Effects of heat shock on the expression of thrombospondin by endothelial cells in culture.

Abstract

Abstract. Heat-shock proteins from confuent primary cultures of bovine aortic endothelial cells were analyzed by SDS-polyacrylamide gels. In addition to the increased synthesis of the classical heat-shock proteins, there is an increase of a 180,000-mol wt polypeptide in the growth media of heat-shocked cells. Immunoprecipitation with specific antiserum indicates that the 180,000-mol wt polypeptide is thrombospondin. Assay of mRNA levels coding for thrombospondin after brief hyperthermic treatment (45~ 10 min), followed by a recovery of 2 h at 37~ results in a twofold increase in mRNA abundance. In contrast, the activation level of the 71,000-mol wt heat-shock protein mRNA occurs at an earlier time than for thrombospondin mRNA. Immunofluorescence microscopy was used to study the intracellular and extracellular distribution of thrombospondin. Thrombospondin is localized to a prominent pattern of granules of intracellular fluorescence in a perinuclear distribution in cells not exposed to heat. Upon heat treatment, the pattern of granules of intracellular fluorescence appears more pronounced, and the fluorescence appears to be clustered more about the nucleus. There are at least three pools of extracellular forms of thrombospondin: (a) the fine fibrillar extracellular matrix thrombospondin; (b) the punctate granular thrombospondin; and (c) the thrombospondin found in the conditioned medium not associated with the extracellular matrix. When bovine aortic endothelial cells are exposed to heat, the extracellular matrix staining of a fibrillar nature is noticeably decreased, with an increase in the number and degree of fluorescence of focal areas where the punctate granule thrombospondin structures are highly localized. No gross morphological changes in extracellular matrix staining of fibronectin was noted. However, the intermediate filament network was very sensitive and collapsed around the nucleus after heat shock. We conclude that the expression of thrombospondin is heat-shock stimulated.

Thrombospondin gene expression by endothelial cells in culture is modulated by cell proliferation, cell shape and the substratum

“…I and 2). The ability of cells to rapidly modulate thrombospondin gene expression in response to cell morphology, growth and substratum (this study, Mumby et al, 1984), heat shock (Ketis et al, 1988) and growth factors (Majack et al, 1986) suggests that this protein plays a key role in the control of various physiological and pathological processes in vivo, such as wound healing and angiogenesis.…”

Local Preconditioning by Thermal Stress Accelerates Microvascular Thrombus Formation

“…Biliverdin is known to act as a potent radical scavenger (14). In addition, in vitro, it has been demonstrated that cells exposed to hyperthermia are capable to induce the anticoagulant factor thrombomodulin (15) and thrombospondin 1 (16), which are known to reduce the multimeric size and therefore hemostatic activity of von Willebrand factor (17).…”

Intercellular adhesion molecule-1 and CD36 synergize to mediate adherence of Plasmodium falciparum-infected erythrocytes to cultured human microvascular endothelial cells.

“…Given that the microvasculature is heterogeneous between different vascular beds (13), and expression of several, if not all, the known receptors is modulated by local environmental factors such as inflammatory cytokines (14)(15)(16), it is likely that disease status depends on both the parasite binding phenotype and the expression of receptors in the critical vascular beds. Recently, we have demonstrated that infected erythrocytes (IEs) colocalize with endothelial ICAM-1 expression (and to a lesser extent with CD36 and E-selectin) in the cerebral microvasculature of fatal cases of cerebral malaria (17).…”