Cytokines elicit pleiotropic and non-redundant activities despite strong overlap in their usage of receptors, JAKs and STATs molecules. We use IL-6 and IL-27 to ask how two cytokines activating the same signaling pathway have different biological roles. We found that IL-27 induces more sustained STAT1 phosphorylation than IL-6, with the two cytokines inducing comparable levels of STAT3 phosphorylation. Mathematical and statistical modeling of IL-6 and IL-27 signaling identified STAT3 binding to GP130, and STAT1 binding to IL-27Rα, as the main dynamical processes contributing to sustained pSTAT1 levels by IL-27. Mutation of Tyr613 on IL-27Rα decreased IL-27-induced STAT1 phosphorylation by 80% but had limited effect on STAT3 phosphorgylation. Strong receptor/STAT coupling by IL-27 initiated a unique gene expression program, which required sustained STAT1 phosphorylation and IRF1 expression and was enriched in classical Interferon Stimulated Genes. Interestingly, the STAT/receptor coupling exhibited by IL-6/IL-27 was altered in patients with systemic lupus erythematosus (SLE). IL-6/IL-27 induced a more potent STAT1 activation in SLE patients than in healthy controls, which correlated with higher STAT1 expression in these patients. Partial inhibition of JAK activation by sub-saturating doses of Tofacitinib specifically lowered the levels of STAT1 activation by IL-6. Our data show that receptor and STATs concentrations critically contribute to shape cytokine responses and generate functional pleiotropy in health and disease.

Background: Inadequacy of testing for melanoma BRAF status results in delayed access to systemic therapy. BRAF mutations and their association with patient/tumour characteristics and survival is poorly understood. Objectives: To report national data from England on the frequency of molecular BRAF testing; the association of patient/tumour characteristics with BRAF mutations; and the treatment and survival of patients with BRAF mutations. Methods: This national retrospective cohort study identified all new melanomas and molecular BRAF testing in England diagnosed from 2016 to 2021 using population-based data from the National Disease Registration Service. Multivariate logistic regression determined the association between BRAF testing with patient/tumour characteristics and BRAF genotype with patient/tumour characteristics. Age-standardized net survival analysed melanoma-specific mortality by BRAF genotype. Results: Of new cases of melanoma, 14% (n = 13 138/91 415) had a BRAF test registered. The proportion of successfully tested tumours that were BRAF-mutated was 34% (n = 4424/13 012). The West Midlands tested the highest proportion of cutaneous tumours (23%; n = 1783/7901) vs. the lowest in Yorkshire and the Humber (11%; n = 856/7760). Female patients [odds ratio (OR) 0.82, 95% confidence interval (CI) 0.79–0.86] and those aged > 80 years (OR 0.88, 95% CI 0.83–0.93) were less likely to be tested for BRAF mutations. BRAF mutations were associated with female gender (OR 1.16, 95% CI 1.07–1.26). Patients aged > 80 (OR 0.36, 95% CI 0.32–0.40) had lower odds of having BRAF-mutated tumours. Patients with BRAF mutations had a lower 5-year net survival [55.9% (95% CI 52.7–59.2) vs. BRAF wildtype 5-year net survival 62.2% (95% CI 60.1-64.5)], particularly in stage II disease. Conclusions: This study presents the largest dataset on national melanoma BRAF status published to date. The data highlight geographical and demographic variations in BRAF testing and the impact of BRAF mutations on survival rates, particularly in patients with stage II disease. This highlights the critical role of consistent, early and accurate testing to ensure equal care, guide treatment decisions and understand prognosis.

A fire in one of the Windscale nuclear reactors at Sellafield (Cumbria, England) in October 1957 released 1,800 TBq of ¹³¹I (half-life, 8 days) to atmosphere. Measurements of ¹³¹I activity in thyroids of exposed children showed typical thyroid doses of tens of milligray, but with some exceeding 100 mGy. Radiation exposure in childhood is known to increase the risk of thyroid cancer. Consequently, an investigation was conducted into whether raised numbers of thyroid cancer cases occurred in those exposed to ¹³¹I as young children in Cumbria. A database of Cumbrian births from 1950 onwards allowed cohorts of 56,086 births during 1950–1958 and 137,444 births during 1959–1980 to be constructed, periods including children potentially exposed and unexposed, respectively, to ¹³¹I. Three areas of Cumbria with different ¹³¹I contamination levels were identified from monitoring data, and births assigned to these three areas for the two periods of birth. Members of these six sub-cohorts were linked to incident thyroid cancer cases in Great Britain during 1981–2020 using national cancer registration databases, providing thyroid cancer incidence rates. Incidence rate ratios (IRRs), with the lowest contamination area as a reference, were computed. No IRR differed discernibly from unity. For births during 1950–1958, the IRR for the combined highest and intermediate ¹³¹I contamination areas was 0.68 (95% confidence interval: 0.24, 1.56), and no case of thyroid cancer was found in the small cohort born in the highest contamination area. In conclusion, no increased risk of thyroid cancer in those exposed to ¹³¹I as young children in Cumbria in 1957 was detected. This study adds to the evidence on the long-term risk of thyroid cancer following childhood exposure to low and moderate levels of ¹³¹I, such as occurred following the Fukushima nuclear accident in 2011.

Cytokines elicit pleiotropic and non-redundant activities despite strong overlap in their usage of receptors, JAKs and STATs molecules. We use IL-6 and IL-27 to ask how two cytokines activating the same signaling pathway have different biological roles. We found that IL-27 induces more sustained STAT1 phosphorylation than IL-6, with the two cytokines inducing comparable levels of STAT3 phosphorylation. Mathematical and statistical modelling of IL-6 and IL-27 signaling identified STAT3 binding to GP130, and STAT1 binding to IL-27Rα, as the main dynamical processes contributing to sustained pSTAT1 by IL-27. Mutation of Tyr613 on IL-27Rα decreased IL-27-induced STAT1 phosphorylation by 80% but had limited effect on STAT3 phosphorylation. Strong receptor/STAT coupling by IL-27 initiated a unique gene expression program, which required sustained STAT1 phosphorylation and IRF1 expression and was enriched in classical Interferon Stimulated Genes. Interestingly, the STAT/receptor coupling exhibited by IL-6/IL-27 was altered in patients with Systemic lupus erythematosus (SLE). IL-6/IL-27 induced a more potent STAT1 activation in SLE patients than in healthy controls, which correlated with higher STAT1 expression in these patients. Partial inhibition of JAK activation by sub-saturating doses of Tofacitinib specifically lowered the levels of STAT1 activation by IL-6. Our data show that receptor and STATs concentrations critically contribute to shape cytokine responses and generate functional pleiotropy in health and disease.

Cellular receptors on the cell membrane can bind ligand molecules in the extra-cellular medium to form ligand-bound monomers. These interactions ultimately determine the fate of a cell through the resulting intra-cellular signalling cascades. Often, several receptor types can bind a shared ligand leading to the formation of different monomeric complexes, and in turn to competition for the common ligand. Here, we describe competition between two receptors which bind a common ligand in terms of a bi-variate stochastic process. The stochastic description is important to account for fluctuations in the number of molecules. Our interest is in computing two summary statistics—the steady-state distribution of the number of bound monomers and the time to reach a threshold number of monomers of a given kind. The matrix-analytic approach developed in this manuscript is exact, but becomes impractical as the number of molecules in the system increases. Thus, we present novel approximations which can work under low-to-moderate competition scenarios. Our results apply to systems with a larger number of population species (i.e., receptors) competing for a common resource (i.e., ligands), and to competition systems outside the area of molecular dynamics, such as Mathematical Ecology.

Receptor tyrosine kinases (RTKs), the largest class of transmembrane cell surface receptors, initiate signalling pathways which regulate diverse cellular processes. On activation these receptors rapidly recruit multiple downstream effector proteins to moderate affinity tyrosyl phosphate (pY) binding sites. However, the mechanism for expedient downstream effector protein recruitment via random molecular diffusion through the cytoplasm is not fully understood. One way in which the probabilistic outcome associated with random diffusion could be alleviated is through localized accumulation of high effective concentrations of signalling proteins in discrete pools in the cell ( 1 ). The inclusion of interacting proteins into liquid-liquid phase-separated (LLPS), membraneless protein droplets maintains functionally relevant proteins at high concentrations in a liquid phase at the required point of action, enhancing equilibrium binding and enzyme activity ( 2–6 ). These LLPS states have been associated with a wide range of cellular functions including regulation of signalling through, for example, nephrin ( 7, 8 ), the T-cell receptor ( 9 ), mTOR ( 10 ), and Sos-Ras ( 11 ), however, whether LLPS extends to RTK-mediated signal transduction has not been investigated. Here, we show that an RTK, fibroblast growth factor receptor 2 (FGFR2), forms a signalling competent LLPS state with two downstream effectors, a tandem Src homology 2 (SH2) domain-containing protein tyrosine phosphatase 2 (Shp2), and 1-phosphatidylinositol 4,5-bisphosphate phosphodiesterase gamma 1 (Plcγ1). We show that these proteins assemble into a ternary complex which exploits LLPS condensation to simultaneously modulate kinase, phosphatase and phospholipase activities. Therefore, LLPS formation ensures that the requirement for prolonged, high-fidelity signalling is achieved. Additional RTKs also form LLPS with their downstream effectors, suggesting that formation of biological condensates is a key organising principle of RTK-mediated signalling, with broad implications for further mechanistic studies as well as therapeutic intervention.