title: Differential expression of nucleoskeleton- and cytoskeleton-associated proteins in Burkitt lymphoma-derived and Epstein-Barr virus-immortalized lymphoblastoid cell lines.
abstract: Mouse monoclonal antibodies raised against nuclear bodies isolated from an EBV-immortalized lymphoblastoid cell line (LCL) known to contain several viral and cellular proteins (Jiang et al., Exp. Cell Res., 197: 314-318, 1991; Szekely et al., J. Gen. Virol., 76: 2423-2432, 1995; Szekely et al., J. Virol., 70: 2562-2568, 1996). Seventy six clones gave detectable immunofluorescence staining on LCLs. Five independent monoclonal antibodies detected a group of apparently novel, high M(r) (> 200,000) proteins that shared common features of subcellular distribution. In LCLs, these proteins were preferentially associated with vimentin filaments in the cytoplasm and with distinct nuclear foci. The appearance of the latter differed from the premyelocytic leukemia-associated protein, EBV nuclear antigen #5, and retinoblastoma-protein-positive bodies that were used for immunization. They seemed to be connected to the cytoplasmic filaments through thin fibrillar nuclear structures. In mitotic cells, these complex structures rearranged into a perichromosomal basket that was associated with vimentin filaments. The target proteins, operationally designated as proteins associated with nuclear dots and cytoplasmic filaments (pNDCFs), were not present in resting human B cells or were expressed at a low level. The level increased considerably after EBV infection or mitogenic stimulation by interleukin 4 and anti-CD40 antibodies. In Burkitt lymphoma (BL) type I lines phenotypically representative of the in vivo tumors, the pNDCFs were either absent or exclusively localized to the nucleus, usually to well-defined nuclear foci. EBV-positive type I BLs often shift to a more LCL-like (type III) phenotype during prolonged in vitro propagation. Type I cells express only EBV nuclear antigen 1 and the surface markers CD10 and CD77, whereas type III express all nine growth-associated EBV-encoded proteins and a gamut of B-cell activation markers. Most of the type III BL cell lines contained increased amounts of pNDCFs bound to cytoplasmic filaments, as seen in the LCLs. We propose that the expression of vimentin-associated pNDCFs should be included in the definition of type III BL phenotype.
authors.affiliation: Microbiology and Tumor Biology Center, Karolinska Institute, Stockholm, Sweden.
authors.forename: L
authors.initials: L
authors.lastname: Szekely
authors.forename: K
authors.initials: K
authors.lastname: Pokrovskaja
authors.forename: G
authors.initials: G
authors.lastname: Klein
mesh_terms: D002051:Burkitt Lymphoma / Q000378:metabolism* / Q000648:ultrastructure; D002461:Cell Line, Transformed; D002467:Cell Nucleus / Q000378:metabolism*; D002472:Cell Transformation, Viral; D003599:Cytoskeleton / Q000378:metabolism*; D004854:Herpesvirus 4, Human; D006801:Humans; D009687:Nuclear Proteins / Q000378:metabolism; D014176:Protein Biosynthesis; D014407:Tumor Cells, Cultured
chemical_list: D009687:Nuclear Proteins