title: Soluble TLT-1 modulates platelet-endothelial cell interactions and actin polymerization.
abstract: Triggering receptor expressed on myeloid cells (TREM) like transcript-1 (TLT-1) is a membrane protein receptor found in alpha-granules of platelets and megakaryocytes. Upon platelet activation TLT-1 is rapidly brought to the surface of platelets. Recently, we demonstrated that activated platelets release a soluble form of TLT-1 (sTLT-1) that is found in serum but not in the plasma of healthy individuals and can enhance platelet aggregation in vitro. Furthermore, evaluation of patients diagnosed with inflammatory diseases, such as sepsis, show that these patients have significantly elevated levels of sTLT-1 in their blood. Accordingly, mice deficient in TLT-1 are predisposed to bleeding in response to an inflammatory challenge; however, the mechanism of TLT-1 function remains unknown. In this investigation, we demonstrate an increase in the amount of platelets that adhere to endothelial cell monolayers in the presence of recombinant sTLT-1 (rsTLT-1). Additionally, we present evidence that rsTLT-1 increases platelet adherence to glass slides by stimulating actin polymerization in platelets, as determined by increased staining of rodamine phalloidin. These results suggest that during inflammation, sTLT-1 may mediate hemostasis by enhancing actin polymerization, resulting in increased platelet aggregation and adherence to the endothelium.
authors.affiliation: Laboratory of Anatomy and Cell Biology, Universidad Central del Caribe, Bayamón, Puerto Rico.
authors.forename: Jessica
authors.initials: J
authors.lastname: Morales
authors.forename: Karina
authors.initials: K
authors.lastname: Villa
authors.forename: Jim
authors.initials: J
authors.lastname: Gattis
authors.forename: William
authors.initials: W
authors.lastname: Castro
authors.forename: Katiria
authors.initials: K
authors.lastname: Colon
authors.forename: Jacek
authors.initials: J
authors.lastname: Lubkowski
authors.forename: Priscilla
authors.initials: P
authors.lastname: Sanabria
authors.forename: Robert
authors.initials: R
authors.lastname: Hunter
authors.forename: A Valance
authors.initials: AV
authors.lastname: Washington
mesh_terms: D000199:Actins / Q000378:metabolism*; D000818:Animals; D001792:Blood Platelets / Q000166:cytology*; D002417:Cattle; D002448:Cell Adhesion; D042783:Endothelial Cells / Q000166:cytology*; D006801:Humans; D051379:Mice; D011971:Receptors, Immunologic / Q000235:genetics / Q000378:metabolism*
chemical_list: D000199:Actins; D011971:Receptors, Immunologic; C473366:TREML1 protein, human