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result(s) for
"Lo, Tzu-Chi"
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Targeting ST3GAL1 to downregulate ligands for the glycoimmune checkpoint Siglec-7 and reverse immune escape in hepatocellular carcinoma
by
Yu, Alice L.
,
Hung, Tsai-Hsien
,
Fan, Tan-chi
in
ADCC
,
Antibodies
,
Antibody-Dependent Cell Cytotoxicity
2026
Sorafenib is the first-line therapy for advanced hepatocellular carcinoma (HCC). However, acquired resistance to sorafenib remains a significant challenge. Previous studies have shown that sorafenib treatment induces the formation of truncated O-glycans in HCC cells, but the relationship between sorafenib-induced glycosylation changes and acquired therapy resistance remains unclear. Primary natural killer (NK) cells, freshly isolated from peripheral blood or following culture and expansion, expressed the glycoimmune checkpoints Siglec-7 and Siglec-9. HCC cells exhibited varying levels of Siglec-7/9 ligands on their surface. Sorafenib-resistant liver cancer cells displayed hypersialylation, leading to increased expression of surface Siglec-7/9 ligands, which conferred protection against NK cell-mediated cytotoxicity. Silencing ST3GAL1 significantly reduced Siglec-7 ligand expression on liver cancer cells, enhancing their susceptibility to NK-mediated cytotoxicity and cetuximab-induced antibody-dependent cellular cytotoxicity (ADCC) in epidermal growth factor receptor (EGFR)-expressing tumor cells. Furthermore, high ST3GAL1 expression correlated with poor clinical outcomes in patients with stage 1-2 HCC. This study highlights the critical role of ST3GAL1 in regulating Siglec-7 ligands to facilitate immune escape from NK cell cytotoxicity. Moreover, its elevated expression is associated with adverse clinical outcomes in HCC. Targeting ST3GAL1 may represent a promising strategy to enhance NK cell-mediated anti-tumor immunity in HCC.
Journal Article
Conformational alteration in glycan induces phospholipase Cβ1 activation and angiogenesis
2022
Background
In endothelial cells, phospholipase C (PLC) β1-activated Ca
2+
is a crucial second messenger for the signaling pathways governing angiogenesis. PLCβ1 is inactivated by complexing with an intracellular protein called translin-associated factor X (TRAX). This study demonstrates specific interactions between Globo H ceramide (GHCer) and TRAX, which highlight a new angiogenic control through PLCβ1 activation.
Methods
Globo-series glycosphingolipids (GSLs), including GHCer and stage-specific embryonic antigen-3 ceramide (SSEA3Cer), were analyzed using enzyme-linked immunosorbent assay (ELISA) and Biacore for their binding with TRAX. Angiogenic activities of GSLs in human umbilical vein endothelial cells (HUVECs) were evaluated. Molecular dynamics (MD) simulation was used to study conformations of GSLs and their molecular interactions with TRAX. Fluorescence resonance energy transfer (FRET) analysis of HUVECs by confocal microscopy was used to validate the release of PLCβ1 from TRAX. Furthermore, the in vivo angiogenic activity of extracellular vesicles (EVs) containing GHCer was confirmed using subcutaneous Matrigel plug assay in mice.
Results
The results of ELISA and Biacore analysis showed a stable complex between recombinant TRAX and synthetic GHCer with K
d
of 40.9 nM. In contrast, SSEA3Cer lacking a fucose residue of GHCer at the terminal showed ~ 1000-fold decrease in the binding affinity. These results were consistent with their angiogenic activities in HUVECs. The MD simulation indicated that TRAX interacted with the glycan moiety of GHCer at amino acid Q223, Q219, L142, S141, and E216. At equilibrium the stable complex maintained 4.6 ± 1.3 H-bonds. TRAX containing double mutations with Q223A and Q219A lost its ability to interact with GHCer in both MD simulation and Biacore assays. Removal of the terminal fucose from GHCer to become SSEA3Cer resulted in decreased H-bonding to 1.2 ± 1.0 by the MD simulation. Such specific H-bonding was due to the conformational alteration in the whole glycan which was affected by the presence or absence of the fucose moiety. In addition, ELISA, Biacore, and in-cell FRET assays confirmed the competition between GHCer and PLCβ1 for binding to TRAX. Furthermore, the Matrigel plug assay showed robust vessel formation in the plug containing tumor-secreted EVs or synthetic GHCer, but not in the plug with SSEA3Cer. The FRET analysis also indicated the disruption of colocalization of TRAX and PLCβ1 in cells by GHCer derived from EVs.
Conclusions
Overall, the fucose residue in GHCer dictated the glycan conformation for its complexing with TRAX to release TRAX-sequestered PLCβ1, leading to Ca
2+
mobilization in endothelial cells and enhancing angiogenesis in tumor microenvironments.
Journal Article
Extracellular Vesicle-Associated MicroRNA-138-5p Regulates Embryo Implantation and Early Pregnancy by Adjusting GPR124
2022
Functional embryo–maternal interactions occur during the embryo implantation and placentation. Extracellular vesicles with microRNA (miR) between cells have been considered of critical importance for embryo implantation and the programming of human pregnancy. MiR-138-5p functions as the transcriptional regulator of G protein-coupled receptor 124 (GPR124). However, the signaling pathway of miR138-5p- and GPR124-adjusted NLRP3 inflammasome activation remains unclear. In this study, we examine the roles of the miR138-5p and GPR124-regulated inflammasome in embryo implantation and early pregnancy. Human decidual stromal cells were isolated from the abortus tissue and collected by curettage from missed abortion patients and normal pregnant women at 6- to 12-week gestation, after informed consent. Isolated extracellular vesicles from decidua and decidual stromal cells were confirmed by transmission electron microscopy (TEM). Next-Generation Sequencing (NGS) and microarray were performed for miR analysis. The predicated target genes of the differentially expressed miR were analyzed to identify the target genes and their pathway. We demonstrated the down-regulation of miR-138-5p and the overexpression of GPR124 in spontaneous miscarriage compared to normal pregnancy. We also showed the excessive activation of the NLRP3 inflammasome in spontaneous miscarriage compared to normal pregnancy. Here, we newly demonstrate that the miR-138-5p and GPR124-adjusted NLRP3 inflammasome were expressed in extracellular vesicles derived from decidua and decidual stromal cells, indicating that the miR-138-5p, GPR124 and NLRP3 (NACHT, LRR, and PYD domains-containing protein 3) inflammasome have a potential modulatory role on the decidual programming and placentation of human pregnancy. Our findings represent a new concept regarding the role of extracellular vesicles, miR-138-5p, GPR124, and the NLRP3 inflammasome in normal early pregnancy and spontaneous miscarriage.
Journal Article
Tzu-Chi Lo Piano Recital With Supporting Documents: Recording and Program Notes of the Recital, and Recording of the Chamber Recital
2023
Program Johann Sebastian Bach: Prelude and Fugue in B-flat Major, BWV 866Joseph Haydn: Piano Sonata in E-flat Major, Hob. XVI: 49 I. Allegro II. Adagio e cantabile III. Finale: Tempo di MinuetFrédéric François Chopin: Etude in C Major, op. 10, no. 1Frédéric François Chopin: Ballade no. 3 in A-flat Major, op. 47Pierre Boulez: Douze Notations (1945)Maurice Ravel: MiroirsI. NoctuellesII. Oiseaux tristesIII. Une barque sur l’océanIV. Alborada del graciosoV. La vallée des cloches
Dissertation
Conformational alteration in glycan induces phospholipase Cbeta1 activation and angiogenesis
2022
Background In endothelial cells, phospholipase C (PLC) [beta]1-activated Ca.sup.2+ is a crucial second messenger for the signaling pathways governing angiogenesis. PLC[beta]1 is inactivated by complexing with an intracellular protein called translin-associated factor X (TRAX). This study demonstrates specific interactions between Globo H ceramide (GHCer) and TRAX, which highlight a new angiogenic control through PLC[beta]1 activation. Methods Globo-series glycosphingolipids (GSLs), including GHCer and stage-specific embryonic antigen-3 ceramide (SSEA3Cer), were analyzed using enzyme-linked immunosorbent assay (ELISA) and Biacore for their binding with TRAX. Angiogenic activities of GSLs in human umbilical vein endothelial cells (HUVECs) were evaluated. Molecular dynamics (MD) simulation was used to study conformations of GSLs and their molecular interactions with TRAX. Fluorescence resonance energy transfer (FRET) analysis of HUVECs by confocal microscopy was used to validate the release of PLC[beta]1 from TRAX. Furthermore, the in vivo angiogenic activity of extracellular vesicles (EVs) containing GHCer was confirmed using subcutaneous Matrigel plug assay in mice. Results The results of ELISA and Biacore analysis showed a stable complex between recombinant TRAX and synthetic GHCer with Kd of 40.9 nM. In contrast, SSEA3Cer lacking a fucose residue of GHCer at the terminal showed ~ 1000-fold decrease in the binding affinity. These results were consistent with their angiogenic activities in HUVECs. The MD simulation indicated that TRAX interacted with the glycan moiety of GHCer at amino acid Q223, Q219, L142, S141, and E216. At equilibrium the stable complex maintained 4.6 [+ or -] 1.3 H-bonds. TRAX containing double mutations with Q223A and Q219A lost its ability to interact with GHCer in both MD simulation and Biacore assays. Removal of the terminal fucose from GHCer to become SSEA3Cer resulted in decreased H-bonding to 1.2 [+ or -] 1.0 by the MD simulation. Such specific H-bonding was due to the conformational alteration in the whole glycan which was affected by the presence or absence of the fucose moiety. In addition, ELISA, Biacore, and in-cell FRET assays confirmed the competition between GHCer and PLC[beta]1 for binding to TRAX. Furthermore, the Matrigel plug assay showed robust vessel formation in the plug containing tumor-secreted EVs or synthetic GHCer, but not in the plug with SSEA3Cer. The FRET analysis also indicated the disruption of colocalization of TRAX and PLC[beta]1 in cells by GHCer derived from EVs. Conclusions Overall, the fucose residue in GHCer dictated the glycan conformation for its complexing with TRAX to release TRAX-sequestered PLC[beta]1, leading to Ca.sup.2+ mobilization in endothelial cells and enhancing angiogenesis in tumor microenvironments. Keywords: Globo H ceramide, TRAX, Phospholipase C[beta]1, Angiogenesis, Glycosphingolipids, Extracellular vesicles
Journal Article