Biology subjects

Dent, L. G.

Publications and source records attributed to Dent, L. G..

6 recordsLinked to original sources

bioRxiv2026

Hippo pathway perturbation disrupts cell fate control in the Drosophila eye

During animal development, cells acquire specialised fates in a precise spatiotemporal order, which is essential for producing tissues that function appropriately. Cell fate specification is governed by multiple signalling pathways, as well as mechanical forces, which impact cellular transcription. Two such signalling pathways are the Hippo pathway and EGFR pathway, which both control organ growth and the fate of certain cell types in multiple species. Here, we show that Hippo signalling is essential for the maintenance of the cone and primary pigment cell fates in the developing Drosophila eye. When Hippo signalling is compromised, its nuclear effectors Yorkie and Scalloped drive increased expression of the EGFR pathway transcription repressor Yan, which antagonises the cone and primary pigment cell fates. Thus, in addition to its role as a growth suppressor, Hippo signalling promotes the fate of multiple eye cells by maintaining their responsiveness to inductive cues from the EGFR pathway. AUTHOR SUMMARYAs multicellular organisms grow and develop from a zygote, individual cells become increasingly specialised. Cell fate is specified and maintained by the coordinate action of different signalling pathways, whose activity must be tightly controlled in a spatiotemporal fashion. If this fails, cell fate can be disturbed, which can cause developmental abnormalities, and diseases such as cancers. Here, we describe a new function for the Hippo signalling pathway, which was originally discovered as a regulator of Drosophila tissue growth and subsequently linked to the genesis of multiple human cancers. Hippo signalling is essential for maintaining the fate of two key cell types in the Drosophila eye, primary pigment cells and cone cells. Without Hippo signalling these cells cannot properly respond to signals from another key signalling network, the EGFR pathway. Our discoveries add to a growing literature where the Hippo growth control pathway is repurposed to control cell fate in tissues that have ceased growth.

developmental biology↗

bioRxiv2022

Characterization of proteome-size scaling by integrative omics reveals mechanisms of proliferation control in cancer

Almost all living cells maintain size uniformity through successive divisions. Proteins that sub- or super-scale with size act as rheostats which regulate cell progression. A comprehensive atlas of these proteins is lacking; particularly in cancer cells where both mitogen and growth signalling are dysregulated. Utilising a multi-omic strategy, that integrates quantitative single cell imaging, phosphoproteomic and transcriptomic datasets, we leverage the inherent size heterogeneity of melanoma cells to investigate how peptides, post-translational modifications, and mRNAs scale with cell size to regulate proliferation. We find melanoma cells have different mean sizes, but all retain uniformity. Across the proteome, we identify proteins and phosphorylation events that sub and super scale with cell size. In particular, G2/M, biosynthetic, and cytoskeletal regulators sub- and super-scale with size. In small cells growth and proliferation processes are tightly coupled by translation which promotes CCND1 accumulation and anabolic increases in mass. Counter intuitively, anabolic growth pathways and translational process are low in large cells, which throttles the expression of factors such as CCND1 and thereby coupling proliferation from anabolic growth. Strikingly, these cells exhibit increased growth and comparable proliferation rates. Mathematical modelling suggests that decoupling growth and proliferative signalling fosters proliferation under mitogenic inhibition. As factors which promote adhesion and actin reorganization super-scale with size or are enriched in large cells, we suggest that growth/proliferation in these cells may be decoupled by cell spreading and mechanics. This study provides one of the first demonstrations of size-scaling phenomena in cancer and how morphology determines the chemistry of the cell.

systems biology↗

bioRxiv2022

3D single-cell shape analysis of cancer cells using geometric deep learning

AO_SCPLOWBSTRACTC_SCPLOWAberrations in 3D cell morphogenesis are linked to diseases such as cancer. Yet there is little systems-level understanding of cell shape determination in 3D, largely because there is a paucity of data-driven methods to quantify and describe 3D cell shapes. We have addressed this need using unsupervised geometric deep learning to learn shape representations of over 95,000 melanoma cells imaged by 3D high-throughput light-sheet microscopy. We used a dynamic graph convolutional foldingnet autoencoder with improved deep embedded clustering to simultaneously learn lower-dimensional representations and classes of 3D cell shapes. We describe a landscape of 3D cell morphology using deep learning-derived 3D quantitative morphological signatures (3DQMS) across different substrate geometries, following treatment by different clinically relevant small molecules and systematic gene depletion in high-throughput. By data integration, we predict modes of action for different small molecules providing mechanistic insights and blueprints for biological re-engineering. Finally, we provide explainability and interpretability for deep learning models.

bioinformatics↗

bioRxiv2022

Actin networks modulate heterogenous NF-κB dynamics in response to TNFα

The canonical NF-{kappa}B transcription factor RELA is a master regulator of immune and stress responses and is upregulated in PDAC tumours. Here, we characterised previously unknown endogenous RELA-GFP dynamics in PDAC cell lines by live single cell imaging, which revealed rapid, sustained and non-oscillatory nuclear RELA following TNF stimulation. Using Bayesian analysis of single cell datasets with variation in nuclear RELA, we computationally predicted that RELA heterogeneity in PDAC cell lines is dependent on F-actin dynamics. By RNA-seq, we identified the actin regulators NUAK2 and ARHGAP31 as transcriptionally regulated by RELA. In turn, NUAK2 or ARHGAP31 siRNA depletion downregulates TNF-stimulated RELA nuclear localisation in PDAC cells, establishing a novel negative feedback loop regulating RELA activation by TNF. We identify an additional actin-independent feedback loop involving RELB, which suppresses TNF-mediated RELA nuclear localisation following RELA mediated upregulation of RELB. Taken together, we provide computational and experimental support for interdependence between the F-actin network and RELA translocation dynamics in PDAC.

cancer biology↗

bioRxiv2021

Environmentally dependent and independent control of cell shape determination by Rho GTPase regulators in melanoma

In order to invade 3D tissues, cancer cells dynamically change cell morphology in response to geometric and mechanical cues in the environment. But how cells determine their shape in 3D versus 2D environments is poorly understood. Studying 2D versus 3D single cell shape determination has historically been technically difficult due to the lack of methodologies to directly compare the two environments. We developed an approach to study cell shape in 2D versus 3D by measuring cell shape at different depths in collagen using stage-scanning oblique plane microscopy (ssOPM). We find characteristic shape changes occur in melanoma cells depending on whether a cell is attached to a 2D surface or 3D environment, and that these changes can be modulated by Rho GTPase regulatory proteins. Our data suggest that regulation of cell protrusivity undergoes a switch of control between different Rho GTPase regulators depending on the physical microenvironment.

cell biology↗

bioRxiv2019

Pits and CtBP control tissue growth in Drosophila melanogaster with the Hippo pathway transcription repressor, Tgi.

The Hippo pathway is an evolutionary conserved signalling network that regulates organ size, cell fate control and tumorigenesis. In the context of organ size control, the pathway incorporates a large variety of cellular cues such as cell polarity and adhesion into an integrated transcriptional response. The central Hippo signalling effector is the transcriptional co-activator Yorkie, which controls gene expression in partnership with different transcription factors, most notably Scalloped. When it is not activated by Yorkie, Scalloped can act as a repressor of transcription, at least in part due to its interaction with the corepressor protein Tgi. The mechanism by which Tgi represses transcription is incompletely understood and therefore we sought to identify proteins that potentially operate together with it. Using an affinity purification and mass-spectrometry approach we identified Pits and CtBP as Tgi-interacting proteins, both of which have been linked to transcriptional repression. Both Pits and CtBP were required for Tgi to suppress the growth of the D. melanogaster eye and CtBP loss suppressed the undergrowth of yorkie mutant eye tissue. Furthermore, as reported previously for Tgi, overexpression of Pits suppressed transcription of Hippo pathway target genes. These findings suggest that Tgi might operate together with Pits and CtBP to repress transcription of genes that normally promote tissue growth. The human orthologues of Tgi, CtBP and Pits (VGLL4, CTBP2 and IRF2BP2) physically and functionally interact to control transcription, implying that the mechanism by which these proteins control transcriptional repression is conserved throughout evolution.

developmental biology↗