Biology subjects

Pope, J.

Publications and source records attributed to Pope, J..

3 recordsLinked to original sources

bioRxiv2026

A PERK/FOXO1 AXIS LINKS DNA DAMAGE TO FIBROBLAST SURVIVAL IN DIFFUSE CUTANEOUS SYSTEMIC SCLEROSIS

ObjectiveDiffuse cutaneous systemic sclerosis (dcSSc) is a life-limiting fibrotic disease. We and others have shown that dcSSc fibroblasts accumulate numerous somatic mutations associated with senescence-like features; however, the mechanism(s) enabling their survival remain unclear. MethodsSkin biopsies were obtained from lesional tissues from dcSSc (n=10), dcSSc treated with autologous hematopoietic stem cell transplantation (ASCT, n=8) or 7 age/sex-matched healthy controls. Primary dermal fibroblasts were generated from biopsies. Spatial RNA sequencing, immunoblotting, confocal microscopy, and functional assays were used to mechanistically delineate signaling pathways linking DNA-damage with fibroblast survival. ResultsdcSSc fibroblasts demonstrated increased pH2AX DNA double-strand-break foci yet remained apoptosis resistant. These cells displayed features of metabolic-stress remodeling, including mitochondrial hyperpolarization, increased reactive oxygen species production, and enhanced mitochondrial biogenesis. Spatial transcriptomics and subsequent biochemical analyses identified activation of a PERK/ATF4/FOXO1 axis, characterized by PERK phosphorylation, selective ATF4 translation, FOXO1 nuclear translocation, and induction of downstream antioxidant and metabolic programs. In contrast, fibroblasts from post-ASCT patients exhibited normalization of DNA-damage markers and mitochondrial parameters without ATF4/FOXO1 activation. Pharmacologic inhibition of either PERK or FOXO1 selectively restored mitochondrial-dependent apoptosis in dcSSc fibroblasts, demonstrating that this axis is required for their survival following extensive genomic injury. ConclusiondcSSc fibroblasts persist despite substantial genomic injury by engaging a PERK/ATF4/FOXO1 metabolic-adaptation program that suppresses mitochondrial-dependent apoptosis. This survival axis is not present after ASCT. Targeting PERK or FOXO1 restores apoptosis selectively in dcSSc fibroblasts, highlighting its potential use as a therapeutic target for eliminating pathogenic senescence-like fibroblasts in dcSSc. HighlightsO_LIBoth ex-vivo skin and in-vitro primary dermal fibroblasts derived from dcSSc patients have a higher frequency of intrinsic DNA damage signals and senescence-associated features; yet they evade mitochondrial-dependent apoptosis. C_LIO_LIPathogenic dcSSc fibroblasts rewire their metabolism, characterized by mitochondrial hyperpolarization and elevated ROS. C_LIO_LISpatial transcriptomics and functional analyses reveal a PERK/ATF4/FOXO1 stress-adaptation axis that drives fibroblast survival in dcSSc. C_LIO_LIThis maladaptive survival program characterized by increased genotoxic stress, and mitochondrial remodelling is absent in post-ASCT fibroblasts. C_LIO_LITargeting PERK or FOXO1 selectively sensitizes dcSSc fibroblasts to apoptosis revealing a potential promising therapeutic strategy in dcSSc. C_LI Graphical abstract O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=142 SRC="FIGDIR/small/706443v1_ufig1.gif" ALT="Figure 1"> View larger version (31K): org.highwire.dtl.DTLVardef@1b3f791org.highwire.dtl.DTLVardef@42548aorg.highwire.dtl.DTLVardef@bc4ce1org.highwire.dtl.DTLVardef@5b4d48_HPS_FORMAT_FIGEXP M_FIG C_FIG

molecular biology↗

bioRxiv2025

An ERα-Dependent Hypoxia Response Defines EMT-Adjacent Tumour Regions and Suppresses the Pro-survival Effects of Amiloride in Estrogen Receptor-Positive Breast Cancer

Estrogen receptor-positive (ER+) breast cancer carries a lifelong risk of recurrence and disease progression, with hypoxia-associated transcriptional signatures linked to poor prognosis and therapy resistance. While the effects of hypoxia on tumour progression are well studied, the impact on ER epigenomic regulation remains poorly characterised. Here, we demonstrate that activation of hypoxia-inducible factors (HIFs) dramatically remodels ER chromatin localisation in ER+ breast cancer cells. Transcripts of genes located near hypoxia-induced ER binding sites are significantly associated with reduced recurrence-free survival in breast cancer patients. Transcriptomic profiling under hypoxic conditions (1% oxygen), with and without ER depletion by fulvestrant, revealed a hypoxia-induced, ER-dependent gene expression programme, including upregulation of epithelial sodium channel (ENaC) regulatory subunits that results in acquired sensitivity to the ENaC inhibitor amiloride. Notably, this transcriptional response is spatially correlated with the epithelial-to-mesenchymal hallmark in patient tumours. Our findings establish an interdependence between ER signalling and the hypoxic response, and present functional evidence that ER reprogramming offers novel therapeutic opportunities that bypass the need to directly target the hypoxic response.

cancer biology↗

bioRxiv2019

The effect of proximity on the function and energy transfer capability of fluorescent protein pairs

Fluorescent proteins (FPs) are commonly used in pairs to monitor dynamic biomolecular events through changes in their proximity via distance dependent processes such as Forster resonance energy transfer (FRET). Many FPs have a tendency to oligomerise, which is likely to be promoted through attachment to associating proteins through increases in local FP concentration. We show here that on association of FP pairs, the inherent function of the FPs can alter. Artificial dimers were constructed using a bioorthogonal Click chemistry approach that combined a commonly used green fluorescent protein (superfolder GFP) with itself, a yellow FP (Venus) or a red FP (mCherry). In each case dimerisation changes the inherent fluorescent properties, including FRET capability. The GFP homodimer demonstrated synergistic behaviour with the dimer being brighter than the sum of the two monomers. The structure of the GFP homodimer revealed that a water-rich interface is formed between the two monomers, with the chromophores being in close proximity with favourable transition dipole alignments. Dimerisation of GFP with Venus results in a complex displaying [~]86% FRET efficiency, which is significantly below the near 100% efficiency predicted. When GFP is complexed with mCherry, FRET and mCherry fluorescence itself is essentially lost. Thus, the simple assumptions used when monitoring interactions between proteins via FP FRET may not always hold true, especially under conditions whereby the protein-protein interactions promote FP interaction. O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=127 SRC="FIGDIR/small/838888v1_ufig1.gif" ALT="Figure 1"> View larger version (25K): org.highwire.dtl.DTLVardef@1863e41org.highwire.dtl.DTLVardef@61255dorg.highwire.dtl.DTLVardef@1dc188forg.highwire.dtl.DTLVardef@d066ad_HPS_FORMAT_FIGEXP M_FIG C_FIG

biochemistry↗