Biology subjects

Grant, R.

Publications and source records attributed to Grant, R..

10 recordsLinked to original sources

bioRxiv2026

Sex-differentiated hormonal microenvironments recapitulate in vivo liver metabolism in human iPSC-derived organoids

Bioengineers strive to recreate in vivo microenvironments in vitro to reduce our use of animal models and provide insights into human biology. While liver models show promise, sex differences in liver biology remain largely neglected in preclinical studies. Despite the 2014 EU mandate for the inclusion of women in clinical trials, decoupling of research data by sex is historically rare, with only 11% of papers disaggregating data by sex. This gap contributes to women being more susceptible to drug-induced liver injury (DILI) and being underserved in drug development, as well as to costly drug attrition levels. Here we present a novel approach to modelling sex differences in vitro. Human induced pluripotent stem cells (iPSCs) from both male (XY) and female (XX) donors, were differentiated into hepatocyte liver spheroids and exposed to in vivo-mimicking levels of testosterone, progesterone, and oestrogen in high-throughput microwell format. We successfully recapitulated sex-specific metabolic profiles and demonstrated significant differences in CYP1A2 and CYP3A4 drug metabolism and gene expression patterns consistent with reported in vivo observations, without compromising cell viability. These findings validate the utility of sex-differentiated microenvironments in early-stage research, offering a pathway to refine animal and clinical trials and improve therapeutic outcomes for all sexes.

cell biology↗

bioRxiv2025

Metformin inhibits mitochondrial complex I in intestinal epithelium to promote glycemic control

Metformin is a therapeutically versatile biguanide drug primarily prescribed for type II diabetes. Despite its extensive use, the mechanisms underlying many of its clinical effects, including attenuated postprandial glucose excursions, elevated intestinal glucose uptake, and increased production of lactate, Lac-Phe and GDF15, remain unclear. Here, we map these and other clinical effects of metformin to intestine-specific mitochondrial complex I inhibition. Using human metabolomic data and an orthogonal genetics approach in male mice, we demonstrate that metformin suppresses citrulline synthesis, a metabolite generated exclusively by small intestine mitochondria, and increases GDF15 by inhibiting the mitochondrial respiratory chain at complex I. This inhibition co-opts the intestines to function as a glucose sink, driving uptake of excess glucose and converting it to lactate and Lac-Phe. Notably, the glucose-lowering effect of another biguanide, phenformin, and berberine, a structurally unrelated nutraceutical, similarly depends on intestine-specific mitochondrial complex I inhibition, underscoring a shared therapeutic mechanism.

physiology↗

bioRxiv2022

Spatiotemporal variations in retrovirus-host interactions among Darwin's finches

Endogenous retroviruses (ERVs) are inherited remnants of past retroviruses that colonized host germline over millions of years, providing a sampling of retroviral diversity across time. The utility of ERVs as markers of host genome evolution is augmented by their ability to reveal historic retrovirus-host interactions, given that ERVs are examples of active retroviruses at the time of germline invasion. Here, we utilize the strength of Darwins finches, a system synonymous with evolutionary studies, for investigating ERV history, revealing recent retrovirus-host interactions in natural populations. By mapping ERV variation across all species of Darwins finches and comparing with outgroup species, we highlight geographical and historical patterns of retrovirus-host occurrence, utilizing the system as a natural model for evaluating the extent and timing of retroviral activity in hosts undergoing adaptive radiation and colonization of new environments. We found shared ERVs among all samples indicating retrovirus-host associations pre-dating host speciation, as well as considerable ERV variation across populations of the entire Darwins finches radiation. Unexpected ERV variation in finch species on different islands suggest historical changes in gene flow and selection. Non-random distribution of ERVs along and between chromosomes, as well as across finch species, suggests association between ERV accumulation and the rapid speciation of Darwins finches.

evolutionary biology↗

bioRxiv2022

Revisiting degron motifs in human AURKA required for its targeting by APC/C-FZR1

Mitotic kinase Aurora A (AURKA) diverges from other kinases in its multiple active conformations that may explain its interphase roles and association with cancer, and the limited efficacy of drugs targeting the kinase pocket. Regulation of AURKA activity by the cell is critically dependent on destruction mediated by the Anaphase-Promoting Complex (APC/CFZR1) during mitotic exit and G1 phase and requires an atypical N-terminal degron in AURKA called the A-box in addition to a reported canonical D-box degron in the C-terminus. Here we find that the proposed C-terminal D-box of AURKA does not act as a degron and instead mediates essential structural features of the protein. In living cells, as previously reported in vitro, the N-terminal intrinsically disordered region (IDR) of AURKA containing the A-box is sufficient to confer FZR1-dependent mitotic degradation. Both in silico and in cellulo assays predict the QRVL Short Linear Interacting Motif (SLiM) of the A-box to be a phospho-regulated D-box. We propose that degradation of full-length AURKA additionally depends on an intact C-terminal domain because of critical conformational parameters permissive for both activity and mitotic degradation of AURKA. Summary blurbAURKA degron motifs are redefined to show that the so-called N-terminal A-box is in fact a D-box, and the so-called D-box in the C-terminus is not a degron but a motif critical for the active, degradable conformation of AURKA

cell biology↗

bioRxiv2021

Lung injury induces alveolar type 2 cell hypertrophy and polyploidy with implications for repair and regeneration

Epithelial polyploidization post-injury is a conserved phenomenon, recently shown to improve barrier restoration during wound healing. Whether lung injury can induce alveolar epithelial polyploidy is not known. We show that bleomycin injury induces AT2 cell hypertrophy and polyploidy. AT2 polyploidization is also seen in short term ex vivo cultures, where AT2-to-AT1 trans-differentiation is associated with substantial binucleation due to failed cytokinesis. Both hypertrophic and polyploid features of AT2 cells can be attenuated by inhibiting the integrated stress response (ISR) using the small molecule ISRIB. These data suggest that AT2 hypertrophic growth and polyploidization may be a feature of alveolar epithelial injury. As AT2 cells serve as facultative progenitors for the distal lung epithelium, a propensity for injury-induced binucleation has implications for AT2 self-renewal and regenerative potential upon reinjury, which may benefit from targeting the ISR.

cell biology↗

bioRxiv2020

Dissociating the effects of distraction and proactive interference on object memory through tests of novelty preference

Encoding information into memory is sensitive to distraction whilst retrieving that memory may be compromised by proactive interference from pre-existing memories. These two debilitating effects are common in neuropsychiatric conditions but modelling them preclinically to date is slow as it requires prolonged operant training. A step change would be the validation of functionally equivalent but fast, simple, high-throughput tasks based on spontaneous behaviour. Here, we show that spontaneous object preference testing meets these requirements in the subchronic phencyclidine (scPCP) rat model for cognitive impairments associated with schizophrenia. scPCP rats show clear memory sensitivity to distraction in the standard novel object recognition task (stNOR). However, due to this, stNOR cannot assess proactive interference. Therefore, we compared scPCP performance in stNOR to that using the continuous NOR task (conNOR), which offers minimal distraction, allowing disease-relevant memory deficits to be assessed directly. We first determined that scPCP treatment did not affect whisker movements during object exploration. scPCP rats exhibited the expected distraction stNOR effect but had intact performance on the first conNOR trial, effectively dissociating distraction by using two NOR task variants. In remaining conNOR trials, scPCP rats performed above chance throughout but, importantly, their detection of object novelty was increasingly impaired relative to controls. We attribute this effect to the accumulation of proactive interference. This is the first demonstration that increased sensitivity to distraction and proactive interference, both key cognitive impairments in schizophrenia, can be dissociated in the scPCP rat using two variants of the same fast, simple, spontaneous object memory paradigm.

animal behavior and cognition↗

bioRxiv2019

AURKA destruction is decoupled from its activity at mitotic exit but suppresses interphase activity

Activity of AURKA is controlled through multiple mechanisms including phosphorylation, ubiquitin-mediated degradation, and allosteric interaction with TPX2. Activity peaks at mitosis before AURKA is degraded during mitotic exit in a process strictly dependent on APC/C coactivator FZR1. We used FZR1 knockout cells (FZR1KO) and a novel FRET-based AURKA biosensor to investigate how activity is regulated in absence of destruction. We found that AURKA activity in FZR1KO cells dropped at mitotic exit as rapidly as in parental cells, despite absence of destruction. Unexpectedly, TPX2 was degraded normally in FZR1KO cells. Overexpression of an N-terminal TPX2 fragment sufficient for AURKA binding, but not degraded at mitotic exit, caused delay in AURKA inactivation. We conclude that AURKA inactivation in mitotic exit is determined not by its own degradation but by degradation of TPX2 and therefore dependent on CDC20 rather than FZR1. The biosensor revealed that FZR1 instead suppresses AURKA activity in interphase and is critically required for assembly of the interphase mitochondrial network after mitosis.

cell biology↗

bioRxiv2019

Assessing metadata and curation quality: a case study from the development of a third-party curation service at Springer Nature

Since 2017, the publisher Springer Nature has provided an optional Research Data Support service to help researchers deposit and curate data that support their peer-reviewed publications. This service builds on a Research Data Helpdesk, which since 2016 has provided support to authors and editors who need advice on the options available for sharing their research data. In this paper we describe a short project which aimed to facilitate an objective assessment of metadata quality, undertaken during the development of a third-party curation service for researchers (Research Data Support). We provide details on the single-blind user-testing which was undertaken, and the results gathered during this experiment. We also briefly describe the curation services which have been developed and introduced following an initial period of testing and piloting. This paper will be presented at the International Digital Curation Conference 2019, and has been submitted to the International Journal of Digital curation.

scientific communication and education↗

bioRxiv2018

The impact on authors and editors of introducing Data Availability Statements at Nature journals

This paper describes the adoption of a standard policy for the inclusion of data availability statements in all research articles published at the Nature family of journals, and the subsequent research which assessed the impacts that these policies had on authors, editors, and the availability of datasets. The key findings of this research project include the determination of average and median times required to add a data availability statement to an article; and a correlation between the way researchers make their data available, and the time required to add a data availability statement. This paper will be presented at the International Digital Curation Conference 2018, and has been submitted to the International Journal of Digital curation.

scientific communication and education↗

bioRxiv2017

Regulation of mitochondrial dynamics by Aurora A kinase

Aurora A kinase (AURKA) is a major regulator of mitosis and an important driver of cancer progression. The roles of AURKA outside of mitosis, and how these might contribute to cancer progression, are not well understood. Here we show that a fraction of cytoplasmic AURKA is associated with mitochondria, co-fractionating in cell extracts and interacting with mitochondrial proteins by reciprocal co-immunoprecipitation. We have also found that the dynamics of the mitochondrial network are sensitive to AURKA inhibition, depletion or overexpression. This can account for the different mitochondrial morphologies observed in RPE1 and U2OS cell lines, which show very different levels of expression of AURKA. We identify the mitochondrial fraction of AURKA as influencing mitochondrial morphology, since an N-terminally truncated version of the kinase that does not localize to mitochondria does not affect the mitochondrial network. We identify a cryptic mitochondrial targeting sequence in the AURKA N-terminus and discuss how alternative conformations of the protein may influence its cytoplasmic fate.

cell biology↗