title: Fetuin-A associates with histones intracellularly and shuttles them to exosomes to promote focal adhesion assembly resulting in rapid adhesion and spreading in breast carcinoma cells.
abstract: The present analyses were undertaken to define the mechanisms by which fetuin-A modulates cellular adhesion. FLAG-tagged fetuin-A was expressed in breast carcinoma and HEK-293T cells. We demonstrated by confocal microscopy that fetuin-A co-localizes with histone H2A in the cell nucleus, forms stable complexes with histones such as H2A and H3 in solution, and shuttles histones to exosomes. The rate of cellular adhesion and spreading to either fibronectin or laminin coated wells was accelerated significantly in the presence of either endogenous fetuin-A or serum derived protein. More importantly, the formation of focal adhesion complexes on surfaces coated by laminin or fibronectin was accelerated in the presence of fetuin-A or histone coated exosomes. Cellular adhesion mediated by histone coated exosomes was abrogated by heparin and heparinase III. Heparinase III cleaves heparan sulfate from cell surface heparan sulfate proteoglycans. Lastly, the uptake of histone coated exosomes and subsequent cellular adhesion, was abrogated by heparin. Taken together, the data suggest a mechanism where fetuin-A, either endogenously synthesized or supplied extracellularly can extract histones from the nucleus or elsewhere in the cytosol/membrane and load them on cellular exosomes which then mediate adhesion by interacting with cell surface heparan sulfate proteoglycans via bound histones.
authors.affiliation: Departments of Biochemistry and Cancer Biology, Meharry Medical College, 1005 D.B. Todd Boulevard, Nashville, TN 37208, USA.
authors.forename: Gladys
authors.initials: G
authors.lastname: Nangami
authors.affiliation: Division of Surgical Oncology and Endocrine Surgery, Vanderbilt University Medical Center, Nashville, TN 37232, USA.
authors.forename: Rainelli
authors.initials: R
authors.lastname: Koumangoye
authors.affiliation: Departments of Biochemistry and Cancer Biology, Meharry Medical College, 1005 D.B. Todd Boulevard, Nashville, TN 37208, USA.
authors.forename: J
authors.initials: J
authors.lastname: Shawn Goodwin
authors.affiliation: Departments of Biochemistry and Cancer Biology, Meharry Medical College, 1005 D.B. Todd Boulevard, Nashville, TN 37208, USA.
authors.forename: Amos M
authors.initials: AM
authors.lastname: Sakwe
authors.affiliation: Departments of Pathology, Anatomy and Cell Biology, Meharry Medical College, Nashville, TN 37208, USA.
authors.forename: Dana
authors.initials: D
authors.lastname: Marshall
authors.affiliation: Department of Medicine, Vanderbilt University Medical Center, Nashville, TN 37232, USA.
authors.forename: James
authors.initials: J
authors.lastname: Higginbotham
authors.affiliation: Departments of Biochemistry and Cancer Biology, Meharry Medical College, 1005 D.B. Todd Boulevard, Nashville, TN 37208, USA. Electronic address: jochieng@mmc.edu.
authors.forename: Josiah
authors.initials: J
authors.lastname: Ochieng
mesh_terms: D001943:Breast Neoplasms / Q000378:metabolism*; D002448:Cell Adhesion / Q000502:physiology*; D002460:Cell Line; D045744:Cell Line, Tumor; D002462:Cell Membrane / Q000378:metabolism; D002467:Cell Nucleus / Q000378:metabolism; D003593:Cytoplasm / Q000378:metabolism; D055354:Exosomes / Q000378:metabolism*; D005260:Female; D005353:Fibronectins / Q000378:metabolism; D022001:Focal Adhesions / Q000378:metabolism*; D057809:HEK293 Cells; D006493:Heparin / Q000378:metabolism; D006497:Heparan Sulfate / Q000378:metabolism; D006657:Histones / Q000378:metabolism*; D006801:Humans; D007797:Laminin / Q000378:metabolism; D011133:Polysaccharide-Lyases / Q000378:metabolism; D011509:Proteoglycans / Q000378:metabolism; D060749:alpha-2-HS-Glycoprotein / Q000378:metabolism*
chemical_list: D005353:Fibronectins; D006493:Heparin; D006497:Heparan Sulfate; D006657:Histones; D007797:Laminin; D011133:Polysaccharide-Lyases; D011509:Proteoglycans; D060749:alpha-2-HS-Glycoprotein; C021349:heparitinsulfate lyase
keywords: Adhesion; Exosomes; Fetuin-A; Histones; Tumor cells