Cellular retinoic acid binding protein 1 (Crabp1) gene is biphasically (proliferation versus differentiation) regulated by thyroid hormone (T3) in 3T3-L1 cells. This study examines T3-repression of Crabp1 gene during adipocyte differentiation. T3 repression of Crabp1 requires receptor interacting protein 140 (RIP140). During differentiation, the juxtaposed chromatin configuration of Crabp1 promoter with its upstream region is maintained, but the 6-nucleosomes spanning thyroid hormone response element to transcription initiation site slide bi-directionally, with the third nucleosome remaining at the same position throughout differentiation. On the basal promoter, RIP140 replaces coactivators GRIP1 and PCAF and forms a repressive complex with CtBP1, HDAC3 and G9a. Initially active chromatin marks on this promoter, histone modifications H3-Ac and H3K4-me3, are weakened whereas repressive chromatin marks, H3K9-me3 and H3K27-me3 modification and recruitment of G9a, HP1alpha, HP1gamma and H1, are intensified. This is the first study to examine chromatin remodeling, during the phase of hormone repression, of a bi-directionally regulated hormone target gene, and provides evidence for a functional role of RIP140 in chromatin remodeling to repress hormone target gene expression.
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http://dx.doi.org/10.1093/nar/gkp780 | DOI Listing |
Nucleic Acids Res
January 2025
Institute of Reproductive Medicine, School of Medicine, Nantong University, Nantong 226001, China.
Chromatin remodeling, which involves the histone-to-protamine exchange process during spermiogenesis, is crucial for sperm nuclear condensation and male fertility. However, the key regulators and underlying molecular mechanisms involved in this process remain largely unexplored. In this study, we discovered that deficiency in the family with sequence similarity 170 member A (Fam170a) led to abnormal sperm nuclear morphology and male infertility in mice, mirroring the observation of very low Fam170a transcription levels in sperm of infertile men with teratozoospermia.
View Article and Find Full Text PDFNucleosome repositioning is essential for establishing nucleosome-depleted regions (NDRs) to initiate transcription. This process has been extensively studied using structural, biochemical, and single-molecule approaches, which require homogenously positioned nucleosomes. This is often achieved using the Widom 601 sequence, a highly efficient nucleosome positioning element (NPE) selected for its unusually strong binding to the H3-H4 histone tetramer.
View Article and Find Full Text PDFMedComm (2020)
February 2025
Historically considered downstream effects of tumorigenesis-arising from changes in DNA content or chromatin organization-nuclear alterations have long been seen as mere prognostic markers within a genome-centric model of cancer. However, recent findings have placed the nuclear envelope (NE) at the forefront of tumor progression, highlighting its active role in mediating cellular responses to mechanical forces. Despite significant progress, the precise interplay between NE components and cancer progression remains under debate.
View Article and Find Full Text PDFJ Exp Bot
January 2025
Institute of Plant Sciences Paris-Saclay, Centre Nationale de la Recherche Scientifique, Institut National de la Recherche Agronomique, Université Evry, Université Paris-Saclay, 91405 Orsay, France.
Nucleosomes, the chromatin building blocks, play an important role in controlling DNA and chromatin accessibility. Nucleosome remodeling and the incorporation of distinct histone variants confer unique structural and biochemical properties, influencing the targeting of multiple epigenetic pathways, particularly DNA methylation. This stable epigenetic mark suppresses transposable element expression in plants and mammals, serving as an additional layer of chromatin regulation.
View Article and Find Full Text PDFNat Commun
January 2025
Robson DNA Science Centre, Charbonneau Cancer Institute, Department of Biochemistry & Molecular Biology, Cumming School of Medicine, University of Calgary, Calgary, Alberta, Canada.
To tolerate oxidative stress, cells enable DNA repair responses often sensitive to poly(ADP-ribose) (PAR) polymerase 1 and 2 (PARP1/2) inhibition-an intervention effective against cancers lacking BRCA1/2. Here, we demonstrate that mutating the CHD6 chromatin remodeler sensitizes cells to PARP1/2 inhibitors in a manner distinct from BRCA1, and that CHD6 recruitment to DNA damage requires cooperation between PAR- and DNA-binding domains essential for nucleosome sliding activity. CHD6 displays direct PAR-binding, interacts with PARP-1 and other PAR-associated proteins, and combined DNA- and PAR-binding loss eliminates CHD6 relocalization to DNA damage.
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