Sulfotransferases in the Synthesis on L-Selectin Ligands

描述（由申请方提供）：L-选择素在淋巴细胞归巢过程中介导淋巴细胞与淋巴结中高内皮微静脉（HEV）的初始粘附。它还在白细胞-内皮相互作用中起作用，这些相互作用是白细胞进入慢性炎症部位的基础。L-选择素作为凝集素样受体通过识别一组离散的HEV表达配体（包括GlyCAM-1、CD 34和足糖萼蛋白）来发挥功能。这些配体带有O-连接的碳水化合物链，其被硫酸化、岩藻糖基化和唾液酸化。所有这三种修饰都是L-选择素最佳识别所必需的。对GlyCAM-1和CD 34的详细分析表明，L-选择素结合的识别决定簇是一种称为6-磺基sLex的硫酸化结构，这是一种在N-乙酰葡糖胺的C-6位上具有硫酸酯的四糖。在寻找阐述HEV内这种关键修饰的磺基转移酶的过程中，罗森实验室克隆了GlcNAc-6-O-磺基转移酶家族。其中两种，称为GST-2和GST-3，存在于HEV中。GST-3由于其在HEV的高内皮细胞（HEC）中的高度限制性表达而被命名为HEC-GlcNAc 6ST。HEC-GlcNAc 6ST直接参与制备L-选择素配体已经通过在小鼠中破坏该基因而确立。HEC-GlcNAc 6ST基因敲除小鼠表现出HEV表达的L-选择素配体的显著但不完全的损失和淋巴细胞归巢至淋巴结的损伤。目前的拨款将继续研究HEC-GlcNAc 6ST和相关酶GST-2在淋巴细胞归巢和炎性白细胞运输中的功能。具体目标是：1）确定HEC-GlcNAc 6ST对原位产生的L-选择素配体的活性的贡献; 2）确定HEC-GlcNAc 6ST在炎症部位的活化内皮中的表达; 3）确定HEC-GlcNAc 6ST对慢性炎症小鼠模型中白细胞募集和疾病的贡献;和4）确定GST-2对L-选择素配体产生的贡献。进一步了解这些磺基转移酶具有相当大的生物医学意义，因为这些酶是阻断炎症性疾病的潜在治疗靶点。

DESCRIPTION (provided by applicant): L-selectin mediates the initial adhesion of lymphocytes to high endothelial venules (HEV) in lymph nodes during the process of lymphocyte homing. It also functions in leukocyte-endothelial interactions underlying the trafficking of leukocytes into chronic inflammatory sites. L-selectin functions as a lectin-like receptor by recognizing a discrete set of HEV-expressed ligands including GlyCAM-1, CD34, and podocalyxin. These ligands bear O-linked carbohydrate chains that are sulfated, fucosylated and sialylated. All three of these modifications are required for optimal recognition by L-selectin. A detailed analysis of GlyCAM-1 and CD34 has revealed that tile recognition determinant for L-selectin binding is a sulfated structure known as 6-sulfo sLex, a tetrasaccharide that possesses a sulfate ester on the C-6 position of N-acetylglucosamine. In the search for the sulfotransferase that elaborates this critical modification within HEV, the Rosen laboratory has cloned a family of GlcNAc-6-O-sulfotransferases. Two of these, known as GST-2 and GST-3, are present in HEV. GST-3 has been given the name HEC-GlcNAc6ST because of its highly restricted expression in high endothelial cells (HEC) of HEV. The direct involvement of HEC-GlcNAc6ST in elaborating L-selectin ligands has been established by disrupting this gene in mice. HEC-GIcNAc6ST knockout mice exhibit a significant but incomplete loss of HEV-expressed ligands for L-selectin and an impairment of lymphocyte homing to lymph nodes. The present grant will continue the study of HEC-GlcNAc6ST and the related enzyme, GST-2, with respect to their functions in lymphocyte homing and inflammatory leukocyte trafficking. The specific aims are: 1) To determine the contribution of HEC-GIcNAc6ST to the activity of L-selectin ligands generated in situ; 2) To determine the expression of HEC-GlcNAc6ST in activated endothelium at sites of inflammation; 3) To determine the contribution of HEC-GlcNAc6ST to leukocyte recruitment and disease in mouse models of chronic inflammation; and 4) To determine the contribution of GST-2 to the generation of L-selectin ligands. Gaining further understanding of these sulfotransferases has considerable biomedical relevance, because these enzymes are potential therapeutic targets for blocking inflammatory diseases.