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Thrombospondin induces glomerular mesangial cell adhesion and migration
G Taraboletti1, M Morigi, M Figliuzzi
1Istituto di Ricerche Farmacologiche Mario Negri, Bergamo, Italy.
Background:
Extracellular matrix components are known to modulate mesangial cell functions as adhesion, motility and proliferation. Among other extracellular matrix components, mesangial cells have been recently described to secrete thrombospondin (TSP), a high molecular weight glycoprotein, produced by several cell types, and known to play a role in embryogenesis, wound healing, angiogenesis, and tumorigenesis. The aim of this work was the functional and molecular characterization of TSP interactions with mesangial cells.
Experimental Design:
Adhesion of mesangial cells to TSP-coated plastic, and chemotaxis in the Boyden chamber assay were tested. In order to identify TSP active domains, heparin, known to bind to the amino-terminal region of TSP, four monoclonal antibodies directed against specific domains of the molecule, and TSP fragments obtained by enzymatic digestion were used.
Results:
We found that TSP induces mesangial cell adhesion and chemotaxis, in a dose dependent manner. Adhesion was inhibited by antiserum against TSP, and by an anti-CD36 monoclonal antibody tested in the presence of heparin, but not by the peptide Gly-Arg-Gly-Asp-Ser. We have also found that only the carboxy-terminal end of TSP retains the adhesive properties of the molecule, while all the fragments tested showed some degree of chemotactic activity.
Conclusions:
We conclude that TSP modulates mesangial cell adhesion and motility, thus acting as a potential autocrine and paracrine regulator of mesangial cell functions in normal and pathologic conditions.
Insights
Thrombospondin (TSP) enhances mesangial cell adhesion and motility. This glycoprotein acts as a potential regulator for mesangial cell functions in both normal and pathological conditions.
Area of Science:
- Cell Biology
- Biochemistry
- Extracellular Matrix Research
Background:
- Extracellular matrix components influence mesangial cell functions like adhesion, motility, and proliferation.
- Mesangial cells secrete thrombospondin (TSP), a glycoprotein involved in development, healing, and tumorigenesis.
Purpose of the Study:
- To functionally and molecularly characterize thrombospondin (TSP) interactions with mesangial cells.
Main Methods:
- Mesangial cell adhesion to TSP-coated surfaces and chemotaxis were assessed.
- Heparin, monoclonal antibodies against TSP domains, and TSP fragments were used to identify active domains.
Main Results:
- TSP dose-dependently induced mesangial cell adhesion and chemotaxis.
- Adhesion was inhibited by anti-TSP antiserum and an anti-CD36 antibody with heparin.
- The carboxy-terminal end of TSP retained adhesive properties, while all fragments exhibited chemotactic activity.
Conclusions:
- TSP modulates mesangial cell adhesion and motility.
- TSP may function as an autocrine and paracrine regulator in normal and pathological mesangial cell processes.