Summary
Cellular senescence, the irreversible cessation of the cell cycle, has emerged as an important regulator of
age- associated pathologies. Senescence is linked to compromised genome organization, loss of coordinated
gene expression, and activation of a senescence-associated secretory phenotype (SASP), an inflammatory
cascade that can affect neighboring cells. Aspects of senescence are likely beneficial to tissue homeostasis
through immune-mediated clearance of damaged cells, while other aspects and the SASP are likely deleterious
and have been linked to chronic inflammation and age-related pathologies. Thus, dissecting the molecular
mechanisms that direct the emergence of senescence remains of interest to a wide variety of scientists,
including those studying aging, age-linked disease, and cellular identity. Nuclear architecture is a powerful
mechanism underlying coordinated gene expression. While senescence is associated with a loss of peripheral
chromatin organization, it is unclear if these changes to genome organization result in loss of spatial LAD
positioning; if so, do these positioning changes precede senescence or are they a byproduct of senescence?
Moreover, because of the population-based approach of genomics assays used to probe senescence, it
remains unknown if there is heterogeneity of genome organization as cells senesce or if synchronous changes
occur in all cells. The importance of this question is highlighted by studies using state-of-the-art imaging
technologies, similar to the ones we propose, demonstrating remarkable heterogeneity in genome organization
across single cells that have been masked by bulk assays. In the proposed studies, we seek to test the
hypothesis that compromised transcriptional mechanisms that maintain the spatial positioning of loci relative
to the nuclear lamina underlie senescence phenotypes. We will use a combination of Oligopaints and super-
resolution microscopy to identify and dissect the molecular players that guide spatial positioning and their
relationship to chromatin structure and senescence at single-cell resolution. Our interdisciplinary team will
reveal how locus positioning changes are linked to senescence and will manipulate regulators of genome
spatial positioning that we have started to identify to determine if senescence phenotypes are accelerated by
their alteration. Given the emerging importance of nuclear architecture in several human diseases, our studies
will provide critical insights into the molecular rationale for targeting genome organization changes in
senescence, knowledge that can be applied to other diseases including aging-associated conditions and
cancer.