RADIATION PROTECTION: RADIATION TOXICOLOGY. GLYCOPROTEINS. DMITRI POPOV MD (RUSSIA), PHD RADIOBIOLOGY.ADVANCED MEDICAL TECHNOLOGY AND SYSTEMS INC. CANADA.

GLYCOPROTEINS

• DOI: 10.13140/RG.2.1.3464.9849

GLYCOPROTEINS

• Keywords: • ACUTE RADIATION SYNDROMES, BIOLOGICAL RRADIATION

EFFECTS, GAMMA RADIATION, RADIOSENSETIVITY, BIOLOGICAL EFFECTS.  

GLYCOPROTEINS

• Glycoproteins play key roles in inflammatory and pathological processes. The Differential Diagnosis of Acute Radiation Syndromes can be assessed by quantifying circulating levels of glycoproteins with ELISA.• Measurements based on the glycan structures of circulating proteins

represent critically important path for improving diagnosis, prognosis and risk prediction of common inflammatory disorders after electromagnetic irradiation.

GLYCOPROTEINS

• Inflammatory glycoproteins are predominantly synthesized and secreted by hepatocytes but can be produced by activated macrophages and neutrophils in the periphery.

• C. Gabay, I. Kushner, Acute-phase proteins and other systemic responses to inflammation,

• N. Engl. J. Med. 340 (6) (1999) 448–454.

GLYCOPROTEINS

• E. Gruys, M.J. Toussaint, T.A. Niewold, S.J. Koopmans, Acute phase reaction and acute phase proteins, J. Zhejiang Univ. Sci. B 6 (11) (2005) 1045–1056.

• X.L. Zhang, Roles of glycans and glycopeptides in immune system and immune-related diseases, Curr. Med. Chem. 13 (10) (2006) 1141–1147.

• J.D.Marth, P.K. Grewal, Mammalian glycosylation in immunity, Nat. Rev. Immunol. 8 (11) (2008) 874–887.

GLYCOPROTEINS

• Acute-phase proteins are a class of proteins whose plasma concentrations increase (positive acute-phase proteins) or decrease (negative acute-phase proteins) in response to inflammation.

• This response is called the acute-phase reaction (also called acute-phase response).

GLYCOPROTEINS

• In response to injury, local inflammatory cells (neutrophil granulocytes, and macrophages) secrete a number of cytokines into the bloodstream, most notable of which are the interleukins IL1, IL6 and IL8, and TNFα. The liver responds by producing a large number of acute-phase reactants. At the same time, the production of a number of other proteins is reduced; these are, therefore, referred to as "negative" acute-phase reactants. Increased acute phase proteins from the liver may also contribute to the promotion of sepsis, or acute radiation syndromes (after irradiation).

ACUTE PHASE PROTEINS.

• Positive acute-phase proteins serve (part of the innate immune system) different physiological functions for the immune system. Some act to destroy or inhibit growth of microbes, e.g., C-reactive protein, mannose-binding protein, complement factors….etc.

GLYCOPROTEINS

• Therefore, there are both intracellular and extracellular post-translational• processes that contribute to the overall diversity of glycan structures• that can occur in any one individual. These are also many factors that• can influence glycan complexity including: 1) cell-type specific expression• of glycosyltransferases, glycosidases, 2) availability of the various• monosaccharides, 3) age, 4) gender, 5) epigenetic background, 5) environment• (e.g. health, diet, smoking and alcohol consumption) and 6)• disease processes (e.g. autoimmune diseases, cancer as well as low grade• inflammatory diseases such as CVD and T2DM).

GLYCOPROTEINS

• W. Dijk, G. Turner, A. Mackiewicz, Changes in glycosylation of acute-phase proteins

• in health and disease: occurrence, regulation and function, Glycoconj. J. 1 (1)

• (1994) 5–14.

GLYCOPROTEINS

• F. Ceciliani, V. Pocacqua, The acute phase protein alpha1-acid glycoprotein: a model for altered glycosylation during diseases, Curr. Protein Pept. Sci. 8 (1) (2007) 91–108.

• O. Gornik, G. Lauc, Glycosylation of serum proteins in inflammatory diseases, Dis.

• Markers 25 (4–5) (2008) 267–278.

GLYCOPROTEINS

GLYCOPROTEINS.

• Besides changes in circulating protein levels, the glycan structures of acute phase glycoproteins are dynamically altered by glycosidases, glycosyltransferases and sialyl transferases in the blood and lymph- circulation.

GLYCOPROTEINS

• Glycoproteins are proteins that contain oligosaccharide chains (glycans) covalently attached to polypeptide side-chains. The carbohydrate is attached to the protein in a co-translational or post-translational modification. This process is known as glycosylation. Secreted extracellular proteins are often glycosylated.

GLYCOPROTEINS

•  Glycoproteins are also often important integral membrane proteins, where they play a role in cell–cell interactions. It is important to distinguish endoplasmic reticulum-based glycosylation of the secretory system without of reversible cytosolic/nuclear glycosylation. Glycoprotein of the cytosol and nucleus can be modified through the reversible addition of a single GlcNAc residues that is consider reciprocal to phosphorylation and the functions of these are likely to be additional regulatory mechanism that controls phosphorylation-based signalling

GLYCOPROTEINS• One example of glycoproteins found in the body is mucins, which are secreted in the

mucus of the respiratory and digestive tracts. The sugars when attached to mucins give them considerable water-holding capacity and also make them resistant to proteolysis by digestive enzymes.

• Glycoproteins are important for white blood cell recognition, especially in mammals. Examples of glycoproteins in the immune system are:

• molecules such as antibodies (immunoglobulins), which interact directly with antigens.

• molecules of the major histocompatibility complex (or MHC), which are expressed on the surface of cells and interact with T cells as part of the adaptive immune response.

• sialyl Lewis X antigen on the surface of leukocytes.

GLYCOPROTEINS

• Sialyl LewisX, also known as sialyl LeX and SLeX, is a tetra saccharide carbohydrate that is usually attached to O-glycans on the surface of cells. It is known to play a vital role in cell-to-cell recognition processes.

GLYCOPROTEINS

• Sialyl Lewis X is also one of the most important blood group antigens and is displayed on the terminus of glycolipids that are present on the cell surface. The Sialyl Lewis X determinant, E-selectin ligand carbohydrate structure, is constitutively expressed on granulocytes and monocytes and mediates inflammatory extravasation of these cells. Resting T and B lymphocytes lack its expression and are induced to strongly express sialyl Lewis X upon activation. The Sialyl Lewis X determinant is expressed preferentially on activated Th1 cells but not on Th2 cells.

GLYCOPROTEINS• Defective synthesis of the sialyl Lewis X antigen results in immunodeficiency (leukocyte adhesion

deficiency type 2). Defective synthesis can be caused by the loss of fucosyltransferase, impairing the glycosylation of the glycosphingolipid.

• Sialyl Lewis x is being used in studies to fight tumors and cancer cell growth. It has been shown that there is frequent overexpression of sialyl Lewis x on cancer cells and is found on both N-glycan and O-glycans. Sialyl Lewis x is being researched with CD markers to find new ways to create biosensors for cancer cells. Also, it is being used in new ways to target cancer cells specifically for cancer treatment.

• It plays a key role in the inflammatory response and may be used to increase the leukocyte response to infections.

• Sialyl Lewis x is an inflammation-associated antigen on liver cells. It becomes over expressed on diseased liver cells and can be used as a way to detect liver disease in a patient.

• Sialyl Lewis x is also being researched for detection and treatment of immune disorders because of its presence on leukocytes. There is congenital disorder where there is an inclination to recurring severe infections. This stems from an absence of sialyl Lewis x attached to E-selectin ligands on their neutrophils. https://en.wikipedia.org/wiki/Sialyl-Lewis_X

GLYCOPROTEINS • Leukocyte homing and cancer metastasis

• Sialyl-Lewisx is important in leukocyte tethering and rolling. Leukocytes move through the blood stream and then tether themselves to the endothelial wall and roll along the endothelial tissue to determine if they want to leave the bloodstream to get to necessary tissue.

• Sialyl-Lewisx is a necessary partner for the three selectins that bind the leukocyte and endothelial cells. When sialyl-Lewisx is part of an O-glycan and attached to CD34 it can then bind to L-selectin. For the binding to L-selectin to occur sialyl-Lewisx must undergo sulfation.

• For sialyl-Lewisx to attach to P-selectin it must bind to P-Selectin Glycoprotein Ligand-1 (PSGL-1) first which is then sulfated allowing sialyl-Lewisx to attach to P-selectin. For sialyl-Lewisx to bind to E-selectin it needs to be part of an N-glycan and then bind to CD44 or possibly glycolipids which have also been implicated to assist in binding.

• This binding allows the leukocytes to stick to and be released from the endothelial cells as needed to reach their destination.

• Sialyl-Lewisx also plays a critical role in cancer metastasis, facilitating the extravasation of cancer cells out of the bloodstream while they are moving through the body.

• https://en.wikipedia.org/wiki/Sialyl-Lewis_X

GLYCOPROTEINS• H antigen of the ABO blood compatibility antigens. Other

examples of glycoproteins include:• glycoprotein IIb/IIIa, an integrin found on platelets that is

required for normal platelet aggregation and adherence to the endothelium.

• components of the zona pellucida, which surrounds the oocyte, and is important for sperm-egg interaction.

GLYCOPROTEINS AND LYMPHOCYTES.

• “Antigen-specific receptors and functionally related molecules Recognition of substances foreign to an organism is the basis of immune response. The recognition is accomplished by soluble recognition molecules, i.e. immunoglobulins, and by membrane-bound antigen specific receptors. There are basically two kinds of these receptors: membrane immunoglobulins of B lymphocytes and so called T cell antigen receptors of T lymphocytes.”

GLYCOPROTEINS

Most, if not all, external proteins of mammalian cells are glycoproteins.’ These comprise both various receptors and antigenic determinants.

GLYCOPROTEIN (EBOLA VIRUS EXAMPLE)• Ebola virus infection causes a highly lethal hemorrhagic fever

syndrome associated with profound immunosuppression through its ability to induce widespread inflammation and cellular damage. Though GP, the viral envelope glycoprotein, mediates many of these effects, the molecular events that underlie Ebola virus cytopathicity are poorly understood. Here, we define a cellular mechanism responsible for Ebola virus GP cytotoxicity. GP selectively decreased the expression of cell surface molecules that are essential for cell adhesion and immune function

GLYCOPROTEINS (EBOLA VIRUS EXAMPLE)

• GP dramatically reduced levels of αVβ3 without affecting the levels of α2β1 or cadherin, leading to cell detachment and death. This effect was inhibited in vitro and in vivo by brefeldin A and was dependent on dynamin, the GTP ase. GP also decreased cell surface expression of major histocompatibility complex class I molecules, which alters recognition by immune cells, and this effect was also dependent on the mucin domain previously implicated in GP cytotoxicity. By altering the trafficking of select cellular proteins, Ebola virus GP inflicts cell damage and may facilitate immune escape by the virus

GLYCOPROTEINS• The human leukocyte antigen (HLA) system is a gene

complex encoding the major histocompatibility complex (MHC) proteins in humans. These cell-surface proteins are responsible for the regulation of the immune system in humans. The HLA gene complex resides on a 3 Mbp stretch within chromosome 6p 21. HLA genes are highly polymorphic, which means that they have many different alleles, allowing them to fine-tune the adaptive immune system. The proteins encoded by certain genes are also known as antigens, as a result of their historic discovery as factors in organ transplants.

GLYCOPROTEINS.

• Inflammatory glycoproteins in cardio-metabolic disorders, autoimmune diseases and cancer.

• Margery A. Connelly a, Eke G. Gruppen b,c, James D. Otvos a, Robin P.F. Dullaart b,⁎

• a LipoScience, Laboratory Corporation of America® Holdings, Raleigh, NC, USA• b Department of Endocrinology, University Medical Center Groningen, University

of Groningen, Groningen, The Netherlands• c Department of Nephrology, University Medical Center Groningen, University of

Groningen, Groningen, The Netherlands

GLYCOPROTEINSKnowledge of the membrane glycoprotein patterns on the surface of normal leukocytes and encoded with the  human leukocyte antigen (HLA) system, and membrane glycoprotein patterns on surface classes of the major histocompatibility complex (MHC) for other vertebrates is fundamental for the discovery of possible molecular defects and development of toxic effects associated with Acute Radiation Syndromes.

GLYCOPROTEINS

• Currently, concentrations of individual inflammatory glycoproteins• are determined using immunochemical methods such as enzyme linked• Immuno-sorbent assays (ELISAs), electro-chemiluminescence immuno assay• (ECLIA), luminex based assays, radioimmunoassays (RIA)• and nephelometric assays that quantify the amount of protein present• in biological samples. • Method of Differential Diagnosis of Acute Radiation Diseases was elaborated in All

Union Institute of vet. Medicine. Kazan. Tatarstan. 1990 yy. Authors: Popov D.N., Kirshin V.A.

GLYCOPROTEINS.

• 1. Glycoproteins playing important role in the development clinical picture and biological sequela after different types of radiation.

• 2. Method ELISA effective for Differential Diagnosis of Acute Radiation Syndromes and effective for monitoring possible cancer transformation after irradiation.

• 3. Specific Auto antibodies to several glycoproteins can be effective Antidote.