Sublytic C5b-9 Induces IL-23 and IL-36a Production by Glomerular Mesangial Cells via PCAF-Mediated KLF4 Acetylation in Rat Thy-1 Nephritis

Abstract

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.

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KLF6 Acetylation Promotes Sublytic C5b-9-Induced Production of MCP-1 and RANTES in Experimental Mesangial Proliferative Glomerulonephritis

“…C5b-9-dependent in rat Thy-1N (6)(7)(8). GMCs exposed to sublytic C5b-9 in vitro can significantly elevate the synthesis of IL-23, IL-36a (7) and . Because several documents have pointed out that some inflammatory chemokines i.e.…”

“…GMCs were transiently transfected with corresponding plasmids by using the Neon Transfection System (Invitrogen) as previously mentioned (8). Besides, 0.5 × 10 4 GMCs were infected with LV-shRNA at the titer of 1 × 10 6 or 1 × 10 7 TU/ml for 48 h as previous document (7).…”

“…Many studies have confirmed that the pathologic changes, such as inflammatory cytokines production and GMCs damage, are C5b-9-dependent, especially sublytic C5b-9-dependent in rat Thy-1N 6 - 8 . GMCs exposed to sublytic C5b-9 in vitro can significantly elevate the synthesis of IL-23, IL-36a 7 and IL-6 8 . Because several documents have pointed out that some inflammatory chemokines i.e.…”

“…Generally, transcription factor regulate target gene transcription by recruiting chromatin modifier, co-factor, and transcription machinery to gene promoter. It has demonstrated that a number of KLFs bind to co-factors that possess histone acetyltransferase (HAT) activity, such as cAMP response element binding-binding protein (CBP), p300, and p300/CBP-associated factor (P/CAF) 7 , 22 , 23 . As a co-factor, lysine acetyltransferase 7 (KAT7, also known as HBO1 or MYST2) is also a member of the HAT family 24 , and KAT7 is involved in gene transcription via acetylation of histone H3/H4 and non-histone proteins 25 - 27 .…”