Apo- and holo-lactoferrin are both internalized by lactoferrin receptor via clathrin-mediated endocytosis but differentially affect ERK-signaling and cell proliferation in Caco-2 cells.
Apo- and holo-lactoferrin are both internalized by lactoferrin receptor via clathrin-mediated endocytosis but differentially affect ERK-signaling and cell proliferation in Caco-2 cells.
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DOI：
10.1002/jcp.22650
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发表时间：
2011-11
影响因子：
5.6
通讯作者：
Loennerdal, Bo
中科院分区：
文献类型：
--
作者：
Jiang, Rulan;Lopez, Veronica;Kelleher, Shannon L.;Loennerdal, Bo
乳铁蛋白(Lactoferrin，LF)是乳汁和粘膜分泌物等外分泌液中一种主要的铁结合多功能蛋白质。Lf的功能似乎依赖于Lf蛋白的铁饱和度，并被认为是通过Lf受体(LFR)内化Lf来实现的。然而，LFR介导肠上皮细胞LF内化的机制尚不清楚。我们现在证明了以前从小肠克隆的LFR在人类肠细胞模型(Caco-2细胞)中介导了LF内吞。LFR通过细胞表面生物素化在细胞膜上检测到，LFR siRNA对apo-LF和holo-LF摄取均有明显的抑制作用。高渗蔗糖和笼状蛋白siRNA的处理以及LFR与笼状蛋白接头AP2的免疫共沉淀表明，LFR通过分子筛介导的内吞作用来调节LF的内吞作用。虽然无铁的Lf(apo-Lf)和铁饱和的Lf(holo-Lf)通过相似的机制进入Caco-2细胞，但apo-Lf对Caco-2细胞的结合和摄取无明显差异，apo-Lf而不是Hloo-Lf刺激Caco-2细胞增殖。有趣的是，apo-LF刺激细胞外信号调节的丝裂原活化蛋白激酶(ERK)级联的程度显著高于holo-LF，并且apo-LF诱导的增殖被ERK级联抑制剂(U0126)和clathrin siRNA显著抑制。综上所述，我们的数据表明，LFR是肠细胞摄取LF的主要途径，其发生与铁饱和无关，通过网状蛋白介导的内吞作用发生。Apo-和holo-LF的不同作用不是由于细胞内化机制的不同。
Lactoferrin (Lf) is a major iron-binding and multi-functional protein in exocrine fluids such as breast milk and mucosal secretions. The functions of Lf appear dependent upon the iron-saturation of the Lf protein and are postulated to be mediated through Lf internalization by a Lf receptor (LfR). However, mechanisms by which LfR mediates Lf internalization in enterocytes are unknown. We now demonstrate that a LfR previously cloned from the small intestine mediates Lf endocytosis in a human enterocyte model (Caco-2 cells). LfR was detected at the plasma membrane by cell surface biotinylation; both apo-Lf and holo-Lf uptake were significantly inhibited in cells transfected with LfR siRNA. Treatments of hypertonic sucrose and clathrin siRNA and co-immunoprecipitation of LfR with clathrin adaptor AP2 indicate that LfR regulates Lf endocytosis via clathrin-mediated endocytosis. Although both iron-free Lf (apo-Lf) and iron-saturated Lf (holo-Lf) enter Caco-2 cells via a similar mechanism and no significant differences were observed in the binding and uptake of apo- and holo-Lf in Caco-2 cells, apo-Lf but not holo-Lf stimulates proliferation of Caco-2 cells. Interestingly, apo-Lf stimulated extracellular signal-regulated mitogen-activated protein kinase (ERK) cascade to a significantly greater extent than holo-Lf and the apo-Lf induced proliferation was significantly inhibited by an ERK cascade inhibitor (U0126) and clathrin siRNA. Taken together, our data suggest that LfR is a major pathway through which Lf is taken up by enterocytes, which occurs independently of iron saturation through clathrin-mediated endocytosis. The differential effects of apo- and holo-Lf are not due to differences in cellular internalization mechanisms.
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影响因子：
3.6
作者：
HUTCHENS, TW;HENRY, JF;GARZA, C
通讯作者：
GARZA, C
影响因子：
3.5
作者：
Ashida, K;Sasaki, H;Lönnerdal, B
通讯作者：
Lönnerdal, B
DOI：
10.1016/s0304-4165(01)00222-7
发表时间：
2001-12-19
影响因子：
3
作者：
El Yazidi-Belkoura, I;Legrand, D;Spik, G
通讯作者：
Spik, G
影响因子：
3.6
作者：
Buccigrossi, Vittoria;De Marco, Giulio;Guarino, Alfredo
通讯作者：
Guarino, Alfredo
影响因子：
64.8
作者：
AbdAlla, S;Lother, H;Quitterer, U
通讯作者：
Quitterer, U