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Yokosaki Y, Nishimichi N. New Therapeutic Targets for Hepatic Fibrosis in the Integrin Family, α8β1 and α11β1, Induced Specifically on Activated Stellate Cells. Int J Mol Sci 2021; 22:12794. [PMID: 34884600 PMCID: PMC8657911 DOI: 10.3390/ijms222312794] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/28/2021] [Revised: 11/22/2021] [Accepted: 11/23/2021] [Indexed: 12/24/2022] Open
Abstract
A huge effort has been devoted to developing drugs targeting integrins over 30 years, because of the primary roles of integrins in the cell-matrix milieu. Five αv-containing integrins, in the 24 family members, have been a central target of fibrosis. Currently, a small molecule against αvβ1 is undergoing a clinical trial for NASH-associated fibrosis as a rare agent aiming at fibrogenesis. Latent TGFβ activation, a distinct talent of αv-integrins, has been intriguing as a therapeutic target. None of the αv-integrin inhibitors, however, has been in the clinical market. αv-integrins commonly recognize an Arg-Gly-Asp (RGD) sequence, and thus the pharmacophore of inhibitors for the 5-integrins is based on the same RGD structure. The RGD preference of the integrins, at the same time, dilutes ligand specificity, as the 5-integrins share ligands containing RGD sequence such as fibronectin. With the inherent little specificity in both drugs and targets, "disease specificity" has become less important for the inhibitors than blocking as many αv-integrins. In fact, an almighty inhibitor for αv-integrins, pan-αv, was in a clinical trial. On the contrary, approved integrin inhibitors are all specific to target integrins, which are expressed in a cell-type specific manner: αIIbβ3 on platelets, α4β1, α4β7 and αLβ2 on leukocytes. Herein, "disease specific" integrins would serve as attractive targets. α8β1 and α11β1 are selectively expressed in hepatic stellate cells (HSCs) and distinctively induced upon culture activation. The exceptional specificity to activated HSCs reflects a rather "pathology specific" nature of these new integrins. The monoclonal antibodies against α8β1 and α11β1 in preclinical examinations may illuminate the road to the first medical agents.
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Affiliation(s)
- Yasuyuki Yokosaki
- Integrin-Matrix Biomedical Science, Translational Research Center, Hiroshima University, 1-2-3 Kasumi, Minami-Ku, Hiroshima 734-8551, Japan;
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Cai C, Sun H, Hu L, Fan Z. Visualization of integrin molecules by fluorescence imaging and techniques. ACTA ACUST UNITED AC 2021; 45:229-257. [PMID: 34219865 PMCID: PMC8249084 DOI: 10.32604/biocell.2021.014338] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
Abstract
Integrin molecules are transmembrane αβ heterodimers involved in cell adhesion, trafficking, and signaling. Upon activation, integrins undergo dynamic conformational changes that regulate their affinity to ligands. The physiological functions and activation mechanisms of integrins have been heavily discussed in previous studies and reviews, but the fluorescence imaging techniques -which are powerful tools for biological studies- have not. Here we review the fluorescence labeling methods, imaging techniques, as well as Förster resonance energy transfer assays used to study integrin expression, localization, activation, and functions.
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Affiliation(s)
- Chen Cai
- Department of Immunology, School of Medicine, UConn Health, Farmington, 06030, USA
| | - Hao Sun
- Department of Medicine, University of California, San Diego, La Jolla, 92093, USA
| | - Liang Hu
- Cardiovascular Institute of Zhengzhou University, Department of Cardiology, The First Affiliated Hospital of Zhengzhou University, Zhengzhou, 450051, China
| | - Zhichao Fan
- Department of Immunology, School of Medicine, UConn Health, Farmington, 06030, USA
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Nishimichi N, Tsujino K, Kanno K, Sentani K, Kobayashi T, Chayama K, Sheppard D, Yokosaki Y. Induced hepatic stellate cell integrin, α8β1, enhances cellular contractility and TGFβ activity in liver fibrosis. J Pathol 2021; 253:366-373. [PMID: 33433924 PMCID: PMC7986747 DOI: 10.1002/path.5618] [Citation(s) in RCA: 16] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/08/2020] [Revised: 12/23/2020] [Accepted: 01/08/2021] [Indexed: 02/04/2023]
Abstract
No effective therapy exists for fatal fibrosis. New therapeutic targets are needed for hepatic fibrosis because the incidence keeps increasing. The activation and differentiation of fibroblasts into myofibroblasts that causes excessive matrix deposition is central to fibrosis. Here, we investigated whether (and which) integrin receptors for matrix proteins activate hepatic stellate cells (HSCs). First, integrin α‐subunits were investigated systematically for their expression over the course of HSC activation and their distribution on fibroblasts and other systemic primary cells. The most upregulated in plate culture‐activated HSCs and specifically expressed across fibroblast linages was the α8 subunit. An anti‐α8 neutralizing mAb was evaluated in three different murine fibrosis models: for cytotoxic (CCl4 treatment), non‐alcoholic steatohepatitis‐associated and cholestatic fibrosis. In all models, pathology and fibrosis markers (hydroxyproline and α‐smooth muscle actin) were improved following the mAb injection. We also CCl4‐treated mice with inducible Itga8−/−; these mice were protected from increased hydroxyproline levels. Furthermore, ITGA8 was upregulated in specimens from 90 patients with liver fibrosis, indicating the relevance of our findings to liver fibrosis in people. Mechanistically, inhibition or ligand engagement of HSC α8 suppressed and enhanced myofibroblast differentiation, respectively, and HSC/fibroblast α8 activated latent TGFβ. Finally, integrin α8β1 potentially fulfils the growing need for anti‐fibrotic drugs and is an integrin not to be ignored. © 2021 The Authors. The Journal of Pathology published by John Wiley & Sons, Ltd. on behalf of The Pathological Society of Great Britain and Ireland.
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Affiliation(s)
- Norihisa Nishimichi
- Integrin-Matrix Biomedical Science, Translational Research Center, Hiroshima University, Hiroshima, Japan
| | - Kazuyuki Tsujino
- Lung Biology Center, Department of Medicine, Cardiovascular Research Institute, University of California San Francisco (UCSF), San Francisco, CA, USA
| | - Keishi Kanno
- General Internal Medicine, Hiroshima University Hospital, Hiroshima University, Hiroshima, Japan
| | - Kazuhiro Sentani
- Molecular Pathology, Graduate School of Biomedical and Health Sciences, Hiroshima University, Hiroshima, Japan
| | - Tsuyoshi Kobayashi
- Gastroenterological and Transplant Surgery, Graduate School of Biomedical and Health Sciences, Hiroshima University, Hiroshima, Japan
| | - Kazuaki Chayama
- Gastroenterology and Metabolism, Graduate School of Biomedical and Health Sciences, Hiroshima University, Hiroshima, Japan
| | - Dean Sheppard
- Lung Biology Center, Department of Medicine, Cardiovascular Research Institute, University of California San Francisco (UCSF), San Francisco, CA, USA
| | - Yasuyuki Yokosaki
- Integrin-Matrix Biomedical Science, Translational Research Center, Hiroshima University, Hiroshima, Japan
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Sackey-Aboagye B, Olsen AL, Mukherjee SM, Ventriglia A, Yokosaki Y, Greenbaum LE, Lee GY, Naga H, Wells RG. Fibronectin Extra Domain A Promotes Liver Sinusoid Repair following Hepatectomy. PLoS One 2016; 11:e0163737. [PMID: 27741254 PMCID: PMC5065221 DOI: 10.1371/journal.pone.0163737] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/16/2016] [Accepted: 09/13/2016] [Indexed: 11/19/2022] Open
Abstract
Liver sinusoidal endothelial cells (LSECs) are the main endothelial cells in the liver and are important for maintaining liver homeostasis as well as responding to injury. LSECs express cellular fibronectin containing the alternatively spliced extra domain A (EIIIA-cFN) and increase expression of this isoform after liver injury, although its function is not well understood. Here, we examined the role of EIIIA-cFN in liver regeneration following partial hepatectomy. We carried out two-thirds partial hepatectomies in mice lacking EIIIA-cFN and in their wild type littermates, studied liver endothelial cell adhesion on decellularized, EIIIA-cFN-containing matrices and investigated the role of cellular fibronectins in liver endothelial cell tubulogenesis. We found that liver weight recovery following hepatectomy was significantly delayed and that sinusoidal repair was impaired in EIIIA-cFN null mice, especially females, as was the lipid accumulation typical of the post-hepatectomy liver. In vitro, we found that liver endothelial cells were more adhesive to cell-deposited matrices containing the EIIIA domain and that cellular fibronectin enhanced tubulogenesis and vascular cord formation. The integrin α9β1, which specifically binds EIIIA-cFN, promoted tubulogenesis and adhesion of liver endothelial cells to EIIIA-cFN. Our findings identify a role for EIIIA-cFN in liver regeneration and tubulogenesis. We suggest that sinusoidal repair is enhanced by increased LSEC adhesion, which is mediated by EIIIA-cFN.
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Affiliation(s)
- Bridget Sackey-Aboagye
- Department of Medicine, Perelman School of Medicine, The University of Pennsylvania, Philadelphia, Pennsylvania, United States of America
- Cell and Molecular Biology Graduate Group, Perelman School of Medicine, The University of Pennsylvania, Philadelphia, Pennsylvania, United States of America
| | - Abby L. Olsen
- Cell and Molecular Biology Graduate Group, Perelman School of Medicine, The University of Pennsylvania, Philadelphia, Pennsylvania, United States of America
| | - Sarmistha M. Mukherjee
- Department of Physiology, Perelman School of Medicine, The University of Pennsylvania, Philadelphia, Pennsylvania, United States of America
| | - Alexander Ventriglia
- Department of Bioengineering, School of Engineering and Applied Sciences, The University of Pennsylvania, Philadelphia, Pennsylvania, United States of America
| | | | | | - Gi Yun Lee
- Department of Bioengineering, School of Engineering and Applied Sciences, The University of Pennsylvania, Philadelphia, Pennsylvania, United States of America
| | - Hani Naga
- Department of Biology, School of Arts and Sciences, University of Pennsylvania, Philadelphia, Pennsylvania, United States of America
| | - Rebecca G. Wells
- Department of Medicine, Perelman School of Medicine, The University of Pennsylvania, Philadelphia, Pennsylvania, United States of America
- Cell and Molecular Biology Graduate Group, Perelman School of Medicine, The University of Pennsylvania, Philadelphia, Pennsylvania, United States of America
- * E-mail:
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Mould AP, Askari JA, Byron A, Takada Y, Jowitt TA, Humphries MJ. Ligand-induced Epitope Masking: DISSOCIATION OF INTEGRIN α5β1-FIBRONECTIN COMPLEXES ONLY BY MONOCLONAL ANTIBODIES WITH AN ALLOSTERIC MODE OF ACTION. J Biol Chem 2016; 291:20993-21007. [PMID: 27484800 PMCID: PMC5076510 DOI: 10.1074/jbc.m116.736942] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/06/2016] [Revised: 07/29/2016] [Indexed: 11/06/2022] Open
Abstract
We previously demonstrated that Arg-Gly-Asp (RGD)-containing ligand-mimetic inhibitors of integrins are unable to dissociate pre-formed integrin-fibronectin complexes (IFCs). These observations suggested that amino acid residues involved in integrin-fibronectin binding become obscured in the ligand-occupied state. Because the epitopes of some function-blocking anti-integrin monoclonal antibodies (mAbs) lie near the ligand-binding pocket, it follows that the epitopes of these mAbs may become shielded in the ligand-occupied state. Here, we tested whether function-blocking mAbs directed against α5β1 can interact with the integrin after it forms a complex with an RGD-containing fragment of fibronectin. We showed that the anti-α5 subunit mAbs JBS5, SNAKA52, 16, and P1D6 failed to disrupt IFCs and hence appeared unable to bind to the ligand-occupied state. In contrast, the allosteric anti-β1 subunit mAbs 13, 4B4, and AIIB2 could dissociate IFCs and therefore were able to interact with the ligand-bound state. However, another class of function-blocking anti-β1 mAbs, exemplified by Lia1/2, could not disrupt IFCs. This second class of mAbs was also distinguished from 13, 4B4, and AIIB2 by their ability to induce homotypic cell aggregation. Although the epitope of Lia1/2 was closely overlapping with those of 13, 4B4, and AIIB2, it appeared to lie closer to the ligand-binding pocket. A new model of the α5β1-fibronectin complex supports our hypothesis that the epitopes of mAbs that fail to bind to the ligand-occupied state lie within, or very close to, the integrin-fibronectin interface. Importantly, our findings imply that the efficacy of some therapeutic anti-integrin mAbs could be limited by epitope masking.
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Affiliation(s)
- A Paul Mould
- From the Biomolecular Analysis Core Facility and
| | - Janet A Askari
- Wellcome Trust Centre for Cell-Matrix Research, Faculty of Life Sciences, University of Manchester, Manchester M13 9PT, United Kingdom
| | - Adam Byron
- the Edinburgh Cancer Research UK Centre, Institute of Genetics and Molecular Medicine, University of Edinburgh, Edinburgh EH4 2XR, Scotland, United Kingdom, and
| | - Yoshikazu Takada
- the Department of Vascular Biology, VB-1, The Scripps Research Institute, La Jolla, California 92037
| | | | - Martin J Humphries
- Wellcome Trust Centre for Cell-Matrix Research, Faculty of Life Sciences, University of Manchester, Manchester M13 9PT, United Kingdom,
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Khalifeh-Soltani A, Ha A, Podolsky MJ, McCarthy DA, McKleroy W, Azary S, Sakuma S, Tharp KM, Wu N, Yokosaki Y, Hart D, Stahl A, Atabai K. α8β1 integrin regulates nutrient absorption through an Mfge8-PTEN dependent mechanism. eLife 2016; 5. [PMID: 27092791 PMCID: PMC4868538 DOI: 10.7554/elife.13063] [Citation(s) in RCA: 29] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/14/2015] [Accepted: 04/18/2016] [Indexed: 12/25/2022] Open
Abstract
Coordinated gastrointestinal smooth muscle contraction is critical for proper nutrient absorption and is altered in a number of medical disorders. In this work, we demonstrate a critical role for the RGD-binding integrin α8β1 in promoting nutrient absorption through regulation of gastrointestinal motility. Smooth muscle-specific deletion and antibody blockade of α8 in mice result in enhanced gastric antral smooth muscle contraction, more rapid gastric emptying, and more rapid transit of food through the small intestine leading to malabsorption of dietary fats and carbohydrates as well as protection from weight gain in a diet-induced model of obesity. Mechanistically, ligation of α8β1 by the milk protein Mfge8 reduces antral smooth muscle contractile force by preventing RhoA activation through a PTEN-dependent mechanism. Collectively, our results identify a role for α8β1 in regulating gastrointestinal motility and identify α8 as a potential target for disorders characterized by hypo- or hyper-motility. DOI:http://dx.doi.org/10.7554/eLife.13063.001 Animals absorb nutrients from the food they eat in a complicated process that involves multiple steps. In the mouth, teeth break down the food into smaller chunks. Then the food passes through the stomach and small intestine, where enzymes break it down into individual molecules that are small enough to be absorbed by cells that line the small intestine. These cells then package the molecules and release them into the bloodstream so that they can be distributed to the rest of the body. Muscles in the wall of the small intestine control how quickly food travels through this part of the gut. If food moves too quickly, the cells that line the intestine have less time to absorb the food molecules and may fail to absorb enough nutrients. If the food moves too slowly, an individual may experience nausea or vomiting, or the contents of their stomach may spill into their lungs. In 2014, researchers reported that a protein in breast milk called Mfge8 helps to boost the number of fat molecules absorbed from food. Now, Khalifeh-Soltani et al. – including some of the same researchers involved in the earlier work – show that Mfge8 also slows the rate at which food travels through the small intestine in mice. Mfge8 binds to another protein called integrin α8β1 to control how often the intestine muscles contract. Genetically engineered mice that lacked integrin α8β1 developed diarrhea and food passed through their intestines more quickly than in normal mice. Furthermore, these mice did not gain as much weight as normal mice when they were fed a high-fat diet. Khalifeh-Soltani et al.’s findings show that Mfge8 has a dual role in controlling the absorption of food molecules in the small intestine. The next challenge is to find out whether drugs that alter the activity of integrin α8β1 could be used to help treat patients with diseases in which food moves too quickly, or too slowly, through the gut. DOI:http://dx.doi.org/10.7554/eLife.13063.002
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Affiliation(s)
- Amin Khalifeh-Soltani
- Cardiovascular Research Institute, University of California, San Francisco, San Francisco, United States.,Department of Medicine, University of California, San Francisco, San Francisco, United States
| | - Arnold Ha
- Cardiovascular Research Institute, University of California, San Francisco, San Francisco, United States
| | - Michael J Podolsky
- Cardiovascular Research Institute, University of California, San Francisco, San Francisco, United States.,Department of Medicine, University of California, San Francisco, San Francisco, United States
| | - Donald A McCarthy
- Cardiovascular Research Institute, University of California, San Francisco, San Francisco, United States
| | - William McKleroy
- Cardiovascular Research Institute, University of California, San Francisco, San Francisco, United States
| | - Saeedeh Azary
- Cardiovascular Research Institute, University of California, San Francisco, San Francisco, United States
| | - Stephen Sakuma
- Cardiovascular Research Institute, University of California, San Francisco, San Francisco, United States
| | - Kevin M Tharp
- Metabolic Biology, University of California, Berkeley, Berkeley, United States.,Department of Nutritional Sciences and Toxicology, University of California, Berkeley, Berkeley, United States
| | - Nanyan Wu
- Lung Biology Center, University of California, San Francisco, San Francisco, United States
| | - Yasuyuki Yokosaki
- Cell-Matrix Frontier Laboratory, Biomedical Research Unit, Health Administration Center, Hiroshima University, Hiroshima, Japan
| | - Daniel Hart
- Cardiovascular Research Institute, University of California, San Francisco, San Francisco, United States
| | - Andreas Stahl
- Metabolic Biology, University of California, Berkeley, Berkeley, United States.,Department of Nutritional Sciences and Toxicology, University of California, Berkeley, Berkeley, United States
| | - Kamran Atabai
- Cardiovascular Research Institute, University of California, San Francisco, San Francisco, United States.,Department of Medicine, University of California, San Francisco, San Francisco, United States.,Lung Biology Center, University of California, San Francisco, San Francisco, United States
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