Moh Mei Chung, Lee Lay Hoon, Zhang Ting, Shen Shali
Department of Physiology, Yong Loo Lin School of Medicine, National University of Singapore, Singapore.
Biochem Biophys Res Commun. 2009 Jan 23;378(4):755-60. doi: 10.1016/j.bbrc.2008.11.119. Epub 2008 Dec 6.
Subsequent to our identification of the novel immunoglobulin-like cell adhesion molecule hepaCAM, we demonstrated that hepaCAM is capable of modulating cell growth and cell-extracellular matrix interactions. In this study, we examined the localization of hepaCAM in lipid rafts/caveolae as well as the interaction of hepaCAM with the caveolar structural protein caveolin-1 (Cav-1). Our results revealed that a portion of hepaCAM resided in detergent-resistant membranes and co-partitioned with Cav-1 to low buoyant density fractions characteristic of lipid rafts/caveolae. In addition, co-localization and coimmunoprecipitation assays confirmed the association of hepaCAM with Cav-1. Deletion analysis of hepaCAM showed that the extracellular first immunoglobulin domain of hepaCAM was required for binding Cav-1. Furthermore, when co-expressed, Cav-1 induced the expression of hepaCAM as well as distributed hepaCAM to intracellular Cav-1-positive caveolar structures. Taken together, our findings indicate that hepaCAM is partially localized in the lipid rafts/caveolae and interacts with Cav-1 through its first immunoglobulin domain.
在我们鉴定出新型免疫球蛋白样细胞粘附分子hepaCAM之后，我们证明hepaCAM能够调节细胞生长以及细胞与细胞外基质的相互作用。在本研究中，我们检测了hepaCAM在脂筏/小窝中的定位以及hepaCAM与小窝结构蛋白小窝蛋白-1（Cav-1）的相互作用。我们的结果显示，一部分hepaCAM存在于抗去污剂膜中，并与Cav-1共同分配到脂筏/小窝特有的低浮力密度组分中。此外，共定位和免疫共沉淀分析证实了hepaCAM与Cav-1的关联。hepaCAM的缺失分析表明，hepaCAM的细胞外第一个免疫球蛋白结构域是结合Cav-1所必需的。此外，当共表达时，Cav-1诱导hepaCAM的表达，并将hepaCAM分布到细胞内Cav-1阳性的小窝结构中。综上所述，我们的研究结果表明，hepaCAM部分定位于脂筏/小窝中，并通过其第一个免疫球蛋白结构域与Cav-1相互作用。
