Publications by authors named "Guojun Shi"

28 Publications

  • Page 1 of 1

Induced regulatory T cells suppress Tc1 cells through TGF-β signaling to ameliorate STZ-induced type 1 diabetes mellitus.

Cell Mol Immunol 2021 Mar 14;18(3):698-710. Epub 2021 Jan 14.

Department of Endocrinology and Metabolism, Guangdong Provincial Key Laboratory of Diabetology, The Third Affiliated Hospital of Sun Yat-sen University, Guangzhou, 510630, Guangdong, China.

Type 1 diabetes mellitus (T1D) is a chronic autoimmune condition in which the immune system destroys insulin-producing pancreatic β cells. In addition to well-established pathogenic effector T cells, regulatory T cells (Tregs) have also been shown to be defective in T1D. Thus, an increasing number of therapeutic approaches are being developed to target Tregs. However, the role and mechanisms of TGF-β-induced Tregs (iTregs) in T1D remain poorly understood. Here, using a streptozotocin (STZ)-induced preclinical T1D mouse model, we found that iTregs could ameliorate the development of T1D and preserve β cell function. The preventive effect was associated with the inhibition of type 1 cytotoxic T (Tc1) cell function and rebalancing the Treg/Tc1 cell ratio in recipients. Furthermore, we showed that the underlying mechanisms were due to the TGF-β-mediated combinatorial actions of mTOR and TCF1. In addition to the preventive role, the therapeutic effects of iTregs on the established STZ-T1D and nonobese diabetic (NOD) mouse models were tested, which revealed improved β cell function. Our findings therefore provide key new insights into the basic mechanisms involved in the therapeutic role of iTregs in T1D.
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http://dx.doi.org/10.1038/s41423-020-00623-2DOI Listing
March 2021

Lactucopicrin Inhibits Cytoplasmic Dynein-Mediated NF-κB Activation in Inflammated Macrophages and Alleviates Atherogenesis in Apolipoprotein E-Deficient Mice.

Mol Nutr Food Res 2021 02 22;65(4):e2000989. Epub 2021 Jan 22.

Department of Nutrition, School of Public Health, Sun Yat-sen University (Northern Campus), Guangzhou, P. R. China.

Scope: Nuclear factor-κB (NF-κB) activation in macrophages aggravates atherosclerosis. Dietary plant secondary metabolites including sesquiterpene lactone lactucopicrin target multiple organs. This study is focused on the impact of lactucopicrin on NF-κB activation in inflammed macrophages and atherogenesis in a mouse model of atherosclerosis.

Methods And Results: In LPS-stimulated mouse bone marrow-derived macrophages, lactucopicrin inhibits NF-κB activation, and concomitantly represses the expression of IL-1β, IL-6, and tumor necrosis factor-alpha. This effect is not due to modulation of the inhibitor of NF-κB kinases (IKK) α/β/γ and NF-κB inhibitor α, and NF-κB/p65 DNA binding activity. Instead, the lactucopicrin effect is reliant on the inhibition of cytoplasmic dynein-mediated p65 transportation, a prerequisite step for p65 nuclear translocation. In high-fat diet-fed apolipoprotein E-deficient mice, lactucopicrin consumption dose-dependently reduces plaque area, inhibits plaque macrophage accumulation, attenuates plaque macrophage NF-κB activation, and reduces both plaque and serum inflammatory burden. However, lactucopicrin consumption does not affect the levels of serum lipids and anti-inflammatory cytokines (IL-4, IL-10, and transforming growth factor beta).

Conclusion: Dietary lactucopicrin inhibits atherogenesis in mice likely by its anti-inflammatory property. These findings suggest that dietary supplementation with lactucopicrin is a promising strategy to inhibit atherosclerotic cardiovascular disease.
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http://dx.doi.org/10.1002/mnfr.202000989DOI Listing
February 2021

ER-associated degradation preserves hematopoietic stem cell quiescence and self-renewal by restricting mTOR activity.

Blood 2020 12;136(26):2975-2986

Department of Internal Medicine.

Hematopoietic stem cells (HSC) self-renew to sustain stem cell pools and differentiate to generate all types of blood cells. HSCs remain in quiescence to sustain their long-term self-renewal potential. It remains unclear whether protein quality control is required for stem cells in quiescence when RNA content, protein synthesis, and metabolic activities are profoundly reduced. Here, we report that protein quality control via endoplasmic reticulum-associated degradation (ERAD) governs the function of quiescent HSCs. The Sel1L/Hrd1 ERAD genes are enriched in the quiescent and inactive HSCs, and conditional knockout of Sel1L in hematopoietic tissues drives HSCs to hyperproliferation, which leads to complete loss of HSC self-renewal and HSC depletion. Mechanistically, ERAD deficiency via Sel1L knockout leads to activation of mammalian target of rapamycin (mTOR) signaling. Furthermore, we identify Ras homolog enriched in brain (Rheb), an activator of mTOR, as a novel protein substrate of Sel1L/Hrd1 ERAD, which accumulates upon Sel1L deletion and HSC activation. Importantly, inhibition of mTOR, or Rheb, rescues HSC defects in Sel1L knockout mice. Protein quality control via ERAD is, therefore, a critical checkpoint that governs HSC quiescence and self-renewal by Rheb-mediated restriction of mTOR activity.
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http://dx.doi.org/10.1182/blood.2020007975DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7770563PMC
December 2020

Protein quality control through endoplasmic reticulum-associated degradation maintains haematopoietic stem cell identity and niche interactions.

Nat Cell Biol 2020 10 21;22(10):1162-1169. Epub 2020 Sep 21.

Department of Molecular and Cellular Biology, Baylor College of Medicine, Houston, TX, USA.

Stem cells need to be protected from genotoxic and proteotoxic stress to maintain a healthy pool throughout life. Little is known about the proteostasis mechanism that safeguards stem cells. Here we report endoplasmic reticulum-associated degradation (ERAD) as a protein quality checkpoint that controls the haematopoietic stem cell (HSC)-niche interaction and determines the fate of HSCs. The SEL1L-HRD1 complex, the most conserved branch of ERAD, is highly expressed in HSCs. Deletion of Sel1l led to niche displacement of HSCs and a complete loss of HSC identity, and allowed highly efficient donor-HSC engraftment without irradiation. Mechanistic studies identified MPL, the master regulator of HSC identity, as a bona fide ERAD substrate that became aggregated in the endoplasmic reticulum following ERAD deficiency. Restoration of MPL signalling with an agonist partially rescued the number and reconstitution capacity of Sel1l-deficient HSCs. Our study defines ERAD as an essential proteostasis mechanism to safeguard a healthy stem cell pool by regulating the stem cell-niche interaction.
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http://dx.doi.org/10.1038/s41556-020-00581-xDOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7888538PMC
October 2020

DTI study on rehabilitation of the congenital deafness auditory pathway and speech center by cochlear implantation.

Eur Arch Otorhinolaryngol 2019 Sep 24;276(9):2411-2417. Epub 2019 May 24.

Department of Radiology, The Affiliated Hospital of Guizhou Medical University, Guiyi Street 28#, Guiyang, Guizhou, China.

Purpose: To explore the correlation between hearing and speech recovery levels after cochlear implantation and examined the preoperative microstructure of auditory pathways and speech centre using DTI.

Methods: (1) Fifty-two SNHL children between 0 and 6 years and 19 age and gender matched normal hearing subjects had received 3.0 T-MRI examination of the brain.FA, axial diffusion coefficient (λ), radial diffusion coefficient (λ), and MD values in the lateral lemniscus, inferior colliculus, medial geniculate bodies, auditory radiations, Brodmann areas 41, 42, 22, 44, 45, and 39 were all measured bilaterally. (2) CAP and SIR scores were assessed in fourty-six cochlear implantation children at 6 months post-implant. Correlations among deaf children ages, FA value of bilateral inferior colliculus FA values, BA22, BA44, and postoperative CAP, and SIR scores were analyzed using multiple linear regression.

Results: The preoperative standard partial regression age coefficient of deaf children (|bi'| = 0.404) was slightly greater than that of the inferior colliculus (|bi'| = 0.377) FA value.

Conclusion: Preoperative children ages and inferior colliculus FA values were important factors influencing postoperative CAP score. Inferior colliculus FA value is a vital influencing factor in rehabilitation after cochlear implantation.
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http://dx.doi.org/10.1007/s00405-019-05477-7DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6682568PMC
September 2019

SRY-Box Containing Gene 4 Promotes Liver Steatosis by Upregulation of SREBP-1c.

Diabetes 2018 11 4;67(11):2227-2238. Epub 2018 Sep 4.

Key Laboratory of Metabolism and Molecular Medicine, Ministry of Education, and Department of Endocrinology and Metabolism, Zhongshan Hospital, Fudan University, Shanghai, China

Obesity is usually associated with an increased risk of nonalcoholic fatty liver disease that is characterized by accumulation of excessive triglyceride (TG) in hepatocytes. However, the factors involved in the obesity-induced hepatosteatosis are poorly defined. Here, we report that SRY-box containing gene 4 (), a transcription factor that regulates cell proliferation and differentiation, plays an important role in hepatic TG metabolism. expression levels are markedly upregulated in livers of obese rodents and humans. Adenovirus-medicated overexpression of in the livers of lean mice promotes liver steatosis, whereas liver-specific knockdown of ameliorates TG accumulation and improves insulin resistance in obese mice. At the molecular level, we show that could directly control the transcription of gene through binding to its proximal promoter region. Thus, we have identified as an important component of hepatic TG metabolism.
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http://dx.doi.org/10.2337/db18-0184DOI Listing
November 2018

Hypothalamic ER-associated degradation regulates POMC maturation, feeding, and age-associated obesity.

J Clin Invest 2018 03 19;128(3):1125-1140. Epub 2018 Feb 19.

Department of Molecular & Integrative Physiology, University of Michigan Medical School, Ann Arbor, Michigan, USA.

Pro-opiomelanocortin (POMC) neurons function as key regulators of metabolism and physiology by releasing prohormone-derived neuropeptides with distinct biological activities. However, our understanding of early events in prohormone maturation in the ER remains incomplete. Highlighting the significance of this gap in knowledge, a single POMC cysteine-to-phenylalanine mutation at position 28 (POMC-C28F) is defective for ER processing and causes early onset obesity in a dominant-negative manner in humans through an unclear mechanism. Here, we report a pathologically important role of Sel1L-Hrd1, the protein complex of ER-associated degradation (ERAD), within POMC neurons. Mice with POMC neuron-specific Sel1L deficiency developed age-associated obesity due, at least in part, to the ER retention of POMC that led to hyperphagia. The Sel1L-Hrd1 complex targets a fraction of nascent POMC molecules for ubiquitination and proteasomal degradation, preventing accumulation of misfolded and aggregated POMC, thereby ensuring that another fraction of POMC can undergo normal posttranslational processing and trafficking for secretion. Moreover, we found that the disease-associated POMC-C28F mutant evades ERAD and becomes aggregated due to the presence of a highly reactive unpaired cysteine thiol at position 50. Thus, this study not only identifies ERAD as an important mechanism regulating POMC maturation within the ER, but also provides insights into the pathogenesis of monogenic obesity associated with defective prohormone folding.
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http://dx.doi.org/10.1172/JCI96420DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5824855PMC
March 2018

Stanniocalcin2 acts as an anorectic factor through activation of STAT3 pathway.

Oncotarget 2017 Oct 20;8(53):91067-91075. Epub 2017 Jul 20.

Department of Endocrinology, Fudan Institute for Metabolic Diseases, Zhongshan Hospital, Fudan University, Shanghai 200032, China.

The regulation of food intake and body weight has been hotly investigated. In the present study, we show that stanniocalcin2 (STC2), a cytokine ubiquitously expressed and especially upregulated in many types of human cancers, has a regulatory role in food intake and weight loss. Systemic treatment of C57BL/6 mice with recombinant STC2 protein resulted in decreased food intake and body weight, whereas energy expenditure was not affected. Similarly, STC2 treatment also induced anorexia in hyperphagic leptin-deficient mice, leading to a significant reduction in body weight and improvement of blood glucose levels. Furthermore, intracerebroventricular administration of STC2 to mice led to an acute decrease in food intake, which was mediated, at least in part, by activation of STAT3 pathway. Taken together, our results revealed the importance of STC2 in the regulation of feeding behavior as well as body weight.
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http://dx.doi.org/10.18632/oncotarget.19412DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5710906PMC
October 2017

ER-associated degradation is required for vasopressin prohormone processing and systemic water homeostasis.

J Clin Invest 2017 10 18;127(10):3897-3912. Epub 2017 Sep 18.

Department of Molecular and Integrative Physiology, University of Michigan Medical School, Ann Arbor, Michigan, USA.

Peptide hormones are crucial regulators of many aspects of human physiology. Mutations that alter these signaling peptides are associated with physiological imbalances that underlie diseases. However, the conformational maturation of peptide hormone precursors (prohormones) in the ER remains largely unexplored. Here, we report that conformational maturation of proAVP, the precursor for the antidiuretic hormone arginine-vasopressin, within the ER requires the ER-associated degradation (ERAD) activity of the Sel1L-Hrd1 protein complex. Serum hyperosmolality induces expression of both ERAD components and proAVP in AVP-producing neurons. Mice with global or AVP neuron-specific ablation of Se1L-Hrd1 ERAD progressively developed polyuria and polydipsia, characteristics of diabetes insipidus. Mechanistically, we found that ERAD deficiency causes marked ER retention and aggregation of a large proportion of all proAVP protein. Further, we show that proAVP is an endogenous substrate of Sel1L-Hrd1 ERAD. The inability to clear misfolded proAVP with highly reactive cysteine thiols in the absence of Sel1L-Hrd1 ERAD causes proAVP to accumulate and participate in inappropriate intermolecular disulfide-bonded aggregates, promoted by the enzymatic activity of protein disulfide isomerase (PDI). This study highlights a pathway linking ERAD to prohormone conformational maturation in neuroendocrine cells, expanding the role of ERAD in providing a conducive ER environment for nascent proteins to reach proper conformation.
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http://dx.doi.org/10.1172/JCI94771DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5617659PMC
October 2017

Serum Human Epidermal Growth Factor 2 is a Novel Biomarker for Recurrence and Metastasis in Triple Negative Breast Cancer.

Clin Lab 2017 Jan;63(1):53-58

Background: The aim of this study was to evaluate the predictive value of serum human epidermal growth factor 2 (HER2) for recurrence and metastasis in triple negative breast cancer (TNBC).

Methods: A total of 200 patients with benign breast tumors and 300 patients with breast cancer treated in the Department of Breast Surgery, Women and Children's Hospital of Ningbo City (China) between December 2006 and December 2013 were enrolled. Another 500 age- and gender-matched healthy individuals served as controls. The serum level of HER2 was determined using suspension array technology. Patients with breast cancer were further divided into ER-/PR-/HER2- and ER-/PR-/HER2+ groups and followed up for 5 years to analyze the serum concentration of HER2.

Results: The serum HER2 concentration was significantly higher in patients with breast cancer than in healthy controls or patients with benign tumors (both p < 0.01). The serum HER2 concentration also was significantly higher in patients with TNBC than in healthy controls (p < 0.01). The serum concentration of HER2 was significantly higher in TNBC patients who experienced recurrence and metastasis than in TNBC patients who did not experience recurrence and metastasis (both p < 0.01). Notably, the serum HER2 concentration in TNBC patients who experienced recurrence and metastasis was increased to a level statistically similar to that in patients with HER2+ breast cancer (p > 0.05).

Conclusions: Patients with TNBC still have an increased serum HER2 concentration, and serum HER2 may be a valuable, novel biomarker for recurrence and metastasis in TNBC.
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http://dx.doi.org/10.7754/Clin.Lab.2016.160524DOI Listing
January 2017

IRE1α is an endogenous substrate of endoplasmic-reticulum-associated degradation.

Nat Cell Biol 2015 Dec 9;17(12):1546-55. Epub 2015 Nov 9.

Graduate Program in Biochemistry, Molecular and Cell Biology, Cornell University, Ithaca, New York 14853, USA.

Endoplasmic reticulum (ER)-associated degradation (ERAD) represents a principle quality control mechanism to clear misfolded proteins in the ER; however, its physiological significance and the nature of endogenous ERAD substrates remain largely unexplored. Here we discover that IRE1α, the sensor of the unfolded protein response (UPR), is a bona fide substrate of the Sel1L-Hrd1 ERAD complex. ERAD-mediated IRE1α degradation occurs under basal conditions in a BiP-dependent manner, requires both the intramembrane hydrophilic residues of IRE1α and the lectin protein OS9, and is attenuated by ER stress. ERAD deficiency causes IRE1α protein stabilization, accumulation and mild activation both in vitro and in vivo. Although enterocyte-specific Sel1L-knockout mice (Sel1L(ΔIEC)) are viable and seem normal, they are highly susceptible to experimental colitis and inflammation-associated dysbiosis, in an IRE1α-dependent but CHOP-independent manner. Hence, Sel1L-Hrd1 ERAD serves a distinct, essential function in restraint of IRE1α signalling in vivo by managing its protein turnover.
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http://dx.doi.org/10.1038/ncb3266DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4670240PMC
December 2015

A CRISPR-Based Screen Identifies Genes Essential for West-Nile-Virus-Induced Cell Death.

Cell Rep 2015 Jul 16;12(4):673-83. Epub 2015 Jul 16.

Center of Emphasis in Infectious Diseases, Department of Biomedical Sciences, Paul L. Foster School of Medicine, Texas Tech University Health Sciences Center, El Paso, TX 79905, USA. Electronic address:

West Nile virus (WNV) causes an acute neurological infection attended by massive neuronal cell death. However, the mechanism(s) behind the virus-induced cell death is poorly understood. Using a library containing 77,406 sgRNAs targeting 20,121 genes, we performed a genome-wide screen followed by a second screen with a sub-library. Among the genes identified, seven genes, EMC2, EMC3, SEL1L, DERL2, UBE2G2, UBE2J1, and HRD1, stood out as having the strongest phenotype, whose knockout conferred strong protection against WNV-induced cell death with two different WNV strains and in three cell lines. Interestingly, knockout of these genes did not block WNV replication. Thus, these appear to be essential genes that link WNV replication to downstream cell death pathway(s). In addition, the fact that all of these genes belong to the ER-associated protein degradation (ERAD) pathway suggests that this might be the primary driver of WNV-induced cell death.
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http://dx.doi.org/10.1016/j.celrep.2015.06.049DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4559080PMC
July 2015

Free fatty acid receptor 2, a candidate target for type 1 diabetes, induces cell apoptosis through ERK signaling.

J Mol Endocrinol 2014 Dec 8;53(3):367-80. Epub 2014 Oct 8.

Shanghai Institute of Endocrinology and MetabolismEndocrine and Metabolic E-Institutes of Shanghai Universities (EISU), Shanghai Clinical Center for Endocrine and Metabolic Diseases and Key Laboratory for Endocrinology and Metabolism of Chinese Health Ministry, Ruijin Hospital, Shanghai Jiao Tong University School of Medicine, 197th Ruijin 2nd Road, Shanghai 200025, ChinaLaboratory of Endocrinology and MetabolismKey Laboratory of Stem Cell BiologyInstitute of Health Sciences, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences, Shanghai Jiao Tong University School of Medicine, Shanghai, China Shanghai Institute of Endocrinology and MetabolismEndocrine and Metabolic E-Institutes of Shanghai Universities (EISU), Shanghai Clinical Center for Endocrine and Metabolic Diseases and Key Laboratory for Endocrinology and Metabolism of Chinese Health Ministry, Ruijin Hospital, Shanghai Jiao Tong University School of Medicine, 197th Ruijin 2nd Road, Shanghai 200025, ChinaLaboratory of Endocrinology and MetabolismKey Laboratory of Stem Cell BiologyInstitute of Health Sciences, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences, Shanghai Jiao Tong University School of Medicine, Shanghai, China

Recent reports have highlighted the roles of free fatty acid receptor 2 (FFAR2) in the regulation of metabolic and inflammatory processes. However, the potential function of FFAR2 in type 1 diabetes (T1D) remains unexplored. Our results indicated that the mRNA level of FFAR2 was upregulated in peripheral blood mononuclear cells of T1D patients. The human FFAR2 promoter regions were cloned, and luciferase reporter assays revealed that NFκB activation induced FFAR2 expression. Furthermore, we showed that FFAR2 activation by overexpression induced cell apoptosis through ERK signaling. Finally, treatment with the FFAR2 agonists acetate or phenylacetamide 1 attenuated the inflammatory response in multiple-low-dose streptozocin-induced diabetic mice, and improved the impaired glucose tolerance. These results indicate that FFAR2 may play a protective role by inducing apoptosis of infiltrated macrophage in the pancreas through its feedback upregulation and activation, thus, in turn, improving glucose homeostasis in diabetic mice. These findings highlight FFAR2 as a potential therapeutic target of T1D, representing a link between immune response and glucose homeostasis.
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http://dx.doi.org/10.1530/JME-14-0065DOI Listing
December 2014

Role of total hip replacement arthroplasty between transplantation and acute kidney injury.

Ren Fail 2014 Jul;36(6):899-903

Traditional Chinese Medicine-Western Medicine Hospital of Cangzhou of Hebei, Cangzhou City , Hebei Province , China.

Osteonecrosis of the femoral head is a severely disabling complication of steroid immunosuppression in renal transplant patients. The increased number of patients undergoing transplantation has increased the number of transplant recipients undergoing total hip replacement arthroplasty (THRA). In this study, we retrospectively assessed patients who underwent THRA from May 2004 to February 2014, and evaluated their demographic and clinical characteristics, the results of peri-operative laboratory tests, the amounts of fluids transfused during surgery, and anesthesia time. Our results found that post-operative acute kidney injury (AKI) was significantly associated with transplantation, and transplantation was an independent factor predictive of post-operative AKI, so transplant recipients are at risk for AKI following THRA. Total hip replacement is a safe and effective treatment for transplant recipients and, in view of their limited life expectancy, should be considered at an early stage in their treatment.
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http://dx.doi.org/10.3109/0886022X.2014.900387DOI Listing
July 2014

Sel1L is indispensable for mammalian endoplasmic reticulum-associated degradation, endoplasmic reticulum homeostasis, and survival.

Proc Natl Acad Sci U S A 2014 Feb 22;111(5):E582-91. Epub 2014 Jan 22.

Graduate Program in Biochemistry, Molecular and Cell Biology, Division of Nutritional Sciences, and Department of Animal Science, Cornell University, Ithaca, NY 14853.

Suppressor/Enhancer of Lin-12-like (Sel1L) is an adaptor protein for the E3 ligase hydroxymethylglutaryl reductase degradation protein 1 (Hrd1) involved in endoplasmic reticulum-associated degradation (ERAD). Sel1L's physiological importance in mammalian ERAD, however, remains to be established. Here, using the inducible Sel1L knockout mouse and cell models, we show that Sel1L is indispensable for Hrd1 stability, ER homeostasis, and survival. Acute loss of Sel1L leads to premature death in adult mice within 3 wk with profound pancreatic atrophy. Contrary to current belief, our data show that mammalian Sel1L is required for Hrd1 stability and ERAD function both in vitro and in vivo. Sel1L deficiency disturbs ER homeostasis, activates ER stress, attenuates translation, and promotes cell death. Serendipitously, using a biochemical approach coupled with mass spectrometry, we found that Sel1L deficiency causes the aggregation of both small and large ribosomal subunits. Thus, Sel1L is an indispensable component of the mammalian Hrd1 ERAD complex and ER homeostasis, which is essential for protein translation, pancreatic function, and cellular and organismal survival.
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http://dx.doi.org/10.1073/pnas.1318114111DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3918815PMC
February 2014

TAB2, an important upstream adaptor of interleukin-1 signaling pathway, is subject to SUMOylation.

Mol Cell Biochem 2014 Jan 6;385(1-2):69-77. Epub 2013 Oct 6.

Shanghai Clinical Center for Endocrine and Metabolic Diseases, Shanghai Institute of Endocrinology and Metabolism, School of Medicine, Ruijin Hospital, Shanghai Jiao Tong University, Shanghai, 200025, China,

SUMOylation has been considered as an important mechanism to regulate multiple cellular processes, including inflammation. TAB2 (TAK1-binding protein 2) is an upstream adaptor protein in the IL-1 signaling pathway. Covalent modifications of TAB2 have not been well studied. In this study, we demonstrated that TAB2 could be modified by SUMO. Using Ubc9 (SUMO-conjugating enzyme) fusion and mutation analysis, we identified evolutionarily conserved lysine 329 as the major SUMOylation site of TAB2. PIAS3, a SUMO E3 ligase, preferentially interacted with and promoted its SUMOylation. Interestingly, block of SUMOylation by mutation of lysine 329 enhanced the activity of TAB2, as reflected by AP-1 luciferase reporter assays. Taken together, these results suggest that SUMOylation may serve as a novel mechanism for the regulation of TAB2.
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http://dx.doi.org/10.1007/s11010-013-1815-3DOI Listing
January 2014

Yin Yang 1 promotes hepatic steatosis through repression of farnesoid X receptor in obese mice.

Gut 2014 Jan 24;63(1):170-8. Epub 2013 Jan 24.

Department of Endocrine and Metabolic Diseases, Shanghai Institute of Endocrinology and Metabolism, Ruijin Hospital, Shanghai Jiao Tong University School of Medicine, , Shanghai, China.

Background: Non-alcoholic fatty liver disease (NAFLD) is characterised by accumulation of excessive triglycerides in the liver. Obesity is usually associated with NAFLD through an unknown mechanism.

Objective: To investigate the roles of Yin Yang 1 (YY1) in the progression of obesity-associated hepatosteatosis.

Methods: Expression levels of hepatic YY1 were identified by microarray analysis in high-fat-diet (HFD)-induced obese mice. Liver triglyceride metabolism was analysed in mice with YY1 overexpression and suppression.

Results: YY1 expression was markedly upregulated in HFD-induced obese mice and NAFLD patients. Overexpression of YY1 in healthy mice promoted hepatosteatosis under high-fat dietary conditions, whereas liver-specific ablation of YY1 using adenoviral shRNA ameliorated triglyceride accumulation in obese mice. At the molecular level, YY1 suppressed farnesoid X receptor (FXR) expression through binding to the YY1 responsive element at intron 1 of the FXR gene.

Conclusions: These findings indicate that YY1 plays a crucial role in obesity-associated hepatosteatosis, through repression of FXR expression.
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http://dx.doi.org/10.1136/gutjnl-2012-303150DOI Listing
January 2014

4-(2-Fluoro-benzo-yl)-1-[2-(4-hy-droxy-phen-yl)-2-oxoeth-yl]piperazin-1-ium trifluoro-acetate.

Acta Crystallogr Sect E Struct Rep Online 2012 Nov 31;68(Pt 11):o3243. Epub 2012 Oct 31.

College of Chemical Science and Technology, Yunnan University, Kunming City, People's Republic of China.

In the crystal structure of the title compound, C(19)H(20)FN(2)O(3) (+)·C(2)F(3)O(2) (-), N-H⋯O and O-H⋯O hydrogen bonds link two cations and two anions into a 22-atom ring. These rings are further linked into a three dimensional network by weak C-H⋯O contacts.
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http://dx.doi.org/10.1107/S1600536812042857DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3515321PMC
November 2012

Caenorhabditis elegans mom-4 is required for the activation of the p38 MAPK signaling pathway in the response to Pseudomonas aeruginosa infection.

Protein Cell 2013 Jan 5;4(1):53-61. Epub 2012 Dec 5.

Department of Pharmacology, Xinhua Hospital, School of Medicine, Shanghai, China.

The p38 mitogen-activated protein kinase (MAPK) plays an evolutionarily conserved role in the cellular response to microbial infection and environmental stress. Activation of p38 is mediated through phosphorylation by upstream MAPKK, which in turn is activated by MAPKKK. In the Caenorhabditis elegans, the p38 MAPK (also called PMK-1) signaling pathway has been shown to be required in its resistance to bacterial infection. However, how different upstream MAP2Ks and MAP3Ks specifically contribute to the activation of PMK-1 in response to bacterial infection still is not clearly understood. By using double-stranded RNA-mediated interference (RNAi) and genetic mutants of C. elegans, we demonstrate that C. elegans MOM-4, a mammalian TAK1 homolog, is required for the resistance of C. elegans to a P. aeruginosa infection. We have also found that the MKK-4 of C. elegans is required for P. aeruginosa resistance, but not through the regulation of DLK-1. In summary, our results indicate that different upstream MAPKKKs or MAPKKs regulate the activation of PMK-1 in response to P. Aeruginosa.
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http://dx.doi.org/10.1007/s13238-012-2080-zDOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4875442PMC
January 2013

Yin Yang 1 promotes hepatic gluconeogenesis through upregulation of glucocorticoid receptor.

Diabetes 2013 Apr 27;62(4):1064-73. Epub 2012 Nov 27.

Department of Endocrine and Metabolic Diseases, Shanghai Institute of Endocrinology and Metabolism, Shanghai Clinical Center for Endocrine and Metabolic Diseases, Ruijin Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai, China.

Gluconeogenesis is critical in maintaining blood glucose levels in a normal range during fasting. In this study, we investigated the role of Yin Yang 1 (YY1), a key transcription factor involved in cell proliferation and differentiation, in the regulation of hepatic gluconeogenesis. Our data showed that hepatic YY1 expression levels were induced in mice during fasting conditions and in a state of insulin resistance. Overexpression of YY1 in livers augmented gluconeogenesis, raising fasting blood glucose levels in C57BL/6 mice, whereas liver-specific ablation of YY1 using adenoviral shRNA ameliorated hyperglycemia in wild-type and diabetic db/db mice. At the molecular level, we further demonstrated that the major mechanism of YY1 in the regulation of hepatic glucose production is to modulate the expression of glucocorticoid receptor. Therefore, our study uncovered for the first time that YY1 participates in the regulation of hepatic gluconeogenesis, which implies that YY1 might serve as a potential therapeutic target for hyperglycemia in diabetes.
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http://dx.doi.org/10.2337/db12-0744DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3609554PMC
April 2013

Glucocorticoids promote hepatic cholestasis in mice by inhibiting the transcriptional activity of the farnesoid X receptor.

Gastroenterology 2012 Dec 23;143(6):1630-1640.e8. Epub 2012 Aug 23.

Shanghai Institute of Endocrinology and Metabolism, Department of Endocrine and Metabolic Diseases, Shanghai Clinical Center for Endocrine and Metabolic Diseases, Ruijin Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai, China.

Background & Aims: Glucocorticoids have potent anti-inflammatory effects, but also can cause insulin resistance, osteoporosis, and muscle wasting, preventing their long-term use. Glucocorticoids also have been associated with the development of hepatic cholestasis and gallstone disease, but little is known about their pathogenic mechanisms.

Methods: We analyzed levels of bile acids (BAs) and glucocorticoids in serum samples from patients with Cushing disease and obese individuals (body mass index, >30). C57BL/6 mice were injected with dexamethasone and db/db obese mice were injected with glucocorticoid receptor (GR) antagonists or small hairpin RNAs. We analyzed farnesoid X receptor (FXR) signaling in HepG2 cells and cells from mice using immunoprecipitation, luciferase reporter, and glutathione-s-transferase and chromatin immunoprecipitation assays. We analyzed BA metabolism in FXR-/- mice and mice with reduced levels of the transcription factor C-terminal binding protein (CtBP).

Results: Serum levels of BAs were higher in patients with Cushing disease or obesity than in individuals with normal levels of glucocorticoids. Administration of dexamethasone promoted cholestasis and overproduction of BAs in C57BL/6 mice, but not in FXR-/- mice. GR antagonists, or injection of an adenoviral small hairpin RNA against GR, reduced features of hepatic cholestasis in db/db mice. The GR interacted with FXR to reduce its transcriptional activity by recruiting CtBP co-repressor complexes. Mice with reduced levels of CtBP were resistant to induction of hepatic cholestasis by dexamethasone.

Conclusions: Glucocorticoids promote hepatic cholestasis in mice by recruiting CtBP co-repressor complexes to FXR and thereby blocking the transcriptional activity.
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http://dx.doi.org/10.1053/j.gastro.2012.08.029DOI Listing
December 2012

Structural insight into the mechanism of epothilone A bound to beta-tubulin and its mutants at Arg282Gln and Thr274Ile.

J Biomol Struct Dyn 2012 25;30(5):559-73. Epub 2012 Jun 25.

Key Laboratory of Education Ministry for Medicinal Chemistry of Natural Resource, College of Chemical Science and Technology, Yunnan University, Kunming 650091, PR China.

Epothilone A (EpoA) is under investigation as an antitumor agent. To provide better understanding of the activity of EpoA against cancers, by theoretical studies such as using docking method, molecular dynamics simulation and density functional theory calculations, we identify several key residues located on β-tubulin as the active sites to establish an active pocket responsible for interaction with EpoA. Eight residues (Arg276, Asp224, Asp26, His227, Glu27, Glu22, Thr274, and Met363) are identified as the active sites to form the active pocket on β-tubulin. The interaction energy is predicted to be -121.3 kJ/mol between EpoA and β-tubulin. In the mutant of β-tubulin at Thr274Ile, three residues (Arg359, Glu27, and His227) are identified as the active sites for the binding of EpoA. In the mutant of β-tubulin at Arg282Gln, three residues (Arg276, Lys19, and His227) serve as the active sites. The interaction energy is reduced to -77.2 kJ/mol between EpoA and Arg282Gln mutant and to -50.2 kJ/mol between EpoA and Thr274Ile mutant. The strong interaction with β-tubulin is significant to EpoA's activity against cancer cells. When β-tubulin is mutated either at Arg282Gln or at Thr274Ile, the decreased strength of interaction explains the activity reduced for EpoA. Therefore, this work shows that the structural basis of the active pocket plays an important role in regulating the activity for EpoA with a Taxol-like mechanism of action to be promoted as an antitumor agent.
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http://dx.doi.org/10.1080/07391102.2012.687522DOI Listing
December 2012

Inhibitory effect of andrographolide in 3T3-L1 adipocytes differentiation through the PPARγ pathway.

Mol Cell Endocrinol 2012 Jul 16;358(1):81-7. Epub 2012 Mar 16.

Shanghai Clinical Center for Endocrine and Metabolic Diseases, Shanghai Institute of Endocrine and Metabolic Diseases, Rui-Jin Hospital, Shanghai Jiao-Tong University School of Medicine, Shanghai, China.

Andrographolide (AG), an active compound found in Andrographis paniculate Nees, has been shown to exert anti-inflammatory, anticancer and anti-hyperglycemic effects. However, its biological activities against obesity have not been reported. The purpose of this study was to investigate the effect of AG on the differentiation of 3T3-L1 preadipocytes. We found AG significantly inhibited not only on adipocyte differentiation induced by standard adipogenic agents and MDI, but also on the adipogenesis-related transcription factor, peroxisome proliferator-activated receptor γ (PPARγ), as well as the expressions of the PPARγ targeted genes, such as CD36, LPL, FAS and other adiocyte markers. Taken together, our data showed AG inhibited the early stage of adipogenic differentiation, in part via the inhibition of PPARγ-dependent mechanisms.
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http://dx.doi.org/10.1016/j.mce.2012.02.025DOI Listing
July 2012

Protective effect of andrographolide against concanavalin A-induced liver injury.

Naunyn Schmiedebergs Arch Pharmacol 2012 Jan 24;385(1):69-79. Epub 2011 Sep 24.

Shanghai Institute of Endocrine and Metabolic Diseases, Shanghai Clinical Center for Endocrine and Metabolic Diseases, Department of Endocrine and Metabolic Diseases, Rui-jin Hospital, Shanghai Jiao-tong University School of Medicine, No. 197 Rui-Jin 2nd Road, Shanghai, 200025, China.

This study was designed to investigate the hepatic protective effect and the molecular mechanisms of andrographolide in concanavalin A-induced liver injury model. Results showed that andrographolide (Ag) attenuated concanavalin A (Con-A)-induced liver injury and inhibited hepatocyte apoptosis. Further results showed that oxidative stress response genes were significantly elevated during the pathogenesis induced by Con-A. Meanwhile, gadolinium chloride and N-acetyl-L-cysteine (NAC) treatment, which inactivates Kupffer cells or reduces reactive oxygen species, respectively, prevented the liver injury. So the messenger RNA levels of the oxidative response genes mentioned above were detected, and the following results showed that Ag treatment reduced their expression. Besides, serum lactate dehydrogenase and myeloperoxidase activity was significantly reduced by Ag. Finally, Ag treatment did not further reduce serum tumor necrosis factor-α production compared with NAC treatment alone. Thus, our results indicate that Ag prevents Con-A-induced liver injury and reduced the hepatic oxidative stress response. The hepatic protective effect of Ag indicates that Ag supplementation may be beneficial in the treatment of immune-mediated liver injury.
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http://dx.doi.org/10.1007/s00210-011-0685-zDOI Listing
January 2012

Andrographolide attenuates tumor necrosis factor-alpha-induced insulin resistance in 3T3-L1 adipocytes.

Mol Cell Endocrinol 2011 Jan 11;332(1-2):134-9. Epub 2010 Oct 11.

Laboratory of Endocrinology and Metabolism, Institute of Health Sciences, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences, and Shanghai Jiao Tong University School of Medicine, Shanghai, China.

Andrographolide (AG), the primary bioactive component of Andrographils paniculate Nees, has showed an anti-diabetic effect. However, the molecular mechanism has not been clarified. In this study, we demonstrated that AG increased glucose uptake in 3T3-L1 cells in a time- and dosedependent manner. The activation of insulin signaling by AG was initiated from phosphotyrosine of IRS-1 and further passed on through phosphatidylinositol 3-kinase (PI3K) and the downstream signaling cascades. Moreover importantly, pretreatment cells with AG suppressed the TNF-α induced activation of NF-κB signaling pathway and its downstream inflammatory factors expression, therefore ameliorating insulin resistance. In conclusion, AG can improve insulin sensitivity through inhibition of NF-κB pathway. These findings are helpful in understanding the anti-diabetic properties of AG and can be of interest for the therapeutic application of AG in glucose controlling.
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http://dx.doi.org/10.1016/j.mce.2010.10.005DOI Listing
January 2011

Selection of reference genes for quantitative real-time reverse transcription-polymerase chain reaction in concanavalin A-induced hepatitis model.

Anal Biochem 2010 Jun 11;401(1):81-90. Epub 2010 Feb 11.

Institute of Health Sciences, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences and Shanghai Jiao-Tong University School of Medicine, Shanghai 200031, China.

Quantitative real-time reverse transcription-polymerase chain reaction (Q-PCR) has become an indispensable technique for accurate determination of gene expression in various samples. In mice, intravenous injection of concanavalin A (ConA) leads to acute hepatitis and liver injury. Functional studies based on this model have provided insights for understanding the mechanisms of liver injury. However, no data have been reported to validate reference genes during the progression of ConA-induced hepatitis (CIH). In this study, IkappaBalpha and C/EBPbeta messenger RNA (mRNA) levels were examined using Q-PCR with ACTB as the reference gene after ConA injection. However, we got inconsistent results with previous reports determining IkappaBalpha and C/EBPbeta mRNA expression levels. The results indicate the necessity for stability analysis of candidate reference genes in the CIH model. geNorm, NormFinder, and BestKeeper software analysis indicates that ACTB is the most unstable gene during CIH progression among the 10 reference genes tested, whereas RPLP0 or HPRT1 is the most stable one. This study demonstrates that some of the commonly used reference genes are inadequate for normalization of Q-PCR data due to their expression instability. Furthermore, this study validates HPRT1 and RPLP0 as appropriate reference genes for Q-PCR analysis in the CIH model.
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http://dx.doi.org/10.1016/j.ab.2010.02.007DOI Listing
June 2010

An essential role for RIG-I in toll-like receptor-stimulated phagocytosis.

Cell Host Microbe 2009 Aug;6(2):150-61

The Key Laboratory of Stem Cell Biology, Institute of Health Sciences, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences/Shanghai JiaoTong University School of Medicine, Shanghai 200025, China.

Retinoic acid-inducible gene-I (RIG-I) plays an important role in antiviral response by recognizing double-stranded RNA. Here we demonstrate an unanticipated role of RIG-I in Toll-like receptor (TLR)-stimulated phagocytosis. Stimulation with lipopolysaccharide (LPS), a ligand of TLR4, induced the expression of RIG-I in macrophages. Depletion of RIG-I by RNAi or gene targeting inhibited the LPS-induced phagocytosis of bacteria. Cellular processes involved in phagocytosis, such as small GTPase Cdc42/Rac1 activation, actin polymerization, and actin-regulator Arp2/3 recruitment, were also impaired in RIG-I-deficient macrophages activated by LPS. Moreover, RIG-I(-/-) mice were found to be more susceptible to infection with Escherichia coli as compared to wild-type mice. Thus, the regulatory functions of RIG-I are strikingly broad, including a role not only in antiviral responses but in antibacterial responses as well.
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http://dx.doi.org/10.1016/j.chom.2009.06.008DOI Listing
August 2009