Trends in Genetics
ReviewCaenorhabditis elegans Dosage Compensation: Insights into Condensin-Mediated Gene Regulation
Section snippets
Mechanisms That Control Chromosome Structure in Gene Regulation
A flurry of recent studies mapping genome-wide chromosomal interactions has inspired new work focused on understanding the mechanisms that control these interactions, especially as they relate to the regulation of gene expression. Across all organisms, members of the structural maintenance of chromosomes (SMC) family of proteins are key regulators of chromosome structure [1]. While prokaryotes contain only a single SMC complex that functions in chromosome organization and segregation, three
Mechanisms and Specificity of DCC Binding
Condensin association with chromosomes depends on both DNA and chromatin interactions. Condensin ring entrapment of DNA is likely the most stable form of condensin binding [23]. Condensins may contact DNA via their SMC hinge domain 24, 25 and/or their HEAT domain-containing CAP subunits [26]. Condensins may also interact with chromatin by associating with histone proteins 27, 28. Specific targeting of SMC complexes to chromosomal sites is important for their function [29]. Recent work on
Condensin-Mediated Regulation of Transcription, Chromosome Structure, and Organization
Similar to DCC, studies in C. elegans, Drosophila melanogaster, and mammalian cells suggest that canonical condensins are primarily repressive 22, 71, 72, 73. However, not all studies have reported repressive functions 74, 75, 76, suggesting that condensin-mediated gene regulation is context specific. Regulation of gene expression appears intertwined with canonical condensin functions; a recent study suggested that condensin-mediated transcriptional repression prepares chromosomes for
Concluding Remarks
Over the past two decades, the remarkable structure and function of SMC complexes have made them a focus of intense research. Here, we discussed the molecular mechanisms of a specialized condensin that forms the core of the C. elegans DCC. Research on DCC binding suggests that specific targeting of condensins to large chromosomal domains involves two-steps: recruitment and spreading. DCC recruitment is initiated by a set of strong recruitment sites whose DNA sequence and chromatin features are
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Structural Basis of an Asymmetric Condensin ATPase Cycle
2019, Molecular CellCitation Excerpt :Multi-subunit protein complexes of the structural maintenance of chromosomes (SMC) family direct large-scale organizational changes in genome architecture that are essential for all aspects of chromosome biology. In addition to their central functions in the segregation of replicated genomes during prokaryotic and eukaryotic cell divisions (Hirano, 2016; Uhlmann, 2016), SMC protein complexes also determine the three-dimensional landscape of interphase nuclei to regulate gene expression (Albritton and Ercan, 2018; Merkenschlager and Nora, 2016) and contribute to DNA damage repair, recombination, and replication (Wood et al., 2010; Wu and Yu, 2012). The unifying principle for the diverse actions of SMC complexes, foremost condensin and cohesin, might be their ability to extrude DNA into loop structures (Goloborodko et al., 2016; Nasmyth, 2001).
The Role of Xist in X-Chromosome Dosage Compensation
2018, Trends in Cell BiologyCitation Excerpt :However, unlike the mammalian inactive X chromosome (Xi), lncRNAs have not been reported to regulate X-chromosome dose in the C. elegans. Instead, dampening in the nematode is carried out by the dosage compensation complex, a condensin-containing multi-subunit protein assembly that binds at multiple sites along the X chromosome and leads to chromosome-wide compaction and gene repression [18]. Whether XCD events observed in human preimplantation development and C. elegans are related at the molecular level needs further investigation.
Function and Evolution of the Loop Extrusion Machinery in Animals
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