Thrombospondin‐1‐induced vascular smooth muscle cell chemotaxis: The role of the type 3 repeat and carboxyl terminal domains

Abstract

Thrombospondin-1 (TSP-1), an acute phase reactant implicated in vascular disease, is a matricellular glycoprotein with six domains that confer different functions. The authors have shown TSP-1 induces vascular smooth muscle cell (VSMC) chemotaxis via extracellular signal-regulated kinases-1 and -2 (ERK) and p38 kinase (p38) and that a fusion protein of the carboxyl terminal (COOH) and type 3 repeat (T3) domains independently induce VSMC chemotaxis. The purpose of this study was to determine whether COOH-, T3-induced VSMC chemotaxis, or both, is dependent upon ERK or p38 activation. To determine if the T3, COOH, or type 2 repeat domain (T2, control domain not associated with chemotaxis) activate ERK, p38, or both, VSMCs were exposed to each fusion protein (20 microg/ml for 15, 30, 60, or 120 min), serum-free media (SFM, negative control), or TSP-1 (20 microg/ml for 30 min, positive control). Western immunoblotting was performed for activation studies. Using a microchemotaxis chamber, VSMCs pre-incubated in SFM, DMSO (vehicle control), PD98059 (10 microM), or SB202190 (10 microM) were exposed to each domain, TSP-1, or SFM. After 4 h (37 degrees C), migrated VSMCs were recorded as cells/five fields (400 x) and analyzed by paired t-test. ERK was activated by T2, T3, and COOH. However, p38 was activated by T3 and COOH, but not T2. T3 and COOH-induced VSMC chemotaxis were inhibited by PD98059 or SB202190, but more completely by SB202190. The T2 domain had no effect on VSMC chemotaxis. These results suggest activation of the p38 pathway may be more specific than ERK for COOH- and T3-induced VSMC chemotaxis.

Versican-thrombospondin-1 binding in vitro and colocalization in microfibrils induced by inflammation on vascular smooth muscle cells

“…The conformation of TSP1, therefore, may influence neointima formation through altering its interactions with versican and potentially other ECM components. However, TSP1 also interacts with several receptors on VSMC and thereby has direct effects on HASMC proliferation and migration (Isenberg et al, 2005;Lee et al, 2003;Lymn et al, 2002;Yabkowitz et al, 1993). Thus, TSP1 bound to versican on microfibrils may alter VSMC responses by providing prolonged stimulation of TSP1 receptors on these VSMC.…”

Inflammation and metabolic dysfunction: links to cardiovascular diseases

“…In endothelial cells, IL-4 TSP-1 -EC: 1expression of cell adhesion molecules (189) No data available -VSMC: stimulation of chemotaxis (147,191) -1Aggregation and stability of platelet aggregates (188) ACS, acute coronary syndrome; bFGF, basic fibroblast growth factor; CAD, coronary artery disease; CRP, C-reactive protein; EC, vascular endothelial cells; eNOS, endothelial nitric oxide (NO) synthase; IGT, impaired glucose tolerance; IMT, intima-media thickness; iNOS, inducible NO synthase; MMP, matrix metalloproteinase; oxLDL, oxidized low-density lipoprotein; ROS, reactive oxygen species; T2DM, type 2 diabetes mellitus; VSMC, vascular smooth muscle cells.…”

“…Thrombospondin-1 (TSP-1) is a member of a protein family that mediates cell-matrix and cell-cell interactions. Experimental data have shown that TSP-1 stimulates the aggregation and stability of platelet aggregates (188), induces the expression of cell adhesion molecules (189) in endothelial cells, and stimulates chemotaxis in vascular SMCs (147,191). In TSP-1 knockout mice, more extensive postinfarction remodeling has been observed compared with wild-type mice (72).…”

Antiangiogenic Treatment with the Three Thrombospondin-1 Type 1 Repeats Recombinant Protein in an Orthotopic Human Pancreatic Cancer Model

“…Besides its antiangiogenesis efficacy, thrombospondin-1 activates latent TGF-h and suppresses tumor cells that respond to TGF-h inhibition (16). However, thrombospondin-1 is a complex macromolecule (450 kDa) with numerous other receptors, and its use may be clinically limited because of its size, difficulty in large-scale production, and more importantly, concerns about side effects that might result from its multiple other biological functions, such as the induction of vascular smooth muscle cell chemotaxis by the type 3 repeats and COOH-terminal domains (25). The antiangiogenic domain of thrombospondin-1, 3TSR, provides a promising alternative for clinical administration, because both antiangiogenic and TGF-h activation (KRFK) sequences are located within 3TSR (16).…”