Sulfotransferases in the Synthesis on L-Selectin Ligands

描述(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与淋巴结中高内皮微静脉(HEV)的初始黏附。它还在白细胞与内皮细胞的相互作用中发挥作用，这是白细胞向慢性炎症部位运输的基础。L-选择素通过识别HEV表达的一组离散的配体，包括GlyCAM-1，CD34和Podocalysin，发挥凝集素样受体的作用。这些配体含有O-连接的碳水化合物链，这些碳水化合物链是硫化、岩藻糖化和唾液酸化的。所有这三个修饰都是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与选择素结合的识别决定因素是一种被称为6-磺基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位上具有硫酸酯。在寻找阐述HEV内这一关键修饰的磺基转移酶的过程中，罗森实验室克隆了一组GlcNAc-6-O-磺基转移酶。其中两种被称为GST-2和GST-3，存在于混合动力汽车中。GST-3被命名为HEC-GlcNAc6ST，因为它在HEV的高内皮细胞(HEC)中表达高度受限。通过在小鼠中破坏L-选择素配体基因，证实了HEC-GlcNAc6ST直接参与了L-选择素配体的形成。HEC-GIcNAc6ST基因敲除小鼠表现出明显但不完全的L选择素HEV表达配体的丢失，以及淋巴细胞归巢到淋巴结的障碍。这笔赠款将继续研究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。其具体目的是：1)确定HEC-GIcNAc6ST对原位生成的L-选择素配体活性的贡献；2)测定炎症部位激活的内皮细胞中HEC-GlcNAc6ST的表达；3)确定HEC-GlcNAc6ST对慢性炎症模型小鼠白细胞募集和疾病的贡献；以及4)确定GST-2对L-选择素配体生成的贡献。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.