title: Transitions from high to low molecular weight isoforms of CD45 (T200) involve rapid activation of alternate mRNA splicing and slow turnover of surface CD45R.
abstract: The expression of CD45 isoforms and of CDw29 has been analyzed as a function of time by correlating cell surface phenotype with mRNA synthesis. After activation, T cells lose CD45R and acquire a high density of CD45 p180 and of CDw29. Throughout this transition the density of CD45 common determinants steadily increases, resulting in a net gain of surface CD45. The gradual loss of CD45R could reflect a rapid switch in CD45 mRNA splicing patterns followed by a slow loss of surface CD45R. Alternatively it could reflect a delayed activation of splicing to produce the 4.8-kb CD45 mRNA, or long lived 5.4-kb CD45 mRNA. Analysis of CD45 mRNA indicated that at 24 h postactivation, 5.4-kb CD45 mRNA is lost and only 4.8-kb mRNA is detectable. The amount of 4.8-kb mRNA increases until day 3 and then decreases somewhat. Thus our results support the interpretation that transitions in CD45 isoform mRNA expression occur within the first 24 h after activation and that the persistence of CD45R+ T cells until day 3 to 4 of culture results from slow turnover of surface CD45R glycoprotein.
authors: Department of Immunology, University of Alberta, Edmonton, Canada.
authors: J P
authors: JP
authors: Deans
authors: A W
authors: AW
authors: Boyd
authors: L M
authors: LM
authors: Pilarski
mesh_terms: D000943:Antigens, Differentiation / Q000378:metabolism*; D005455:Fluorescent Antibody Technique; D006649:Histocompatibility Antigens / Q000378:metabolism*; D006801:Humans; D019012:Integrin beta1; D007399:Interphase; D017493:Leukocyte Common Antigens; D008213:Lymphocyte Activation; D008970:Molecular Weight; D010641:Phenotype; D011233:Precipitin Tests; D011487:Protein Conformation; D012326:RNA Splicing; D012333:RNA, Messenger / Q000302:isolation & purification / Q000378:metabolism*; D013601:T-Lymphocytes / Q000145:classification / Q000276:immunology / Q000378:metabolism
chemical_list: D000943:Antigens, Differentiation; D006649:Histocompatibility Antigens; D019012:Integrin beta1; D012333:RNA, Messenger; D017493:Leukocyte Common Antigens