Kelley, M. E. | Search bioRxiv

bioRxiv2026

VPS4 and CHMP7 release centromeres from the nuclear envelope for post-mitotic positioning in daughter nuclei

Eukaryotic chromosomes occupy ordered configurations within the nucleus, an organization that must be re-established in daughter cells as the nuclear envelope reforms at the end of mitosis. The conserved enzyme VPS4 and ESCRT-III proteins mediate nuclear envelope reformation, yet their role in post-mitotic centromere positioning remains unclear. Here, we develop a chemical genetics approach to analyze the role of VPS4 in human cells. VPS4 inhibition prevents the clearance of CHMP7 from centromeres, which remain constrained in ring-like configurations established during mitosis. Without VPS4 activity, CHMP7, but not other ESCRT-III proteins, forms nuclear foci, nuclear envelope protein distribution is altered and inner nuclear membrane invaginations appear. Following these defects, DNA damage is observed in the vicinity of centromeres. Depletion of CHMP7, but not CHMP4B, suppresses this damage. We propose that VPS4-mediated turnover of CHMP7 releases centromeres from transient nuclear envelope contacts, ensuring their proper positioning after mitosis and maintaining genome integrity.

cell biology↗

bioRxiv2023

High-content microscopy reveals a morphological signature of bortezomib resistance

Drug resistance is a challenge in anticancer therapy, particularly with targeted therapeutics and cytotoxic compounds. In many cases, cancers can be resistant to the drug prior to exposure, i.e., possess intrinsic drug resistance. However, we lack target-independent methods to anticipate resistance in cancer cell lines or characterize intrinsic drug resistance without a priori knowledge of its cause. We hypothesized that cell morphology could provide an unbiased readout of drug sensitivity prior to treatment. We therefore isolated clonal cell lines that were either sensitive or resistant to bortezomib, a well-characterized proteasome inhibitor and anticancer drug to which many cancer cells possess intrinsic resistance. We then measured high-dimensional single-cell morphology profiles using Cell Painting, a high-content microscopy assay. Our imaging- and computation-based profiling pipeline identified morphological features typically different between resistant and sensitive clones. These features were compiled to generate a morphological signature of bortezomib resistance, which correctly predicted the bortezomib treatment response in seven of ten cell lines not included in the training dataset. This signature of resistance was specific to bortezomib over other drugs targeting the ubiquitin-proteasome system. Our results provide evidence that intrinsic morphological features of drug resistance exist and establish a framework for their identification.

cancer biology↗