Sublytic C5b-9 formation on glomerular mesangial cells in rat Thy-1 nephritis (Thy-1N)， a model of human mesangioproliferative glomerulonephritis， is accompanied by the production of proinflammatory cytokines， but the relationship between sublytic C5b-9 and cytokine synthesis and the underlying mechanism remains unclear. To explore the problems mentioned above， in this study， we first examined the levels of proinflammatory ILs (e.g.， IL-23 and IL-36a) as well as transcription factor (KLF4) and coactivator (PCAF) in the renal tissues of Thy-1N rats and in the glomerular mesangial cell line (HBZY-1) stimulated by sublytic C5b-9. Then， we further determined the role of KLF4 and PCAF in sublytic C5b-9... More
Sublytic C5b-9 formation on glomerular mesangial cells in rat Thy-1 nephritis (Thy-1N)， a model of human mesangioproliferative glomerulonephritis， is accompanied by the production of proinflammatory cytokines， but the relationship between sublytic C5b-9 and cytokine synthesis and the underlying mechanism remains unclear. To explore the problems mentioned above， in this study， we first examined the levels of proinflammatory ILs (e.g.， IL-23 and IL-36a) as well as transcription factor (KLF4) and coactivator (PCAF) in the renal tissues of Thy-1N rats and in the glomerular mesangial cell line (HBZY-1) stimulated by sublytic C5b-9. Then， we further determined the role of KLF4 and PCAF in sublytic C5b-9-induced IL-23 and IL-36a production as well as the related mechanism. Our results showed that the levels of KLF4， PCAF， IL-23， and IL-36a were obviously elevated. Mechanistic investigation revealed that sublytic C5b-9 stimulation could increase IL-23 and IL-36a synthesis through KLF4 and PCAF upregulation， and KLF4 and PCAF could form a complex， binding to the IL-23 or IL-36a promoter in a KLF4-dependent manner， causing gene transcription. Importantly， KLF4 acetylation by PCAF contributed to sublytic C5b-9-induced IL-23 and IL-36a transcription. Besides， the KLF4 binding regions on IL-23 or IL-36a promoters and the KLF4 lysine site acetylated by PCAF were identified. Furthermore， silencing renal KLF4 or PCAF gene could significantly inhibit IL-23 or IL-36a secretion and tissue damage of Thy-1N rats. Collectively， these findings implicate that the KLF4/PCAF interaction and KLF4 acetylation by PCAF play a pivotal role in the sublytic C5b-9-mediated IL-23 and IL-36a production of Thy-1N rats.
