Sulfotransferases in the Synthesis on L-Selectin Ligands

描述（由申请人提供）：l -选择素在淋巴细胞归巢过程中介导淋巴细胞对淋巴结高内皮小静脉（HEV）的初始粘附。它还在白细胞-内皮相互作用中发挥作用，这些相互作用是白细胞进入慢性炎症部位的基础。l -选择素作为一种凝集素样受体，通过识别一系列hev表达的配体，包括GlyCAM-1、CD34和足alyxin。这些配体带有o链碳水化合物链，这些碳水化合物链被硫酸化、聚焦化和唾液化。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CD34的详细分析表明，l -选择素结合的tile识别决定因素是一种被称为6-sulfo sLex的硫酸化结构，这是一种四糖，在n -乙酰氨基葡萄糖的C-6位置上具有硫酸酯。在寻找在HEV中阐述这一关键修饰的硫转移酶的过程中，Rosen实验室克隆了一个glcnac -6- o -硫转移酶家族。其中两种，称为GST-2和GST-3，存在于HEV中。由于GST-3在HEV的高内皮细胞（HEC）中的表达高度受限，因此被命名为HEC- glcnac6st。HEC-GlcNAc6ST直接参与了l -选择素配体的形成，这是通过在小鼠中破坏该基因而确定的。HEC-GIcNAc6ST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缺失和淋巴细胞归巢到淋巴结的损伤。目前的拨款将继续研究HEC-GlcNAc6ST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。具体目的是：1)确定HEC-GIcNAc6ST对原位生成l -选择素配体活性的贡献；2)检测炎症部位活化内皮中HEC-GlcNAc6ST的表达；3)确定HEC-GlcNAc6ST在慢性炎症小鼠模型中对白细胞募集和疾病的贡献；4)确定GST-2对l -选择素配体生成的贡献。进一步了解这些硫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.