The AKT‐mTOR pathway is a central regulator of cell growth and metabolism. Upon sustained mTOR activity, AKT activity is attenuated by a feedback loop that restrains upstream signaling. However, how ...cells control the signals that limit AKT activity is not fully understood. Here, we show that MASTL/Greatwall, a cell cycle kinase that supports mitosis by phosphorylating the PP2A/B55 inhibitors ENSA/ARPP19, inhibits PI3K‐AKT activity by sustaining mTORC1‐ and S6K1‐dependent phosphorylation of IRS1 and GRB10. Genetic depletion of MASTL results in an inefficient feedback loop and AKT hyperactivity. These defects are rescued by the expression of phosphomimetic ENSA/ARPP19 or inhibition of PP2A/B55 phosphatases. MASTL is directly phosphorylated by mTORC1, thereby limiting the PP2A/B55‐dependent dephosphorylation of IRS1 and GRB10 downstream of mTORC1. Downregulation of MASTL results in increased glucose uptake in vitro and increased glucose tolerance in adult mice, suggesting the relevance of the MASTL‐PP2A/B55 kinase‐phosphatase module in controlling AKT and maintaining metabolic homeostasis.
Synopsis
In the presence of excessive signaling, the AKT‐mTOR pathway limits its activity by phosphorylating upstream regulators. When phosphorylated by mTOR, the MASTL/Greatwall kinase contributes to this negative feedback loop by inhibiting the phosphatase PP2A to prevent excessive AKT activity.
MASTL is a new component of the feedback loop that restricts mTOR activity.
MASTL inhibits dephosphorylation of IRS1 and GRB10 by PP2A/B55.
mTOR phosphorylates and activates MASTL to inhibit PP2A/B55.
MASTL inhibition results in improved glucose homeostasis in vivo.
The MASTL/Greatwall kinase is a new component of the feedback loop that restricts mTOR pathway activity in the presence of excessive signaling.
Parallel evolution of similar phenotypes provides strong evidence for the operation of natural selection. Where these phenotypes contribute to reproductive isolation, they further support a role for ...divergent, habitat-associated selection in speciation. However, the observation of pairs of divergent ecotypes currently occupying contrasting habitats in distinct geographical regions is not sufficient to infer parallel origins. Here we show striking parallel phenotypic divergence between populations of the rocky-shore gastropod, Littorina saxatilis, occupying contrasting habitats exposed to either wave action or crab predation. This divergence is associated with barriers to gene exchange but, nevertheless, genetic variation is more strongly structured by geography than by ecotype. Using approximate Bayesian analysis of sequence data and amplified fragment length polymorphism markers, we show that the ecotypes are likely to have arisen in the face of continuous gene flow and that the demographic separation of ecotypes has occurred in parallel at both regional and local scales. Parameter estimates suggest a long delay between colonization of a locality and ecotype formation, perhaps because the postglacial spread of crab populations was slower than the spread of snails. Adaptive differentiation may not be fully genetically independent despite being demographically parallel. These results provide new insight into a major model of ecologically driven speciation.
Objective
The purpose of this study was to describe the feasibility of respiratory oscillometry (RO) in schoolchildren with asthma, and the concordance of its results with those of spirometry, to ...determine its clinical usefulness.
Methods
RO and spirometry were performed in 154 children (6 to 14‐year‐old) with asthma, following strict quality criteria for the tests. Their feasibility (probability of valid test, time of execution, number of maneuvers needed to achieve a valid test, and perceived difficulty) was compared. The factors that influence feasibility were analyzed with multivariate methods. FEV1, FEV1/FVC, FVC and FEF25‐75 for spirometry, and R5, AX and R5‐19 for RO, were converted into z‐scores and their concordance was investigated through intraclass correlation coefficients (ICC) and kappa indices for normal/abnormal values.
Results
There were no differences in the probability of obtaining a valid RO or spirometry (83.1% vs. 81.8%, p = 0.868). RO required a lower number of maneuvers mean (SD) 4.2 (1.8) versus 6.0 (1.6), p < 0.001 and less execution time 5.1 (2.7) versus 7.6 (2.4) minutes, p < 0.001, and patients considered it less difficult. Age increased the probability of obtaining valid RO and spirometry. The concordance of results between RO and spirometry was low, and only between zFEV1 and zAX could it be considered moderate (ICC = 0.412, kappa = 0.427).
Conclusion
RO and spirometry are feasible in children with asthma. RO has some practical advantages, but the concordance of its results with spirometry is low.
Bladder cancer is a current clinical and social problem. At diagnosis, most patients present with nonmuscle-invasive tumors, characterized by a high recurrence rate, which could progress to ...muscle-invasive disease and metastasis. Bone morphogenetic protein (BMP)-dependent signaling arising from stromal bladder tissue mediates urothelial homeostasis by promoting urothelial cell differentiation. However, the possible role of BMP ligands in bladder cancer is still unclear.
Tumor and normal tissue from 68 patients with urothelial cancer were prospectively collected and analyzed for expression of BMP and macrophage markers. The mechanism of action was assessed
by experiments with bladder cancer cell lines and peripheral blood monocyte-derived macrophages.
We observed
expression is associated and favored type II macrophage differentiation.
experiments showed that both recombinant BMP4 and BMP4-containing conditioned media from bladder cancer cell lines favored monocyte/macrophage polarization toward M2 phenotype macrophages, as shown by the expression and secretion of IL10. Using a series of human bladder cancer patient samples, we also observed increased expression of
in advanced and undifferentiated tumors in close correlation with epithelial-mesenchymal transition (EMT). However, the p-Smad 1,5,8 staining in tumors showing EMT signs was reduced, due to the increased miR-21 expression leading to reduced
expression.
These findings suggest that BMP4 secretion by bladder cancer cells provides the M2 signal necessary for a protumoral immune environment. In addition, the repression of
by miR-21 makes the tumor cells refractory to the prodifferentiating actions mediated by BMP ligands, favoring tumor growth.
.
NOTCH signaling suppresses tumor growth and proliferation in several types of stratified epithelia. Here, we show that missense mutations in NOTCH1 and NOTCH2 found in human bladder cancers result in ...loss of function. In murine models, genetic ablation of the NOTCH pathway accelerated bladder tumorigenesis and promoted the formation of squamous cell carcinomas, with areas of mesenchymal features. Using bladder cancer cells, we determined that the NOTCH pathway stabilizes the epithelial phenotype through its effector HES1 and, consequently, loss of NOTCH activity favors the process of epithelial-mesenchymal transition. Evaluation of human bladder cancer samples revealed that tumors with low levels of HES1 present mesenchymal features and are more aggressive. Together, our results indicate that NOTCH serves as a tumor suppressor in the bladder and that loss of this pathway promotes mesenchymal and invasive features.
Greatwall is a protein kinase involved in the inhibition of protein phosphatase 2 (PP2A)-B55 complexes to maintain the mitotic state. Although its biochemical activity has been deeply characterized ...in Xenopus, its specific relevance during the progression of mitosis is not fully understood. By using a conditional knockout of the mouse ortholog, Mastl , we show here that mammalian Greatwall is essential for mouse embryonic development and cell cycle progression. Yet, Greatwall-null cells enter into mitosis with normal kinetics. However, these cells display mitotic collapse after nuclear envelope breakdown (NEB) characterized by defective chromosome condensation and prometaphase arrest. Intriguingly, Greatwall is exported from the nucleus to the cytoplasm in a CRM1-dependent manner before NEB. This export occurs after the nuclear import of cyclin B–Cdk1 complexes, requires the kinase activity of Greatwall, and is mediated by Cdk-, but not Polo-like kinase 1-dependent phosphorylation. The mitotic collapse observed in Greatwall-deficient cells is partially rescued after concomitant depletion of B55 regulatory subunits, which are mostly cytoplasmic before NEB. These data suggest that Greatwall is an essential protein in mammals required to prevent mitotic collapse after NEB.
Background
We explore the utility of TruSight Tumor 170 panel (TST170) for detecting somatic mutations in tumor and cfDNA from locoregional recurrent and/or metastatic head and neck squamous cell ...carcinoma (HNSCC).
Methods
Targeted NGS of tumor DNA and plasma cfDNA was performed using TST170 panel. In addition, a set of somatic mutations previously described in HNSCC were selected for validating in tumor, plasma, and saliva by digital droplet PCR.
Results
The TST170 panel identified 13 non‐synonymous somatic mutations, of which five were detected in tumoral tissue, other five in plasma cfDNA, and three in both tissue and plasma cfDNA. Of the eight somatic mutations identified in tissue, three were also identified in plasma cfDNA, showing an overall concordance rate of 37.5%.
Conclusions
This preliminary study shows the possibility to detect somatic mutations in tumor and plasma of HNSCC patients using a single assay that would facilitate the clinical implementation of personalized medicine in the clinic.
This study aims to explore whether a NGS panel (TST170) could be suitable for detecting somatic mutations in tumor and cfDNA from locoregional recurrent and/or metastatic HNSCC patients. Furthermore, we also carried out an orthogonal validation of somatic mutations in tumor, plasma cfDNA, and salivary DNA.
Bladder cancer is lethal in its advanced, muscle-invasive phase with very limited therapeutic advances
. Recent molecular characterization has defined new (epi)genetic drivers and potential targets ...for bladder cancer
. The immune checkpoint inhibitors have shown remarkable efficacy but only in a limited fraction of bladder cancer patients
. Here, we show that high G9a (EHMT2) expression is associated with poor clinical outcome in bladder cancer and that targeting G9a/DNMT methyltransferase activity with a novel inhibitor (CM-272) induces apoptosis and immunogenic cell death. Using an immunocompetent quadruple-knockout (Pten
; Trp53
; Rb1
; Rbl1
) transgenic mouse model of aggressive metastatic, muscle-invasive bladder cancer, we demonstrate that CM-272 + cisplatin treatment results in statistically significant regression of established tumors and metastases. The antitumor effect is significantly improved when CM-272 is combined with anti-programmed cell death ligand 1, even in the absence of cisplatin. These effects are associated with an endogenous antitumor immune response and immunogenic cell death with the conversion of a cold immune tumor into a hot tumor. Finally, increased G9a expression was associated with resistance to programmed cell death protein 1 inhibition in a cohort of patients with bladder cancer. In summary, these findings support new and promising opportunities for the treatment of bladder cancer using a combination of epigenetic inhibitors and immune checkpoint blockade.
Both clinical and experimental observations show that the skin is affected by the thyroidal status. In hypothyroid patients the epidermis is thin and alopecia is common, indicating that thyroidal ...status might influence not only skin proliferation but also hair growth. We demonstrate here that the thyroid hormone receptors (TRs) mediate these effects of the thyroid hormones on the skin. Mice lacking TRα1 and TRβ (the main thyroid hormone binding isoforms) display impaired hair cycling associated to a decrease in follicular hair cell proliferation. This was also observed in hypothyroid mice, indicating the important role of the hormone-bound receptors in hair growth. In contrast, the individual deletion of either TRα1 or TRβ did not impair hair cycling, revealing an overlapping or compensatory role of the receptors in follicular cell proliferation. In support of the role of the receptors in hair growth, TRα1/TRβ-deficient mice developed alopecia after serial depilation. These mice also presented a wound-healing defect, with retarded re-epithelialization and wound gaping, associated to impaired keratinocyte proliferation. These results reinforce the idea that the thyroid hormone nuclear receptors play an important role on skin homeostasis and suggest that they could be targets for the treatment of cutaneous pathologies.
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