Life Sciences Commons^™

Myxobacteria Versus Sponge-Derived Alkaloids: The Bengamide Family Identified As Potent Immune Modulating Agents By Scrutiny Of Lc-Ms/Elsd Libraries., Tyler A. Johnson, Johann Sohn, Yvette M Vaske, Kimberly N White, Tanya L Cohen, Helene C Vervoort, Karen Tenney, Frederick A Valeriote, Leonard F Bjeldanes, Phillip Crews

Tyler Johnson

A nuclear factor-κB (NF-κB) luciferase assay has been employed to identify the bengamides, previously known for their anti-tumor activity, as a new class of immune modulators. A unique element of this study was that the bengamide analogs were isolated from two disparate sources, Myxococcus virescens (bacterium) and Jaspis coriacea (sponge). Comparative LC-MS/ELSD and NMR analysis facilitated the isolation of M. viriscens derived samples of bengamide E (8) and two congeners, bengamide E' (13) and F' (14) each isolated as an insperable mixture of diastereomers. Additional compounds drawn from the UC, Santa Cruz repository allowed expansion of the structure activity relationship …

The Marine Sponge Metabolite Mycothiazole: A Novel Prototype Mitochondrial Complex I Inhibitor., J Brian Morgan, Fakhri Mahdi, Yang Liu, Veena Coothankandaswamy, Mika B Jekabsons, Tyler A. Johnson, Koneni V Sashidhara, Phillip Crews, Dale G Nagle, Yu-Dong Zhou

Tyler Johnson

A natural product chemistry-based approach was applied to discover small-molecule inhibitors of hypoxia-inducible factor-1 (HIF-1). A Petrosaspongia mycofijiensis marine sponge extract yielded mycothiazole (1), a solid tumor selective compound with no known mechanism for its cell line-dependent cytotoxic activity. Compound 1 inhibited hypoxic HIF-1 signaling in tumor cells (IC(50) 1nM) that correlated with the suppression of hypoxia-stimulated tumor angiogenesis in vitro. However, 1 exhibited pronounced neurotoxicity in vitro. Mechanistic studies revealed that 1 selectively suppresses mitochondrial respiration at complex I (NADH-ubiquinone oxidoreductase). Unlike rotenone, MPP(+), annonaceous acetogenins, piericidin A, and other complex I inhibitors, mycothiazole is a mixed polyketide/peptide-derived compound …

Chemically Diverse Microtubule Stabilizing Agents Initiate Distinct Mitotic Defects And Dysregulated Expression Of Key Mitotic Kinases., Cristina C Rohena, Jiangnan Peng, Tyler A. Johnson, Phillip Crews, Susan L Mooberry

Tyler Johnson

Microtubule stabilizers are some of the most successful drugs used in the treatment of adult solid tumors and yet the molecular events responsible for their antimitotic actions are not well defined. The mitotic events initiated by three structurally and biologically diverse microtubule stabilizers; taccalonolide AJ, laulimalide/fijianolide B and paclitaxel were studied. These microtubule stabilizers cause the formation of aberrant, but structurally distinct mitotic spindles leading to the hypothesis that they differentially affect mitotic signaling. Each microtubule stabilizer initiated different patterns of expression of key mitotic signaling proteins. Taccalonolide AJ causes centrosome separation and disjunction failure to a much greater extent …

Discovery Of Platelet-Type 12-Human Lipoxygenase Selective Inhibitors By High-Throughput Screening Of Structurally Diverse Libraries., Joshua D. Deschamps, Jeffrey T. Gautschi, Stephanie Whitman, Tyler A. Johnson, Nadine C. Gassner, Phillip Crews, Theodore R. Holman

Tyler Johnson

Human lipoxygenases (hLO) have been implicated in a variety of diseases and cancers and each hLO isozyme appears to have distinct roles in cellular biology. This fact emphasizes the need for discovering selective hLO inhibitors for both understanding the role of specific lipoxygenases in the cell and developing pharmaceutical therapeutics. To this end, we have modified a known lipoxygenase assay for high-throughput (HTP) screening of both the National Cancer Institute (NCI) and the UC Santa Cruz marine extract library (UCSC-MEL) in search of platelet-type 12-hLO (12-hLO) selective inhibitors. The HTP screen led to the characterization of five novel 12-hLO inhibitors …

The Glia Response After Peripheral Nerve Injury: A Comparison Between Schwann Cells And Olfactory Ensheathing Cells And Their Uses For Neural Regenerative Therapies, Matthew J Barton, James St John, Alison Wright, Jenny Ekberg

Jenny Ekberg

The peripheral nervous system (PNS) exhibits a much larger capacity for regeneration than the central nervous system (CNS). One reason for this difference is the difference in glial cell types between the two systems. PNS glia respond rapidly to nerve injury by clearing debris from the injury site, supplying essential growth factors and providing structural support; all of which enhances neuronal regeneration. Thus, transplantation of glial cells from the PNS is a very promising therapy for injuries to both the PNS and the CNS. There are two key types of PNS glia: olfactory ensheathing cells (OECs), which populate the olfactory …

Crosstalk Between Brca-Fanconi Anemia And Mismatch Repair Pathways Prevents Msh2-Dependent Aberrant Dna Damage Responses, Min Peng, Jenny X. Xie, Anna J. Ucher, Janet Stavnezer, Sharon B. Cantor

Janet M. Stavnezer

Several proteins in the BRCA-Fanconi anemia (FA) pathway, such as FANCJ, BRCA1, and FANCD2, interact with mismatch repair (MMR) pathway factors, but the significance of this link remains unknown. Unlike the BRCA-FA pathway, the MMR pathway is not essential for cells to survive toxic DNA interstrand crosslinks (ICLs), although MMR proteins bind ICLs and other DNA structures that form at stalled replication forks. We hypothesized that MMR proteins corrupt ICL repair in cells that lack crosstalk between BRCA-FA and MMR pathways. Here, we show that ICL sensitivity of cells lacking the interaction between FANCJ and the MMR protein MLH1 is …

A Laminin 511 Matrix Is Regulated By Taz And Functions As The Ligand For The Alpha6bbeta1 Integrin To Sustain Breast Cancer Stem Cells, Cheng Chang, Hira Lal Goel, Huijie Gao, Bryan M. Pursell, Leonard D. Shultz, Dale L. Greiner, Sulev Ingerpuu, Manuel Patarroyo, Shiliang Cao, Elgene Lim, Junhao Mao, Karen Kulju. Mckee, Peter D. Yurchenco, Arthur M. Mercurio

Arthur M. Mercurio

Understanding how the extracellular matrix impacts the function of cancer stem cells (CSCs) is a significant but poorly understood problem. We report that breast CSCs produce a laminin (LM) 511 matrix that promotes self-renewal and tumor initiation by engaging the alpha6Bbeta1 integrin and activating the Hippo transducer TAZ. Although TAZ is important for the function of breast CSCs, the mechanism is unknown. We observed that TAZ regulates the transcription of the alpha5 subunit of LM511 and the formation of a LM511 matrix. These data establish a positive feedback loop involving TAZ and LM511 that contributes to stemness in breast cancer.

Nonenzymatic Glycosylation Of Erythrocyte Membrane Proteins. Relevance To Diabetes, J A. Miller, Ellen M. Gravallese, H F. Bunn

Ellen M. Gravallese

Nonenzymatic glycosylation of proteins of the erythrocyte membrane was determined by incubating erythrocyte ghosts with [3H]borohydride. The incorporation of tritium into protein provides a reliable assay of ketoamine linkages. The membrane proteins from 18 patients with diabetes incorporated twice as much radioactivity as membrane proteins from normal erythrocytes. After acid hydrolysis, amino acid analysis showed that the majority of radioactivity was localized to glucosyllysine. Autoradiograms showed that all of the major proteins of the erythrocyte membrane, separated by electrophoresis on sodium dodecyl sulfate gels, contained ketoamine linkages. No protein bands in either normal or diabetic erythrocytes showed significant preferential labeling. …

The Role Of Tnf-Receptor Family Members And Other Traf-Dependent Receptors In Bone Resorption, Ellen M. Gravallese, Deborah L. Galson, Steven R. Goldring, Philip E. Auron

Ellen M. Gravallese

The contribution of osteoclasts to the process of bone loss in inflammatory arthritis has recently been demonstrated. Studies in osteoclast biology have led to the identification of factors responsible for the differentiation and activation of osteoclasts, the most important of which is the receptor activator of NF-kappa B ligand/osteoclast differentiation factor (RANKL/ODF), a tumor necrosis factor (TNF)-like protein. The RANKL/ODF receptor, receptor activator of NF-kappa B (RANK), is a TNF-receptor family member present on both osteoclast precursors and mature osteoclasts. Like other TNF-family receptors and the IL-1 receptor, RANK mediates its signal transduction via TNF receptor-associated factor (TRAF) proteins, suggesting …

Dual Engagement Of The Nlrp3 And Aim2 Inflammasomes By Plasmodium-Derived Hemozoin And Dna During Malaria, Parisa Kalantari, Rosane B. Deoliveira, Jennie Chan, Yolanda Corbett, Vijay A. K. Rathinam, Andrea Stutz, Eicke Latz, Ricardo T. Gazzinelli, Douglas T. Golenbock, Katherine A. Fitzgerald

Katherine A. Fitzgerald

Hemozoin (Hz) is the crystalline detoxification product of hemoglobin in Plasmodium-infected erythrocytes. We previously proposed that Hz can carry plasmodial DNA into a subcellular compartment that is accessible to Toll-like receptor 9 (TLR9), inducing an inflammatory signal. Hz also activates the NLRP3 inflammasome in primed cells. We found that Hz appears to colocalize with DNA in infected erythrocytes, even before RBC rupture or phagolysosomal digestion. Using synthetic Hz coated in vitro with plasmodial genomic DNA (gDNA) or CpG oligodeoxynucleotides, we observed that DNA-complexed Hz induced TLR9 translocation, providing a priming and an activation signal for inflammasomes. After phagocytosis, Hz and …

Imp3 Expression Is Associated With Poor Outcome And Epigenetic Deregulation In Intrahepatic Cholangiocarcinoma, Yuanyuan Gao, Michelle Yang, Zhong Jiang, Bruce A. Woda, Arthur M. Mercurio, Jianjie Qin, Xinli Huang, Feng Zhang

Arthur M. Mercurio

IMP3 is a fetal protein not expressed in normal adult tissues. IMP3 is an oncoprotein and a useful biomarker for a variety of malignancies and is associated with reduced overall survival of a number of them. IMP3 expression and its prognostic value for patients with intrahepatic cholangiocarcinoma (ICC) have not been well investigated. The molecular mechanism underlying IMP3 expression in human cancer cells remains to be elucidated. Here we investigated IMP3 expression in ICC and adjacent nonneoplastic liver in 72 unifocal primary ICCs from a single institute by immunohistochemistry, immunoblotting, and real-time polymerase chain reaction. IMP3 was specifically expressed in …

Temporal Trends In Serum Concentrations Of Polychlorinated Dioxins, Furans, And Pcbs Among Adult Women Living In Chapaevsk, Russia: A Longitudinal Study From 2000 To 2009, Olivier Humblet, Oleg Sergeyev, Larisa Altshul, Susan A. Korrick, Paige L. Williams, Claude Emond, Linda S. Birnbaum, Jane S. Burns, Mary M. Lee, Boris Revich, Andrey Shelepchikov, Denis Feshin, Russ Hauser

Mary M. Lee

BACKGROUND: The present study assessed the temporal trend in serum concentrations of polychlorinated dibenzo-p-dioxins, dibenzofurans, and biphenyls (PCBs) among residents of a Russian town where levels of these chemicals are elevated due to prior industrial activity.

METHODS: Two serum samples were collected from eight adult women (in 2000 and 2009), and analyzed with gas chromatography-high-resolution mass spectrometry.

RESULTS: The average total toxic equivalency (TEQ) decreased by 30% (from 36 to 25 pg/g lipid), and the average sum of PCB congeners decreased by 19% (from 291 to 211 ng/g lipid). Total TEQs decreased for seven of the eight women, and the …

Parental Mastery Of Continuous Subcutaneous Insulin Infusion Skills And Glycemic Control In Youth With Type 1 Diabetes, Kathleen Mitchell, Kimberley Johnson, Karen Cullen, Mary M. Lee, Olga T. Hardy

Mary M. Lee

OBJECTIVE: The purpose of this study is to determine whether parental knowledge of the continuous subcutaneous insulin infusion (CSII) device affects glycemic control as measured by hemoglobin A1c (A1C) level. SUBJECTS AND METHODS: Parents of children with type 1 diabetes mellitus (T1DM) using CSII completed a 14-item questionnaire. Questions 1-10 were knowledge-based questions that required the parent to extract specific information from their child's CSII device. Questions 11-14 asked parents to provide a self-assessment of their CSII knowledge. RESULTS: Twenty-two parents of youth with T1DM participated in the study. Ten of the youth were in the Low-A1C group (A1C/=8%). Parents …

Dengue Virus Nonstructural Protein Ns5 Induces Interleukin-8 Transcription And Secretion, Carey L. Medin, Katherine A. Fitzgerald, Alan L. Rothman

Alan Rothman

Elevated circulating levels of chemokines have been reported in patients with dengue fever and are proposed to contribute to the pathogenesis of dengue disease. To establish in vitro models for chemokine induction by dengue 2 virus (DEN2V), we studied a variety of human cell lines and primary cells. DEN2V infection of HepG2 and primary dendritic cells induced the production of interleukin-8 (IL-8), RANTES, MIP-1alpha, and MIP-1beta, whereas only IL-8 and RANTES were induced following dengue virus infection of HEK293 cells. Chemokine secretion was accompanied by an increase in steady-state mRNA levels. No chemokine induction was observed in HEK293 cells treated …

Determinants Of Inapparent And Symptomatic Dengue Infection In A Prospective Study Of Primary School Children In Kamphaeng Phet, Thailand, Timothy P. Endy, Kathryn B. Anderson, Ananda Nisalak, In-Kyu Yoon, Sharone Green, Alan L. Rothman, Stephen J. Thomas, Richard G. Jarman, Daniel H. Libraty, Robert V. Gibbons

Sharone Green

BACKGROUND: Dengue viruses are a major cause of morbidity in tropical and subtropical regions of the world. Inapparent dengue is an important component of the overall burden of dengue infection. It provides a source of infection for mosquito transmission during the course of an epidemic, yet by definition is undetected by health care providers. Previous studies of inapparent or subclinical infection have reported varying ratios of symptomatic to inapparent dengue infection. METHODOLOGY/PRINCIPAL FINDINGS: In a prospective study of school children in Northern Thailand, we describe the spatial and temporal variation of the symptomatic to inapparent (S:I) dengue illness ratio. Our …

T Cell Receptor Vbeta Gene Usage In Thai Children With Dengue Virus Infection, Susan J. Gagnon, Anita M. Leporati, Sharone Green, Siripen Kalayanarooj, David W. Vaughn, Henry A. F. Stephens, Saroj Suntayakorn, Ichiro Kurane, Francis A. Ennis, Alan L. Rothman

Sharone Green

T lymphocyte activation during dengue is thought to contribute to the pathogenesis of dengue hemorrhagic fever (DHF). We examined the T cell receptor Vbeta gene usage by a reverse transcriptase-polymerase chain reaction assay during infection and after recovery in 13 children with DHF and 13 children with dengue fever (DF). There was no deletion of specific Vbeta gene families. We detected significant expansions in usage of single Vbeta families in six subjects with DHF and three subjects with DF over the course of infection, but these did not show an association with clinical diagnosis, viral serotype, or HLA alleles. Differences …

Prediction Of Dengue Disease Severity Among Pediatric Thai Patients Using Early Clinical Laboratory Indicators, James A. Potts, Robert V. Gibbons, Alan L. Rothman, Anon Srikiatkhachorn, Stephen J. Thomas, Pra-On Supradish, Stephenie C. Lemon, Daniel H. Libraty, Sharone Green, Siripen Kalayanarooj

Sharone Green

BACKGROUND: Dengue virus is endemic in tropical and sub-tropical resource-poor countries. Dengue illness can range from a nonspecific febrile illness to a severe disease, Dengue Shock Syndrome (DSS), in which patients develop circulatory failure. Earlier diagnosis of severe dengue illnesses would have a substantial impact on the allocation of health resources in endemic countries. METHODS AND FINDINGS: We compared clinical laboratory findings collected within 72 hours of fever onset from a prospective cohort children presenting to one of two hospitals (one urban and one rural) in Thailand. Classification and regression tree analysis was used to develop diagnostic algorithms using different …

Virus-Induced Decline In Soluble Vascular Endothelial Growth Receptor 2 Is Associated With Plasma Leakage In Dengue Hemorrhagic Fever, Anon Srikiatkhachorn, Chuanpis Ajariyakhajorn, Timothy P. Endy, Siripen Kalayanarooj, Daniel H. Libraty, Sharone Green, Francis A. Ennis, Alan L. Rothman

Sharone Green

Some individuals infected with dengue virus develop dengue hemorrhagic fever (DHF), a viral hemorrhagic disease characterized by a transient period of localized plasma leakage. To determine the importance of vascular endothelial growth factor A (VEGF-A) in this syndrome, we compared plasma levels of VEGF-A and the soluble forms of its receptors in patients with DHF to patients with dengue fever (DF), a milder form of dengue virus infection without plasma leakage. We observed a rise in the plasma levels of free, but not total VEGF-A in DHF patients at the time of plasma leakage. This was associated with a decline …

Definition Of An Hla-Dpw2-Restricted Epitope On Ns3, Recognized By A Dengue Virus Serotype-Cross-Reactive Human Cd4+ Cd8- Cytotoxic T-Cell Clone, Ichiro Kurane, Li Chen Dai, Peter G. Livingston, Elaine Reed, Francis A. Ennis

Li Dai

We previously reported that the clone JK34 was cross-reactive for dengue virus types 1, 2, 3, and 4 and recognized NS3 (I. Kurane, M. A. Brinton, A. L. Samson, and F. A. Ennis, J. Virol. 65:1823-1828, 1991). In the present experiments, we defined the epitope at the amino acid level, with 93 15-mer overlapping peptides which cover the entire NS3. A peptide 4 which contains amino acids 251 to 265 of NS3 sensitized the autologous B lymphoblastoid cell line (LCL) to the lysis by JK34. The smallest peptide recognized by JK34 was a 10-mer peptide which contains amino acids 255 …

Mutation Of Human Immunodeficiency Virus Type 1 At Amino Acid 585 On Gp41 Results In Loss Of Killing By Cd8+ A24-Restricted Cytotoxic T Lymphocytes, Li Chen Dai, Kim West, Rebecca A. Littaua, Kazuo Takahashi, Francis A. Ennis

Li Dai

A human leukocyte antigen A24-restricted CD8+ cytotoxic T-cell clone specific for gp41 of human immunodeficiency virus type 1 was isolated from an infected individual. The epitope was localized to amino acids 584 to 591 (YLKDQQLL, NL43 env sequence) of gp41 by using a panel of recombinant vaccinia viruses that contain truncated env genes and synthetic peptides. The clone killed autologous B-lymphoblastoid cell lines pulsed with a synthetic peptide reflecting the sequence of the IIIB and MN strains. This clone, however, failed to kill target cells pulsed with the peptides that have a mutation from Lys to Arg or Gln at …

Initial Multicenter Experience With Double Nucleoside Therapy For Human Immunodeficiency Virus Infection During Pregnancy, Neal S. Silverman, D. Heather Watts, Joseph Hitti, D. M. Money, E. Livingston, J. Axelrod, J. M. Ernest, Douglas Robbins, M. M. Divito

Neal Silverman

OBJECTIVE: To study maternal and neonatal effects of combination nucleoside analog therapy administered to human immunodeficiency virus (HIV)-infected pregnant women for maternal indications. METHODS: A multicenter, prospective observational study was undertaken at six perinatal centers in the United States and Canada that supported regional referral programs for the treatment of HIV-infected pregnant women. Demographic, laboratory, and pregnancy outcome data were collected for 39 women whose antiretroviral treatment regimens were expanded to include more than one nucleoside analog for maternal indications. The 40 newborns were monitored at pediatric referral centers through at least three months of age to ascertain their HIV …

Reflex Changes Associated With Anticipatory Postural Adjustments Preceding Voluntary Arm Movements In Standing Humans, Siddharth Vedula, Paul J. Stapley, Robert E. Kearney

Dr Paul J Stapley

Dynamic changes in human stability, such as those induced by upper body movements, are preceded by anticipatory postural adjustments (APAs) in the rest of the body. We measured the excitability of the stretch reflex of the triceps-surae muscle group during APAs associated with unilateral right arm raises in standing humans. Our results demonstrate that reflex excitability and underlying muscle activity are linked during the APA period, but that they differ in their relative timing. This supports the idea that reflexes are controlled independently of muscle activation.

Mechanism Of Substrate Recognition By Drug-Resistant Human Immunodeficiency Virus Type 1 Protease Variants Revealed By A Novel Structural Intermediate, Moses Prabu-Jeyabalan, Ellen A. Nalivaika, Keith Romano, Celia A. Schiffer

Celia A. Schiffer

Human immunodeficiency virus type 1 (HIV-1) protease processes and cleaves the Gag and Gag-Pol polyproteins, allowing viral maturation, and therefore is an important target for antiviral therapy. Ligand binding occurs when the flaps open, allowing access to the active site. This flexibility in flap geometry makes trapping and crystallizing structural intermediates in substrate binding challenging. In this study, we report two crystal structures of two HIV-1 protease variants bound with their corresponding nucleocapsid-p1 variant. One of the flaps in each of these structures exhibits an unusual "intermediate" conformation. Analysis of the flap-intermediate and flap-closed crystal structures reveals that the intermonomer …

Role Of Hypoxia And Glycolysis In The Development Of Multi-Drug Resistance In Human Tumor Cells And The Establishment Of An Orthotopic Multi-Drug Resistant Tumor Model In Nude Mice Using Hypoxic Pre-Conditioning, Lara Milane, Zhenfeng Duan, Mansoor M. Amiji

Mansoor M. Amiji

Background The development of multi-drug resistant (MDR) cancer is a significant challenge in the clinical treatment of recurrent disease. Hypoxia is an environmental selection pressure that contributes to the development of MDR. Many cancer cells, including MDR cells, resort to glycolysis for energy acquisition. This study aimed to explore the relationship between hypoxia, glycolysis, and MDR in a panel of human breast and ovarian cancer cells. A second aim of this study was to develop an orthotopic animal model of MDR breast cancer. Methods Nucleic and basal protein was extracted from a panel of human breast and ovarian cancer cells; …

Dengue Virus Nonstructural Protein Ns5 Induces Interleukin-8 Transcription And Secretion, Carey L. Medin, Katherine A. Fitzgerald, Alan L. Rothman

Katherine A. Fitzgerald

Elevated circulating levels of chemokines have been reported in patients with dengue fever and are proposed to contribute to the pathogenesis of dengue disease. To establish in vitro models for chemokine induction by dengue 2 virus (DEN2V), we studied a variety of human cell lines and primary cells. DEN2V infection of HepG2 and primary dendritic cells induced the production of interleukin-8 (IL-8), RANTES, MIP-1alpha, and MIP-1beta, whereas only IL-8 and RANTES were induced following dengue virus infection of HEK293 cells. Chemokine secretion was accompanied by an increase in steady-state mRNA levels. No chemokine induction was observed in HEK293 cells treated …

Lps-Tlr4 Signaling To Irf-3/7 And Nf-Kappab Involves The Toll Adapters Tram And Trif, Katherine A. Fitzgerald, Daniel C. Rowe, Betsy J. Barnes, Daniel R. Caffrey, Alberto Visintin, Eicke Latz, Brian G. Monks, Paula M. Pitha, Douglas T. Golenbock

Katherine A. Fitzgerald

Toll-IL-1-resistance (TIR) domain-containing adaptor-inducing IFN-beta (TRIF)-related adaptor molecule (TRAM) is the fourth TIR domain-containing adaptor protein to be described that participates in Toll receptor signaling. Like TRIF, TRAM activates interferon regulatory factor (IRF)-3, IRF-7, and NF-kappaB-dependent signaling pathways. Toll-like receptor (TLR)3 and 4 activate these pathways to induce IFN-alpha/beta, regulated on activation, normal T cell expressed and secreted (RANTES), and gamma interferon-inducible protein 10 (IP-10) expression independently of the adaptor protein myeloid differentiation factor 88 (MyD88). Dominant negative and siRNA studies performed here demonstrate that TRIF functions downstream of both the TLR3 (dsRNA) and TLR4 (LPS) signaling pathways, whereas the …

Integrin (Alpha 6 Beta 4) Regulation Of Eif-4e Activity And Vegf Translation: A Survival Mechanism For Carcinoma Cells, Jun Chung, Robin E. Bachelder, Elizabeth A. Lipscomb, Leslie M. Shaw, Arthur M. Mercurio

Arthur M. Mercurio

We define a novel mechanism by which integrins regulate growth factor expression and the survival of carcinoma cells. Specifically, we demonstrate that the alpha 6 beta 4 integrin enhances vascular endothelial growth factor (VEGF) translation in breast carcinoma cells. The mechanism involves the ability of this integrin to stimulate the phosphorylation and inactivation of 4E-binding protein (4E-BP1), a translational repressor that inhibits the function of eukaryotic translation initiation factor 4E (eIF-4E). The regulation of 4E-BP1 phosphorylation by alpha 6 beta 4 derives from the ability of this integrin to activate the PI-3K-Akt pathway and, consequently, the rapamycin-sensitive kinase mTOR that …

The Integrin Alpha6beta4 Functions In Carcinoma Cell Migration On Laminin-1 By Mediating The Formation And Stabilization Of Actin-Containing Motility Structures, Isaac Rabinovitz, Arthur M. Mercurio

Arthur M. Mercurio

Functional studies on the alpha6beta4 integrin have focused primarily on its role in the organization of hemidesmosomes, stable adhesive structures that associate with the intermediate filament cytoskeleton. In this study, we examined the function of the alpha6beta4 integrin in clone A cells, a colon carcinoma cell line that expresses alpha6beta4 but no alpha6beta1 integrin and exhibits dynamic adhesion and motility on laminin-1. Time-lapse videomicroscopy of clone A cells on laminin-1 revealed that their migration is characterized by filopodial extension and stabilization followed by lamellae that extend in the direction of stabilized filopodia. A function-blocking mAb specific for the alpha6beta4 integrin …

Integrin Alpha 6 Beta 4 Mediates Dynamic Interactions With Laminin, Aydin Tozeren, Hynda K. Kleinman, Stephen Wu, Arthur M. Mercurio, Stephen W. Byers

Arthur M. Mercurio

We present here a novel form of dynamic adhesion in which both the integrin receptor and the ligand supporting dynamic adhesion have been identified. Laminar flow assays showed that laminin supported attachment of alpha 6 beta 4-positive cells in the presence of fluid shear stress (tau < or = 2 dyn/cm2), indicating that these cells adhered to laminin within a fraction of a second. Further increases in flow rate (3.5 dyn/cm2 < or = tau < or = 100 dyn/cm2) initiated rolling of attached cells in the direction of flow, suggesting that rapidly formed adhesion is reversible and repeatable. Laminin fragment E8, which …

Role Of E-Cadherin In The Response Of Tumor Cell Aggregates To Lymphatic, Venous And Arterial Flow: Measurement Of Cell-Cell Adhesion Strength, Stephen W. Byers, Connie L. Sommers, Becky Hoxter, Arthur M. Mercurio, Aydin Tozeren

Arthur M. Mercurio

Defects in the expression or function of the calcium dependent cell-cell adhesion molecule E-cadherin are common in invasive, metastatic carcinomas. In the present study the response of aggregates of breast epithelial cells and breast and colon carcinoma cells to forces imposed by laminar flow in a parallel plate flow channel was examined. Although E-cadherin negative tumor cells formed cell aggregates in the presence of calcium, these were significantly more likely than E-cadherin positive cell aggregates to disaggregate in response to low shear forces, such as those found in a lymphatic vessel or venule (< 3.5 dyn/cm2). E-cadherin positive normal breast epithelial cells and E-cadherin positive breast tumor cell aggregates could not be disaggregated when exposed to shear forces in excess of those found in arteries (> 100 dyn/cm2). E-cadherin negative cancer cells …