Organization of the synaptonemal complex during meiosis in Caenorhabditis elegans.

Four different SYP proteins (SYP-1, SYP-2, SYP-3, and SYP-4) have been proposed to form the central region of the synaptonemal complex (SC) thereby bridging the axes of paired meiotic chromosomes in Caenorhabditis elegans. Their interdependent localization suggests that they may interact within the SC. Our studies reveal for the first time how these SYP proteins are organized in the central region of the SC.

A yeast two-hybrid screen for SYP-3 interactors identifies SYP-4, a component required for synaptonemal complex assembly and chiasma formation in Caenorhabditis elegans meiosis.

The proper assembly of the synaptonemal complex (SC) between homologs is critical to ensure accurate meiotic chromosome segregation. The SC is a meiotic tripartite structure present from yeast to humans, comprised of proteins assembled along the axes of the chromosomes and central region (CR) proteins that bridge the two chromosome axes. Here we identify SYP-4 as a novel structural component of the SC in Caenorhabditis elegans.

LAB-1 antagonizes the Aurora B kinase in C. elegans.

The Shugoshin/Aurora circuitry that controls the timely release of cohesins from sister chromatids in meiosis and mitosis is widely conserved among eukaryotes, although little is known about its function in organisms whose chromosomes lack a localized centromere. Here we show that Caenorhabditis elegans chromosomes rely on an alternative mechanism to protect meiotic cohesin that is shugoshin-independent and instead involves the activity of a new chromosome-associated protein named LAB-1 (Long Arm of the Bivalent). LAB-1 preserves meiotic sister chromatid cohesion by restricting the localization of the C.

CRA-1 uncovers a double-strand break-dependent pathway promoting the assembly of central region proteins on chromosome axes during C. elegans meiosis.

The synaptonemal complex (SC), a tripartite proteinaceous structure that forms between homologous chromosomes during meiosis, is crucial for faithful chromosome segregation. Here we identify CRA-1, a novel and conserved protein that is required for the assembly of the central region of the SC during C. elegans meiosis.

Synapsis-defective mutants reveal a correlation between chromosome conformation and the mode of double-strand break repair during Caenorhabditis elegans meiosis.

SYP-3 is a new structural component of the synaptonemal complex (SC) required for the regulation of chromosome synapsis. Both chromosome morphogenesis and nuclear organization are altered throughout the germlines of syp-3 mutants. Here, our analysis of syp-3 mutants provides insights into the relationship between chromosome conformation and the repair of meiotic double-strand breaks (DSBs).

SYP-3 restricts synaptonemal complex assembly to bridge paired chromosome axes during meiosis in Caenorhabditis elegans.

Synaptonemal complex (SC) formation must be regulated to occur only between aligned pairs of homologous chromosomes, ultimately ensuring proper chromosome segregation in meiosis. Here we identify SYP-3, a coiled-coil protein that is required for assembly of the central region of the SC and for restricting its loading to occur only in an appropriate context, forming structures that bridge the axes of paired meiotic chromosomes in Caenorhabditis elegans. We find that inappropriate loading of central region proteins interferes with homolog pairing, likely by triggering a premature change in chromosome configuration during early prophase that terminates the search for homologs.

Reversal of histone lysine trimethylation by the JMJD2 family of histone demethylases.

Histone methylation regulates chromatin structure, transcription, and epigenetic state of the cell. Histone methylation is dynamically regulated by histone methylases and demethylases such as LSD1 and JHDM1, which mediate demethylation of di- and monomethylated histones. It has been unclear whether demethylases exist that reverse lysine trimethylation.

The yeast VPS genes affect telomere length regulation.

Eukaryotic cells invest a large proportion of their genome in maintaining telomere length homeostasis. Among the 173 non-essential yeast genes found to affect telomere length, a large proportion is involved in vacuolar traffic. When mutated, these vacuolar protein-sorting (VPS) genes lead to telomeres shorter than those observed in the wild type.

A genome-wide screen for Saccharomyces cerevisiae deletion mutants that affect telomere length.

Telomeres are nucleoprotein structures present at the ends of eukaryotic chromosomes that play a central role in guarding the integrity of the genome by protecting chromosome ends from degradation and fusion. Length regulation is central to telomere function. To broaden our knowledge about the mechanisms that control telomere length, we have carried out a systematic examination of approximately 4,800 haploid deletion mutants of Saccharomyces cerevisiae for telomere-length alterations.

ELG1, a regulator of genome stability, has a role in telomere length regulation and in silencing.

Telomeres, the natural ends of eukaryotic chromosomes, prevent the loss of chromosomal sequences and preclude their recognition as broken DNA. Telomere length is kept under strict boundaries by the action of various proteins, some with negative and others with positive effects on telomere length. Recently, data have been accumulating to support a role for DNA replication in the control of telomere length, although through a currently poorly understood mechanism.

The Rap1p-telomere complex does not determine the replicative capacity of telomerase-deficient yeast.

Telomeres are nucleoprotein structures that cap the ends of chromosomes and thereby protect their stability and integrity. In the presence of telomerase, the enzyme that synthesizes telomeric repeats, telomere length is controlled primarily by Rap1p, the budding yeast telomeric DNA binding protein which, through its C-terminal domain, nucleates a protein complex that limits telomere lengthening. In the absence of telomerase, telomeres shorten with every cell division, and eventually, cells enter replicative senescence.