title: Distinct expression patterns of polycomb oncoproteins and their binding partners during the germinal center reaction.
abstract: Polycomb group (PcG) genes encode two chromatin-binding protein complexes, the PRC1 and the PRC2 PcG complexes, which are essential for the maintenance of cell identity and play a role in oncogenesis. PcG complexes were recently identified as novel regulators of hematopoiesis, and appear to be expressed in a non-overlapping pattern in resting and mature follicular B cells. Using highly specific antisera in combination with immunohistochemistry and triple immunofluorescence, we investigated the expression pattern of nine human PcG genes in germinal center (GC) B cells and highly purified germinal center B cell subpopulations. PcG proteins were detected in characteristic binding patterns that were not necessarily related to mutually exclusive expression of the two PcG complexes. We conclude that the two PcG complexes are expressed throughout GC development, and that the fine composition of each complex is determined by the differentiation status of the cell. In addition, a subset of dividing cells with a centrocyte CD marker profile was identified that co-expresses core components of the PRC1 and PRC2 complex. We propose that these cells reflect a transitional stage between resting and dividing follicular B lymphocytes, and that they possibly represent the healthy precursors of nodal large B cell lymphomas.
authors.affiliation: Department of Pathology, VU Medical Center, Amsterdam, The Netherlands.
authors.forename: Joost C
authors.initials: JC
authors.lastname: van Galen
authors.forename: Danny F
authors.initials: DF
authors.lastname: Dukers
authors.forename: Cindy
authors.initials: C
authors.lastname: Giroth
authors.forename: Richard G A B
authors.initials: RG
authors.lastname: Sewalt
authors.forename: Arie P
authors.initials: AP
authors.lastname: Otte
authors.forename: Chris J L M
authors.initials: CJ
authors.lastname: Meijer
authors.forename: Frank M
authors.initials: FM
authors.lastname: Raaphorst
mesh_terms: D001402:B-Lymphocytes / Q000166:cytology / Q000276:immunology / Q000378:metabolism*; D018797:Cell Cycle Proteins / Q000737:chemistry* / Q000378:metabolism*; D002469:Cell Separation; D005434:Flow Cytometry; D005455:Fluorescent Antibody Technique; D005786:Gene Expression Regulation; D018858:Germinal Center / Q000166:cytology / Q000276:immunology / Q000378:metabolism*; D006801:Humans; D007150:Immunohistochemistry; D046911:Macromolecular Substances; D018613:Microscopy, Confocal; D015513:Oncogene Proteins / Q000737:chemistry / Q000378:metabolism*; D063146:Polycomb-Group Proteins; D011485:Protein Binding; D012097:Repressor Proteins / Q000737:chemistry / Q000378:metabolism*
chemical_list: D018797:Cell Cycle Proteins; D046911:Macromolecular Substances; D015513:Oncogene Proteins; C116662:PRC1 protein, human; D063146:Polycomb-Group Proteins; D012097:Repressor Proteins