Biology subjects

Cornwell, J. A.

Publications and source records attributed to Cornwell, J. A..

3 recordsLinked to original sources

bioRxiv2024

Lineage-specific CDK activity dynamics characterize early mammalian development

Cyclin-dependent kinases (CDK) are key regulatory enzymes that regulate proliferation dynamics and cell fate in response to extracellular inputs. It remains largely unknown how CDK activity fluctuates and influences cell commitment in vivo during early mammalian development. Here, we generated a transgenic mouse model expressing a CDK kinase translocation reporter (KTR) that enabled quantification of CDK activity in live single cells. By examining pre- and post- implantation mouse embryos at different stages, we observed a progressive decrease in CDK activity in cells from the trophectoderm (TE) prior to implantation. This drop correlated with the establishment of an FGF4-dependent signaling gradient through the embryonic-abembryonic axis. Furthermore, we showed that CDK activity levels do not determine cell fate decisions during pre-implantation development. Finally, we uncovered the existence of conserved regulatory mechanisms in mammals by revealing lineage-specific regulation of CDK activity in TE-like human cells.

developmental biology↗

bioRxiv2023

Comprehensive mapping of cell fates in microsatellite unstable cancer cells support dual targeting of WRN and ATR

Addiction to the WRN helicase is a unique vulnerability of human cancers with high levels of microsatellite instability (MSI-H). However, while prolonged loss of WRN ultimately leads to cell death, little is known about how MSI-H cancers initially respond to acute loss of WRN, knowledge that would be helpful for informing clinical development of WRN-targeting therapy, predicting possible resistance mechanisms, and identifying useful biomarkers of successful WRN inhibition. Here, we report the construction of an inducible ligand-mediated degradation system wherein the stability of endogenous WRN protein can be rapidly and specifically tuned, enabling us to track the complete sequence of cellular events elicited by acute loss of WRN function. We find that WRN degradation leads to immediate accrual of DNA damage in a replication-dependent manner that curiously did not robustly engage checkpoint mechanisms to halt DNA synthesis. As a result, WRN-degraded MSI-H cancer cells accumulate DNA damage across multiple replicative cycles and undergo successive rounds of increasingly aberrant mitoses, ultimately triggering cell death. Of potential therapeutic importance, we find no evidence of any generalized mechanism by which MSI-H cancers could adapt to near-complete loss of WRN. However, under conditions of partial WRN degradation, addition of low dose ATR inhibitor significantly increased their combined efficacy to levels approaching full inactivation of WRN. Overall, our results provided the first comprehensive view of molecular events linking upstream inhibition of WRN to subsequent cell death and suggested a potential therapeutical rationale for dual targeting of WRN and ATR.

cancer biology↗

bioRxiv2021

Cell-Projection Pumping of Fibroblast Contents into Osteosarcoma SAOS-2 Cells Correlates with Increased SAOS-2 Proliferation and Migration, and also with Altered Morphology

We earlier reported that cell-projection pumping transfers fibroblast contents to cancer cells, and this alters cancer cell phenotype. We now report on single-cell tracking of time lapse recordings from co-cultured fluorescent fibroblasts and SAOS-2 osteosarcoma cells, tracking 5,201 cells across 7 experiments. The fluorescent lipophilic marker DiD was used to label fibroblast organelles, and to trace transfer of fibroblast cytoplasm into SAOS-2. We related SAOS-2 phenotypic change to levels of fluorescence transfer from fibroblasts to SAOS-2, and also to what we term compensated fluorescence, that numerically projects mother cell fluorescence post-mitosis, into daughter cells. Comparison of absolute with compensated fluorescence, allowed deduction if phenotypic effects in mother SAOS-2, were inherited by their daughters. SAOS-2 receipt of fibroblast fluorescence correlated by Kendalls tau: with cell-profile area, and without evidence for persistence in daughter cells (median tau = 0.51, p < 0. 016); negatively and weakly with cell circularity, and with evidence for persistence (median tau = -0.19, p < 0.05); and very weakly with cell migration velocity, and without evidence for persistence (median tau = 0.01, p < 0.016). Also, mitotic SAOS-2 had higher rates of prior fluorescence uptake (median = 64.9 units/day), compared with non dividing cells (median = 35.6 units/day, p < 0.016), and there was no evidence for persistence post-mitosis. We conclude there is appreciable impact of cell-projection pumping on cancer cell phenotype, relevant to cancer histopathological diagnosis, clinical spread, and growth, with most effects reset by cancer cell mitosis.

cancer biology↗