1
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Katsuki R, Kanuka M, Ohta R, Yoshida S, Tamura T. Turnover of EDEM1, an ERAD-enhancing factor, is mediated by multiple degradation routes. Genes Cells 2024; 29:486-502. [PMID: 38682256 PMCID: PMC11163939 DOI: 10.1111/gtc.13117] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/09/2023] [Revised: 03/21/2024] [Accepted: 03/23/2024] [Indexed: 05/01/2024]
Abstract
Quality-based protein production and degradation in the endoplasmic reticulum (ER) are essential for eukaryotic cell survival. During protein maturation in the ER, misfolded or unassembled proteins are destined for disposal through a process known as ER-associated degradation (ERAD). EDEM1 is an ERAD-accelerating factor whose gene expression is upregulated by the accumulation of aberrant proteins in the ER, known as ER stress. Although the role of EDEM1 in ERAD has been studied in detail, the turnover of EDEM1 by intracellular degradation machinery, including the proteasome and autophagy, is not well understood. To clarify EDEM1 regulation in the protein level, degradation mechanism of EDEM1 was examined. Our results indicate that both ERAD and autophagy degrade EDEM1 alike misfolded degradation substrates, although each degradation machinery targets EDEM1 in different folded states of proteins. We also found that ERAD factors, including the SEL1L/Hrd1 complex, YOD1, XTP3B, ERdj3, VIMP, BAG6, and JB12, but not OS9, are involved in EDEM1 degradation in a mannose-trimming-dependent and -independent manner. Our results suggest that the ERAD accelerating factor, EDEM1, is turned over by the ERAD itself, similar to ERAD clients.
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Affiliation(s)
- Riko Katsuki
- Department of Life Science, Graduated School of Engineering ScienceAkita UniversityAkitaJapan
| | - Mai Kanuka
- Department of Life Science, Graduated School of Engineering ScienceAkita UniversityAkitaJapan
| | - Ren Ohta
- Department of Life Science, Graduated School of Engineering ScienceAkita UniversityAkitaJapan
| | - Shusei Yoshida
- Department of Life Science, Faculty of Engineering ScienceAkita UniversityAkitaJapan
| | - Taku Tamura
- Department of Life Science, Graduated School of Engineering ScienceAkita UniversityAkitaJapan
- Department of Life Science, Faculty of Engineering ScienceAkita UniversityAkitaJapan
- Present address:
Biococoon Laboratories Inc.4‐3‐5, UedaMoriokaJapan
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2
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Muraoka T, Okumura M, Saio T. Enzymatic and synthetic regulation of polypeptide folding. Chem Sci 2024; 15:2282-2299. [PMID: 38362427 PMCID: PMC10866363 DOI: 10.1039/d3sc05781j] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/29/2023] [Accepted: 01/04/2024] [Indexed: 02/17/2024] Open
Abstract
Proper folding is essential for the biological functions of all proteins. The folding process is intrinsically error-prone, and the misfolding of a polypeptide chain can cause the formation of toxic aggregates related to pathological outcomes such as neurodegenerative disease and diabetes. Chaperones and some enzymes are involved in the cellular proteostasis systems that assist polypeptide folding to diminish the risk of aggregation. Elucidating the molecular mechanisms of chaperones and related enzymes is important for understanding proteostasis systems and protein misfolding- and aggregation-related pathophysiology. Furthermore, mechanistic studies of chaperones and related enzymes provide important clues to designing chemical mimics, or chemical chaperones, that are potentially useful for recovering proteostasis activities as therapeutic approaches for treating and preventing protein misfolding-related diseases. In this Perspective, we provide a comprehensive overview of the latest understanding of the folding-promotion mechanisms by chaperones and oxidoreductases and recent progress in the development of chemical mimics that possess activities comparable to enzymes, followed by a discussion of future directions.
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Affiliation(s)
- Takahiro Muraoka
- Department of Applied Chemistry, Graduate School of Engineering, Tokyo University of Agriculture and Technology Koganei Tokyo 184-8588 Japan
- Kanagawa Institute of Industrial Science and Technology (KISTEC) Kanagawa 243-0435 Japan
| | - Masaki Okumura
- Frontier Research Institute for Interdisciplinary Sciences, Tohoku University Sendai Miyagi 980-8578 Japan
| | - Tomohide Saio
- Division of Molecular Life Science, Institute of Advanced Medical Sciences, Tokushima University Tokushima 770-8503 Japan
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3
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Miura K, Katsuki R, Yoshida S, Ohta R, Tamura T. Identification of EGF Receptor and Thrombospondin-1 as Endogenous Targets of ER-Associated Degradation Enhancer EDEM1 in HeLa Cells. Int J Mol Sci 2023; 24:12171. [PMID: 37569550 PMCID: PMC10418772 DOI: 10.3390/ijms241512171] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/08/2023] [Revised: 07/26/2023] [Accepted: 07/27/2023] [Indexed: 08/13/2023] Open
Abstract
Secretory and membrane proteins are vital for cell activities, including intra- and intercellular communication. Therefore, protein quality control in the endoplasmic reticulum (ER) is an essential and crucial process for eukaryotic cells. Endoplasmic reticulum-associated degradation (ERAD) targets misfolded proteins during the protein maturation process in the ER and leads to their disposal. This process maintains the ER productive function and prevents misfolded protein stress (i.e., ER stress). The ERAD-stimulating factor ER degradation-enhancing α mannosidase-like 1 protein (EDEM1) acts on misfolded proteins to accelerate ERAD, thereby maintaining the productivity of the ER. However, the detail mechanism underlying the function of EDEM1 in ERAD is not completely understood due to a lack of established physiological substrate proteins. In this study, we attempted to identify substrate proteins for EDEM1 using siRNA. The matrix component thrombospondin-1 (TSP1) and epidermal growth factor receptor (EGFR) were identified as candidate targets of EDEM1. Their protein maturation status and cellular localization were markedly affected by knockdown of EDEM1. We also showed that EDEM1 physically associates with EGFR and enhances EGFR degradation via ERAD. Our data highlight the physiological role of EDEM1 in maintaining specific target proteins and provide a potential approach to the regulation of expression of clinically important proteins.
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Affiliation(s)
- Kohta Miura
- Department of Life Science, Graduate School of Engineering Science, Akita University, Akita 010-8502, Japan
| | - Riko Katsuki
- Department of Life Science, Graduate School of Engineering Science, Akita University, Akita 010-8502, Japan
| | - Shusei Yoshida
- Department of Life Science, Faculty of Engineering Science, Akita University, Akita 010-8502, Japan
| | - Ren Ohta
- Department of Life Science, Graduate School of Engineering Science, Akita University, Akita 010-8502, Japan
| | - Taku Tamura
- Department of Life Science, Graduate School of Engineering Science, Akita University, Akita 010-8502, Japan
- Department of Life Science, Faculty of Engineering Science, Akita University, Akita 010-8502, Japan
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4
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Sulimai NH, Brown J, Lominadze D. Fibrinogen, Fibrinogen-like 1 and Fibrinogen-like 2 Proteins, and Their Effects. Biomedicines 2022; 10:biomedicines10071712. [PMID: 35885017 PMCID: PMC9313381 DOI: 10.3390/biomedicines10071712] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/27/2022] [Revised: 07/11/2022] [Accepted: 07/13/2022] [Indexed: 12/05/2022] Open
Abstract
Fibrinogen (Fg) and its derivatives play a considerable role in many diseases. For example, increased levels of Fg have been found in many inflammatory diseases, such as Alzheimer’s disease, multiple sclerosis, traumatic brain injury, rheumatoid arthritis, systemic lupus erythematosus, and cancer. Although associations of Fg, Fg chains, and its derivatives with various diseases have been established, their specific effects and the mechanisms of actions involved are still unclear. The present review is the first attempt to discuss the role of Fg, Fg chains, its derivatives, and other members of Fg family proteins, such as Fg-like protein 1 and 2, in inflammatory diseases and their effects in immunomodulation.
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Affiliation(s)
- Nurul H. Sulimai
- Departments of Surgery, University of South Florida Morsani College of Medicine, Tampa, FL 33612, USA; (N.H.S.); (J.B.)
| | - Jason Brown
- Departments of Surgery, University of South Florida Morsani College of Medicine, Tampa, FL 33612, USA; (N.H.S.); (J.B.)
| | - David Lominadze
- Departments of Surgery, University of South Florida Morsani College of Medicine, Tampa, FL 33612, USA; (N.H.S.); (J.B.)
- Departments of Molecular Pharmacology and Physiology, University of South Florida Morsani College of Medicine, Tampa, FL 33612, USA
- Correspondence:
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5
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Ceznerová E, Kaufmanová J, Stikarová J, Pastva O, Loužil J, Chrastinová L, Suttnar J, Kotlín R, Dyr JE. Thrombosis-associated hypofibrinogenemia: novel abnormal fibrinogen variant FGG c.8G>A with oxidative posttranslational modifications. Blood Coagul Fibrinolysis 2022; 33:228-237. [PMID: 35067535 DOI: 10.1097/mbc.0000000000001125] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
Abstract
Here, we present the first case of fibrinogen variant FGG c.8G>A. We investigated the behaviour of this mutated fibrinogen in blood coagulation using fibrin polymerization, fibrinolysis, fibrinopeptides release measurement, mass spectrometry (MS), and scanning electron microscopy (SEM). The case was identified by routine coagulation testing of a 34-year-old man diagnosed with thrombosis. Initial genetic analysis revealed a heterozygous mutation in exon 1 of the FGG gene encoding gamma chain signal peptide. Fibrin polymerization by thrombin and reptilase showed the normal formation of the fibrin clot. However, maximal absorbance within polymerization was lower and fibrinolysis had a longer degradation phase than healthy control. SEM revealed a significant difference in clot structure of the patient, and interestingly, MS detected several posttranslational oxidations of fibrinogen. The data suggest that the mutation FGG c.8G>A with the combination of the effect of posttranslational modifications causes a novel case of hypofibrinogenemia associated with thrombosis.
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Affiliation(s)
- Eliška Ceznerová
- Department of Biochemistry, Institute of Hematology and Blood Transfusion, U Nemocnice 2094/1, Prague 2, Czech Republic
- Department of Biochemistry and Microbiology, University of Chemistry and Technology Prague, Technická 5, Prague 6, Czech Republic
| | - Jiřina Kaufmanová
- Department of Biochemistry and Microbiology, University of Chemistry and Technology Prague, Technická 5, Prague 6, Czech Republic
| | - Jana Stikarová
- Department of Biochemistry, Institute of Hematology and Blood Transfusion, U Nemocnice 2094/1, Prague 2, Czech Republic
| | - Ondřej Pastva
- Department of Biochemistry, Institute of Hematology and Blood Transfusion, U Nemocnice 2094/1, Prague 2, Czech Republic
| | - Jan Loužil
- Department of Biochemistry, Institute of Hematology and Blood Transfusion, U Nemocnice 2094/1, Prague 2, Czech Republic
| | - Leona Chrastinová
- Department of Biochemistry, Institute of Hematology and Blood Transfusion, U Nemocnice 2094/1, Prague 2, Czech Republic
| | - Jiři Suttnar
- Department of Biochemistry, Institute of Hematology and Blood Transfusion, U Nemocnice 2094/1, Prague 2, Czech Republic
| | - Roman Kotlín
- Department of Biochemistry, Institute of Hematology and Blood Transfusion, U Nemocnice 2094/1, Prague 2, Czech Republic
| | - Jan Evangelista Dyr
- Department of Biochemistry, Institute of Hematology and Blood Transfusion, U Nemocnice 2094/1, Prague 2, Czech Republic
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6
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Li H, Sun S. Protein Aggregation in the ER: Calm behind the Storm. Cells 2021; 10:cells10123337. [PMID: 34943844 PMCID: PMC8699410 DOI: 10.3390/cells10123337] [Citation(s) in RCA: 18] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/02/2021] [Revised: 11/19/2021] [Accepted: 11/22/2021] [Indexed: 02/06/2023] Open
Abstract
As one of the largest organelles in eukaryotic cells, the endoplasmic reticulum (ER) plays a vital role in the synthesis, folding, and assembly of secretory and membrane proteins. To maintain its homeostasis, the ER is equipped with an elaborate network of protein folding chaperones and multiple quality control pathways whose cooperative actions safeguard the fidelity of protein biogenesis. However, due to genetic abnormalities, the error-prone nature of protein folding and assembly, and/or defects or limited capacities of the protein quality control systems, nascent proteins may become misfolded and fail to exit the ER. If not cleared efficiently, the progressive accumulation of misfolded proteins within the ER may result in the formation of toxic protein aggregates, leading to the so-called “ER storage diseases”. In this review, we first summarize our current understanding of the protein folding and quality control networks in the ER, including chaperones, unfolded protein response (UPR), ER-associated protein degradation (ERAD), and ER-selective autophagy (ER-phagy). We then survey recent research progress on a few ER storage diseases, with a focus on the role of ER quality control in the disease etiology, followed by a discussion on outstanding questions and emerging concepts in the field.
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Affiliation(s)
- Haisen Li
- Center for Molecular Medicine and Genetics, Wayne State University School of Medicine, Detroit, MI 48201, USA;
| | - Shengyi Sun
- Center for Molecular Medicine and Genetics, Wayne State University School of Medicine, Detroit, MI 48201, USA;
- Department of Biochemistry, Microbiology and Immunology, Wayne State University School of Medicine, Detroit, MI 48201, USA
- Correspondence:
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7
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Kanemura S, Matsusaki M, Inaba K, Okumura M. PDI Family Members as Guides for Client Folding and Assembly. Int J Mol Sci 2020; 21:ijms21249351. [PMID: 33302492 PMCID: PMC7763558 DOI: 10.3390/ijms21249351] [Citation(s) in RCA: 16] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/25/2020] [Revised: 12/06/2020] [Accepted: 12/06/2020] [Indexed: 12/27/2022] Open
Abstract
Complicated and sophisticated protein homeostasis (proteostasis) networks in the endoplasmic reticulum (ER), comprising disulfide catalysts, molecular chaperones, and their regulators, help to maintain cell viability. Newly synthesized proteins inserted into the ER need to fold and assemble into unique native structures to fulfill their physiological functions, and this is assisted by protein disulfide isomerase (PDI) family. Herein, we focus on recent advances in understanding the detailed mechanisms of PDI family members as guides for client folding and assembly to ensure the efficient production of secretory proteins.
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Affiliation(s)
- Shingo Kanemura
- School of Science and Technology, Kwansei Gakuin University, 2-1 Gakuen, Sanda, Hyogo 669-1337, Japan;
| | - Motonori Matsusaki
- Institute of Multidisciplinary Research for Advanced Materials, Tohoku University, 2-1-1 Katahira, Aoba-ku, Sendai, Miyagi 980-8577, Japan; (M.M.); (K.I.)
- Frontier Research Institute for Interdisciplinary Sciences, Tohoku University, 6-3 Aramakiaza Aoba, Aoba-ku, Sendai, Miyagi 980-8578, Japan
| | - Kenji Inaba
- Institute of Multidisciplinary Research for Advanced Materials, Tohoku University, 2-1-1 Katahira, Aoba-ku, Sendai, Miyagi 980-8577, Japan; (M.M.); (K.I.)
| | - Masaki Okumura
- Frontier Research Institute for Interdisciplinary Sciences, Tohoku University, 6-3 Aramakiaza Aoba, Aoba-ku, Sendai, Miyagi 980-8578, Japan
- Correspondence: ; Tel.: +81-22-217-5628
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8
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Asselta R, Paraboschi EM, Duga S. Hereditary Hypofibrinogenemia with Hepatic Storage. Int J Mol Sci 2020; 21:ijms21217830. [PMID: 33105716 PMCID: PMC7659954 DOI: 10.3390/ijms21217830] [Citation(s) in RCA: 14] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/28/2020] [Revised: 10/21/2020] [Accepted: 10/21/2020] [Indexed: 12/14/2022] Open
Abstract
Fibrinogen is a 340-kDa plasma glycoprotein constituted by two sets of symmetrical trimers, each formed by the Aα, Bβ, and γ chains (respectively coded by the FGA, FGB, and FGG genes). Quantitative fibrinogen deficiencies (hypofibrinogenemia, afibrinogenemia) are rare congenital disorders characterized by low or unmeasurable plasma fibrinogen antigen levels. Their genetic basis is represented by mutations within the fibrinogen genes. To date, only eight mutations, all affecting a small region of the fibrinogen γ chain, have been reported to cause hereditary hypofibrinogenemia with hepatic storage (HHHS), a disorder characterized by protein aggregation in the endoplasmic reticulum, hypofibrinogenemia, and liver disease of variable severity. Here, we will briefly review the clinic characteristics of HHHS patients and the histological feature of their hepatic inclusions, and we will focus on the molecular genetic basis of this peculiar type of coagulopathy.
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Affiliation(s)
- Rosanna Asselta
- Department of Biomedical Sciences, Humanitas University, Via Rita Levi Montalcini 4, Pieve Emanuele, 20090 Milan, Italy; (E.M.P.); (S.D.)
- Humanitas Clinical and Research Center, IRCCS, Via Manzoni 56, Rozzano, 20089 Milan, Italy
- Correspondence: ; Tel.: +39-02-8224-5215
| | - Elvezia Maria Paraboschi
- Department of Biomedical Sciences, Humanitas University, Via Rita Levi Montalcini 4, Pieve Emanuele, 20090 Milan, Italy; (E.M.P.); (S.D.)
- Humanitas Clinical and Research Center, IRCCS, Via Manzoni 56, Rozzano, 20089 Milan, Italy
| | - Stefano Duga
- Department of Biomedical Sciences, Humanitas University, Via Rita Levi Montalcini 4, Pieve Emanuele, 20090 Milan, Italy; (E.M.P.); (S.D.)
- Humanitas Clinical and Research Center, IRCCS, Via Manzoni 56, Rozzano, 20089 Milan, Italy
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9
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Kanuka M, Ouchi F, Kato N, Katsuki R, Ito S, Miura K, Hikida M, Tamura T. Endoplasmic Reticulum Associated Degradation of Spinocerebellar Ataxia-Related CD10 Cysteine Mutant. Int J Mol Sci 2020; 21:ijms21124237. [PMID: 32545905 PMCID: PMC7352294 DOI: 10.3390/ijms21124237] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/30/2020] [Revised: 06/12/2020] [Accepted: 06/12/2020] [Indexed: 12/31/2022] Open
Abstract
Spinocerebellar ataxia (SCA) is one of the most severe neurodegenerative diseases and is often associated with misfolded protein aggregates derived from the genetic mutation of related genes. Recently, mutations in CD10 such as C143Y have been identified as SCA type 43. CD10, also known as neprilysin or neuroendopeptidase, digests functional neuropeptides, such as amyloid beta, in the extracellular region. In this study, we explored the cellular behavior of CD10 C143Y to gain an insight into the functional relationship of the mutation and SCA pathology. We found that wild-type CD10 is expressed on the plasma membrane and exhibits endopeptidase activity in a cultured cell line. CD10 C143Y, however, forms a disulfide bond-mediated oligomer that does not appear by the wild-type CD10. Furthermore, the CD10 C143Y mutant was retained in the endoplasmic reticulum (ER) by the molecular chaperone BiP and was degraded through the ER-associated degradation (ERAD) process, in which representative ERAD factors including EDEM1, SEL1L, and Hrd1 participate in the degradation. Suppression of CD10 C143Y ERAD recovers intracellular transport but not enzymatic activity. Our results indicate that the C143Y mutation in CD10 negatively affects protein maturation and results in ER retention and following ERAD. These findings provide beneficial insight into SCA type 43 pathology.
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Affiliation(s)
- Mai Kanuka
- Department of Life Science, Graduate school of Engineering and Resource, Akita University, Akita 010-8502, Japan; (M.K.); (N.K.); (R.K.); (S.I.); (K.M.); (M.H.)
| | - Fuka Ouchi
- Department of Life Science, Faculty of Engineering Science, Akita University, Akita 010-8502, Japan;
| | - Nagisa Kato
- Department of Life Science, Graduate school of Engineering and Resource, Akita University, Akita 010-8502, Japan; (M.K.); (N.K.); (R.K.); (S.I.); (K.M.); (M.H.)
| | - Riko Katsuki
- Department of Life Science, Graduate school of Engineering and Resource, Akita University, Akita 010-8502, Japan; (M.K.); (N.K.); (R.K.); (S.I.); (K.M.); (M.H.)
| | - Saori Ito
- Department of Life Science, Graduate school of Engineering and Resource, Akita University, Akita 010-8502, Japan; (M.K.); (N.K.); (R.K.); (S.I.); (K.M.); (M.H.)
| | - Kohta Miura
- Department of Life Science, Graduate school of Engineering and Resource, Akita University, Akita 010-8502, Japan; (M.K.); (N.K.); (R.K.); (S.I.); (K.M.); (M.H.)
| | - Masaki Hikida
- Department of Life Science, Graduate school of Engineering and Resource, Akita University, Akita 010-8502, Japan; (M.K.); (N.K.); (R.K.); (S.I.); (K.M.); (M.H.)
- Department of Life Science, Faculty of Engineering Science, Akita University, Akita 010-8502, Japan;
| | - Taku Tamura
- Department of Life Science, Graduate school of Engineering and Resource, Akita University, Akita 010-8502, Japan; (M.K.); (N.K.); (R.K.); (S.I.); (K.M.); (M.H.)
- Department of Life Science, Faculty of Engineering Science, Akita University, Akita 010-8502, Japan;
- Correspondence: ; Tel.: +81-18-889-2377
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10
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Proteomic profile of histotroph during early embryo development in mares. Theriogenology 2019; 125:224-235. [DOI: 10.1016/j.theriogenology.2018.11.002] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/22/2018] [Revised: 10/31/2018] [Accepted: 11/04/2018] [Indexed: 01/16/2023]
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11
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Abstract
Fibrinogen and fibrin are essential for hemostasis and are major factors in thrombosis, wound healing, and several other biological functions and pathological conditions. The X-ray crystallographic structure of major parts of fibrin(ogen), together with computational reconstructions of missing portions and numerous biochemical and biophysical studies, have provided a wealth of data to interpret molecular mechanisms of fibrin formation, its organization, and properties. On cleavage of fibrinopeptides by thrombin, fibrinogen is converted to fibrin monomers, which interact via knobs exposed by fibrinopeptide removal in the central region, with holes always exposed at the ends of the molecules. The resulting half-staggered, double-stranded oligomers lengthen into protofibrils, which aggregate laterally to make fibers, which then branch to yield a three-dimensional network. Much is now known about the structural origins of clot mechanical properties, including changes in fiber orientation, stretching and buckling, and forced unfolding of molecular domains. Studies of congenital fibrinogen variants and post-translational modifications have increased our understanding of the structure and functions of fibrin(ogen). The fibrinolytic system, with the zymogen plasminogen binding to fibrin together with tissue-type plasminogen activator to promote activation to the active proteolytic enzyme, plasmin, results in digestion of fibrin at specific lysine residues. In spite of a great increase in our knowledge of all these interconnected processes, much about the molecular mechanisms of the biological functions of fibrin(ogen) remains unknown, including some basic aspects of clotting, fibrinolysis, and molecular origins of fibrin mechanical properties. Even less is known concerning more complex (patho)physiological implications of fibrinogen and fibrin.
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Affiliation(s)
- John W Weisel
- Department of Cell and Developmental Biology, University of Pennsylvania School of Medicine, Philadelphia, PA, USA.
| | - Rustem I Litvinov
- Department of Cell and Developmental Biology, University of Pennsylvania School of Medicine, Philadelphia, PA, USA
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12
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Klein C. Early pregnancy in the mare: old concepts revisited. Domest Anim Endocrinol 2016; 56 Suppl:S212-7. [PMID: 27345319 DOI: 10.1016/j.domaniend.2016.03.006] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/28/2015] [Revised: 03/16/2016] [Accepted: 03/24/2016] [Indexed: 11/22/2022]
Abstract
"Maternal recognition of pregnancy" (MRP) is commonly used to describe the ongoing embryo-maternal communication during early pregnancy that culminates in prevention of luteolysis and ensures ongoing progestin support. The conceptus-derived pregnancy recognition signal has not yet been identified in the mare. Although equine conceptuses produce substantial amounts of estrogens, there is a lack of evidence that estrogens are the pregnancy recognition signal in mares. Conceptus mobility is integral to MRP and is driven by conceptus-derived prostaglandin production. Cessation of conceptus mobility, referred to as fixation, is caused by increases in conceptus size and uterine tone and reduction in sialic acid content of the embryonic capsule. Gene expression profiling of equine preimplantation conceptuses revealed expression of neuraminidase 2 (NEU2), an enzyme that cleaves sialic acid from polysaccharide chains. Furthermore, secretion of NEU2 by conceptuses in vitro was functionally active; it appears therefore, that the conceptus itself regulates sialic acid content through expression of NEU2. Based on gene expression profiling, equine conceptuses express increasing amounts of fibrinogen during early development. Western blot analysis confirmed secretion of fibrinogen into culture medium when conceptuses were cultured in vitro and with immunohistochemistry, the acellular glycoprotein capsule of the conceptus had particularly intense staining for fibrinogen. Therefore, we hypothesize that conceptus-derived fibrinogen interacts with endometrial integrins to promote cessation of conceptus mobility and fixation. Indeed, next generation sequencing analysis of conceptus and endometrial samples 16 d after ovulation revealed that the integrin signaling pathway is significantly enriched in both sample types. Real-time reverse transcription polymerase chain reaction (RT-PCR) confirmed ITGAVB1 as the most abundant integrin receptor in endometrium; fibrinogen has the highest affinity for ITGAVB1 among integrins receptors to which it binds. Finally, the equine conceptus expresses increasing quantities of relaxin during preimplantation development, with the endometrium expressing relaxin receptors. In the pig, mouse, and human, relaxin is produced by the corpus luteum and is known to promote angiogenesis during early pregnancy. In summary, substantial advances in understanding MRP in the horse are underway.
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Affiliation(s)
- C Klein
- Department of Veterinary Clinical and Diagnostic Sciences, Faculty of Veterinary Medicine, University of Calgary, Calgary, AB, T2N 4Z6, Canada.
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