To study the expression and regulatory mechanism of Siglec-7 along cell differentiation

• Main Authors: Yi-Chi Huang, 黃奕齊
• Other Authors: Yuh-Ching Twu
• Format: Others
• Language: zh-TW
• Published: 2019
• Online Access: http://ndltd.ncl.edu.tw/handle/9x95fx

碩士 === 國立陽明大學 === 醫學生物技術暨檢驗學系 === 107 === Sialic acid binding immunoglobulin-like lectin-7 (Siglec-7), type I transmembrane protein, is one of inhibitory receptor on the surface of human blood cell cells. With specific sialylated glycan engagement, immunoreceptor tyrosine-based inhibitory motifs (ITIMs) of Siglec-7 delivery inhibitory signals to suppress cell proliferation and cellular unctions, as well as to regulate apoptosis. First, we detected the Siglec-7 expression of different blood cells in human peripheral blood. The results showed that platelets, granules, lymphocytes and mononuclear cells of 10 subjects expressed Siglec-7, and each subject also had more than 50% of natural killer cells expressed Siglec-7. The above results indicate that Siglec-7 has different expression levels in different blood cells, so we tried to use different models of cell differentiation to explore the regulatory mechanism and function of Siglec-7 in various cells. According to transcriptome analysis, transcription factor forkhead box O1 (FoxO1) might be one of the candidates to regulate Siglec-7 activation in NK-92MI and its derived cell lines. Next, we found that higher FoxO1 expression and lower phosphorylation of FoxO1 in NK-92MI-S by comparing to parental and NK-92MI-S7N, indicated the FoxO1 may play role in Siglec-7 regulation. To correlate FoxO1 to Siglec-7 activation in peripheral NK cells, we isolate NK cells from 5 healthy donors. The nuclear FoxO1 levels were no significantly difference between Siglec-7+ and Siglec-7- NK cells. Taken together, transcription factors FoxO1 seems to be not involved in Siglec-7 regulation in peripheral NK cells, the detail regulatory mechanism for Siglec-7 need further investigation. In addition, we attempted to induce K-562 cells to differentiate into different blood cells. The results showed that K-562 cells undergo megakaryocyte differentiation, and the expression of Siglec-7 is gradually increased and is regulated by transcriptional regulation. On the other hand, recent studies have suggested that Siglec-7 in natural killer cells of obese subjects is lower than normal subjects, which draws our attention and attempts to explore whether Siglec-7 participates in the process of fat metabolism. By inducing differentiation of 3T3-L1 mouse embryonic fibroblasts into adipocytes, the correlation between Siglec-E, a mouse homolog of Siglec-7, and fat metabolism were investigated. The results showed that the expression of Siglec-E gene gradually increased during the differentiation of adipocytes, but there was no Siglec-E expression on the surface of adipocytes.