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Shipston, M. J.

Publications and source records attributed to Shipston, M. J..

5 recordsLinked to original sources

ProteinFlux: accurate, rapid and scalable generative prediction of protein dynamics driven by post-translational modifications

The function of proteins, the building blocks of life, in health and disease depends not only on their 3D-conformational states but most importantly on the dynamic transition between states controlled by a wide array of post-translational modifications (PTMs). Recent major advances have been made in our ability to predict static 3D structures; however, understanding and predicting the impact of PTMs on protein conformational dynamics remains a major question and challenge in the field. Molecular dynamics (MD) simulation remains the major computational approach for studying protein dynamics. However, the high computational cost, lack of integration of PTMs as conditioning inputs and inefficient generation of continuous protein dynamics largely precludes PTM-regulated conformational dynamics and the study of slow conformational processes. To address this critical bottleneck, we developed ProteinFlux, a flow-matching generative framework that links PTM-conditioned conformational dynamics to evolutionary constraints encoded by PTM sites. Evolutionary information plays a critical role in capturing conformational dynamics beyond sequence identity, and PTM sites inherently encode evolutionary constraints critical to protein functional regulation. We therefore built FluxSite, a dual-modal PTM site predictor that integrates sequence evolutionary information and 3D structural features to generate a continuous conditional signal encoding conservation and functional importance for each predicted site. FluxSite achieves robust generalization across 18 PTM types and 30 disease-associated proteomes. ProteinFlux generates phosphorylation-conditioned, all-atom conformational trajectories across diverse protein fold classes, faithfully reproducing both thermodynamic properties such as free energy landscapes and kinetic features such as conformational transition pathways. It outperforms state-of-the-art predictors while achieving inference speeds several orders of magnitude faster than traditional MD. In addition, we introduce DynaMo-phos, a benchmark dataset of phosphorylated protein MD simulations. Together, ProteinFlux, FluxSite and DynaMo-phos provide a scalable, high-throughput platform for elucidating PTM-driven conformational mechanisms, with potential applications across allosteric drug design, functional annotation of disease-associated modifications and mechanism-guided therapeutic development.

bioinformatics↗

Adenylyl cyclase 9: fundamental change of regulation in vertebrates and gene sub-functionalization after teleost-specific whole-genome duplication

Adenosine 3:5 monophosphate (cAMP) is a ubiquitous signalling molecule generated by the adenylyl cyclase family of proteins which is encoded by ten genes. The biological significance of this diversity is not well understood. In mammals, transmembrane adenylyl cyclase 9 (AC9) is resistant to regulation by heterotrimeric G proteins. A major facet of this resistance is auto-inhibition -- in the presence of activated Gs, AC9 is inhibited by its C-terminal domain. Here, we examined the natural evolution of this seemingly paradoxical control mechanism. At the primary sequence level, the hallmarks of auto-inhibition are apparent in all vertebrates, none are found in invertebrates. Teleost-specific genome duplication (TGD) resulted in adcy9 ohnologs, one of which lacked the hallmarks of auto-inhibition. This was confirmed in functional assays upon cloning and heterologous expression of the requisite cDNAs. The tissue distributions of the adcy9 ohnologs in teleost species also pointed to their sub-functionalization. Above all, auto-inhibited adcy9 was largely restricted to the brain indicating a fundamental role in brain development or function. Our findings document a quantum leap of the regulation of the enzymatic activity of AC9 in vertebrates and the potency of TGD to meet an adaptational challenge through functionally diversified ohnologs.

evolutionary biology↗

Dynamic transcriptional heterogeneity in pituitary corticotrophs

A large body of evidence has shown that corticotrophs, the anterior pituitary cells central to the generation of hormonal stress responses, exhibit heterogeneous functional behavior, suggesting the presence of functional sub-populations of corticotrophs. We investigated whether this was the case at the transcriptomic level by conducting a comprehensive analysis of scRNA-seq datasets from rodent pituitary cells. We envisaged two alternative scenarios, one where robust subtypes of corticotrophs exist, and the other where these subpopulations were only transient states, possibly transitioning into one another. Our findings suggest that corticotrophs transition between multiple transcriptional states rather than existing as rigidly defined subpopulations. We employed marker gene-based comparisons and whole transcriptome label transfer approaches to analyze transcriptional signatures across datasets. Marker-based clustering revealed strikingly low similarity in the identified subpopulations across datasets. This analysis evidenced the presence of transcriptional states with different functional relevance, related to different stages of hormonal signalling. Similarly, the label transfer approach, which considers non-linear interactions across the entire transcriptome showed that transcriptional states could be detected across independent datasets. This classification relied on broader gene expression patterns rather than conventional marker genes, reinforcing the notion of continuous rather than discrete cell states. Furthermore, trajectory analysis by RNA velocity indicated dynamic transitions between transcriptional states, suggesting the presence of transcriptional mechanisms facilitating rapid recruitment of corticotrophs in response to physiological demands. Our findings align with evidence from other endocrine cell types, such as lactotrophs and pancreatic {beta}-cells, where hormone secretion is linked to fluctuating transcriptional activity. The observed transitions in corticotroph states suggest a mechanism allowing flexible hormonal responses to unpredictable and time-varying stressful events. Additionally, this study highlights the challenges associated with scRNA-seq methodologies, including data sparsity, batch effects, and pseudoreplication, underscoring the need for rigorous experimental design and reproducibility in single-cell transcriptomics research. These insights contribute to a broader understanding of pituitary cell plasticity and endocrine adaptation mechanisms.

cell biology↗

LKB1 is the gatekeeper of carotid body chemo-sensing and the hypoxic ventilatory response

The hypoxic ventilatory response (HVR) is critical to breathing and thus oxygen supply to the body and is primarily mediated by the carotid bodies. Here we reveal that carotid body afferent discharge during hypoxia and hypercapnia is determined by the expression of Liver Kinase B1 (LKB1), the principal kinase that activates the AMP-activated protein kinase (AMPK) during metabolic stresses. Conversely, conditional deletion in catecholaminergic cells of AMPK had no effect on carotid body responses to hypoxia or hypercapnia. By contrast, the HVR was attenuated by LKB1 and AMPK deletion. However, in LKB1 knockouts hypoxia evoked hypoventilation, apnoea and Cheyne-Stokes-like breathing, while only hypoventilation and apnoea were observed after AMPK deletion. We therefore identify LKB1 as an essential regulator of carotid body chemosensing and uncover a divergence in dependency on LKB1 and AMPK between the carotid body on one hand and the HVR on the other.

physiology↗

Dissection of the corticotroph transcriptome in a mouse model of glucocorticoid-induced suppression of the HPA axis

Glucocorticoids (GC) are prescribed for periods >3 months to 1-3% of the UK population; 10-50% of these patients develop hypothalamus-pituitary-adrenal (HPA) axis suppression, which may last over 6 months and is associated with morbidity and mortality. Recovery of higher nodes of the axis is necessary for recovery of adrenal function. We developed a mouse model of Dexamethasone (DEX)-induced HPA axis dysfunction in order to further explore recovery in the pituitary. Adult male C57BL6/J or those crossed with Pomc-eGFP mice were randomly assigned to receive DEX (~0.4 mg/kg bodyweight/day) or vehicle via drinking water for 4 weeks following which treatment was withdrawn. Tissues were harvested at 0, 1, and 4 weeks following withdrawal of treatment. Corticotrophs were isolated from Pomc-eGFP pituitaries using FACS, and RNA extracted for RNA-seq. DEX treatment suppressed corticosterone production, which remained partially suppressed at least 1 week following DEX withdrawal. In the adrenal, at time 0, Hsd3b2, Cyp11a1, and Mc2r mRNA levels were significantly reduced, with Mc2r and Cyp11a1 remaining reduced 1 week following DEX withdrawal. The corticotroph transcriptome was modified by DEX treatment with some differences between groups persisting 4 weeks following withdrawal. No genes supressed by DEX exhibited ongoing attenuation 1 and 4 weeks following withdrawal, whilst only 2 genes were upregulated and remained so following withdrawal. A pattern of rebound at 1 and 4 weeks was observed in 14 genes that increased following suppression, and 6 genes that were reduced by DEX and then increased. Chronic GC treatment may induce persistent changes in the pituitary that may influence future response to GC treatment or stress.

physiology↗