Center for Hemochromatosis, University Hospital of Modena, Modena, Italy.
Blood Cells Mol Dis. 2010 Dec 15;45(4):308-12. doi: 10.1016/j.bcmd.2010.08.010. Epub 2010 Sep 21.
Human hemochromatosis (HC) has been associated with the common C282Y polymorphism of HFE or rare pathogenic mutations of TfR2, HJV, FPN and HAMP. All forms of human HC seem to be caused by low or inadequate levels of hepcidin, the iron hormone. We and others have recently shown that Hfe(-/-) mice exhibit an impairment in the bone morphogenetic protein (BMP) signaling pathway controlling hepcidin. However, all data indicating the central role of BMPs in hepcidin regulation and an impaired BMP/SMAD signaling in HC have been collected in mice. In this study we investigated whether also in humans the expression of BMP signaling targets, SMAD7 and Id1, are associated with liver iron concentration (LIC) and whether such regulation is disrupted in HFE-HC. We correlated the mRNA expression, assessed by RT-PCR, of HAMP, SMAD7 and Id1 with LIC in liver biopsies from patients with normal iron status, HFE-HC or non-HC hepatic iron overload. We found that in human liver, not only HAMP, but also SMAD7 and Id1 mRNA significantly correlate with the extent of hepatic iron burden. However, this correlation is lost in patients with HFE-HC, but maintained in subjects with non-hemochromatotic iron overload. These data indicate that in human HFE-HC a disrupted BMP/SMAD signaling in the liver is key in the pathogenesis of the disease.
人类血色病(HC)与 HFE 基因的常见 C282Y 多态性或 TfR2、HJV、FPN 和 HAMP 等罕见的致病性突变有关。所有形式的人类 HC 似乎都是由铁激素——低或不足的血红素水平引起的。我们和其他人最近表明,Hfe(-/-) 小鼠的骨形态发生蛋白(BMP)信号通路控制血红素的能力受损。然而,所有表明 BMP 在血红素调节中的核心作用以及在 HC 中 BMP/SMAD 信号转导受损的证据均来自于小鼠。在这项研究中,我们研究了人类的 BMP 信号靶标 SMAD7 和 Id1 的表达是否与肝铁浓度(LIC)相关,以及这种调节是否在 HFE-HC 中受到破坏。我们通过 RT-PCR 评估了正常铁状态、HFE-HC 或非 HFE 肝铁过载患者肝活检中 HAMP、SMAD7 和 Id1 的 mRNA 表达与 LIC 的相关性。我们发现,在人类肝脏中,不仅 HAMP,而且 SMAD7 和 Id1 的 mRNA 与肝铁负荷的程度显著相关。然而,这种相关性在 HFE-HC 患者中丢失,但在非血色病性铁过载患者中保持。这些数据表明,在人类 HFE-HC 中,肝脏中破坏的 BMP/SMAD 信号转导是疾病发病机制的关键。