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The Hippo pathway is a central regulator of tissue development and homeostasis, and has been reported to have a role during vascular development. Here we develop a bioluminescence-based biosensor that monitors the activity of the Hippo core component LATS kinase. Using this biosensor and a library of small molecule kinase inhibitors, we perform a screen for kinases modulating LATS activity and identify VEGFR as an upstream regulator of the Hippo pathway. We find that VEGFR activation by VEGF triggers PI3K/MAPK signaling, which subsequently inhibits LATS and activates the Hippo effectors YAP and TAZ. We further show that the Hippo pathway is a critical mediator of VEGF-induced angiogenesis and tumor vasculogenic mimicry. Thus, our work offers a biosensor tool for the study of the Hippo pathway and suggests a role for Hippo signaling in regulating blood vessel formation in physiological and pathological settings.

In only a few months after initial discovery in Wuhan, China, SARS-CoV-2 and the associated coronavirus disease 2019 (COVID-19) have become a global pandemic causing significant mortality and morbidity and implementation of strict isolation measures. In the absence of vaccines and effective therapeutics, reliable serological testing must be a key element of public health policy to control further spread of the disease and gradually remove quarantine measures. Serological diagnostic tests are being increasingly used to provide a broader understanding of COVID-19 incidence and to assess immunity status in the population. However, there are discrepancies between claimed and actual performance data for serological diagnostic tests on the market. In this study, we conducted a review of independent studies evaluating the performance of SARS-CoV-2 serological tests. We found significant variability in the accuracy of marketed tests and highlight several lab-based and point-of-care rapid serological tests with high levels of performance. The findings of this review highlight the need for ongoing independent evaluations of commercialized COVID-19 diagnostic tests.

The ability to generate or repair injured tissue is essential to the continuity of human life. As in all other organs, wound healing in the skin is a dynamic process involving tissue response to different types of insults. This process involves a continuous sequence of signals and responses in which platelets, fibroblasts, epithelial, endothelial, and immune cells come together outside their usual domains to orchestrate a very complex event that results in tissue repair. These signals, which are mainly growth factors and cytokines, orchestrate the initiation, continuation, and termination of wound healing. An imbalance in the synthesis and release of these cytokines and growth factors at the wound site, therefore, may result in either retarded wound healing, as is seen in diabetic patients and the elderly population, or overhealing wounds such as fibroproliferative disorders frequently seen following surgical incision, traumatic wounds, and severe electrical and thermal injury. In general, regardless of the site of injury, in any phase of the dynamic healing process, a fine balance between synthesis of extracellular matrix and degradation by a large family of enzymes, known as matrix metalloproteinases, is required for maintaining the structural integrity of healing tissue. The availability of new models such as organotypic co-culture systems have allowed us to gain new insight into the cell-cell interactions at both cellular and molecular levels. Recent evidence indicates that mesenchymal-epithelial interactions play a critical role in regulation of skin homeostasis and this cross-talk is mediated by soluble factors acting as autocrine/paracrine regulators of fibroblast and keratinocyte growth, function, and differentiation. In this review we address the question of how keratinocyte-fibroblast interaction plays a role in controlling the expression of key extracellular matrix molecules such as matrix metalloproteinases, which are critical in the healing process following any types of insults to the skin.

These findings will enable rational design of clinical trials aimed at combinatorial approaches to improve chemotherapy response and survival in HGSC patients.

Termination of wound-healing process requires a fine balance between connective tissue deposition and its hydrolysis. Previously, we have demonstrated that keratinocyte-releasable stratifin, also known as 14-3-3 sigma protein, stimulates collagenase (MMP-1) expression in dermal fibroblasts. However, role of extracellular stratifin in regulation of extracellular matrix (ECM) factors and other matrix metalloproteinases (MMPs) in dermal fibroblast remains unexplored. To address this question, large-scale ECM gene expression profile were analyzed in human dermal fibroblasts co-cultured with keratinocytes or treated with recombinant stratifin. Superarray pathway-specific microarrays were utilized to identify upregulation or downregulation of 96 human ECM and adhesion molecule genes. RT-PCR and Western blot were used to validate microarray expression profiles of selected genes. Comparison of gene profiles with the appropriate controls showed a significant (more than twofold) increase in expression of collagenase-1, stromelysin-1 and -2, neutrophil collagenase, and membrane type 5 MMP in dermal fibroblasts treated with stratifin or co-cultured with keratinocytes. Expression of type I collagen and fibronectin genes decreased in the same fibroblasts. The results of a dose-response experiment showed that stratifin stimulates the expression of stromelysin-1 (MMP-3) mRNA by dermal fibroblasts in a concentration-dependent fashion. Furthermore, Western blot analysis of fibroblast-conditioned medium showed a peak in MMP-3 protein levels 48 h following treatment with recombinant stratifin. In a lasting-effect study, MMP-3 protein was detected in fibroblast-condition medium for up to 72 h post removal of stratifin. In conclusion, our results suggest that keratinocyte-releasable stratifin plays a major role in induction of ECM degradation by dermal fibroblasts through stimulation of key MMPs, such as MMP-1 and MMP-3. Therefore, stratifin protein may prove to be a useful target for clinical intervention in controlling excessive wound healing in fibrotic conditions.

The expression of indoleamine 2,3-dioxygenase (IDO), which metabolizes tryptophan, an essential amino acid, into kynurenine, has been identified as having a key role in the prevention of the immune rejection of the semi-allogeneic fetus during pregnancy. We have previously demonstrated that IDO expressed in fibroblasts causes bystander CD4(+) T cell damage as well as THP-1 cell damage by apoptosis. As T cells are primarily responsible for graft rejection, here, we asked the question of whether engraftment of IDO-expressing xenogeneic fibroblasts populated in a collagen matrix can be immuno-protected in an animal model. The results show a significant reduction in the number of infiltrated CD3(+) T lymphocytes on days 14 and 28 post-transplantation in the wounds receiving IDO-expressing fibroblasts relative to controls. IDO-expressing human fibroblasts embedded in bovine collagen on wounds in a rat model accelerates wound healing by promoting neovascularization during the early stages and providing protection of the xenograft fibroblasts. Using a co-culture system, we further confirm that IDO can induce angiogenesis through the depletion of tryptophan. These findings suggest that IDO may have an application in promoting the engraftment of skin substitutes and other transplanted organs.

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