Sublytic complement C5b-9 complexes induce thrombospondin-1 production in rat glomerular mesangial cells via PI3-k/Akt: association with activation of latent transforming growth factor-beta1.
Mesangial cell proliferation is a common cellular response to a variety of different types of glomerular injury. Complement C5b-9 is a prime candidate to mediate mesangial cell proliferation, especially sublytic C5b-9, which can induce the production of multiple inflammatory factors and cytokines. Transforming growth factor (TGF)-beta1 plays a major role in the accumulation of extracellular matrix (ECM), while thrombospondin (TSP)-1 has been identified as an activator of latent TGF-beta1 in an in vitro system. Using rat glomerular mesangial cells (GMCs) as a model system, we assessed the effect of sublytic C5b-9 on the expression of TSP-1 and TGF-beta1 and explored the relevant pathway of signal transduction. First, we ensured the concentrations of anti-Thy1 antibody and complement, which were regarded as a sublytic C5b-9 dose, and examined whether the sublytic C5b-9 induced expression of TSP-1 in rat GMCs which, in turn, activated latent TGF-beta1 by real-time polymerase chain reaction (PCR) and enzyme-linked immunosorbent assay (ELISA), respectively. Then, we investigated the role of the PI3-k/Akt pathway in sublytic C5b-9-induced TSP-1 production in rat GMCs by Western blot analysis. The addition of sublytic C5b-9 (5% anti-Thy1 antibody and 4% normal serum) to rat GMCs induced activation of latent TGF-beta1 via TSP-1. The addition of sublytic C5b-9 apparently increased the protein of Akt phosphorylation, whereas PI3-k inhibitor LY294002 could clearly reduce the increase of TSP-1 induced by sublytic C5b-9. These results indicate that TSP-1 is an activator of latent TGF-beta1 in sublytic C5b-9-induced rat GMCs; furthermore, the PI3-k/Akt signal transduction pathway may play a key role in sublytic C5b-9-induced TSP-1 production.
Gao
L
L
Department of Immunology, Nanjing Medical University, 210019 Nanjing, China.
Qiu
W
W
Wang
Y
Y
Xu
W
W
Xu
J
J
Tong
J
J
D000818:Animals; D000911:Antibodies, Monoclonal / Q000276:immunology; D002478:Cells, Cultured; D002867:Chromones / Q000276:immunology; D015938:Complement Membrane Attack Complex / Q000276:immunology*; D004791:Enzyme Inhibitors / Q000276:immunology; D015432:Glomerulonephritis, Membranoproliferative / Q000276:immunology; D047908:Intracellular Signaling Peptides and Proteins / Q000276:immunology*; D007518:Isoantibodies / Q000276:immunology; D053779:Latent TGF-beta Binding Proteins; D050527:Mesangial Cells / Q000276:immunology*; D009025:Morpholines / Q000276:immunology; D019869:Phosphatidylinositol 3-Kinases / Q000276:immunology*; D010766:Phosphorylation; D051057:Proto-Oncogene Proteins c-akt / Q000276:immunology; D051381:Rats; D015398:Signal Transduction / Q000276:immunology; D013601:T-Lymphocytes / Q000276:immunology; D019700:Thrombospondin 1 / Q000276:immunology*; D016212:Transforming Growth Factor beta / Q000276:immunology; D015854:Up-Regulation / Q000276:immunology
D000911:Antibodies, Monoclonal; D002867:Chromones; D015938:Complement Membrane Attack Complex; D004791:Enzyme Inhibitors; D047908:Intracellular Signaling Peptides and Proteins; D007518:Isoantibodies; D053779:Latent TGF-beta Binding Proteins; D009025:Morpholines; D019700:Thrombospondin 1; D016212:Transforming Growth Factor beta; C035678:anti-Thy antibody; C085911:2-(4-morpholinyl)-8-phenyl-4H-1-benzopyran-4-one; D019869:Phosphatidylinositol 3-Kinases; D051057:Proto-Oncogene Proteins c-akt