Shaping meiotic prophase chromosomes: Cohesins and synaptonemal complex proteins
Institute of Physiological Chemistry , Technische Universität Dresden, Dresden, Saxony, Germany Chromosoma
(Impact Factor: 4.6).
07/2006; 115(3):235-40. DOI: 10.1007/s00412-006-0060-x
Recent progress in elucidating the function of synaptonemal complex (SC) proteins and of cohesins in meiocytes made possible, in particular, through the analysis of mice deficient in SC or cohesin proteins has significantly enriched our understanding of how meiotic chromosome architecture is determined. Cohesins and the SC proteins act together in generating the characteristic axis-loop structure of meiotic chromosomes, their pairing into bivalents, their ability to recombine, and to be properly segregated. This minireview attempts to summarize the current knowledge with a focus on higher eukaryotic systems and to ask questions that ought to be addressed in the future.
Available from: cshperspectives.cshlp.org
- "Mitotic prophase chromosome organization may turn out to be the same as that of meiotic prophase chromosomes (Kleckner et al. 2012). Molecular studies of pachytene chromosomes have identified several types of axis components: mitotic structural proteins like topoisomerase II, condensins, cohesins, and cohesin-associated proteins, including meiosisspecific versions of some of these proteins; meiosis-specific axis components; and structural components of the SC, which are also unique to meiosis (Moens and Earnshaw 1989; Page and Hawley 2004; Revenkova and Jessberger 2006; Wojtasz et al. 2009; Wood et al. 2010, and references therein; Liu and Colaiácovo 2013). In many organisms (including budding and fission yeast, mammals, Arabidopsis, rice, Drosophila, and C. elegans), prominent meiotic axis components include one or more HORMA-domain proteins. "
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ABSTRACT: Recombination is a prominent feature of meiosis in which it plays an important role in increasing genetic diversity during inheritance. Additionally, in most organisms, recombination also plays mechanical roles in chromosomal processes, most notably to mediate pairing of homologous chromosomes during prophase and, ultimately, to ensure regular segregation of homologous chromosomes when they separate at the first meiotic division. Recombinational interactions are also subject to important spatial patterning at both early and late stages. Recombination-mediated processes occur in physical and functional linkage with meiotic axial chromosome structure, with interplay in both directions, before, during, and after formation and dissolution of the synaptonemal complex (SC), a highly conserved meiosis-specific structure that links homolog axes along their lengths. These diverse processes also are integrated with recombination-independent interactions between homologous chromosomes, nonhomology-based chromosome couplings/clusterings, and diverse types of chromosome movement. This review provides an overview of these diverse processes and their interrelationships.
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- "The other complex is the cohesin complex, which is important for many aspects of chromosome structure and function (Hirano, 2000; Wood et al., 2010). Importantly, the cohesin complex is essential for the organization of meiotic chromosomes; in particular, it is intimately linked to the structure and assembly of the synaptonemal complex (Revenkova and Jessberger, 2006; Stack and Anderson, 2001). The synaptonemal complex holds the homologs together during the recombination process; therefore, its integrity is required for the chromosome segregation process, which relies on homologous recombination (Page and Hawley, 2004). "
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ABSTRACT: Meiosis is characterized by two chromosome segregation rounds (Meiosis I and II), which follow a single round of DNA replication, resulting in haploid genome formation. Chromosome reduction occurs at meiosis I. It relies on key structures, such as chiasma, which is formed by repair between homologous chromatids of a double-strand break (DSB) in one of them; to function for segregation of homologues chiasma in turn relies on maintenance of sister chromatid cohesion. In most species, chiasma formation requires the prior synapsis of homologous chromosome axes, which is signaled by the Synaptonemal Complex (SC), a tripartite proteinaceous structure specific to prophase I of meiosis. Yemanuclein (YEM) is a maternal factor that is crucial for sexual reproduction. It is required in the zygote for chromatin assembly of the male pronucleus as a histone H3.3 chaperone in complex with HIRA. We report here YEM association to the SC and the cohesin complex. A genetic interaction between yem(1) (V478E) and the Spo11 homologue mei-W68, added to a yem(1) dominant effect on crossover distribution suggest an early role in meiotic recombination. This is further supported by the impact of yem mutations on DSB kinetics. Hira mutant showed a similar effect presumably through disruption of HIRA-YEM complex.
Available from: Tatiana Mikhailovna Grishaeva
- "It is worthwhile to consider several details of SC protein diversity. Lateral elements (LEs) of the SC are formed on the basis of chromosomal axial elements, which connect sister chromatids and consist mostly of cohesins . The LEs are joined together to produce the integral SC structure via a zipper of transversal filaments, which pass through the SC central space. "
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ABSTRACT: The problems of the origin and evolution of meiosis include the enigmatic variability of the synaptonemal complexes (SCs) which, being morphology similar, consist of different proteins in different eukaryotic phyla. Using bioinformatics methods, we monitored all available eukaryotic proteomes to find proteins similar to known SC proteins of model organisms. We found proteins similar to SC lateral element (LE) proteins and possessing the HORMA domain in the majority of the eukaryotic taxa and assume them the most ancient among all SC proteins. Vertebrate LE proteins SYCP2, SYCP3, and SC65 proved to have related proteins in many invertebrate taxa. Proteins of SC central space are most evolutionarily variable. It means that different protein-protein interactions can exist to connect LEs. Proteins similar to the known SC proteins were not found in Euglenophyta, Chrysophyta, Charophyta, Xanthophyta, Dinoflagellata, and primitive Coelomata. We conclude that different proteins whose common feature is the presence of domains with a certain conformation are involved in the formation of the SC in different eukaryotic phyla. This permits a targeted search for orthologs of the SC proteins using phylogenetic trees. Here we consider example of phylogenetic trees for protozoans, fungi, algae, mosses, and flowering plants.
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