title: Involvement of CD45 in adhesion and suppression of apoptosis of mouse malignant T-lymphoma cells.
abstract: Mouse malignant T-lymphoma CS-21 cells undergo apoptotic cell death in vitro in the absence of lymph node stromal cells but escape apoptosis and proliferate when they are attached to CA-12 stromal cells. A monoclonal antibody raised against CS-21 cell surface molecules (MCS-5) recognized a M(r) 168,000 protein, inhibited binding of CS-21 cells to CA-12 stromal cells, and suppressed apoptosis in CS-21 cells. To identify the M(r) 168,000 protein, we purified it with MCS-5 affinity chromatography and ion exchange chromatography. Partial amino acid sequences of the purified M(r) 168,000 protein were identical to those of CD45, a transmembrane tyrosine phosphatase. The purified protein possessed tyrosine phosphatase activity and was recognized by an anti-CD45 monoclonal antibody. The M(r) 168,000 protein was identified as CD45. To determine the CD45 isoform, we cloned the CD45 gene from the cDNA library of CS-21. Sixteen of 18 clones encoded CD45RO (CD45 lacking exons 4, 5, and 6), and the remainder lacked exons 4, 5, 6, and 7. Like MCS-5, an anti-CD45 monoclonal antibody, also inhibited binding of CS-21 cells to CA-12 cells and suppressed apoptosis in CS-21 cells. Our present results indicate that CD45RO expressed on CS-21 cells mediates adhesion to CA-12 cells and suppression of apoptosis.
authors.affiliation: Laboratory of Biomedical Research, University of Tokyo, Japan.
authors.forename: K
authors.initials: K
authors.lastname: Hanaoka
authors.forename: N
authors.initials: N
authors.lastname: Fujita
authors.forename: S H
authors.initials: SH
authors.lastname: Lee
authors.forename: H
authors.initials: H
authors.lastname: Seimiya
authors.forename: M
authors.initials: M
authors.lastname: Naito
authors.forename: T
authors.initials: T
authors.lastname: Tsuruo
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D017209:Apoptosis; D002448:Cell Adhesion; D017493:Leukocyte Common Antigens / Q000032:analysis* / Q000737:chemistry / Q000502:physiology; D008214:Lymphocytes / Q000378:metabolism; D016399:Lymphoma, T-Cell / Q000737:chemistry* / Q000378:metabolism / Q000473:pathology; D051379:Mice; D008969:Molecular Sequence Data; D008970:Molecular Weight; D017027:Protein Tyrosine Phosphatases / Q000378:metabolism; D014407:Tumor Cells, Cultured
chemical_list: D017493:Leukocyte Common Antigens; D017027:Protein Tyrosine Phosphatases