Medicine and Health Sciences Commons^™

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 …

P53 Inhibits Alpha 6 Beta 4 Integrin Survival Signaling By Promoting The Caspase 3-Dependent Cleavage Of Akt/Pkb, Robin E. Bachelder, Mark J. Ribick, Alessandra Marchetti, Rita Falcioni, Silvia Soddu, Kathryn R. Davis, Arthur M. Mercurio

Arthur M. Mercurio

Although the interaction of matrix proteins with integrins is known to initiate signaling pathways that are essential for cell survival, a role for tumor suppressors in the regulation of these pathways has not been established. We demonstrate here that p53 can inhibit the survival function of integrins by inducing the caspase-dependent cleavage and inactivation of the serine/threonine kinase AKT/PKB. Specifically, we show that the alpha6beta4 integrin promotes the survival of p53-deficient carcinoma cells by activating AKT/PKB. In contrast, this integrin does not activate AKT/PKB in carcinoma cells that express wild-type p53 and it actually stimulates their apoptosis, in agreement with …

Release Of Camp Gating By The Alpha6beta4 Integrin Stimulates Lamellae Formation And The Chemotactic Migration Of Invasive Carcinoma Cells, Kathleen L. O'Connor, Leslie M. Shaw, Arthur M. Mercurio

Arthur M. Mercurio

The alpha6beta4 integrin promotes carcinoma in-vasion by its activation of a phosphoinositide 3-OH (PI3-K) signaling pathway (Shaw, L.M., I. Rabinovitz, H.H.-F. Wang, A. Toker, and A.M. Mercurio. Cell. 91: 949-960). We demonstrate here using MDA-MB-435 breast carcinoma cells that alpha6beta4 stimulates chemotactic migration, a key component of invasion, but that it has no influence on haptotaxis. Stimulation of chemotaxis by alpha6beta4 expression was observed in response to either lysophosphatidic acid (LPA) or fibroblast conditioned medium. Moreover, the LPA-dependent formation of lamellae in these cells is dependent upon alpha6beta4 expression. Both lamellae formation and chemotactic migration are inhibited or "gated" by …

Protein Kinase C-Dependent Mobilization Of The Alpha6beta4 Integrin From Hemidesmosomes And Its Association With Actin-Rich Cell Protrusions Drive The Chemotactic Migration Of Carcinoma Cells, Isaac Rabinovitz, Alex Toker, Arthur M. Mercurio

Arthur M. Mercurio

We explored the hypothesis that the chemotactic migration of carcinoma cells that assemble hemidesmosomes involves the activation of a signaling pathway that releases the alpha6beta4 integrin from these stable adhesion complexes and promotes its association with F-actin in cell protrusions enabling it to function in migration. Squamous carcinoma-derived A431 cells were used because they express alpha6beta4 and migrate in response to EGF stimulation. Using function-blocking antibodies, we show that the alpha6beta4 integrin participates in EGF-stimulated chemotaxis and is required for lamellae formation on laminin-1. At concentrations of EGF that stimulate A431 chemotaxis ( approximately 1 ng/ml), the alpha6beta4 integrin is …

Rsa 2004: Combined Basic Research Satellite Symposium - Session Three: Alcohol And Mitochondrial Metabolism: At The Crossroads Of Life And Death, Gyongyi Szabo, Jan Hoek, Victor Darley-Usmar, Gyorgy Hajnoczky, Thomas Knudsen, Daria Mochly-Rosen, Samir Zakhari

Gyongyi Szabo

This article summarizes the proceedings of the RSA 2004 Combined Basic Research Satellite Meeting convened at the Westin Bayshore Resort and Marina, Vancouver, CA. One of the sessions "Alcohol and mitochondrial metabolism: At the crossroads of life and death" featured five speakers and was chaired by Drs. Jan Hoek and Sam Zakhari. The presentations were 1) Introduction: Alcohol and cellular energy metabolism by Jan Hoek, 2) Ethanol-dependent dysfunction of mitochondrial energy metabolism: the role of NO by Victor Darley-Usmar, 3) Ethanol and apoptosis in the heart by Gyorgy Hajnoczky, 4) Alcohol and mitochondrial biogenesis in development by Thomas Knudsen, and …

The Opposite Effects Of Acute And Chronic Alcohol On Lipopolysaccharide-Induced Inflammation Are Linked To Irak-M In Human Monocytes, Pranoti Mandrekar, Shashi Bala, Donna Catalano, Karen Kodys, Gyongyi Szabo

Gyongyi Szabo

Impaired host defense after alcohol use is linked to altered cytokine production, however, acute and chronic alcohol differently modulate monocyte/macrophage activation. We hypothesized that in human monocytes, acute alcohol induces hyporesponsiveness to LPS, resulting in decreased TNF-alpha, whereas chronic alcohol increases TNF-alpha by sensitization to LPS. We found that acute alcohol increased IL-1R-associated kinase-monocyte (IRAK-M), a negative regulator of IRAK-1, in human monocytes. This was associated with decreased IkappaB alpha kinase activity, NFkappaB DNA binding, and NFkappaB-driven reporter activity after LPS stimulation. In contrast, chronic alcohol decreased IRAK-M expression but increased IRAK-1 and IKK kinase activities, NFkappaB DNA binding, and …

Signalling Pathways In Alcohol-Induced Liver Inflammation, Pranoti Mandrekar, Gyongyi Szabo

Gyongyi Szabo

The pathogenesis of alcoholic liver injury involves interactions of several intracellular signalling pathways in different cell types of the liver. Alcohol-induced sensitization of liver macrophages to portal endotoxin/lipopolysaccharide (LPS) is considered a hallmark of alcoholic liver disease (ALD). Intracellular mechanisms associated with LPS-induced signalling play a crucial role in the initiation and progression of alcoholic liver injury, and are being extensively explored. LPS recognition by Toll-like receptor 4 (TLR4) on macrophages and other cell types in the liver, activation of downstream signalling pathways culminating in activation of transcription factors such as NFkappaB, AP-1 leads to increased inflammatory cytokine production in …

Acute Alcohol Activates Stat3, Ap-1, And Sp-1 Transcription Factors Via The Family Of Src Kinases To Promote Il-10 Production In Human Monocytes, Oxana Norkina, Angela Dolganiuc, Taryn Shapiro, Karen Kodys, Pranoti Mandrekar, Gyongyi Szabo

Gyongyi Szabo

Alcohol consumption is associated with an imbalance in pro- and anti-inflammatory cytokines and immunosuppression, partially as a result of enhanced IL-10 production. The mechanisms of IL-10 induction by alcohol remain poorly understood. We identified that increased IL-10 production in human monocytes after acute in vivo alcohol consumption or in vitro alcohol treatment was associated with increased STAT3 activation. Alcohol alone induced and in combination with LPS augmented STAT3 phosphorylation at tyrosine 705 (tyr705) and serine 727 (ser727) residues and increased STAT3 binding to DNA. Upstream, alcohol activated the Src kinases, as indicated by an increase in phosphorylated and a decrease …

Antigen-Presenting Cells Under The Influence Of Alcohol, Audrey Lau, Gyongyi Szabo, Angus Thomson

Gyongyi Szabo

The negative influence of alcohol (ethanol) and its metabolites on innate and adaptive immunity is well-recognized. Much attention has recently been focused on the impact of acute and chronic alcohol exposure on antigen-presenting cells (APC). In particular, insights have been gained into how the properties of human blood monocytes and rodent macrophages are influenced by alcohol in vitro and in vivo. Here, we review the impact of alcohol on various aspects of APC function and the underlying mechanisms, including its effects on intracellular signaling events. We also discuss new information regarding the influence of alcohol on various APC populations in …

Alcohol-Induced Modulation Of Signaling Pathways In Liver Parenchymal And Nonparenchymal Cells: Implications For Immunity, Bharath Nath, Gyongyi Szabo

Gyongyi Szabo

Alcoholic liver injury involves a complex array of derangements in cellular signaling of hepatic parenchymal and nonparenchymal cells as well as cells of the immune system. In the hepatocyte, chronic ethanol abuse leads to lipid accumulation and liver steatosis. Multiple pathways are affected to promote lipid accumulation in the ethanol-exposed hepatocyte. Chronic ethanol renders Kupffer cells hyperresponsive to endotoxin, which results in production of inflammatory cytokines and the tumor necrosis factor-alpha via a toll-like receptor 4 dependent pathway, leading to inflammation and hepatic necrosis. Dysfunction of the innate and adaptive immune responses caused by ethanol contributes to impaired antiviral response, …

Vsl#3 Probiotic Treatment Attenuates Fibrosis Without Changes In Steatohepatitis In A Diet-Induced Nonalcoholic Steatohepatitis Model In Mice, Arumugam Velayudham, Angela Dolganiuc, Michael Ellis, Jan Petrasek, Karen Kodys, Pranoti Mandrekar, Gyongyi Szabo

Gyongyi Szabo

Nonalcoholic fatty liver disease (NAFLD) and its advanced stage, nonalcoholic steatohepatitis (NASH), are the most common causes of chronic liver disease in the United States. NASH features the metabolic syndrome, inflammation, and fibrosis. Probiotics exhibit immunoregulatory and anti-inflammatory activity. We tested the hypothesis that probiotic VSL#3 may ameliorate the methionine-choline-deficient (MCD) diet-induced mouse model of NASH. MCD diet resulted in NASH in C57BL/6 mice compared to methionine-choline-supplemented (MCS) diet feeding evidenced by liver steatosis, increased triglycerides, inflammatory cell accumulation, increased tumor necrosis factor alpha levels, and fibrosis. VSL#3 failed to prevent MCD-induced liver steatosis or inflammation. MCD diet, even in …

The Emerging Role Of Toll-Like Receptor Pathways In Surgical Diseases, Laszlo Romics, Gyongyi Szabo, John Calvin Coffey, Jiang Huai Wang, Henry Paul Redmond

Gyongyi Szabo

OBJECTIVE: To outline the emerging significance of Toll-like receptor (TLR) signaling pathways in surgical diseases. DATA

SOURCES: A systematic review of the literature was undertaken by searching the MEDLINE database for the period 1966 to 2005 without language restriction.

STUDY SELECTION: Original or review articles that described experimental data on the activation of TLR signaling pathways in surgically relevant diseases were selected for inclusion in this review.

DATA EXTRACTION: Data were obtained from peer-reviewed articles and references.

DATA SYNTHESIS: The role of TLRs in the recognition of pathogens renders them a key figure in the activation of both innate and …

Hepatitis C Infection And Alcohol Use: A Dangerous Mix For The Liver And Antiviral Immunity, Gyongyi Szabo, Costica Aloman, Stephen Polyak, Steven Weinman, Jack Wands, Samir Zakhari

Gyongyi Szabo

This article presents the proceedings of a symposium presented at the meeting of the Research Society on Alcoholism, held in Santa Barbara, California, in June 2005. The organizers and chairs were Sam Zakhari and Gyongyi Szabo. The presentations included (1) Mitochondrial Abnormalities Induced by Hepatitis C -Alcohol Interaction by Steven Weinman; (2) Effects of Acute and Chronic Ethanol on Innate Antiviral Signaling Pathways, Hepatitis C Replication, and Human Liver Cell Transcription by Stephen Polyak; (3) Ethanol Alters Dendritic Cell Function In Vivo and Impairs the Subsequent Cellular Immune Responses to Hepatitis C Proteins by Costica Aloman; and (4) Pathogenic Interactions …

The Critical Role Of Toll-Like Receptor (Tlr) 4 In Alcoholic Liver Disease Is Independent Of The Common Tlr Adapter Myd88, Istvan Hritz, Pranoti Mandrekar, Arumugam Velayudham, Donna Catalano, Angela Dolganiuc, Karen Kodys, Evelyn Kurt-Jones, Gyongyi Szabo

Gyongyi Szabo

The Toll-like receptor 4 (TLR4) that recognizes endotoxin, a trigger of inflammation in alcoholic liver disease (ALD), activates two signaling pathways utilizing different adapter molecules: the common TLR adapter, myeloid differentiation factor 88 (MyD88), or Toll/interleukin immune-response-domain-containing adaptor inducing interferon (IFN)-beta. The MyD88 pathway induces proinflammatory cytokine activation, a critical mediator of ALD. Here we evaluated the role of MyD88 in alcohol-induced liver injury in wild-type, TLR2-deficient, TLR4-deficient, or MyD88-deficient (knockout [KO]) mice after administration of the Lieber-De-Carli diet (4.5% volume/volume ethanol) or an isocaloric liquid control diet for 5 weeks. Alcohol feeding resulted in a significant increase in serum …

Acute Ethanol Treatment Modulates Toll-Like Receptor-4 Association With Lipid Rafts, Angela Dolganiuc, Genadyi Bakis, Karen Kodys, Pranoti Mandrekar, Gyongyi Szabo

Gyongyi Szabo

BACKGROUND: Alcohol, a substance that is most frequently abused, suppresses innate immune responses to microbial pathogens. The host senses pathogens via Toll-like receptors (TLRs). Recent studies indicate that alcohol affects TLR signaling. METHODS: Here, we hypothesized that acute alcohol treatment may interfere with early steps of membrane-associated TLR2 and TLR4 signaling at the level of lipid rafts. Human monocytes and Chinese hamster ovary (CHO) cells, transfected with human TLR2, TLR4, or CD14, were stimulated with peptidoglycan (PGN, TLR2 ligand) or lipopolysaccharide (LPS, TLR4 ligand) with or without alcohol (50 mM) and analyzed for cytokine production (enzyme-linked immunosorbent assay), nuclear factor-kappaB …

Tlr2- And Tlr4-Mediated Signals Determine Attenuation Or Augmentation Of Inflammation By Acute Alcohol In Monocytes, Shilpa Oak, Pranoti Mandrekar, Donna Catalano, Karen Kodys, Gyongyi Szabo

Gyongyi Szabo

Most pathogens express ligands for multiple TLRs that share common downstream signaling. In this study, we investigated the effects of acute alcohol on inflammatory pathways induced by TLR2 or TLR4 ligands and their combination. In human monocytes, alcohol attenuated TLR4- but not TLR2-induced TNF-alpha protein and mRNA levels and NF-kappaB activation. In contrast, acute alcohol augmented TNF-alpha production when both TLR2 and TLR4 ligands were present. IL-1R-associated kinase (IRAK)-1 activity was reduced by alcohol in TLR4, but it was augmented in TLR2- plus TLR4-stimulated cells. IRAK-monocyte, an inhibitor of IRAK-1, was induced in TLR4, but it was reduced in TLR2- …

Toll-Like Receptors, Gyongyi Szabo, Pranoti Mandrekar

Gyongyi Szabo

Szabo G, Mandrekar P. Toll-like Receptors. In Signaling Pathways in Liver Diseases. Eds., JF Dufour, PA Clavien. 2nd ed. Springer, 2010, p. 149-159. ISBN 3642001491, 9783642001499.

Full preview available via Google Book Search.