Project description:Epigenetic alterations are a key hallmark of aging but have not been extensively explored in tissues. Here, using naturally aged murine liver as a model and extending study to other quiescent tissues, we find that aging is driven by temporal chromatin alterations that promote a refractory cellular state and compromise cellular identity. Using an integrated multi-omics approach and the first direct visualization of aged chromatin, we find that old cells show global H3K27me3-driven broad heterochromatinization and transcription suppression. At the local level, site-specific loss of H3K27me3 from promoters of genes encoding developmental transcription factors leads to expression in liver of non-hepatocyte markers. Interestingly, liver regeneration reverses H3K27me3 patterns and rejuvenates multiple molecular and physiological aspects of the aged liver.
Project description:Epigenetic alterations are a key hallmark of aging but have not been extensively explored in tissues. Here, using naturally aged murine liver as a model and extending study to other quiescent tissues, we find that aging is driven by temporal chromatin alterations that promote a refractory cellular state and compromise cellular identity. Using an integrated multi-omics approach and the first direct visualization of aged chromatin, we find that old cells show global H3K27me3-driven broad heterochromatinization and transcription suppression. At the local level, site-specific loss of H3K27me3 from promoters of genes encoding developmental transcription factors leads to expression in liver of non-hepatocyte markers. Interestingly, liver regeneration reverses H3K27me3 patterns and rejuvenates multiple molecular and physiological aspects of the aged liver.
Project description:Epigenetic alterations are one of the key hallmarks of aging. Emerging evidence in model organisms, senescent cell cultures and limitedly, murine, and human tissue samples suggest local effects impacting genes and regulatory elements. However, how chromatin changes broadly affect euchromatin-heterochromatin balance, three-dimensional chromatin conformation, histone composition and global transcriptome has not been addressed. Furthermore, the cause and impact of these alterations on tissue function and age-related loss of regeneration is not well-understood. Here, using murine liver as a model for regeneration and an integrated multi-omics approach, we find that aged cells assume a severely repressed hyper-quiescent chromatin state characterized by a condensed chromatin, broad heterochromatinization driven by H3K27me3, global suppression of the transcriptome and inability of the chromatin to self-interact over long distances. Interestingly, concomitant targeted chromatin opening occurs over developmental gene promoters leading to loss of cell identity. We extend our findings to other quiescent tissues including human liver biopsies. Our findings reveal that global chromatin alterations promote a cellular state that is refractory to injury sensing and repair. Local chromatin changes compromise cellular identity. Together, this study provides possible explanations for age-related loss of regeneration and tissue function at the chromatin level.
Project description:Epigenetic alterations are one of the key hallmarks of aging. Emerging evidence in model organisms, senescent cell cultures and limitedly, murine, and human tissue samples suggest local effects impacting genes and regulatory elements. However, how chromatin changes broadly affect euchromatin-heterochromatin balance, three-dimensional chromatin conformation, histone composition and global transcriptome has not been addressed. Furthermore, the cause and impact of these alterations on tissue function and age-related loss of regeneration is not well-understood. Here, using murine liver as a model for regeneration and an integrated multi-omics approach, we find that aged cells assume a severely repressed hyper-quiescent chromatin state characterized by a condensed chromatin, broad heterochromatinization driven by H3K27me3, global suppression of the transcriptome and inability of the chromatin to self-interact over long distances. Interestingly, concomitant targeted chromatin opening occurs over developmental gene promoters leading to loss of cell identity. We extend our findings to other quiescent tissues including human liver biopsies. Our findings reveal that global chromatin alterations promote a cellular state that is refractory to injury sensing and repair. Local chromatin changes compromise cellular identity. Together, this study provides possible explanations for age-related loss of regeneration and tissue function at the chromatin level.
Project description:Epigenetic alterations are one of the key hallmarks of aging. Emerging evidence in model organisms, senescent cell cultures and limitedly, murine, and human tissue samples suggest local effects impacting genes and regulatory elements. However, how chromatin changes broadly affect euchromatin-heterochromatin balance, three-dimensional chromatin conformation, histone composition and global transcriptome has not been addressed. Furthermore, the cause and impact of these alterations on tissue function and age-related loss of regeneration is not well-understood. Here, using murine liver as a model for regeneration and an integrated multi-omics approach, we find that aged cells assume a severely repressed hyper-quiescent chromatin state characterized by a condensed chromatin, broad heterochromatinization driven by H3K27me3, global suppression of the transcriptome and inability of the chromatin to self-interact over long distances. Interestingly, concomitant targeted chromatin opening occurs over developmental gene promoters leading to loss of cell identity. We extend our findings to other quiescent tissues including human liver biopsies. Our findings reveal that global chromatin alterations promote a cellular state that is refractory to injury sensing and repair. Local chromatin changes compromise cellular identity. Together, this study provides possible explanations for age-related loss of regeneration and tissue function at the chromatin level.