Differentiation-dependent expression and localization of the class B type I scavenger receptor in intestine.
Differentiation-dependent expression and localization of the class B type I scavenger receptor in intestine.
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DOI：
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发表时间：
2001-06
影响因子：
6.5
通讯作者：
Sheng F. Cai;R. Kirby;P. Howles;David Y. Hui
中科院分区：
文献类型：
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作者：
Sheng F. Cai;R. Kirby;P. Howles;David Y. Hui
本研究利用人Caco-2细胞系和小鼠小肠探索B类I型清道夫受体（SR-BI）在肠细胞中的表达拓扑。结果显示，肠细胞仅表达SR-BI同种型，很少或不表达SR-BII变体。SR-BI在Caco-2细胞中的表达是分化依赖性的，在融合前未分化细胞中很少或没有表达。对在Transwell多孔膜中培养的Caco-2细胞的分析显示，在顶侧和基底侧细胞表面均存在SR-BI。小鼠肠细胞提取物的免疫印迹分析表明SR-BI表达沿肠的胃结肠轴沿着分级，在近端肠中表达水平最高，在远端肠中降低至最低表达水平。使用SR-BI特异性抗体的免疫荧光研究也证实了这种表达模式。重要的是，免疫荧光研究还显示，SR-BI免疫反应性在十二指肠刷状缘的顶膜中最强。隐窝细胞未显示与SR-BI抗体的任何反应性。发现空肠中SR-BI的定位与在十二指肠中观察到的不同。SR-BI存在于空肠绒毛的顶面和底侧面。SR-BI在回肠中的定位也不同，在顶膜或基底外侧膜上几乎检测不到SR-BI。总之，这些结果表明，SR-BI有可能在肠道中发挥多种功能。SR-BI在近端肠顶面的定位与其在膳食胆固醇吸收中可能发挥作用的假设一致，而SR-BI存在于远端肠的基底外侧表面表明其可能参与肠脂蛋白摄取。
The current study used the human Caco-2 cell line and mouse intestine to explore the topology of expression of the class B type I scavenger receptor (SR-BI) in intestinal cells. Results showed that intestinal cells expressed only the SR-BI isoform with little or no expression of the SR-BII variant. The expression of SR-BI in Caco-2 cells is differentiation dependent, with little or no expression in preconfluent undifferentiated cells. Analysis of Caco-2 cells cultured in Transwell porous membranes revealed the presence of SR-BI on both the apical and basolateral cell surface. Immunoblot analysis of mouse intestinal cell extracts demonstrated a gradation of SR-BI expression along the gastrocolic axis of the intestine, with the highest level of expression in the proximal intestine and decreasing to minimal expression levels in the distal intestine. Immunofluorescence studies with SR-BI-specific antibodies also confirmed this expression pattern. Importantly, the immunofluorescence studies also revealed that SR-BI immunoreactivity was most intense in the apical membrane of the brush border in the duodenum. The crypt cells did not show any reactivity with SR-BI antibodies. The localization of SR-BI in the jejunum was found to be different from that observed in the duodenum. SR-BI was present on both apical and basolateral surfaces of the jejunum villus. Localization of SR-BI in the ileum was also different, with little SR-BI detectable on either apical or basolateral membranes. Taken together, these results suggest that SR-BI has the potential to serve several functions in the intestine. The localization of SR-BI on the apical surface of the proximal intestine is consistent with the hypothesis of its possible role in dietary cholesterol absorption, whereas SR-BI present on the basolateral surface of the distal intestine suggests its possible involvement in intestinal lipoprotein uptake.