Disease relevance of Prophase

• Individuals with ataxia telangiectasia as well as Atm(-/-) mice are predisposed to cancer and are infertile due to spermatogenesis disruption during first meiotic prophase [1].
• Aberrant hypermethylation of the CHFR prophase checkpoint gene in human lung cancers [2].
• In yeast an Escherichia coli RecA-like gene, DMC1, is expressed in meiotic prophase and its product co-localizes with Rad51 protein on zygotene chromosomes [3].
• In the human U2OS osteosarcoma cell line, hBUB1 first appeared at kinetochores during early prophase before all kinetochores were occupied by hBUBR1 or CENP-F [4].
• In this investigation peripheral blood lymphocytes from 3 Fanconi's anemia (FA) patients, 2 FA heterozygotes and 4 normal subjects were treated with caffeine and/or adenosine, and/or niacinamide during G2 prophase [5].

High impact information on Prophase

• Mnd2, an essential antagonist of the anaphase-promoting complex during meiotic prophase [6].
• But CDK2 is essential for completion of prophase I during meiotic cell division in male and female germ cells, an unforeseen role for this cell cycle kinase [7].
• Female Cdc25b-/- mice were sterile, and Cdc25b-/- oocytes remained arrested at prophase with low MPF activity [8].
• We then used this strategy to carry out the first temporal analysis of meiotic recombination in mouse spermatogenesis and demonstrate that crossover events occur during the pachytene stage of meiotic prophase [9].
• However, the introduction of Eif2s3y restores normal spermatogonial proliferation and progression through meiotic prophase [10].

Biological context of Prophase

• We propose that in vertebrates, a cleavage-independent pathway removes cohesin from chromosome arms during prophase, whereas a separin-dependent pathway cleaves centromeric cohesin at the metaphase-anaphase transition [11].
• Immunofluorescent staining revealed that cyclin A accumulates in the interphase cytoplasm of cellularized embryos, but relocates to the nuclear region early in prophase and is completely degraded within metaphase [12].
• In synchronous cultures of S. cerevisiae undergoing meiosis, an early event in the meiotic recombination pathway, site-specific double strand breaks (DSBs), occurs early in prophase, in some instances well before tripartite synaptonemal complex (SC) begins to form [13].
• In vertebrate cells, the nuclear entry of Cdc2-cyclin B1 (MPF) during prophase is thought to be essential for the induction and coordination of M-phase events [14].
• Nuclear events of mitosis are initiated when the protein kinase cyclin-B1-Cdk1 is translocated into the nucleus during prophase [15].

Anatomical context of Prophase

• Immunocytochemistry and subcellular fractionation studies indicate that the majority of TFIID is displaced from the disassembling prophase nucleus to the mitotic cytoplasm around the time of nuclear envelope breakdown [16].
• With antibodies that have been immunodepleted of cross-reactive epitopes, we demonstrate that RAD51 and DMC1 have identical distribution patterns in extracts of mouse spermatocytes in successive prophase I stages, suggesting coordinate functionality [17].
• Immunolabeling of HeLa cells for E-MAP-115 indicates that the protein is absent from microtubules during early prophase and progressively reassociates with microtubules after late prophase [18].
• Near simultaneous fluorescence and DIC light microscopy reveals that the amount of gamma-tubulin associated with the centrosome remains relatively constant throughout interphase, suddenly increases during prophase, and then decreases to interphase levels as the cell exits mitosis [19].
• We propose that a RAF1-dependent activation of MEK1 and its presence on the Golgi apparatus in late prophase is required for Golgi complex fragmentation [20].

Associations of Prophase with chemical compounds

• A mutant cyclin B1 in which S133 and S147 are replaced by alanines remains in the cytoplasm, whereas wild-type cyclin B1 accumulates in the nucleus during prophase [14].
• The cytoplasmic distribution of the antigen was also seen in nocodazole-arrested cells and prophase cells in populations treated with taxol [21].
• Microinjection of a catalytically inactive mutant of X-PAK1 with a K/R substitution in the ATP binding site, also deleted of its Nter-half that contains the conserved domains responsible for binding of both Cdc42/Rac GTPases and SH3-containing proteins, greatly facilitates oocyte release from G2/prophase arrest by progesterone and insulin [22].
• Prophase-accociated elongation of procentrioles appeared to occur normally in cells treated with cycloheximide for up to 4 h before prophase, though the mitotic index in treated cultures decreased somewhat [23].
• In contrast, deletion of amino acids 19-68 or 18-61 of the NH2-terminal "head" domain produced proteins that formed extended filaments in the animal hemisphere of the prophase oocyte [24].

Gene context of Prophase

• Furthermore, these breaks occur in a processed form in wild-type cells and in a discrete, unprocessed form in certain nonnull rad50 mutants, rad50S, which block meiotic prophase at an intermediate stage [25].
• Polo-like kinase 1 phosphorylates cyclin B1 and targets it to the nucleus during prophase [14].
• Early prophase nuclei undergo normal reorganization in syp-1 mutants, and chromosomes initially pair [26].
• Plants transformed with a SWI1-GFP fusion indicated that SWI1 protein is present in meiocyte nuclei, before meiosis and at a very early stage of prophase [27].
• Meiosis in Exo1(-/-) animals proceeded through prophase I; however, the chromosomes exhibited dynamic loss of chiasmata during metaphase I, resulting in meiotic failure and apoptosis [28].

Analytical, diagnostic and therapeutic context of Prophase

• Immunofluorescence results in prophase I cells suggest that STAG3 is a component of the axial/lateral element of the synaptonemal complex [29].
• By indirect immunofluorescence, cdc25 protein is found essentially localized in the nucleus throughout interphase and during early prophase [30].
• Electron microscopy studies showed that E6 cells may die at prophase or prometaphase [31].
• Peripheral blood samples were taken before treatment (day 0), after the prednisone prophase (day 8), and during (day 15) and after (day 33) remission induction [32].
• The treatment of termite male spermatogonia with actinomycin D induces highly elongated and finely banded late prophase and prometaphase chromosomes as evidenced by the silver staining method [33].

References