HIGH-DENSITY-LIPOPROTEIN INTERACTION WITH HUMAN PLACENTA - BIOCHEMICAL AND ULTRASTRUCTURAL CHARACTERIZATION OF BINDING TO MICROVILLOUS RECEPTOR AND LACK OF INTERNALIZATION
HIGH-DENSITY-LIPOPROTEIN INTERACTION WITH HUMAN PLACENTA - BIOCHEMICAL AND ULTRASTRUCTURAL CHARACTERIZATION OF BINDING TO MICROVILLOUS RECEPTOR AND LACK OF INTERNALIZATION
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DOI：
10.1016/0303-7207(91)90063-x
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发表时间：
1991-05-01
影响因子：
4.1
通讯作者：
MALASSINE, A
中科院分区：
文献类型：
--
作者：
ALSAT, E;MALASSINE, A
低密度脂蛋白（LDL）和修饰LDL（乙酰-LDL）的特异性受体和内化过程在培养的胎盘微绒毛和滋养细胞中得到了很好的表征。本研究的目的是研究高密度脂蛋白（HDL3）在这两种纯化胎盘制剂中的结合及其最终的内化。分离的足月胎盘微绒毛用于结合[I-125]HDL3（缺乏载脂蛋白E）。将HDL3与胶体金结合，观察培养过程中合胞滋养细胞结合和内化的超微结构。确定了HDL3的饱和结合。Scatchard分析显示膜蛋白的K(d)值为24.2 +/- 8.0 mu-g HDL3蛋白/ml， 4℃下膜蛋白的最大结合能力为128.2 +/- 54.5 mu-g HDL3蛋白/mg。这些位点具有广泛的特异性：LDL和乙酰-LDL都能部分抑制HDL3的结合。超微结构研究证实金- hdl3特异性结合到合体滋养细胞膜上。然而，在37℃孵育后，金- hdl3没有观察到与金- ldl和金-乙酰- ldl相似的内化过程。这些结果证明了没有内部化的特定HDL3绑定。HDL3膜相互作用和胎盘类固醇生成的生理意义仍有待确定。
Specific receptor and internalization process for low density lipoprotein (LDL) and modified LDL (acetyl-LDL) have been well characterized in placental microvilli and in trophoblastic cells in culture. The aim of this study was to investigate high density lipoprotein (HDL3) binding and its eventual subsequent internalization in both these purified placental preparations. Isolated term placental microvilli were used for binding of [I-125]HDL3 (devoid of apoprotein E). HDL3 were conjugated to colloidal gold for ultrastructural visualization of binding and internalization in syncytiotrophoblast in culture. Saturable binding of HDL3 was identified. Scatchard analysis revealed a K(d) value of 24.2 +/- 8.0-mu-g HDL3 protein/ml and a maximum binding capacity at 4-degrees-C of 128.2 +/- 54.5-mu-g HDL3 protein/mg of membrane protein. These sites have broad specificity: both LDL and acetyl-LDL were able to partially inhibit the HDL3 binding. Ultrastructural study confirms that gold-HDL3 bind specifically to syncytiotrophoblast membrane. However, after incubation at 37-degrees-C, an internalization process similar to those described for gold-LDL and gold-acetyl-LDL was not observed for gold-HDL3. These results demonstrate specific HDL3 binding without internalization. The physiological significance of an HDL3 membranous interaction and the placental steroidogenesis remains to be established.