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Pausing of RNA polymerase II (Pol II) in promoter-proximal regions and its release to initiate productive elongation are key steps in the regulation of transcription, and involve many factors. Evidence is now emerging that transcriptional elongation is highly dynamic. Elongation rates vary between genes and across the length of a gene, affecting splicing, termination and genome stability.
Access of RNA polymerase II to DNA is regulated by the ordered disassembly of nucleosomes and by histone exchange. Chromatin modifications, chromatin remodellers, histone chaperones and histone variants control nucleosomal dynamics, and dysregulation of these components results in aberrant transcription.
Transcription termination has a central role in regulating gene expression, maintaining the stability of the transcriptome and controlling pervasive transcription. New insights have recently been gained into the molecular basis of termination and the timely and efficient dismantling of elongation complexes at mRNA-coding and non-coding RNA loci.
Many gene expression patterns are dictated by enhancers. Mammalian genomes contain millions of potential enhancers, but only a small subset of them is active in any cell type. Emerging data uncover how cell type-specific enhancer function is established, including the involvement of higher-order genomic organization in the process.
Considerable progress has been made in the past few years in our ability to visualize the structure of G protein-coupled receptors (GPCRs) and their signalling complexes. This is due to a series of technical improvements in areas such as protein engineering, lipidic cubic phase-based crystallization and microfocus synchrotron beamlines.
The anaphase-promoting complex (also known as the cyclosome) is an E3 ubiquitin ligase that has a crucial function in the regulation of mitosis, particularly during anaphase and mitotic exit. Its activity is tightly controlled by several factors to ensure the timely degradation of key mitotic regulators and thus the proper progression of mitotic events.
Retinoic acid regulates transcription by interacting with nuclear retinoic acid receptors, which bind to retinoic acid response elements near target genes. Recent studies have refined our knowledge of retinoic acid function in the limb, which serves as a paradigm for understanding how it regulates other developmental processes, such as somitogenesis, neuronal differentiation and organogenesis.
