Project description:Total RNA was isolated from proliferating and senescent IMR90 cells to compare gene-expression to the changes in nucleolus-association in proliferating and senescent IMR90 cells.
Project description:Cellular senescence is a stable proliferation arrest and tumor suppressor mechanism. Abundance of histone modification, H4K20me3, has been reported to increase in senescent cells. Generally, H4K20me3 promotes formation of compacted transcriptionally silent constitutive heterochromatin, but its specific role in senescence is unknown. Here, we show that in senescent cells H4K20me3 is enriched at specific families of gene repeats (ZNFs, Olfactory Receptors, Protocadherins), and DNA sequences contained within senescence-associated heterochromatin (senescence-associated heterochromatin (SAHF)). Furthermore, in senescent cells, but not proliferating cells, H4K20me3 is also markedly enriched at bodies of repressed genes, including proliferation-promoting genes. Ectopic expression of SUV420H2, responsible for deposition of H4K20me3, reinforces senescence-associated proliferation arrest, and slows proliferation of transformed cells and tumorigenesis in vivo. These results indicate a dedicated role for H4K20me3 in control of nuclear organization and gene expression in senescent cells and stable senescence-associated proliferation arrest and tumor suppression.
Project description:Analysis of the H3K9me3 and H4K20me3 differential localization over the genome of cancer cells in three conditions: proliferating cells, doxorubicin-treated cells (senescent) and INK128-treated cells (diapause-like). Two cell lines were used to perform the experiment: human melanoma SK-mel-103 cells and human NSCLC A549 cells.
Project description:RNAseq replicate in Proliferating and Senescent IMR90s We used RNAseq to examine RNA levels in human IMR90 replicative senescence (RS)
Project description:H3K9me3 ChIPseq in Proliferating and Senescent IMR90s We used ChIP-seq to examine the global binding of H3K9me3 in human IMR90 replicative senescence (RS) and oncogene-induced (OIS)
Project description:Nucleolus-associated DNA was isolated from cross-linked proliferating and senescent IMR90 human fibroblasts and hybridized against genomic (1) or non-nucleolar (2) DNA to map nucleolus-associated chromosomal domains.
Project description:Cellular senescence is a stable proliferation arrest that suppresses tumorigenesis. Histone chaperone HIRA deposits nucleosome-destabilizing histone variant H3.3 into chromatin in a DNA replication-independent manner. Histone H3.3 and a subset of other typically M-bM-^@M-^\replication-dependentM-bM-^@M-^] core histones were expressed in non-proliferating senescent cells, the latter linked to alternative mRNA splicing and polyadenylation. Senescent cells incorporated newly-synthesized histones into chromatin, partially dependent on HIRA. HIRA and newly-deposited histone H3.3 co-localized at promoters of expressed genes, and their distribution shifted between proliferating and senescent cells, paralleling changes in gene expression. In senescent cells, gene promoters showed exceptional enrichment of a histone acetylation linked to open and dynamic chromatin, H4K16ac. Abundance of H4K16ac depended on HIRA. In the mouse, inactivation of HIRA downregulated H4K16ac and dramatically enhanced oncogene-induced hyperplasia. To conclude, HIRA controls a previously undefined dynamic non-canonical H4K16ac-decorated chromatin landscape in senescence, and also plays an unanticipated role in suppression of oncogene-induced neoplasia. Examination of HIRA protein binding alongside histone modification H4K16ac and H3.3 in proliferating and senescent IMR90 cells
