title: Impaired TCR signaling through dysfunction of lipid rafts in sphingomyelin synthase 1 (SMS1)-knockdown T cells.
abstract: During T cell activation, TCRs cluster at the center of the T cell-antigen-presenting cell interface forming the central supramolecular activation cluster. Although it has been suggested that sphingolipid- and cholesterol-rich microdomains, termed lipid rafts, form platforms for the regulation and transduction of TCR signals, an actual role for membrane sphingomyelin (SM), a key component of lipid rafts, has not been reported. After cloning a gene responsible for SM synthesis, sphingomyelin synthase (SMS) 1, we established a SM-knockdown cell line (Jurkat-SMS1/kd) by transfection of SMS1-short-interfering RNA into Jurkat T cells, which is deficient in membrane expression of SM. Upon CD3 stimulation, expression of CD69 (the earliest leukocyte activation antigen), activation-induced cell adhesion and proliferation as well as TCR clustering was severely impaired in Jurkat-SMS1/kd cells. CD3-induced tyrosine phosphorylation and association of linker for activation of T cell with ZAP-70 and Grb2 and phosphorylation of protein kinase C (PKC) were also severely impaired in Jurkat-SMS1/kd cells. Finally, translocation of TCR, ZAP-70 and PKC into lipid rafts was markedly decreased in Jurkat-SMS1/kd cells. These findings indicate that membrane SM is crucial for TCR signal transduction, leading to full T cell activation through lipid raft function.
authors.affiliation: Department of Hematology and Immunology, Kanazawa Medical University, 1-1 Daigaku, Uchinada, Ishikawa 920-0293, Japan.
authors.forename: Zhe-Xiong
authors.initials: ZX
authors.lastname: Jin
authors.forename: Cheng-Ri
authors.initials: CR
authors.lastname: Huang
authors.forename: Lingli
authors.initials: L
authors.lastname: Dong
authors.forename: Seiji
authors.initials: S
authors.lastname: Goda
authors.forename: Takafumi
authors.initials: T
authors.lastname: Kawanami
authors.forename: Toshioki
authors.initials: T
authors.lastname: Sawaki
authors.forename: Tomoyuki
authors.initials: T
authors.lastname: Sakai
authors.forename: Xiao-Peng
authors.initials: XP
authors.lastname: Tong
authors.forename: Yasufumi
authors.initials: Y
authors.lastname: Masaki
authors.forename: Toshihiro
authors.initials: T
authors.lastname: Fukushima
authors.forename: Masao
authors.initials: M
authors.lastname: Tanaka
authors.forename: Tsuneyo
authors.initials: T
authors.lastname: Mimori
authors.forename: Hiromasa
authors.initials: H
authors.lastname: Tojo
authors.forename: Eda T
authors.initials: ET
authors.lastname: Bloom
authors.forename: Toshiro
authors.initials: T
authors.lastname: Okazaki
authors.forename: Hisanori
authors.initials: H
authors.lastname: Umehara
mesh_terms: D015703:Antigens, CD / Q000096:biosynthesis / Q000235:genetics; D000945:Antigens, Differentiation, T-Lymphocyte / Q000096:biosynthesis / Q000235:genetics; D017252:CD3 Complex / Q000378:metabolism; D002448:Cell Adhesion / Q000235:genetics; D002458:Cell Fractionation; D054443:Cell Migration Assays; D049109:Cell Proliferation; D002851:Chromatography, High Pressure Liquid; D055785:Gene Knockdown Techniques; D006801:Humans; D019169:Jurkat Cells; D037181:Lectins, C-Type; D008213:Lymphocyte Activation / Q000235:genetics; D021962:Membrane Microdomains / Q000235:genetics / Q000378:metabolism*; D008565:Membrane Proteins / Q000235:genetics / Q000378:metabolism*; D009419:Nerve Tissue Proteins / Q000235:genetics / Q000378:metabolism*; D010766:Phosphorylation; D034741:RNA, Small Interfering / Q000235:genetics; D011940:Receptor Aggregation / Q000235:genetics; D020239:Receptor Cross-Talk / Q000276:immunology*; D011948:Receptors, Antigen, T-Cell / Q000378:metabolism*; D015398:Signal Transduction; D013601:T-Lymphocytes / Q000166:cytology / Q000276:immunology / Q000378:metabolism*; D017855:Transferases (Other Substituted Phosphate Groups) / Q000235:genetics / Q000378:metabolism*; D000099192:CD69 Antigens
chemical_list: D015703:Antigens, CD; D000945:Antigens, Differentiation, T-Lymphocyte; D017252:CD3 Complex; D037181:Lectins, C-Type; D008565:Membrane Proteins; D009419:Nerve Tissue Proteins; D034741:RNA, Small Interfering; D011948:Receptors, Antigen, T-Cell; D017855:Transferases (Other Substituted Phosphate Groups); D000099192:CD69 Antigens; C455440:SGMS1 protein, human