| First Author | Choi H | Year | 2023 |
| Journal | Free Radic Biol Med | Volume | 209 |
| Issue | Pt 1 | Pages | 152-164 |
| PubMed ID | 37852546 | Mgi Jnum | J:342375 |
| Mgi Id | MGI:7548134 | Doi | 10.1016/j.freeradbiomed.2023.10.397 |
| Citation | Choi H, et al. (2023) Extracellular SOD modulates canonical TNFalpha signaling and alpha5beta1 integrin transactivation in vascular smooth muscle cells. Free Radic Biol Med 209(Pt 1):152-164 |
| abstractText | TNFalpha activates NADPH oxidase 1 (Nox1) in vascular smooth muscle cells (VSMCs). The extracellular superoxide anion (O(2)(*-)) produced is essential for the pro-inflammatory effects of the cytokine but the specific contributions of O(2)(*-) to signal transduction remain obscure. Extracellular superoxide dismutase (ecSOD, SOD3 gene) is a secreted protein that binds to cell surface heparin sulfate proteoglycans or to Fibulin-5 (Fib-5, FBLN5 gene), an extracellular matrix protein that also associates with elastin and integrins. ecSOD converts O(2)(*-) to hydrogen peroxide (H(2)O(2)) which prevents NO(*) inactivation, limits generation of hydroxyl radical (OH(*)), and creates high local concentrations of H(2)O(2). We hypothesized that ecSOD modifies TNFalpha signaling in VSMCs. Knockdown of ecSOD (siSOD3) suppressed downstream TNFalpha signals including MAPK (JNK and ERK phosphorylation) and NF-kappaB activation (luciferase reporter and IkappaB phosphorylation), interleukin-6 (IL-6) secretion, iNOS and VCAM expression, and proliferation (Sulforhodamine B assay, PCNA western blot). These effects were associated with significant reductions in the expression of both Type1 and 2 TNFalpha receptors. Reduced Fib-5 expression (siFBLN5) similarly impaired NF-kappaB activation by TNFalpha, but potentiated FAK phosphorylation at Y925. siSOD3 also increased both resting and TNFalpha-induced phosphorylation of FAK and of glycogen synthase kinase-3beta (GSK3beta), a downstream target of integrin linked kinase (ILK). These effects were dependent upon alpha5beta1 integrins and siSOD3 increased resting sulfenylation (oxidation) of both integrin subunits, while preventing TNFalpha-induced increases in sulfenylation. To determine how ecSOD modified TNFalpha-induced inflammation in intact blood vessels, mesenteric arteries from VSMC-specific ecSOD knockout (KO) mice were exposed to TNFalpha (10 ng/ml) in culture for 48 h. Relaxation to acetylcholine and sodium nitroprusside was impaired in WT but not ecSOD KO vessels. Thus, ecSOD association with Fib-5 supports pro-inflammatory TNFalpha signaling while tonically inhibiting alpha5beta1 integrin activation. |
