Interleukin-17 (IL-17), a potent proinflammatory cytokine, can trigger the metastasis of non-small cell lung cancer (NSCLC). However, the underlying mechanism involved in IL-17-induced NSCLC cell metastasis remains unclear. In this study, we found that not only the expression of IL-17, IL-17RA, and/or general control nonrepressed protein 5 (GCN5), SRY-related HMG-BOX gene 4 (SOX4), and matrix metalloproteinase 9 (MMP9) was increased in the NSCLC tissues and in the IL-17-stimulated NSCLC cells, but also IL-17 treatment could enhance NSCLC cell migration and invasion. Further mechanism exploration revealed that IL-17-upregulated GCN5 and SOX4 could bind to the same region (-915 to -712 nt) of downstream MMP9 gene promoter driving its gene transcription. In the process, GCN5 could mediate SOX4 acetylation at lysine 118 (K118, a newly identified site) boosting MMP9 gene expression as well as cell migration and invasion. Moreover, the SOX4 acetylation or MMP9 induction and metastatic nodule number in the lung tissues of the BALB/c nude mice inoculated with the NSCLC cells stably infected by corresponding LV-shGCN5 or LV-shSOX4, LV-shMMP9 plus IL-17 incubation were markedly reduced. Overall, our findings implicate that NSCLC metastasis is closely associated with IL-17-GCN5-SOX4-MMP9 axis.

Interleukin-6 (IL-6) overproduction has been considered to contribute to inflammatory damage of glomerular mesangial cells (GMCs) in human mesangial proliferative glomerulonephritis (MsPGN) and its rat model called Thy-1 nephritis (Thy-1N). However, the regulatory mechanisms of IL-6 expression in GMCs upon sublytic C5b-9 timulation remain poorly understood. We found that Krüppel-like factor 4 (KLF4) bound to the IL-6 promoter (−618 to −126 nt) and activated IL-6 gene transcription. Furthermore, lysine residue 224 of KLF4 was acetylated by p300/CBP-associated factor (PCAF), which was important for KLF4-mediated transactivation. Moreover, lysine residue 5 on histone H2B and lysine residue 9 on histone H3 at the IL-6 promoter were also acetylated by PCAF, which resulted in an increase in IL-6 transcription. Besides, NF-κB activation promoted IL-6 expression by elevating the expression of PCAF. Overall, these findings suggest that sublytic C5b-9-induced the expression of IL-6 involves KLF4-mediated transactivation, PCAF-mediated acetylation of KLF4 and histones, and NF-κB activation in GMCs.

Rat Thy-1 nephritis (Thy-1N) is an experimental mesangial proliferative glomerulonephritis (MsPGN) for studying human MsPGN. Although sublytic C5b-9 complex formation on glomerular mesangial cells (GMCs) and renal MCP-1 and RANTES production in rats with Thy-1N have been proved, the role and mechanism of MCP-1 or RANTES synthesis in GMCs induced by sublytic C5b-9 are poorly elucidated. In this study, we first found the expression of transcription factor (KLF6), co-activator (KAT7) and chemokines (MCP-1 and RANTES) was all up-regulated both in renal tissue of Thy-1N rats (in vivo) and in sublytic C5b-9-induced GMCs (in vitro). Further in vitro experiments revealed that KLF6 bound to MCP-1 promoter (-297 to -123 nt) and RANTES promoter (-343 to -191 nt), leading to MCP-1 and RANTES gene transcription. Meanwhile, KAT7 also bound to the same region of MCP-1 and RANTES promoter in a KLF6-dependent manner, and KLF6 was acetylated by KAT7 at lysine residue 100, which finally promoted MCP-1 and RANTES expression. Moreover, our in vivo experiments discovered that knockdown of renal KAT7 or KLF6 gene obviously reduced MCP-1 and RANTES production, GMCs proliferation, ECM accumulation, and proteinuria secretion in Thy-1N rats. Collectively, our study indicates that sublytic C5b-9-induced MCP-1 and RANTES synthesis is associated with KAT7-mediated KLF6 acetylation and elevated KLF6 transcriptional activity, which might provide a new insight into the pathogenesis of rat Thy-1N and human MsPGN.

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.

目的:研究转录因子KLF4调控sublytic C5b-9刺激肾小球系膜细胞（glomerular mesangial cell,GMC）诱导促炎因子白介素-23（IL-23）生成的作用。方法:构建KLF4的短发夹状小干扰RNA（shKLF4）及过表达质粒（pIRES2-KLF4）。将pIRES2-KLF4或shKLF4转染GMC后再行sublytic C5b-9刺激,用qPCR、Western blot和ELISA法检查沉默或过表达KLF4基因后对GMC产生IL-23的影响。此外,构建IL-23基因近端启动子全长质粒,行荧光素酶报告基因实验测定沉默或过表达KLF4基因后对IL-23启动子活性的影响。结果:（1）Sublytic C5b-9刺激GMC后能明显促进IL-23的生成,而沉默KLF4基因后,由sublytic C5b-9诱导GMC产生的IL-23明显减少,但过表达KLF4后IL-23的水平则显著增加。（2）Sublytic C5b-9刺激GMC能显著上调IL-23的启动子活性,而沉默KLF4基因后由sublytic C5b-9诱导的IL-23启动子活性明显降低,但过表达KLF4后又能显著升高IL-23的启动子活性。结论:Sublytic C5b-9刺激诱导IL-23的生成可通过其刺激上调转录因子KLF4的表达而实现。

BACKGROUND/AIMS:The activation of complement system and the formation of C5b-9 complex have been confirmed in the glomeruli of patients with mesangioproliferative glomerulonephritis (MsPGN). However, the role and mechanism of C5b-9-induced injury in glomerular mesangial cell (GMC) are poorly understood. Rat Thy-1N is an animal model for studying MsPGN. It has been revealed that the attack of C5b-9 to the GMC in rat Thy-1N is sublytic, and sublytic C5b-9 can cause GMC apoptosis, but the underlying mechanism is not fully elucidated. To explore the role and regulatory mechanism of C5b-9 in MsPGN lesion, we used rat Thy-1N model and first detected the change of microRNA (miRNA) profiles both in Thy-1N rat renal tissues (in vivo) and in the cultured GMCs with sublytic C5b-9 stimulation (in vitro). Then we determined the effect of miR-3546, which increased both in vivo and in vitro, on GMC apoptosis upon sublytic C5b-9 as well as the involved mechanism.METHODS:Rat Thy-1N model was established and GMCs were treated with sublytic C5b-9. The rat renal cortex and the stimulated GMCs were obtained for miRNA microarray detection. Subsequently, the increased miRNAs were verified by real-time PCR. Meanwhile, to ascertain the ability of some miRNAs to upregulate cleaved caspase 3 and induce GMC apoptosis, the corresponding miRNA mimics were transfected into GMCs, followed by western blotting (WB) and flow cytometry mesurement. Thereafter, the miR-3546-targeted gene (SOX4) was predicted using bioinformatics approaches, and SOX4 expression in Thy-1N tissues and in the GMCs upon sublytic C5b-9 stimulation or miR-3546 mimic/inhibitor transfection were detected using real-time PCR and WB. To prove that miR-3546 can affect SOX4 gene transcription and SOX4 can regulate survivin expression, dual luciferase reporter assay, real-time PCR, WB and chromatin immunoprecipitation (ChIP) assays were performed. Furthermore, the role of miR-3546/SOX4/survivin axis in the GMC apoptosis induced by sublytic C5b-9 was examined using WB and flow cytometry.RESULTS:Compared with normal renal tissues and untreated GMCs, there were 43 and 62 upregulated miRNAs (> 2-fold) in Thy-1N tissues and sublytic C5b-9-stimulated GMCs respectively. A total of 17 miRNAs were increased both in vivo and in vitro, 11 of which were validated by real-time PCR. Among them, miR-3546 could markedly promote GMC apoptosis and inhibit SOX4 or survivin expression in response to sublytic C5b-9, and either SOX4 or survivin overexpression markedly rescued the GMC apoptosis mediated by miR-3546 mimic. Additionally, SOX4 overexpression could reverse the survivin suppression by miR-3546 mimic, and SOX4 could bind to survivin promoter (-1,278 to -853 nt) and activate survivin gene transcription.CONCLUSION:MiR-3546/ SOX4/survivin axis has a promoting role in the GMC apoptosis triggered by sublytic C5b-9, and our findings may provide a new insight into the pathogenesis of rat Thy-1N and human MsPGN.

Objective:To explore the effect of silencing rat(lysine acetyltransferase 7)KAT7 gene on the production of monocyte chemotactic protein-1(MCP-1)in rat glomerular messangial cells(GMC)by sublytic C5b-9 stimulation. Methods:Four kinds of short hairpin RNA(shRNA)stargeting KAT7 gene were synthesized and cloned into eukaryotic expression vector pGCsi-U6/Neo/GFP/ shRNA. The recombinant plasmids were transfected into cultured rat GMC by NeonTM transfection system, and KAT7 protein in the transfected cells was detected by Western blot to find out the optimal shRNA against KAT7 gene. Moreover, the expression of MCP-1 both in GMC and in the supernatant was measured by real-time PCR and ELISA assays. Results:Nucleotide sequencing demonstrated that the constructed KAT7 shRNAs were correct. Western blot experiment showed that the shKAT7-2 could effectively silence the target gene. Meanwhile, after the knockdown of KAT7 by shRNA in the GMC, the production of MCP-1 was significantly decreased upon sublytic C5b-9 stimulation. Conclusion:The rat eukaryotic expression vector shKAT7 was successfully constructed. It is preliminarily confirmed that the expression of KAT7 could obviously promote the production of MCP-1 in rat GMC treated by sublytic C5b-9.

目的:鉴定亚溶解型C5b-9刺激大鼠肾小球系膜细胞(GMC)诱导Kruppel样因子4(KLF4)与P300/CBP相关因子(PCAF)相互结合以及结合部位.方法:以亚溶解型C5b-9刺激GMC,应用免疫沉淀(IP)和免疫印迹(IB)法检测KLF4与PCAF相互结合情况.另构建KLF4、PCAF过表达和KLF4、PCAF不同结构域的质粒,将质粒转染GMC,应用IP和IB鉴定KLF4与PCAF的结合部位.结果与结论:亚溶解型C5b-9刺激GMC后能够诱导KLF4与PCAF相互结合,KLF4结合于PCAF转录结合结构域,而PCAF则结合在KLF4的转录激活结构域.