Biology subjects

Bishop, T. R.

Publications and source records attributed to Bishop, T. R..

10 recordsLinked to original sources

bioRxiv2025

A chemical-genetic interaction between PAF1 and ENL/AF9 YEATS inhibition

Transcriptional regulatory proteins are frequent drivers of oncogenesis and common targets for drug discovery. The transcriptional co-activator, ENL, which is localized to chromatin through its acetyllysine-binding YEATS domain, is preferentially required for the survival and pathogenesis of acute leukemia. Small molecules that inhibit the ENL YEATS domain show anti-leukemia effects in preclinical models, which is thought to be caused by the downregulation of pro-leukemic ENL target genes. However, the transcriptional effects of ENL YEATS domain inhibitors have not been studied in models of intrinsic or acquired resistance and, therefore, the connection between proximal transcriptional effects and downstream anti-proliferative response is poorly understood. To address this, we identified models of intrinsic and acquired resistance and used them to study the effects of ENL YEATS domain inhibitors. We first discovered that ENL YEATS domain inhibition produces similar transcriptional responses in naive models of sensitive and resistant leukemia. We then performed a CRISPR/Cas9-based genetic modifier screen and identified in-frame deletions of the essential transcriptional regulator, PAF1, that confer resistance to ENL YEATS domain inhibitors. Using these drug-resistance alleles of PAF1 to construct isogenic models, we again found that the downregulation of ENL target genes is shared in both sensitive and resistant leukemia. Altogether, these data support the conclusion that the suppression of ENL target genes is not sufficient to explain the anti-leukemia effects of ENL antagonists.

biochemistry↗

bioRxiv2025

The economic strategies of superorganisms

The leaf economics spectrum links strategies of plant investment in resource-acquiring leaves to overall fitness. We test whether an economic spectrum can also explain variation in ecological strategies of ant species across environmental gradients, where colony investment in workers is analogous to plant investment in leaves. A fast return of resource investment was associated with large colonies of smaller, less robust, short-lived workers with low nitrogen:phosphorus ratios. Slow resource payback was associated with small colonies of densely built, energetically conservative and longer-lived workers with high nitrogen:phosphorus ratios. Species representing the entire economic continuum co-occurred in all communities. Phylogenetic analyses suggest genus level conservation of core investment templates. These results unify studies of plants and ants, suggesting common economic principles apply across the tree of life.

ecology↗

bioRxiv2024

High-throughput diversification of protein-ligand surfaces to discover chemical inducers of proximity

Chemical inducers of proximity (CIPs) stabilize biomolecular interactions, often causing an emergent rewiring of cellular biochemistry1,2. While rational design strategies can expedite the discovery of heterobifunctional CIPs, monovalent, molecular glue-like CIPs have relied predominantly on serendipity3. Envisioning a prospective approach to discover molecular glues for a pre-selected target, we hypothesized that pre-existing ligands could be systematically decorated with chemical modifications to empirically discover protein-ligand surfaces that are tuned to cooperatively engage another protein interface. Here, we used sulfur(VI)-fluoride exchange (SuFEx)-based high-throughput chemistry (HTC) to install 3,163 structurally diverse chemical building blocks onto ENL and BRD4 ligands and then screened the crude products for degrader activity. This revealed dHTC1, a potent, selective, and stereochemistry-dependent degrader of ENL. It recruits CRL4CRBN to ENL through an extended interface of protein-protein and protein-ligand contacts, but only after pre-forming the ENL:dHTC1 complex. We also characterized two structurally distinct BRD4 degraders, including dHTC3, a molecular glue that selectively dimerizes the first bromodomain of BRD4 to SCFFBXO3, an E3 ligase not previously accessible for chemical rewiring. Altogether, this study introduces HTC as a facile tool to discover new CIPs and actionable cellular effectors of proximity pharmacology.

biochemistry↗

bioRxiv2024

Variable responses of individual species to tropical forest degradation

The functional stability of ecosystems depends greatly on interspecific differences in responses to environmental perturbation. However, responses to perturbation are not necessarily invariant among populations of the same species, so intraspecific variation in responses might also contribute. Such inter-population response diversity has recently been shown to occur spatially across species ranges, but we lack estimates of the extent to which individual populations across an entire community might have perturbation responses that vary through time. We assess this using 524 taxa that have been repeatedly surveyed for the effects of tropical forest logging at a focal landscape in Sabah, Malaysia. Just 39 % of taxa - all with non-significant responses to forest degradation - had invariant responses. All other taxa (61 %) showed significantly different responses to the same forest degradation gradient across surveys, with 6 % of taxa responding to forest degradation in opposite directions across multiple surveys. Individual surveys had low power (< 80 %) to determine the correct direction of response to forest degradation for one-fifth of all taxa. Recurrent rounds of logging disturbance increased the prevalence of intra-population response diversity, while uncontrollable environmental variation and/or turnover of intraspecific phenotypes generated variable responses in at least 44 % of taxa. Our results show that the responses of individual species to local environmental perturbations are remarkably flexible, likely providing an unrealised boost to the stability of disturbed habitats such as logged tropical forests.

ecology↗

bioRxiv2023

Disturbance increases functional diversity but decreases phylogenetic diversity of an arboreal tropical ant community

O_LITropical rainforest canopies host a highly diverse arthropod fauna, which contribute to ecosystem function through their functional (FD) and phylogenetic diversity (PD). While a lot of previous research has documented the severe negative impacts of disturbance on the FD and PD of ground invertebrate communities, our understanding of arboreal counterparts is limited. C_LIO_LIHere, we studied the effects of forest disturbance on an ecologically important invertebrate group, the ants, in a lowland rainforest in New Guinea. We exhaustively sampled 4000 m2 area of a primary and a secondary forest for canopy ants. We report > 2800 occurrences of 128 ant species in 852 trees, one of the most comprehensive arboreal collections to date. C_LIO_LITo test how ant PD and FD differ between the two forests, we constructed the ant species-level community phylogeny and measured 10 functional traits. Furthermore, we assessed by data exclusion the influence of species which were not nesting in individual trees (visitors) or only nesting (nesters), and of non-native species on FD and PD values. We expected that disturbance would decrease FD and PD in tree dwelling ants. We hypothesized that traits in primary forests would be more overdispersed due to the greater availability of ecological niches, while secondary forests would have stronger trait clustering due to a a stronger habitat filtering caused by more extreme microclimate. C_LIO_LIPrimary forests had higher species richness and PD than secondary forest. Surprisingly, we found higher FD in secondary forest. This pattern was robust even if we decoupled functional and phylogenetic signals or if non-native ant species were excluded from the data. Visitors did not contribute strongly to FD, but they increased PD. Community trait means further corroborate the functional distinctiveness of arboreal ants among secondary and primary forest, with almost all traits being impacted by disturbance and forest succession. C_LIO_LIWe conclude that the most plausible explanation is increased competition among closely related ant species in the secondary forest, which drives trait divergence. In the primary forest, abiotic habitat filters leads to more similar morphology and thus lower FD of phylogenetically more diverse ant assemblages. C_LI

ecology↗

bioRxiv2022

Metabolic adaptations underpin resistance to histone acetyltransferase inhibition

Histone acetyltransferases (HAT) catalyze the acylation of lysine side chains and are implicated in diverse human cancers as both oncogenes and non-oncogene dependencies1. Acetyl-CoA-competitive HAT inhibitors have garnered attention as potential cancer therapeutics and the first clinical trial for this class is ongoing (NCT04606446). Despite broad enthusiasm for these targets, notably including CBP/p300 and KAT6A/B2-5, the potential mechanisms of therapeutic response and evolved drug resistance remain poorly understood. Using comparative transcriptional genomics, we found that the direct gene regulatory consequences of CBP/p300 HAT inhibition are indistinguishable in models of intrinsically hypersensitive and insensitive acute myeloid leukemia (AML). We therefore modelled acquired drug resistance using a forward genetic selection and identified dysregulation of coenzyme A (CoA) metabolism as a facile driver of resistance to HAT inhibitors. Specifically, drug resistance selected for mutations in PANK3, a pantothenate kinase that controls the rate limiting step in CoA biosynthesis6. These mutations prevent negative feedback inhibition, resulting in drastically elevated concentrations of intracellular acetyl-CoA, which directly outcompetes drug-target engagement. This not only impacts the activity of structurally diverse CBP/p300 HAT inhibitors, but also agents related to an investigational KAT6A/B inhibitor that is currently in Phase-1 clinical trials. We further validated these results using a genome-scale CRISPR/Cas9 loss-of-function genetic modifier screen, which identified additional gene-drug interactions between HAT inhibitors and the CoA biosynthetic pathway. Top hits from the screen included the phosphatase, PANK4, which negatively regulates CoA production and therefore suppresses sensitivity to HAT inhibition upon knockout7, as well as the pantothenate transporter, SLC5A68, which enhances sensitivity. Altogether, this work uncovers CoA plasticity as an unexpected but potentially class-wide liability of anti-cancer HAT inhibitors and will therefore buoy future efforts to optimize the efficacy of this new form of targeted therapy.

molecular biology↗

bioRxiv2022

Collateral lethality between HDAC1 and HDAC2 exploits cancer-specific NuRD complex vulnerabilities

Histone deacetylases (HDACs) have been widely pursued as targets for anti-cancer therapeutics. However, many of these targets are universally essential for cell survival, which may limit the therapeutic window that can be achieved by drug candidates. By examining large collections of CRISPR/Cas9-based essentiality screens, we discovered a genetic interaction between HDAC1 and HDAC2 wherein each paralog is synthetically lethal with hemizygous deletion of the other. This collateral synthetic lethality is caused by recurrent chromosomal translocations that occur in diverse solid and hematological malignancies, including neuroblastoma and multiple myeloma. Using genetic deletion or dTAG-mediated degradation, we show that HDAC2 disruption suppresses the growth of HDAC1-deficient neuroblastoma in vitro and in vivo. Mechanistically, we find that targeted degradation of HDAC2 in these cells prompts the degradation of several members of the nucleosome remodeling and deacetylase (NuRD) complex, leading to diminished chromatin accessibility at HDAC2/NuRD-bound sites of the genome and impaired control of enhancer-associated transcription. Furthermore, we reveal that several of the degraded NuRD complex subunits are dependencies in neuroblastoma and multiple myeloma, providing motivation to develop paralog-selective HDAC1 or HDAC2 degraders. Altogether, we identify HDAC1/2 collateral synthetic lethality as a new therapeutic target and reveal a novel mechanism for exploiting NuRD-associated cancer dependencies.

cancer biology↗

bioRxiv2022

dsSurvival: Privacy preserving survival models for federated individual patient meta-analysis in DataSHIELD

ObjectiveAchieving sufficient statistical power in a survival analysis usually requires large amounts of data from different sites. Sensitivity of individual-level data, ethical and practical considerations regarding data sharing across institutions could be a potential challenge for achieving this added power. Hence we implemented a federated meta-analysis approach of survival models in DataSHIELD, where only anonymous aggregated data are shared across institutions, while simultaneously allowing for exploratory, interactive modelling. In this case, meta-analysis techniques to combine analysis results from each site are a solution, but an analytic workflow involving local analysis undertaken at individual studies hinders exploration. Thus, the aim is to provide a framework for performing meta-analysis of Cox regression models across institutions without manual analysis steps for the data providers. ResultsWe introduce a package (dsSurvival) which allows privacy preserving meta-analysis of survival models, including the calculation of hazard ratios. Our tool can be of great use in biomedical research where there is a need for building survival models and there are privacy concerns about sharing data.

bioinformatics↗

bioRxiv2020

Chemical inhibition of ENL/AF9 YEATS domains in acute leukemia

Transcriptional co-regulators, which mediate chromatin-dependent transcriptional signaling, represent tractable targets to modulate tumorigenic gene expression programs with small molecules. Genetic loss-of-function studies have recently implicated the transcriptional co-activator, ENL, as a selective requirement for the survival of acute leukemia and highlighted an essential role for its chromatin reader YEATS domain. Motivated by these discoveries, we executed a screen of nearly 300,000 small molecules and identified an amido-imidazopyridine inhibitor of the ENL YEATS domain (IC50 = 7 {micro}M). Leveraging a SuFEx-based high-throughput approach to medicinal chemistry optimization, we discovered SR-0813 (IC50 = 25 nM), a potent and selective ENL/AF9 YEATS domain inhibitor that exclusively inhibits the growth of ENL-dependent leukemia cell lines. Armed with this tool and a first-in-class ENL PROTAC, SR-1114, we detailed the response of AML cells to pharmacological ENL disruption for the first time. Most notably, displacement of ENL from chromatin by SR-0813 elicited a strikingly selective suppression of ENL target genes, including HOXA9/10, MYB, MYC and a number of other leukemia proto-oncogenes. Our study reproduces a number of key observations previously made by CRISPR/Cas9 loss of function and dTAG-mediated degradation, and therefore, both reinforces ENL as an emerging leukemia target and validates SR-0813 as a high-quality chemical probe.

cancer biology↗

bioRxiv2019

Harmonisation of Physical Activity Variables by Indirect Validation: A Doubly Labelled Water Study

Harmonisation of data for pooled analysis relies on the principle of inferential equivalence between variables from different sources. Ideally, this is achieved using models of the direct relationship with gold standard criterion measures, but the necessary validation data are often unavailable. This study examines an alternative method of harmonisation by indirect validation. Starting methods were self-report or accelerometry, from which we derived indirect models of relationships with doubly labelled water (DLW)-measured physical activity energy expenditure (PAEE) using sets of two bridge equations via one of three intermediate measures. Coefficients and performance of indirect models were compared to corresponding direct validation models (linear regression of DLW-measured PAEE on starting methods). Indirect model beta coefficients were attenuated compared to direct model betas (10-63%), narrowing the range of PAEE values; attenuation was greater when bridge equations were weak. Directly and indirectly harmonised models had similar error variance but most indirectly derived values were biased at group-level. Correlations with DLW-measured PAEE were identical after harmonisation using continuous linear but not categorical models. Wrist acceleration harmonised to DLW-measured PAEE via combined accelerometry and heart rate sensing had lowest error variance (24.5%) and non-significant mean bias 0.9 (95%CI: -1.6; 3.4) kJ*day-1*kg-1. Associations between PAEE and BMI were similar for directly and indirectly harmonised values, but most fell outside the confidence interval of the criterion PAEE-to-BMI association. Indirect models can be used for harmonisation. Performance depends on the measurement properties of original data, variance explained by available bridge equations, and similarity of population characteristics.

epidemiology↗