Oncogenic mutations in KRAS or BRAF are frequent in colorectal cancer and activate the ERK kinase. Here, we find graded ERK phosphorylation correlating with cell differentiation in patient-derived colorectal cancer organoids with and without KRAS mutations. Using reporters, single cell transcriptomics and mass cytometry, we observe cell type-specific phosphorylation of ERK in response to transgenic KRAS G12V in mouse intestinal organoids, while transgenic BRAF V600E activates ERK in all cells. Quantitative network modelling from perturbation data reveals that activation of ERK is shaped by cell type-specific MEK to ERK feed forward and negative feedback signalling. We identify dual-specificity phosphatases as candidate modulators of ERK in the intestine. Furthermore, we find that oncogenic KRAS, together with β-Catenin, favours expansion of crypt cells with high ERK activity. Our experiments highlight key differences between oncogenic BRAF and KRAS in colorectal cancer and find unexpected heterogeneity in a signalling pathway with fundamental relevance for cancer therapy.

As the death toll from the COVID-19 pandemic caused by SARS-CoV-2 continues to mount globally, scientists, healthcare agencies, and pharmaceutical companies are trying hard to find a "cure" and devise treatment strategies to reduce mortality. "Repurposing" existing drugs to fight COVID-19 remains an important strategy. Since respiratory failure remains one of the leading causes of death in COVID-19 patients, in this commentary, we have critically discussed the potential benefit of neutrophil elastase inhibitors (NEIs) in patients hospitalised with severe COVID-19.Around one in three COVID-19 patients admitted to a hospital develop systemic inflammatory conditions such as cytokine release syndrome (CRS) [1] and acute respiratory distress syndrome (ARDS) [2]. Since lymphocyappropriate credit to the original author(s) and the source, provide a link to the Creative Commons licence, and indicate if changes were made. The images or other third party material in this article are included in the article's Creative Commons licence, unless indicated otherwise in a credit line to the material.

No abstract

As the death toll of Coronavirus disease 19 (COVID‐19) continues to rise worldwide, it is imperative to explore novel molecular mechanisms for targeting SARS‐CoV‐2. Rather than looking for drugs that directly interact with key viral proteins inhibiting its replication, an alternative and possibly add‐on approach is to dismantle the host cell machinery that enables the virus to infect the host cell and spread from one cell to another. Excellent examples of such machinery are host cell proteases whose role in viral pathogenesis has been demonstrated in numerous coronaviruses. In this review, we propose two therapeutic modalities to tackle SARS‐CoV‐2 infections; the first is to transcriptionally modulate the expression of cellular proteases and their endogenous inhibitors and the second is to directly inhibit their enzymatic activity. We present a nonexhaustive collection of clinically investigated drugs that act by one of these mechanisms and thus represent promising candidates for preclinical in vitro testing and hopefully clinical testing in COVID‐19 patients.

1Mutations activating the KRAS GTPase or the BRAF kinase are frequent in colorectal cancer and are 2 thought to constitutively activate the terminal mitogen-activated protein kinase, ERK. Using mass 3 cytometry, we found graded phosphorylation of ERK anti-correlated with cell differentiation in patient-4 derived colorectal cancer organoids, independent of KRAS mutational status. Reporter, single cell 5 transcriptome and mass cytometry analyses showed that transgenic KRAS G12V activated ERK in a cell 6 type-specific pattern in mouse intestinal organoids. In contrast, transgenic BRAF V600E triggered high ERK 7activity and downstream gene expression in all intestinal cell types, followed by epithelial 8 disorganisation. Quantitative network modelling from perturbation data revealed that activation of 9 ERK is shaped by cell type-specific MEK to ERK feed forward and negative feedback signalling. We 10 identified dual-specificity phosphatases as candidate modulators of ERK activity between intestinal cell 11 types. Furthermore, we found that oncogenic KRAS, together with β-Catenin, favoured expansion of 12 crypt cells with high ERK activity. Our experiments highlight key differences between ERK activity 13 elicited by the BRAF or KRAS oncogenes in colorectal cancer and find unexpected heterogeneity in a 14 signalling pathway with fundamental relevance for cancer therapy. 15

Calcineurin inhibitors (CNI) are the backbone for immunosuppression after solid organ transplantation. Although successful in preventing kidney transplant rejection, their nephrotoxic side effects notoriously contribute to allograft injury despite attempts to optimize their application, often with additional medications. The etiology of chronic renal parenchymal changes is complex irrespective of chosen therapy with either cyclosporine A (CsA) or currently favoured tacrolimus (Tac). The pathogenetic detail of their respective toxicities has not been fully understood. To test whether CsA and Tac cause adverse renal responses differentially, we employed a chronic rat model with continous drug application. Histopathology of the renal compartments was combined with multiomics analysis. Both drugs caused significant albeit differential damage in vasculature and nephron. The glomerular filtration barrier was more affected by Tac than by CsA, showing prominent deteriorations in pore endothelium and podocytes along with impaired VEGF/VEGFR2 signaling and podocyte-specific gene expression. By contrast, proximal tubule epithelia were more severely affected by CsA than by Tac, revealing lysosomal dysfunction and enhanced apoptosis along with impaired proteostasis and oxidative stress. We conclude that pathogenetic alterations in renal microenvironments are specific for either treatment. We have identified related biomarkers to adequately address chronic CNI nephropathy in transplant recipients.

fibronectin motif) surfaces. However, only those exposing the IGDQ sequence induced significant migration of MDA-MB-231 cells. The observed migratory behaviour suggests the presence of cell subpopulations associated with a 'stationary' or a 'migratory' phenotype, the latter determining a considerable cell migration at the sub-cm length scale. Material and methods We created gold-titanium (Au-Ti) surface and we coated them with a gradient of IGDQ-peptide and PSH (tetraethylenglycol) as a filler (PACMAN). The role of a5b1 and avb3 was studied using knockdown of b3 integrin using siRNA, shRNA and CRISPR/Cas9 strategies in MDA-MB-231 cells. Results and discussions According to literature and to our previous results published in, Marega et al, Small (2016) we focus on the integrins a5b1 and avb3, already known to be implicated in cell migration, angiogenesis and resistance to cell death. They can be activated indirectly by EGFR pathway or directly by IGD type I fibronectin motif. Our preliminary results evidenced the implication of avb3 in distal migration and a potential compensatory system through a5b1 in shb3 cell line. Cells migrated following the motogenic peptide gradient. The fibronectin type I is implied in cell migration through the formation of focal adhesion with an activation of avb3 integrin. Conclusion The influence of both integrin invalidation (alone or together) will be studied on cell migration in usual culture plates and on IGDQ-exposing surfaces. The subpopulations of native MADA-MB-231 cells with a 'stationary', 'intermediary' and a 'migratory' phenotype, obtained on PACMAN surfaces, are characterised using a single-cell RNA-sequencing in order to identify new pathways regulating the metastasis process (on going).