Nuclear envelope-limited chromatin sheets are part of mitotic death

Abstract

Nuclear envelope-limited chromatin sheets (ELCS) are enigmatic membranous structures of uncertain function. This study describes the induction of ELCS in p53 mutated Burkitt's lymphoma cell lines after treatment with irradiation or the microtubule inhibitor, SK&F 96365. Both treatments evoked similar mitotic death, involving metaphase arrest followed by extensive endopolyploidisation and delayed apoptosis, although the kinetics were different. We found that induction of ELCS and nuclear segmentation correlated with the amount and kinetics of M-phase arrest, mitosis restitution and delayed apoptosis of endopolyploid cells. In metaphases undergoing restitution, ELCS are seen participating in the restoration of the nuclear envelope, mediating the attachment of peripheral chromatin to it. In interphase cells, ELCS join nuclear segments, ectopically linking and fusing with heterochromatin regions. In cells with segmented nuclei, continued DNA replication was observed, along with activation and redistribution of Ku70, suggestive of non-homologous DNA end-joining. Induction of ELCS also parallels the induction of cytoplasmic stacked membrane structures, such as confronting cisternae and annulate lamellae, which participate in the turnover and degeneration of ELCS. The results suggest that arrest at a spindle checkpoint and the uncoupling of mitosis from DNA replication lead to the emergence of ELCS in the resulting endopolyploid cells.

Nuclear envelope-limited chromatin sheets (ELCS) and heterochromatin higher order structure

“…Fanconi's anemia granulocytes Barton et al 1987 Acquired sideroblastic anemia granulocytes Djaldetti et al 2004 Megaloblastic anemia (B12 deficiency) granulocytes Bunting and Selig 2002;Bunting et al 1996 Congenital dyserythropoietic anemia (CDA) erythrocyte precursors Bjorksten et al 1978 Chromosomal aneuploidy D 1 (13-15) trisomy granulocytes Fine et al 1965;Huehns et al 1964;Lutzner and Hecht 1966;Mehes 1966;Rogers 1984;Salama et al 2004 14 trisomy granulocytes Dallapiccola et al 1984 21 Trisomy (Down's Syndrome) granulocytes Djaldetti et al 1974;Gericke et al 1977 Various combinations of aneuploidy, translocations and inversions granulocytes Ahearn et al 1974;Dalton et al 1987;Tricot and Broeckaert-Van Orshoven 1984 Chemotherapy/mitotic agents 5-Fluorouracil granulocytes Stalzer et al 1965 Cytosine arabinoside granulocytes Ahearn et al 1967 Mitotic inhibitor SK & F Burkitt's lymphoma cells Erenpreisa et al 2002 Phytohemagglutinin Blood mononuclear cells Mollo and Stramignoni 1967 Sodium periodate CLL cells McGill et al 1976 Cytochalasin B and concanavalin A lymphocytes Viklicky et al 1978 B12 deficiency), which is thought to provoke a perturbation of DNA replication in the bone marrow (Bunting and Selig 2002;Bunting et al 1996). It may be that the common feature of these cell cycle insults is the induction of a "mitotic crisis" (Erenpreisa et al 2002).…”

“…It may be that the common feature of these cell cycle insults is the induction of a "mitotic crisis" (Erenpreisa et al 2002). But the relationship of these chemical agents to ELCS formation is currently obscure.…”

Cell Cycle Modification in Trophoblast Cell Populations in the Course of Placenta Formation

“…The selective DNA cytometry in these nuclei and their segments showed the most frequently the 2N multiple DNA content. In irradiated cells, single ALs were seen in the close vicinity to ELCS, where they were observed to sequester the cytoplasm around the micronuclei, nuclear segments and buds (Erenpreisa, 2002). The process is similar to cytoplasm compartmentalization around the trophoblast cell nuclear fragments.…”

“…Investigation of mechanisms of depolyploidization showed some traits similar to fragmentation of the highly endopolyploid nuclei in the mammalian trophoblast. A reserve mechanism that allows overcoming the impossibility of cell division under conditions of disorder of the mitotic spindle microtubules was observed in the experiment of irradiation and treatment by a microtubule inhibitor SK&F on the p53 mutated Burkitt lymphoma cell lines (Erenpreisa et al, 2002). Electron microscopy showed large cells with the lobulating, segmenting, and budding nuclei that gave rise to many micronuclei and/or subnuclei.…”

Innovative techniques and applications in histochemistry and cell biology

“…Compartmentalization of the nucleus, the dynamic nature of nuclear organization enabling transcription to occur rapidly at any site in the genome, and the trafficking of RNA and proteins have been the subjects of numerous original investigations and reviews (see, for example, Erenpreisa et al 2002;Iborra 2002;Icardo et al 2002;Roix and Misteli 2002). Miyagishima et al (2003) drew our interest to a group of genes, the Polycomb group (PcG), which was first identified as being required for the maintenance of the stable repression of HOX genes during the development of Drosophila melanogaster (Paro 1995;Pirrotta 1997).…”