Biology subjects

Prince, K.

Publications and source records attributed to Prince, K..

6 recordsLinked to original sources

bioRxiv2026

Nuclear blebs are composed of variable chromatin states but consistently enrich transcription initiation relative to elongation

Nuclear blebs are herniations of the nucleus that occur in many human conditions including aging, heart disease, muscular dystrophy, and many cancers. Nuclear blebbing causes nuclear rupture and cellular dysfunction. However, understanding the formation, stability, and identification of nuclear blebs remains an ongoing challenge. Our previous studies reveal that nuclear blebs are best hallmarked by decreased DNA density. To determine if chromatin decompaction underlies decreased DNA density in nuclear blebs, we investigated the histone composition of nuclear blebs across multiple cell lines. Time lapse and immunofluorescence imaging revealed that global histone H2B and H3 levels are decreased in the nuclear bleb relative to the nuclear body. Next, we imaged histone modification states of euchromatin and heterochromatin, which respectively track decompact and compact states of chromatin. Overall, we find that nuclear blebs display variable histone modification state across cell lines, as euchromatin does not consistently enrich nor is heterochromatin consistently depleted. Nuclear blebs did consistently show active RNA Pol II initiation is enriched relative to elongation. Thus, we find that the local histone modification state is not an essential component of nuclear blebs while transcription initiation enrichment over elongation is reproducible across cell lines and conditions. Summary statementWe measured histones and their modification states in nuclear blebs. We find that chromatin state is variable while transcription initiation is consistently enriched relative to elongation in nuclear blebs.

cell biology↗

bioRxiv2025

Transcriptional activity generates chromatin motion that drives nuclear blebbing

Abnormal nuclear morphology is a hallmark of human diseases, including cancers and age-related disorders. Previously, maintenance of nuclear morphology and integrity was thought to be solely dependent on a force balance between nuclear mechanical resistance and actin antagonism. However, our recent work revealed that inhibiting RNA polymerase II suppresses nuclear blebbing independent of altering force balance, but the mechanism remains unknown. Through removing cell culture media serum and then adding it back, we can decrease and then restore transcriptional activity. Decreasing transcriptional activity decreases nuclear bleb formation, stability, and rupture while returning transcriptional activity restores nuclear blebbing. These modulations of transcriptional activity did not alter nuclear or actin mechanics. The mean square displacement (MSD) of chromatin domains labeled via transfected Cy3-dNTPs revealed that transcription activity regulates chromatin motion. To determine if increasing chromatin motion is a mechanism to increase nuclear blebbing, we used an established RAD51 inhibitor BO2. We verified BO2 increases chromatin domain motion which resulted in increased nuclear blebbing. We reveal the mechanism by which transcriptional activity drives nuclear blebbing is through chromatin motion. Thus, two hallmarks of human disease are directly linked via transcriptional activity and abnormal nuclear shape. Statement of SignificanceO_LINuclear blebs are hallmarks of disease progression that cause dysfunction, but how they are formed remains unanswered. C_LIO_LIWe find that chromatin motion generated by transcriptional activity is essential for both nuclear bleb formation and stability. This was independent of changes in nuclear stiffness or actin antagonism. C_LIO_LIThis finding provides a key advancement in our understanding of nuclear bleb formation. Furthermore, it reveals transcriptional activity as a novel contributor to nuclear blebbing in addition to the paradigm of nuclear shape determined as a force balance between nuclear resistance and actin antagonism. C_LI

cell biology↗

bioRxiv2025

Lamin B loss in nuclear blebs is rupture dependent while increased DNA damage is rupture independent

The nucleus houses genetic information and functions separate from the rest of the cell. Loss of nuclear shape results in nuclear ruptures. Nuclear blebs are deformations identified by decreased DNA density, while lamin B levels vary drastically. To determine if decreased lamin B levels are due to nuclear rupture, we used immunofluorescence to measure levels of lamin B and emerin, a nuclear envelope protein that enriches to sites of nuclear rupture. We observed that cell types that exhibit decreased levels of lamin B also show an enrichment of emerin in nuclear blebs. Oppositely, in other cell types, nuclear blebs display maintained levels of lamin B1 and showed no emerin enrichment. To determine how nuclear rupture affects DNA damage, we time lapse imaged nuclear rupture dynamics then fixed the same cells to conduct immunofluorescence of {gamma}H2AX and emerin. We find that DNA damage levels are higher in blebbed nuclei independent of nuclear rupture. Thus, we confirm that lamin B1 loss in nuclear blebs is due to nuclear rupture and blebbed nuclei have increased DNA damage that is independent of rupture. Summary statement (180-200 characters): We measured lamin B and DNA damage in blebbed nuclei to determine the effect of nuclear rupture. We find that nuclear rupture causes loss of lamin B in nuclear blebs but that increased DNA damage in blebbed nuclei is independent of rupture.

cell biology↗

bioRxiv2024

A self-limiting Sterile Insect Technique alternative for Ceratitis capitata

Genetic biocontrol systems have broad applications in population control of insects implicated in both disease spread and food security. In this study we establish and characterise a novel split-CRISPR/Cas9 system we term Sex Conversion Induced by CRISPR (SCIC) in Ceratitis capitata (the Mediterranean fruit fly), a major agricultural pest with a global distribution. Using the white eye gene for toolkit selection, we achieved up to 100% CRISPR/Cas9 efficiency, displaying the feasibility of C. capitata split-CRISPR/Cas9 systems using constitutive promoters. We then induce sex-conversion by targeting the transformer gene in a SCIC approach aimed for SIT-mediated releases upon radiation-based sterilisation. Knock-out of transformer induced partial to full female-to-male sex-conversion, with remaining individuals all being intersex and sterile. SCIC population modelling shows superior performance to traditional population control strategies, allowing for faster population elimination with fewer released sterile males. Our results build the foundation for further genetic pest control methods of C. capitata and related tephritid agricultural pests. Significance statementAgricultural industry faces increasing threat from a multitude of pests including the domineering tephritid fruit flies. Genetic engineering of these pests has been recently tested to develop more efficient and affordable population control strategies. Here, we develop a new approach to improve existing population control measures by testing it in one of the most famous and dangerous tephritids, the Mediterranean fruit fly. Through optimisation, we achieved desired outcomes: female fly absence achieved via semi and full female-to-male sex conversion by CRISPR-mediated genome editing through gene mutations. For the first time in this insect, we used a split, and thus inducible, approach for such genome editing. Our work holds the potential to significantly improve tephritid population control strategies.

genetics↗

bioRxiv2024

DNA density is a better indicator of a nuclear bleb than lamin B loss

Nuclear blebs are herniations of the nucleus that occur in diseased nuclei that cause nuclear rupture leading to cellular dysfunction. Chromatin and lamins are two of the major structural components of the nucleus that maintain its shape and function, but their relative roles in nuclear blebbing remain elusive. Lamin B is reported to be lost in blebs by qualitative data while quantitative studies reveal a spectrum of lamin B levels in nuclear blebs dependent on perturbation and cell type. Chromatin has been reported to be decreased or de-compacted in nuclear blebs, but again the data are not conclusive. To determine the composition of nuclear blebs, we compared the immunofluorescence intensity of lamin B and DNA in the main nucleus body and nuclear bleb across cell types and perturbations. Lamin B nuclear bleb levels varied drastically across MEF wild type and chromatin or lamins perturbations, HCT116 lamin B1-GFP imaging, and human disease model cells of progeria and prostate cancer. However, DNA concentration was consistently decreased to about half that of the main nucleus body across all measured conditions. Using Partial Wave Spectroscopic (PWS) microscopy to measure chromatin density in the nuclear bleb vs body we find similar results that DNA is consistently less dense in nuclear blebs. Thus, our data spanning many different cell types and perturbations supports that decreased DNA is a better marker of a nuclear bleb than lamin B levels that vary widely.

cell biology↗

bioRxiv2020

Effectiveness of protected areas in conserving tropical forest birds

Protected areas are the cornerstones of global biodiversity conservation efforts1,2, but to fulfil this role they must be effective at conserving the ecosystems and species that occur within their boundaries. This is particularly imperative in tropical forest hotspots, regions that concentrate a major fraction of the worlds biodiversity while also being under intense human pressure3-5. But these areas strongly lack adequate monitoring datasets enabling to contrast biodiversity in protected areas with comparable unprotected sites6,7. Here we take advantage of the worlds largest citizen science biodiversity dataset - eBird8 - to quantify the extent to which protected areas in eight tropical forest biodiversity hotspots are effective at retaining bird diversity, and to understand the underlying mechanisms. We found generally positive effects of protection on the diversity of bird species that are forest-dependent, endemic to the hotspots, or threatened or Near Threatened, but not on overall bird species richness. Furthermore, we show that in most of the hotspots examined this is driven by protected areas preventing both forest loss and degradation. Our results support calls for increasing the extent and strengthening the management efforts within protected areas to reduce global biodiversity loss9-11.

ecology↗