Browsing by Author "Collings, Clayton K."

Now showing 1 - 2 of 2
  • Thumbnail Image
    Item
    Oligonucleotide Sequence Motifs as Nucleosome Positioning Signals
    (Public Library of Science, 2010-06-03) Collings, Clayton K.; Fernandez, Alfonso G.; Pitschka, Chad G.; Hawkins, Troy B.; Anderson, John N.; Medical and Molecular Genetics, School of Medicine
    To gain a better understanding of the sequence patterns that characterize positioned nucleosomes, we first performed an analysis of the periodicities of the 256 tetranucleotides in a yeast genome-wide library of nucleosomal DNA sequences that was prepared by in vitro reconstitution. The approach entailed the identification and analysis of 24 unique tetranucleotides that were defined by 8 consensus sequences. These consensus sequences were shown to be responsible for most if not all of the tetranucleotide and dinucleotide periodicities displayed by the entire library, demonstrating that the periodicities of dinucleotides that characterize the yeast genome are, in actuality, due primarily to the 8 consensus sequences. A novel combination of experimental and bioinformatic approaches was then used to show that these tetranucleotides are important for preferred formation of nucleosomes at specific sites along DNA in vitro. These results were then compared to tetranucleotide patterns in genome-wide in vivo libraries from yeast and C. elegans in order to assess the contributions of DNA sequence in the control of nucleosome residency in the cell. These comparisons revealed striking similarities in the tetranucleotide occurrence profiles that are likely to be involved in nucleosome positioning in both in vitro and in vivo libraries, suggesting that DNA sequence is an important factor in the control of nucleosome placement in vivo. However, the strengths of the tetranucleotide periodicities were 3–4 fold higher in the in vitro as compared to the in vivo libraries, which implies that DNA sequence plays less of a role in dictating nucleosome positions in vivo. The results of this study have important implications for models of sequence-dependent positioning since they suggest that a defined subset of tetranucleotides is involved in preferred nucleosome occupancy and that these tetranucleotides are the major source of the dinucleotide periodicities that are characteristic of positioned nucleosomes.
  • Thumbnail Image
    Item
    Stepwise activities of mSWI/SNF family chromatin remodeling complexes direct T cell activation and exhaustion
    (Elsevier, 2023) Battistello, Elena; Hixon, Kimberlee A.; Comstock, Dawn E.; Collings, Clayton K.; Chen, Xufeng; Rodriguez Hernaez, Javier; Lee, Soobeom; Cervantes, Kasey S.; Hinkley, Madeline M.; Ntatsoulis, Konstantinos; Cesarano, Annamaria; Hockemeyer, Kathryn; Haining, W. Nicholas; Witkowski, Matthew T.; Qi, Jun; Tsirigos, Aristotelis; Perna, Fabiana; Aifantis, Iannis; Kadoch, Cigall; Medicine, School of Medicine
    Highly coordinated changes in gene expression underlie T cell activation and exhaustion. However, the mechanisms by which such programs are regulated and how these may be targeted for therapeutic benefit remain poorly understood. Here, we comprehensively profile the genomic occupancy of mSWI/SNF chromatin remodeling complexes throughout acute and chronic T cell stimulation, finding that stepwise changes in localization over transcription factor binding sites direct site-specific chromatin accessibility and gene activation leading to distinct phenotypes. Notably, perturbation of mSWI/SNF complexes using genetic and clinically relevant chemical strategies enhances the persistence of T cells with attenuated exhaustion hallmarks and increased memory features in vitro and in vivo. Finally, pharmacologic mSWI/SNF inhibition improves CAR-T expansion and results in improved anti-tumor control in vivo. These findings reveal the central role of mSWI/SNF complexes in the coordination of T cell activation and exhaustion and nominate small-molecule-based strategies for the improvement of current immunotherapy protocols.