Digestive System Diseases Commons^™

A Phospholipid Mimetic Targeting Lrh-1 Ameliorates Colitis, Suzanne G Mays, Emma H D'Agostino, Autumn R Flynn, Xiangsheng Huang, Guohui Wang, Xu Liu, Elizabeth J Millings, C Denise Okafor, Anamika Patel, Michael L Cato, Jeffery L Cornelison, Diana Melchers, René Houtman, David D Moore, John W Calvert, Nathan T Jui, Eric A Ortlund

Faculty, Staff and Students Publications

Phospholipids are ligands for nuclear hormone receptors (NRs) that regulate transcriptional programs relevant to normal physiology and disease. Here, we demonstrate that mimicking phospholipid-NR interactions is a robust strategy to improve agonists of liver receptor homolog-1 (LRH-1), a therapeutic target for colitis. Conventional LRH-1 modulators only partially occupy the binding pocket, leaving vacant a region important for phospholipid binding and allostery. Therefore, we constructed a set of molecules with elements of natural phospholipids appended to a synthetic LRH-1 agonist. We show that the phospholipid-mimicking groups interact with the targeted residues in crystal structures and improve binding affinity, LRH-1 transcriptional activity, …

Depletion Of Transmembrane Mucin 4 (Muc4) Alters Intestinal Homeostasis In A Genetically Engineered Mouse Model Of Colorectal Cancer, Ramesh Pothuraju, Priya Pai, Sanjib Chaudhary, Jawed A Siddiqui, Jesse L Cox, Sukhwinder Kaur, Satyanarayana Rachagani, Hemant K Roy, Michael Bouvet, Surinder K Batra

Faculty, Staff and Students Publications

Mucins are components of the mucus layer overlying the intestinal epithelial cells, which maintains physiological homeostasis. Altered mucin expression is associated with disease progression. Expression of MUC4 decreases in colorectal cancer (CRC); however, its functional role and implications in the intestinal pathology in CRC are not studied well. Therefore, we generated a genetically engineered Muc4 knockout (Muc4-/-) CRC mouse model by crossing with Muc4-/- and Apc^flox/flox mice in the presence of colon-specific inducible Cre. We observed that deficiency of Muc4 results in an increased number of macroscopic tumors in the colon and rectal region and leads to poor survival. …

Regulation Of The Double-Stranded Rna Response Through Adar1 Licenses Metaplastic Reprogramming In Gastric Epithelium, José B Sáenz, Nancy Vargas, Charles J Cho, Jason C Mills

Faculty, Staff and Students Publications

Cells recognize both foreign and host-derived double-stranded RNA (dsRNA) via a signaling pathway that is usually studied in the context of viral infection. It has become increasingly clear that the sensing and handling of endogenous dsRNA is also critical for cellular differentiation and development. The adenosine RNA deaminase, ADAR1, has been implicated as a central regulator of the dsRNA response, but how regulation of the dsRNA response might mediate cell fate during injury and whether such signaling is cell intrinsic remain unclear. Here, we show that the ADAR1-mediated response to dsRNA was dramatically induced in 2 distinct injury models of …

Mapk4 Promotes Triple Negative Breast Cancer Growth And Reduces Tumor Sensitivity To Pi3k Blockade, Wei Wang, Dong Han, Qinbo Cai, Tao Shen, Bingning Dong, Michael T Lewis, Runsheng Wang, Yanling Meng, Wolong Zhou, Ping Yi, Chad J Creighton, David D Moore, Feng Yang

Faculty, Staff and Students Publications

About 15-20% of breast cancer (BCa) is triple-negative BCa (TNBC), a devastating disease with limited therapeutic options. Aberrations in the PI3K/PTEN signaling pathway are common in TNBC. However, the therapeutic impact of PI3K inhibitors in TNBC has been limited and the mechanism(s) underlying this lack of efficacy remain elusive. Here, we demonstrate that a large subset of TNBC expresses significant levels of MAPK4, and this expression is critical for driving AKT activation independent of PI3K and promoting TNBC cell and xenograft growth. The ability of MAPK4 to bypass PI3K for AKT activation potentially provides a direct mechanism regulating tumor sensitivity …

Pathologic Inflammation In Malnutrition Is Driven By Proinflammatory Intestinal Microbiota, Large Intestine Barrier Dysfunction, And Translocation Of Bacterial Lipopolysaccharide, Grace T Patterson, Elvia Y Osorio, Alex Peniche, Sara M Dann, Erika Cordova, Geoffrey A Preidis, Ji Ho Suh, Ichiaki Ito, Omar A Saldarriaga, Michael Loeffelholz, Nadim J Ajami, Bruno L Travi, Peter C Melby

Faculty, Staff and Students Publications

Acute malnutrition, or wasting, is implicated in over half of all deaths in children under five and increases risk of infectious disease. Studies in humans and preclinical models have demonstrated that malnutrition is linked to an immature intestinal microbiota characterized by increased prevalence of Enterobacteriaceae. Observational studies in children with moderate acute malnutrition (MAM) have also observed heightened systemic inflammation and increased circulating bacterial lipopolysaccharides (LPS; endotoxin). However, the mechanisms that underpin the systemic inflammatory state and endotoxemia, and their pathophysiological consequences, remain uncertain. Understanding these pathophysiological mechanisms is necessary to design targeted treatments that will improve the unacceptable rate …

The Autophagic Protein P62 Is A Target Of Reactive Aldehydes In Human And Murine Cholestatic Liver Disease, Colin T Shearn, Aimee L Anderson, Michael W Devereux, David J Orlicky, Cole Michel, Dennis R Petersen, Colin G Miller, Sanjiv Harpavat, Edward E Schmidt, Ronald J Sokol

Faculty, Staff and Students Publications

Inflammatory cholestatic liver diseases, including Primary Sclerosing Cholangitis (PSC), are characterized by periportal inflammation with progression to cirrhosis. The objective of this study was to examine interactions between oxidative stress and autophagy in cholestasis. Using hepatic tissue from male acute cholestatic (bile duct ligated) as well as chronic cholestatic (Mdr2KO) mice, localization of oxidative stress, the antioxidant response and induction of autophagy were analyzed and compared to human PSC liver. Concurrently, the ability of reactive aldehydes to post-translationally modify the autophagosome marker p62 was assessed in PSC liver tissue and in cell culture. Expression of autophagy markers was upregulated in …

Adipose Tissue Hyaluronan Production Improves Systemic Glucose Homeostasis And Primes Adipocytes For Cl 316,243-Stimulated Lipolysis, Yi Zhu, Na Li, Mingyang Huang, Mason Bartels, Sophie Dogné, Shangang Zhao, Xi Chen, Clair Crewe, Leon Straub, Lavanya Vishvanath, Zhuzhen Zhang, Mengle Shao, Yongjie Yang, Christy M Gliniak, Ruth Gordillo, Gordon I Smith, William L Holland, Rana K Gupta, Bingning Dong, Nathalie Caron, Yong Xu, Yucel Akgul, Samuel Klein, Philipp E Scherer

Faculty, Staff and Students Publications

Plasma hyaluronan (HA) increases systemically in type 2 diabetes (T2D) and the HA synthesis inhibitor, 4-Methylumbelliferone, has been proposed to treat the disease. However, HA is also implicated in normal physiology. Therefore, we generated a Hyaluronan Synthase 2 transgenic mouse line, driven by a tet-response element promoter to understand the role of HA in systemic metabolism. To our surprise, adipocyte-specific overproduction of HA leads to smaller adipocytes and protects mice from high-fat-high-sucrose-diet-induced obesity and glucose intolerance. Adipocytes also have more free glycerol that can be released upon beta3 adrenergic stimulation. Improvements in glucose tolerance were not linked to increased plasma …

Vertical Sleeve Gastrectomy Confers Metabolic Improvements By Reducing Intestinal Bile Acids And Lipid Absorption In Mice, Lili Ding, Eryun Zhang, Qiaoling Yang, Lihua Jin, Kyle M Sousa, Bingning Dong, Yangmeng Wang, Jui Tu, Xiaoxiao Ma, Jingyan Tian, Hongli Zhang, Zhipeng Fang, Ana Guan, Yixin Zhang, Zhengtao Wang, David D Moore, Li Yang, Wendong Huang

Faculty, Staff and Students Publications

Vertical sleeve gastrectomy (VSG) is a highly effective bariatric surgery that sustainably treats obesity and type 2 diabetes (T2D). However, the underlying mechanisms governing its metabolic benefits remain unclear. In this study, we have used four different genetically modified mouse lines to understand the link between bile acid circulation and metabolic effects of VSG. Instead of directly activating the nuclear bile acid receptor farnesoid X receptor (Fxr) in the liver or intestine, VSG reduces intestinal levels of bile acids, thereby decreasing fat absorption in the intestine. Given the rising popularity of bariatric surgeries to treat obesity and associated T2D, the …

Discovery Of A Selective Inhibitor Of Doublecortin Like Kinase 1, Fleur M Ferguson, Behnam Nabet, Srivatsan Raghavan, Yan Liu, Alan L Leggett, Miljan Kuljanin, Radha L Kalekar, Annan Yang, Shuning He, Jinhua Wang, Raymond W S Ng, Rita Sulahian, Lianbo Li, Emily J Poulin, Ling Huang, Jost Koren, Nora Dieguez-Martinez, Sergio Espinosa, Zhiyang Zeng, Cesear R Corona, James D Vasta, Ryoma Ohi, Taebo Sim, Nam Doo Kim, Wayne Harshbarger, Jose M Lizcano, Matthew B Robers, Senthil Muthaswamy, Charles Y Lin, A Thomas Look, Kevin M Haigis, Joseph D Mancias, Brian M Wolpin, Andrew J Aguirre, William C Hahn, Kenneth D Westover, Nathanael S Gray

Faculty, Staff and Students Publications

Doublecortin like kinase 1 (DCLK1) is an understudied kinase that is upregulated in a wide range of cancers, including pancreatic ductal adenocarcinoma (PDAC). However, little is known about its potential as a therapeutic target. We used chemoproteomic profiling and structure-based design to develop a selective, in vivo-compatible chemical probe of the DCLK1 kinase domain, DCLK1-IN-1. We demonstrate activity of DCLK1-IN-1 against clinically relevant patient-derived PDAC organoid models and use a combination of RNA-sequencing, proteomics and phosphoproteomics analysis to reveal that DCLK1 inhibition modulates proteins and pathways associated with cell motility in this context. DCLK1-IN-1 will serve as a versatile tool …

Ubiquitination Of The Dna-Damage Checkpoint Kinase Chk1 By Traf4 Is Required For Chk1 Activation, Xinfang Yu, Wei Li, Haidan Liu, Qipan Deng, Xu Wang, Hui Hu, Zijun Y Xu-Monette, Wei Xiong, Zhongxin Lu, Ken H Young, Wei Wang, Yong Li

Faculty, Staff and Students Publications

BACKGROUND: Aberrant activation of DNA damage response (DDR) is a major cause of chemoresistance in colorectal cancer (CRC). CHK1 is upregulated in CRC and contributes to therapeutic resistance. We investigated the upstream signaling pathways governing CHK1 activation in CRC.

METHODS: We identified CHK1-binding proteins by mass spectrometry analysis. We analyzed the biologic consequences of knockout or overexpression of TRAF4 using immunoblotting, immunoprecipitation, and immunofluorescence. CHK1 and TRAF4 ubiquitination was studied in vitro and in vivo. We tested the functions of TRAF4 in CHK1 phosphorylation and CRC chemoresistance by measuring cell viability and proliferation, anchorage-dependent and -independent cell growth, and mouse …

Methyl-Sensing Nuclear Receptor Liver Receptor Homolog-1 Regulates Mitochondrial Function In Mouse Hepatocytes, Sungwoo Choi, Bingning Dong, Chih-Chun Janet Lin, Mi Jeong Heo, Kang Ho Kim, Zhen Sun, Martin Wagner, Nagireddy Putluri, Jae Myoung Suh, Meng C Wang, David D Moore

Faculty, Staff and Students Publications

Liver receptor homologue-1 (LRH-1; NR5A2) is a nuclear receptor that regulates metabolic homeostasis in the liver. Previous studies identified phosphatidylcholines as potential endogenous agonist ligands for LRH-1. In the liver, distinct subsets of phosphatidylcholine species are generated by two different pathways: choline addition to phosphatidic acid via the Kennedy pathway, or trimethylation of phosphatidylethanolamine via Phosphatidylethanolamine N-methyl Transferase (PEMT). Here we report that a PEMT - LRH-1 pathway specifically couples methyl metabolism and mitochondrial activities in hepatocytes. We show that the loss of Lrh-1 reduces mitochondrial number, basal respiration, beta-oxidation and ATP production in hepatocytes, and decreases expression of mitochondrial …

A Novel Triterpenoid Induces Transforming Growth Factor Β Production By Intraepithelial Lymphocytes To Prevent Ileitis, Laurie A. Minns, Dominique Buzoni-Gatel, Kenneth H. Ely, Nicolas Rachinel, Souphalone Luangsay, Lloyd H. Kasper

Dartmouth Scholarship

The loss of homeostasis is a hallmark of inflammatory bowel disease. Oral infection of susceptible mice with Toxoplasma gondii results in an acute lethal ileitis characterized by increased interferon γ, tumor necrosis factor α, and inducible nitric oxide synthase; homeostasis results from transforming growth factor β production by intraepithelial lymphocytes. The synthetic oleanane triterpenoid 2-cyano-3,12-dioxooleana-1,9-dien-28-oic acid (CDDO) is a potent anti-inflammatory molecule previously shown in vitro to suppress the de novo synthesis of inducible nitric oxide synthase and to induce the transcription and activation of genes from the transforming growth factor β signaling pathway. We evaluated the immune response in …