RESUMO
Renal tubular epithelial cells (RTECs) play pivotal roles in the innate immune response in kidneys. Dendritic cell specific intracellular adhesion molecule-3 grabbing nonintegrin (DC-SIGN) functions as both the innate immune recognition receptor and the adhesion molecule. In our previous study, we found that DC-SIGN expression was induced in RTECs during renal inflammation. However, the underlying mechanism remains unclear. Here, we used the human renal proximal tubular epithelial cell lines (HK-2) to investigate the mechanism of TNF-α-induced expression of DC-SIGN. Our results showed that TNF-α up-regulated the expressions of DC-SIGN and Runt-related transcription factor 1 (RUNX1) in a time-dependent manner and that it up-regulated DC-SIGN promoter-driven luciferase activity in a dose-dependent manner. The mTOR inhibitor rapamycin and mTOR siRNA blocked the TNF-α-induced up-regulation of DC-SIGN expression. Meanwhile, DC-SIGN expression was also inhibited by RUNX1 siRNA and its inhibitor Ro5-3335. In addition, both mTOR and RUNX1 inhibitors attenuated TNF-α-induced the increase in DC-SIGN promoter-driven luciferase activity. Finally, we found that HK-2â¯cells exposed to rapamycin or mTOR siRNA reduced the TNF-α-induced up-regulation of RUNX1. In conclusion, these results indicated that the mTOR-RUNX1 pathway participates in the regulation of TNF-α-induced DC-SIGN expression in RTECs.
Assuntos
Moléculas de Adesão Celular/metabolismo , Subunidade alfa 2 de Fator de Ligação ao Core/metabolismo , Células Epiteliais/metabolismo , Túbulos Renais/metabolismo , Lectinas Tipo C/metabolismo , Receptores de Superfície Celular/metabolismo , Serina-Treonina Quinases TOR/metabolismo , Células Cultivadas , Humanos , Túbulos Renais/citologiaRESUMO
Renal fibrosis is widely considered a common mechanism leading to end-stage renal failure. Epithelial-to-mesenchymal transition (EMT) plays important roles in the pathogenesis of renal fibrosis. Runt-related transcription factor 1(RUNX1) plays a vital role in hematopoiesis via Endothelial-to-Hematopoietic Transition (EHT), a process that is conceptually similar to EMT, but its role in EMT and renal fibrosis is unclear. Here, we demonstrate that RUNX1 is overexpressed in the processes of TGF-ß-induced partial EMT and renal fibrosis and that the expression level of RUNX1 is SMAD3-dependent. Knockdown of RUNX1 attenuated both TGF-ß-induced phenotypic changes and the expression levels of EMT marker genes in renal tubular epithelial cells (RTECs). In addition, overexpression of RUNX1 promoted the expression of EMT marker genes in renal tubular epithelial cells. Moreover, RUNX1 promoted TGF-ß-induced partial EMT by increasing transcription of the PI3K subunit p110δ, which mediated Akt activation. Specific deletion of Runx1 in mouse RTECs attenuated renal fibrosis, which was induced by both unilateral ureteral obstruction (UUO) and folic acid (FA) treatment. These findings suggest that RUNX1 is a potential target for preventing renal fibrosis.
Assuntos
Subunidade alfa 2 de Fator de Ligação ao Core/metabolismo , Transição Epitelial-Mesenquimal , Nefropatias/metabolismo , Rim/metabolismo , Fosfatidilinositol 3-Quinases/metabolismo , Fator de Crescimento Transformador beta/metabolismo , Animais , Classe I de Fosfatidilinositol 3-Quinases , Subunidade alfa 2 de Fator de Ligação ao Core/genética , Fibrose , Células HEK293 , Humanos , Rim/patologia , Nefropatias/genética , Nefropatias/patologia , Camundongos , Camundongos Knockout , Fosfatidilinositol 3-Quinases/genética , Fator de Crescimento Transformador beta/genéticaRESUMO
An appropriate inflammatory response plays critical roles in eliminating pathogens, whereas an excessive inflammatory response can cause tissue damage. Runt-related transcription factor 1 (RUNX1), a master regulator of hematopoiesis, plays critical roles in T cells; however, its roles in Toll-like receptor 4 (TLR4)-mediated inflammation in macrophages are unclear. Here, we demonstrated that upon TLR4 ligand stimulation by lipopolysaccharide (LPS), macrophages reduced the expression levels of RUNX1 Silencing of Runx1 attenuated the LPS-induced IL-1ß and IL-6 production levels, but the TNF-α levels were not affected. Overexpression of RUNX1 promoted IL-1ß and IL-6 production in response to LPS stimulation. Moreover, RUNX1 interacted with the NF-κB subunit p50, and coexpression of RUNX1 with p50 further enhanced the NF-κB luciferase activity. Importantly, treatment with the RUNX1 inhibitor, Ro 5-3335, protected mice from LPS-induced endotoxic shock and substantially reduced the IL-6 levels. These findings suggest that RUNX1 may be a new potential target for resolving TLR4-associated uncontrolled inflammation and preventing sepsis.
