■肝脏铁过载可以诱导肝脏骨形态发生蛋白(BMP)6的表达并激活BMP/SMAD通路。然而,血清铁过载也可以激活SMAD,但不诱导BMP6表达。因此,血清铁超负荷激活BMP/SMAD通路的机制尚不清楚.本研究旨在阐明SMURF1在血清铁过载和BMP/SMAD通路中的作用。
■通过用2mg/mL的全转铁蛋白(Holo-Tf)处理肝细胞,建立了血清铁超负荷的细胞模型。通过向C57BL/6小鼠腹膜内注射10mgHolo-Tf,并给予高铁饮食1周,然后低铁饮食2天,建立了血清铁过载小鼠模型和肝脏铁过载小鼠模型。进行蛋白质印迹和实时PCR以评估BMP/SMAD途径的激活和铁调素的表达。
■Holo-Tf增强了肝细胞对BMP6的敏感性和响应性。E3泛素蛋白连接酶SMURF1介导Holo-Tf诱导SMAD1/5激活和铁调素表达;当血清铁浓度增加时,SMURF1表达急剧下降。此外,SMURF1底物的表达,它们是参与BMP/SMAD信号传导的重要分子,显着上调。此外,体内分析证实SMURF1在血清铁超负荷期间特异性调节BMP/SMAD途径。
■SMURF1可以通过增强血清铁超负荷过程中肝细胞对BMP的反应性来特异性调节BMP/SMAD途径。
UNASSIGNED: Liver iron overload can induce hepatic expression of bone morphogenic protein (BMP) 6 and activate the BMP/SMAD pathway. However, serum iron overload can also activate SMAD but does not induce BMP6 expression. Therefore, the mechanisms through which serum iron overload activates the BMP/SMAD pathway remain unclear. This study aimed to clarify the role of SMURF1 in serum iron overload and the BMP/SMAD pathway.
UNASSIGNED: A cell model of serum iron overload was established by treating hepatocytes with 2 mg/mL of holo-transferrin (Holo-Tf). A serum iron overload mouse model and a liver iron overload mouse model were established by intraperitoneally injecting 10 mg of Holo-Tf into C57BL/6 mice and administering a high-iron diet for 1 week followed by a low-iron diet for 2 days. Western blotting and real-time PCR were performed to evaluate the activation of the BMP/SMAD pathway and the expression of hepcidin.
UNASSIGNED: Holo-Tf augmented the sensitivity and responsiveness of hepatocytes to BMP6. The E3 ubiquitin-protein ligase SMURF1 mediated Holo-Tf-induced SMAD1/5 activation and hepcidin expression; specifically, SMURF1 expression dramatically decreased when the serum iron concentration was increased. Additionally, the expression of SMURF1 substrates, which are important molecules involved in the transduction of BMP/SMAD signaling, was significantly upregulated. Furthermore, in vivo analyses confirmed that SMURF1 specifically regulated the BMP/SMAD pathway during serum iron overload.
UNASSIGNED: SMURF1 can specifically regulate the BMP/SMAD pathway by augmenting the responsiveness of hepatocytes to BMPs during serum iron overload.