scholarly journals Membrane anchoring of heparan sulfate proteoglycans by phosphatidylinositol and kinetics of synthesis of peripheral and detergent-solubilized proteoglycans in Schwann cells.

1989 ◽  
Vol 108 (5) ◽  
pp. 1891-1897 ◽  
Author(s):  
D J Carey ◽  
D M Evans
Keyword(s):  
Cell Surface ◽  
Heparan Sulfate ◽  
Schwann Cells ◽  
Electrostatic Interactions ◽  
Heparan Sulfate Proteoglycans ◽  
Membrane Bound ◽  
Covalently Linked ◽  
Mode Of Attachment ◽  
Membrane Anchoring ◽  
Kinetics Of

Previous studies have shown that Schwann cells synthesize both peripheral and integral hydrophobic cell surface heparan sulfate proteoglycans (HSPGs). The experiments reported here were undertaken to investigate the mode of attachment of these proteins to the cell surface and their potential interrelationship. The binding of the hydrophobic HSPGs to membranes appears to be via covalently linked phosphatidylinositol based on the observation that incubation of the detergent-solubilized protein with purified phosphatidylinositol-specific phospholipase C significantly reduces the ability of the HSPGs to associate with phospholipid vesicles in a reconstitution assay. The peripherally associated HSPGs were released from the cells by incubation in the presence of heparin (10 mg/ml), 10 mM phytic acid (inositol hexaphosphate), or 2 M NaCl. These treatments also solubilized basement membrane HSPGs synthesized by the Schwann cells. These data suggest that the peripheral HSPGs are bound to the surface by electrostatic interactions. The peripheral and hydrophobic HSPGs were identical in overall size, net charge, length of glycosaminoglycan chains, and patterns of N-sulfation. To determine whether the peripheral HSPGs were derived from the membrane-bound form by cleavage of the membrane anchor, we examined the kinetics of synthesis and degradation of the two forms of HSPGs. The results obtained indicated the existence of two pools of detergent-solubilized HSPG with fast (t1/2 = 6 h) and slow (t1/2 = 55 h) turnover kinetics. The data were consistent with a model in which the peripheral HSPGs were derived from the slowly turning over pool of detergent-solubilized HSPGs.

scholarly journals Heparan Sulfate Proteoglycans Are Required for Cellular Binding of the Hepatitis E Virus ORF2 Capsid Protein and for Viral Infection

2009 ◽  
Vol 83 (24) ◽  
pp. 12714-12724 ◽  
Author(s):  
Manjula Kalia ◽  
Vivek Chandra ◽  
Sheikh Abdul Rahman ◽  
Deepak Sehgal ◽  
Shahid Jameel
Keyword(s):  
Cell Surface ◽  
Heparan Sulfate ◽  
Capsid Protein ◽  
Marked Reduction ◽  
Electrostatic Interactions ◽  
Hepatitis E Virus ◽  
Hepatitis E ◽  
Heparan Sulfate Proteoglycans ◽  
Productive Infection ◽  
Target Cells

ABSTRACT The hepatitis E virus (HEV), a nonenveloped RNA virus, is the causative agent of hepatitis E. The mode by which HEV attaches to and enters into target cells for productive infection remains unidentified. Open reading frame 2 (ORF2) of HEV encodes its major capsid protein, pORF2, which is likely to have the determinants for virus attachment and entry. Using an ∼56-kDa recombinant pORF2 that can self-assemble as virus-like particles, we demonstrated that cell surface heparan sulfate proteoglycans (HSPGs), specifically syndecans, play a crucial role in the binding of pORF2 to Huh-7 liver cells. Removal of cell surface heparan sulfate by enzymatic (heparinase) or chemical (sodium chlorate) treatment of cells or competition with heparin, heparan sulfate, and their oversulfated derivatives caused a marked reduction in pORF2 binding to the cells. Syndecan-1 is the most abundant proteoglycan present on these cells and, hence, plays a key role in pORF2 binding. Specificity is likely to be dictated by well-defined sulfation patterns on syndecans. We show that pORF2 binds syndecans predominantly via 6-O sulfation, indicating that binding is not entirely due to random electrostatic interactions. Using an in vitro infection system, we also showed a marked reduction in HEV infection of heparinase-treated cells. Our results indicate that, analogous to some enveloped viruses, a nonenveloped virus like HEV may have also evolved to use HSPGs as cellular attachment receptors.

scholarly journals Distinct glycosaminoglycan chain length and sulfation patterns required for cellular uptake of Tau, Aβ, and α-Synuclein

2017 ◽  
Author(s):  
Barbara E. Stopschinski ◽  
Brandon B. Holmes ◽  
Gregory M. Miller ◽  
Jaime Vaquer-Alicea ◽  
Linda C. Hsieh-Wilson ◽  
...  
Keyword(s):  
Cell Surface ◽  
Neurodegenerative Diseases ◽  
Heparan Sulfate ◽  
Chain Length ◽  
Cellular Uptake ◽  
Genetic Manipulation ◽  
Heparan Sulfate Proteoglycans ◽  
Cell Uptake ◽  
Major Genes

AbstractTranscellular propagation of aggregate “seeds” has been proposed to mediate progression of neurodegenerative diseases in tauopathies and α-synucleinopathies. We have previously determined that tau and α-synuclein aggregates bind heparan sulfate proteoglycans (HSPGs) on the cell surface. This mediates uptake and intracellular seeding. The specificity and mode of binding to HSPGs has been unknown. We used modified heparins to determine the size and sulfation requirements of glycosaminoglycan (GAGs) binding to aggregates in biochemical and cell uptake and seeding assays. Aggregates of tau require a precise GAG architecture with defined sulfate moieties in the N- and 6-O-positions, whereas α-synuclein and Aβ rely slightly more on overall charge on the GAGs. To determine the genetic requirements for aggregate uptake, we individually knocked out the major genes of the HSPG synthesis pathway using CRISPR/Cas9 in HEK293T cells. Knockout of EXT1, EXT2 and EXTL3, N-sulfotransferase (NDST1), and 6-O-sulfotransferase (HS6ST2) significantly reduced tau uptake. α-Synuclein was not sensitive to HS6ST2 knockout. Good correlation between pharmacologic and genetic manipulation of GAG binding by tau and α-synuclein indicates specificity that may help elucidate a path to mechanism-based inhibition of transcellular propagation of pathology.

scholarly journals Heparan Sulfate Proteoglycans May Promote or Inhibit Cancer Progression by Interacting with Integrins and Affecting Cell Migration

2015 ◽  
Vol 2015 ◽  
pp. 1-8 ◽  
Author(s):  
Mariana A. Soares ◽  
Felipe C. O. B. Teixeira ◽  
Miguel Fontes ◽  
Ana Lúcia Arêas ◽  
Marcelo G. Leal ◽  
...  
Keyword(s):  
Cell Adhesion ◽  
Cell Surface ◽  
Heparan Sulfate ◽  
Cancer Progression ◽  
Heparan Sulfate Proteoglycans ◽  
Transmembrane Receptors ◽  
Surface Molecules ◽  
Cell Matrix ◽  
Cell Organization ◽  
The Relationship

The metastatic disease is one of the main consequences of tumor progression, being responsible for most cancer-related deaths worldwide. This review intends to present and discuss data on the relationship between integrins and heparan sulfate proteoglycans in health and cancer progression. Integrins are a family of cell surface transmembrane receptors, responsible for cell-matrix and cell-cell adhesion. Integrins’ main functions include cell adhesion, migration, and survival. Heparan sulfate proteoglycans (HSPGs) are cell surface molecules that play important roles as cell receptors, cofactors, and overall direct or indirect contributors to cell organization. Both molecules can act in conjunction to modulate cell behavior and affect malignancy. In this review, we will discuss the different contexts in which various integrins, such asα5,αV,β1, andβ3, interact with HSPGs species, such as syndecans and perlecans, affecting tissue homeostasis.

BETA2/NeuroD Protein Transduction Requires Cell Surface Heparan Sulfate Proteoglycans

2006 ◽  
Vol 0 (0) ◽  
pp. 061206073830001
Author(s):  
Hirofumi Noguchi ◽  
Michiko Ueda ◽  
Shinichi Matsumoto ◽  
Naoya Kobayashi ◽  
Shuji Hayashi
Keyword(s):  
Cell Surface ◽  
Heparan Sulfate ◽  
Heparan Sulfate Proteoglycans ◽  
Protein Transduction

scholarly journals Membrane-bound Steel factor induces more persistent tyrosine kinase activation and longer life span of c-kit gene-encoded protein than its soluble form

Blood ◽  
1995 ◽  
Vol 85 (3) ◽  
pp. 641-649 ◽  
Author(s):  
K Miyazawa ◽  
DA Williams ◽  
A Gotoh ◽  
J Nishimaki ◽  
HE Broxmeyer ◽  
...  
Keyword(s):  
Cell Surface ◽  
Tyrosine Kinase ◽  
Life Span ◽  
Protein Degradation ◽  
Cell Line ◽  
Soluble Form ◽  
Steel Factor ◽  
Degradation Rates ◽  
Membrane Bound ◽  
Kinetics Of

Alternative splicing of exon 6 results in the production of two isoforms of Steel factor (SLF): the membrane-bound and soluble forms. To investigate differences in the kinetics of c-kit tyrosine kinase activated by these two isoforms, we used a stromal cell line (SI/SI4) established from SI/SI homozygous murine embryo fetal liver and its stable transfectants containing either hSCF248 cDNA (including exon 6; secreted form) or hSCF220 cDNA (lacking exon 6; membrane-bound form) as the source of each isoform. Interaction of factor dependent myeloid cell line MO7e with stromal cells producing either isoform resulted in activated c-kit tyrosine kinase and induction of the same series of tyrosine phosphorylated cellular proteins in MO7e cells. However, SI4- h220 (membrane-bound form) induced more persistent activation of c-kit kinase than SI4-h248 (soluble form) did. Flow cytometric analysis and pulse-chase studies using [35S]methionine showed that SI4-h248 induced rapid downmodulation of cell-surface c-kit expression and its protein degradation in MO7e cells, whereas SI4-h220 induced more prolonged life span of c-kit protein. Addition of soluble recombinant human SLF to SI4- h220 cultures enhanced reduction of cell-surface c-kit expression and its protein degradation. Because the kinetics of c-kit inactivation strikingly fits with the protein degradation rates of c-kit under the conditions described above, rapid proteolysis of c-kit protein induced by soluble SLF stimulation may function as a “turn-off switch” for activated c-kit kinase.

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