Chromosomal condensation

The activated CDKl-cyclin B kinase finally phosphor-ylates a large number of proteins most of which are not well characterized, leading to chromosome condensation, nuclear envelope breakdown, spindle assembly, and chromosome segregation. 

Sunkara, P. S., Wright, D. A., and Rao, P. N. (1979). Mitotic factors from mammalian cells induce germinal vesicle breakdown and chromosome condensation in amphibian oocytes. Proc. Natl. Acad. Sci. USA 76 2799-2802. 

Guacci V, Koshland D, Strunnikov A 1997 A direct link between sister chromatid cohesion and chromosome condensation revealed through the analysis of MCD1 in S. cerevisiae. Cell... 

Hirano T, Mitchison TJ 1994 A heterodimeric coiled-coil protein required for mitotic chromosome condensation in vitro. Cell 79 449-458... 

Hirano T, Kobayashi R, Hirano M 1997 Condensins, chromosome condensation protein complexes containing XCAP-C, XCAP-E and a Xenopus homolog of the Drosophila Barren protein. Cell 89 511-521... 

Kimura K, Rybenkov VV, Crisona NJ, Hirano T, Cozzarelli NR 1999 13S condensin actively reconfigures DNA by introducing global positive writhe implications for chromosome condensation. Cell 98 239-248... 

Saka Y, Sutani T, Yamashita Y et al 1994 Fission yeast cut3 and cutl4, members of a ubiquitous protein family, are required for chromosome condensation and segregation in mitosis. EMBO J 13 4938-4952... 

Feng H, Zhong W, Punkosdy G et al 1999 CUL-2 is required for the Gl-to-S-phase transition and mitotic chromosome condensation in Caenorhabditis elegans. Nat Cell Biol 1 486-492 Hedgecock EM, White TG 1985 Polyploid tissue in the nematode Caenorhabditiselegans. Dev Biol 107 128-133... 

The condensin complex has been identified in the same scaffold fraction (Maeshima and Laemmli, 2003) and shown to be essential for the mitotic chromosome condensation (Hirano et al, 1997). The frog condensin complex exhibits ATP-dependent DNA-supercoiling activity (Kimura and Hirano, 1997). It consists of a heterodimer of SMC and a trimer of non-SMC proteins (Hirano et al, 1997). The SMC complex has a globular head domain and a coiled-coil tail region (Anderson et al., 2002 Melby et al, 1998 Yoshimura et al., 2002). In vertebrates, two types of condensin complex, condensin I and condensin II, exist they are composed of the same SMC subunits but with different non-SMC subunits (Ono et al, 2003). 

Phosphorylation has been thought to be correlated to the mitotic chromatin condensation and the transcriptional regulation in interphase (Nowak and Corces, 2004). The mitotic phosphorylation, which was first identified in 1978 (Gurley et al, 1978), occurs at Ser (Wei et al, 1998), Ser (Goto et al, 1999), and Thr (Preuss et al, 2003) in histone H3. The Ser phosphorylation is catalyzed by the aurora kinase family (de la Barre et al, 2000), and is required for the initiation of chromosome condensation but not for its maintenance (dephosphorylation of mitotic chromosomes does not induce chromosome decondensation) (Van Hooser et fl/.,1998). In meiosis, Ser phosphorylation is also required for the cohesion of sister chromatids rather than the condensation (Kaszas and Cande, 2000). 

It is interesting and important to note that several species, such as Schizosac-charomyces pombe, lack histone HI (Wood et al 2002) (see also section 2.4). The nucleosome-repeat length is slightly shorter in S. pombe than in human (Godde and Widom, 1992). The contribution of histone HI to the mitotic chromosome condensation has been examined with the use of a cell-free system of Xenopus eggs, in which the condensed sperm nuclei can be transformed into metaphase chromosomes. Even when histone HI is removed from the extract, the metaphase chromosomes can still be formed (Ohsumi et al, 1993). In addition, an elimination of all HI genes in Tetrahymena exerts no phenotypic effect (Shen et al, 1995). 

Van Hooser A, Goodrich DW, Allis CD, Brinkley BR, Mancini MA (1998) Histone H3 phosphorylation is required for the initiation, but not maintenance, of mammalian chromosome condensation. J Cell Sci lll(Pt 23) 3497-3506... 

Wei Y, Mizzen CA, Cook RG, Gorovsky MA, Allis CD (1998) Phosphorylation of histone H3 at serine 10 is correlated with chromosome condensation during mitosis and meiosis in Tetrahymena. Proc Natl Acad Sci U S A 95 7480-7484... 

H2A(.X) H2Av H2A.X Phosphorylation in DNA damage, Meiotic recombination, Mammals Meiotic Sex chromosome condensation RD/RI... 

Bleomycin induced chromosomal damage in Chinese hamster bone marrow gives rise to micronuclei by means of lagging chromatin main and micronuclei eventually become asynchronous in consecutive cell cycles and mitosing main nuclei induce premature chromosome condensation in the micronuclei (Kurten and Obe, 1975). 

Kurten S, Obe, G (1975) Premature chromosome condensation in the bone marrow of Chinese hamster after pUcation of bleomycin in vivo. Mutat Res 27(2) 285—294 Lee DY, Hayes JJ, Pruss D, Wolffe AP (1993) A positive role for histone acetylation in transcription factor access to nucleosomal DNA. Cell 72 73—84... 

Ku (subunit of PARP) Homo sapiens SKBR3 cell line chromosome condensation, subunit of DNA-dependent protein kinase PARP... 

Histone H3 (Til) phosphorylation occurs during mitosis by Dlk/ZIP kinase (Dlk Death-associated protein (DAP)-like kinase, ZIP Zipper interacting protein kinase) (Preuss et al, 2003) (Table 1). Histone H3 at Serine 28 is phosphorylated by Aurora B kinase at mitosis and this phosphorylation coincides with chromosome condensation (Goto et al., 1999, Goto et al, 2002) (Fig. 2), (Table 1). Histone H3 (S28) phosphorylation initiates at prophase, whereas histone H3 (SIO) phosphorylation initiates during the late G2 phase (Hendzel et al, 1997). 

We have discussed phosphorylation of histone H3, which has been studied in many organisms. Phosphorylation of histone H3 (SIO) has two opposite main functions. One is necessary to initiate chromosome condensation during mitosis and meiosis, while the other is transcriptional activation. Current evidence shows that a combination of phosphorylation of H3 (SIO) and methylation of H3 (K9) or acetylation H3 (K9, K14) play important roles in these phenomena including cell cycle related chromosome dynamics and transcriptional activation. These results suggest that a combination of different histone modifications excute different biological outcomes. 

Ge Z, Liu C, Bjorkholm M, Gruber A, Xu D (2006) Mitogen-activated protein kinase cascade-mediated histone H3 phosphorylation is critical for telomerase reverse transcriptase expression/telomerase activation induced by proliferation. Mol Cell Biol 26(l) 230-237 Giet R, Glover DM (2001) Drosophila aurora B kinase is required for histone H3 phosphorylation and condensin recruitment during chromosome condensation and to organize the central spindle during cytokinesis. J Cell Biol 152(4) 669-682... 

Hendzel MJ, Wei Y, Mancini MA, Van Hooser A, Ranalh T, Brinkley BR, Bazett-Jones DP, Allis CD (1997) Mitosis-specific phosphorylation of histone H3 initiates primarily within pericentromeric heterochromatin during G2 and spreads in an ordered fashion coincident with mitotic chromosome condensation. Chromosoma 106(6) 348—360... 

Wei Y, Yu L, Bowen J, Gorovsky MA, Allis CD (1999) Phosphorylation of histone H3 is required for proper chromosome condensation and segregation. Cell 97(1) 99—109 Wyatt HR, Liaw H, Green GR, Lustig AJ (2003) Multiple roles for Saccharomyces cerevisiae histone H2A in telomere position effect, Spt phenotypes and double-strand-break repair. Genetics 164(l) 47-64... 

In higher eukaryotes, at the onset of S phase cyclin A accumulates which stimulates DNA synthesis. The amount of cyclin A continues to be high after the S phase because of its role in chromosome condensation. Cyclin A is degraded when cells enter prometaphase. The level of another cyclin called cyclin B rises during G2 phase, which helps to complete the chromosome condensation and spindle assembly, which allow transition to metaphase. Cyclin B is degraded by APC during metaphase. ... 

Metaphase Cyclin B Chromosome condensation and spindle assembly 349... 

Histone phosphorylation was first reported in 1966 [1,2]. The four core histones, histone variants, and HI histones are phosphorylated, with the sites of phosphorylation being found in both the amino-terminal and carboxy-terminal portions of the histones [3] (Figs. 1 and 2). Phosphorylation of the core histones has been implicated in transcription, replication, chromosome condensation, and DNA repair. 

---