbetaR II (flox/flox)/MCK- Cre(+) mice genetically ablating TbetaR II in cre-expressing skeletal muscle cells.</p><p><b>RESULTS</b>As predicted, mice lacking TbetaR II by gene targeting in skeletal muscles were generated first in the world using Cre/loxP system. TbetaR II null mutant mice were viable, fertile and showed apparently normal development.</p>