Nucleosomes Bind to Cell Surface Proteoglycans

Abstract

Material on the surface of activated T-cells was displaced following incubation with a sulfated polysaccharide, dextrin 2-sulfate (D2S), and purified by anion-exchange chromatography. This revealed a complex comprising histones H2A, H2B, H3, and H4 and DNA fragmented into 180-base pair units characteristic of mono-, di-, tri, and polynucleosomes, a pattern of fragmentation similar to that found in apoptotic cells. An antibody raised against the purified nucleosome preparation bound to the plasma membrane of activated Tcells confirming the surface location of nucleosomes. The interaction of sulfated polysaccharides with nucleosomes was investigated using a biotinylated derivative of D2S. It was found that sulfated polysaccharides bound to nucleosomes via the N termini of histones, especially H2A and H2B. Treatment of T-cells with either heparinase or heparitinase abolished nucleosome binding to plasma membranes. This suggests that nucleosomes are anchored to the surface of T-cells by heparan sulfate proteoglycans through an ionic interaction with the basic N-terminal residues in the histones. Furthermore, nucleosomes bound to the cell surface in this manner are then able to bind other sulfated polysaccharides, such as D2S, heparin, or dextran sulfate, through unoccupied histone N termini forming a complex comprising cell surface heparan sulfate proteoglycans, nucleosomes, and sulfated polysaccharides.There is increasing evidence that nuclear material, including histones, DNA, and nucleosomes, may under certain conditions become located on the surface of cells (1-4). These observations are likely to have relevance to autoimmune diseases such as systemic lupus erythematosus (SLE), 1 where antibodies against nuclear material are found (5-8).The presence of histones on the cell surface of various cell types has been documented in a number of previous publications. For instance, Rekvig et al. (9) reported that a subset of anti-nuclear antibodies with affinity for mononucleosomes bound to histone H2B present in the plasma membrane of viable leukocytes. Also, when investigating the resistance of cytotoxic T-cells to perforin-mediated hemolysis, Ojcius et al.(10) fractionated plasma membrane proteins from cytotoxic T-cells using high pressure liquid chromatography and showed that histones H2A and H2B were present, an observation that was further supported by fluorescence-activated cell sorter analysis. Histone H2B has also shown to be present on the cell surface of B-cells by Mecheri et al. (11), who used a monoclonal antibody produced by immunizing mice with purified B-cells to immunoprecipitate a polypeptide from the surface of a B-cell line that had 100% homology with histone H2B. Interestingly, this antibody was also able to interact with B-cells from human peripheral blood. Bilozur and Biswas (12) demonstrated that [ 3 H]heparin bound to four proteins present in the plasma membrane of the human lung carcinoma cell line LX-1, and when sequenced two were found to be histones H2A and H2B.In our own work, we have found...

Functional Role of the Interaction between Polysialic Acid and Extracellular Histone H1

“…Furthermore, the results of the in vitro functional tests (e.g., neurite outgrowth from cerebellar neurons, Schwann cell process formation and proliferation, as well as migration of neural progenitor cells) indicated that extracellular histone H1 interacts with PSA at the cell surface and that this interaction induces the observed effects of histone H1 on the investigated neural cells. Indications for the unusual extracellular location of histone H1, which was first identified as a nuclear protein, have been found in several other studies: histone H1 has been observed at the cell surface of cultured mouse cortical neurons (Bolton and Perry, 1997), human monocytes (Holers and Kotzin, 1985), activated human peripheral blood lymphocytes (Watson et al, 1995), cultured T-cells (Watson et al, 1995(Watson et al, , 1999, a macrophage cell line (Brix et al,1998), and skeletal muscle cells (Henriquez et al, 2002). So far, the mechanism(s) by which histone H1 crosses the membrane are not known.…”

Heparanase-mediated Loss of Nuclear Syndecan-1 Enhances Histone Acetyltransferase (HAT) Activity to Promote Expression of Genes That Drive an Aggressive Tumor Phenotype

“…Thus, heparan sulfates may inhibit HAT by binding directly to the enzyme. Alternatively, it is known that heparan sulfate can bind directly to histone proteins, and it has been speculated that heparan sulfate-histone interactions interfere with HAT-mediated acetylation of histone tails (40,41). Importantly, there does appear to be specificity in heparan sulfate inhibition of HAT because inhibition is dependent on the pattern of sulfation and on the length of the heparan sulfate chain (15).…”

Extracellular DNA traps promote thrombosis

“…Adhesion of platelets and RBCs to NETs may be helped by electrostatic interaction of the negatively charged cells with positively charged histones in NETs (37). RBC adhesion to NETs could also play a role in sickle-cell disease, where a lethal crisis is often precipitated by infection (38).…”