The Hippo Signaling Pathway in Development and Disease

ARSD, a novel ERα downstream target gene, inhibits proliferation and migration of breast cancer cells via activating Hippo/YAP pathway

Advanced breast cancer (BC), especially basal like triple-negative BC (TNBC), is a highly malignant tumor without viable treatment option, highlighting the urgent need to seek novel therapeutic targets. Arylsulfatase D (ARSD), localized at Xp22.3, is a female-biased gene due to its escaping from X chromosome inactivation (XCI). Unfortunately, no systematic investigation of ARSD on BC has been reported. In this study, we observed that ARSD expression was positively related to ERα status either in BC cells or tissue specimens, which were associated with good prognosis. Furthermore, we found a set of hormone-responsive lineage-specific transcription factors, FOXA1, GATA3, ERα, directly drove high expression of ARSD through chromatin looping in luminal subtype BC cells. Opposingly, ARSD still subjected to XCI in TNBC cells mediated by Xist, CpG islands methylation, and inhibitory histone modification. Unexpectedly, we also found that ectopic ARSD overexpression could inhibit proliferation and migration of TNBC cells by activating Hippo/YAP pathway, indicating that ARSD may be a molecule brake on ERα signaling pathway, which restricted ERα to be an uncontrolled active status. Combined with other peoples' researches that Hippo signaling maintained ER expression and ER + BC growth, we believed that there should exist a regulative feedback loop formation among ERα, ARSD, and Hippo/YAP pathway. Collectively, our findings will help filling the knowledge gap about the influence of ARSD on BC and providing evidence that ARSD may serve as a potential marker to predict prognosis and as a therapeutic target.

NGF Signaling Interacts With the Hippo/YAP Pathway to Regulate Cervical Cancer Progression

Nerve growth factor (NGF) is increasingly implicated in cervical cancer progression, but its mechanism in cervical cancer is unclear. Here, studies demonstrate that NGF inhibits the Hippo signaling pathway and activates Yes-associated protein (YAP) to induce cervical cancer cell proliferation and migration. Our results suggested that stimulation of NGF promoted cell growth and migration and activated YAP in HeLa and C-33A cell lines. The expression of YAP target genes (CTGF and ANKRD1) was upregulated after NGF treatment. The NGF inhibitor Ro 08-2750 and siRNA-mediated NGF receptor gene silencing suppressed HeLa and C-33A cells proliferation and migration, activated large suppressor kinase 1 (LATS1) kinase activity, and suppressed YAP function. In addition, the expression of YAP target genes (CTGF and ANKRD1) was suppressed by Ro 08-2750 treatment in HeLa and C-33A cells. Interestingly, proliferation was significantly higher in NGF-treated cells than in control cells, and this effect was completely reversed by the YAP small molecule inhibitor-verteporfin. Furthermore, the mouse xenograft model shows that NGF regulates YAP oncogenic activity in vivo. Mechanistically, NGF stimulation inactivates LATS1 and activates YAP, and NGF inhibition was found to induce large suppressor kinase 1 (LATS1) phosphorylation. Taken together, these data provide the first direct evidence of crosstalk between the NGF signaling and Hippo cancer pathways, an interaction that affects cervical cancer progression. Our study indicates that combined targeting of the NGF signaling and the Hippo pathway represents a novel therapeutic strategy for treatment of cervical cancer.

EGFR Regulates the Hippo pathway by promoting the tyrosine phosphorylation of MOB1

The Hippo pathway is frequently dysregulated in cancer, leading to the unrestrained activity of its downstream targets, YAP/TAZ, and aberrant tumor growth. However, the precise mechanisms leading to YAP/TAZ activation in most cancers is still poorly understood. Analysis of large tissue collections revealed YAP activation in most head and neck squamous cell carcinoma (HNSCC), but only 29.8% of HNSCC cases present genetic alterations in the FAT1 tumor suppressor gene that may underlie persistent YAP signaling. EGFR is overexpressed in HNSCC and many other cancers, but whether EGFR controls YAP activation is still poorly understood. Here, we discover that EGFR activates YAP/TAZ in HNSCC cells, but independently of its typical signaling targets, including PI3K. Mechanistically, we find that EGFR promotes the phosphorylation of MOB1, a core Hippo pathway component, and the inactivation of LATS1/2 independently of MST1/2. Transcriptomic analysis reveals that erlotinib, a clinical EGFR inhibitor, inactivates YAP/TAZ. Remarkably, loss of LATS1/2, resulting in aberrant YAP/TAZ activity, confers erlotinib resistance on HNSCC and lung cancer cells. Our findings suggest that EGFR-YAP/TAZ signaling plays a growth-promoting role in cancers harboring EGFR alterations, and that inhibition of YAP/TAZ in combination with EGFR might be beneficial to prevent treatment resistance and cancer recurrence.

Ando et al show in head and neck squamous cell carcinoma cells that EGFR activation leads to the phosphorylation of the Hippo pathway component, MOB1 to inhibit LATS1/2 function resulting in YAP/TAZ activation. Further, EGFR-targeting therapies suppress YAP/TAZ, and loss of LATS1/2-mediated YAP/TAZ activation confers therapy resistance, thus offering insights into potential drug resistance mechanisms in cancers with activated EGFR.

Mitosis, a springboard for epithelial-mesenchymal transition?

Mitosis is a key process in development and remains critical to ensure homeostasis in adult tissues. Besides its primary role in generating two new cells, cell division involves deep structural and molecular changes that might have additional effects on cell and tissue fate and shape. Specific quantitative and qualitative regulation of mitosis has been observed in multiple morphogenetic events in different embryo models. For instance, during mouse embryo gastrulation, the portion of epithelium that undergoes epithelial to mesenchymal transition, where a static epithelial cell become mesenchymal and motile, has a higher mitotic index and a distinct localization of mitotic rounding, compared to the rest of the tissue. Here we explore the potential mechanisms through which mitosis may favor tissue reorganization in various models. Notably, we discuss the mechanical impact of cell rounding on the cell and its environment, and the modification of tissue physical parameters through changes in cell-cell and cell-matrix adhesion.

Quantitative phosphoproteomic analysis reveals chemoresistance-related proteins and signaling pathways induced by rhIL-6 in human osteosarcoma cells

Background

IL-6 plays a pivotal role in resistance to chemotherapeutics, including lobaplatin. However, the underlying mechanisms are still unclear. This study was to investigate the changes in phosphoproteins and their related signaling pathways in the process of IL-6-induced chemoresistance to lobaplain in osteosarcoma cells.

Methods

We performed a quantitative phosphoproteomic analysis of the response of SaOS-2 osteosarcoma cells to recombinant human IL-6 (rhIL-6) intervention prior to lobaplatin treatment. The cells were divided into the control group (Con), the lobaplatin group (Lob), and the rhIL-6-and-lobaplatin group (IL-6). Three biological replicates of each group were included. The differentially expressed phosphoproteins were subjected to Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) enrichment analyses. Netphos 3.1 was used for the prediction of kinases, and STRING was used for the visualization of protein–protein interactions. The conserved motifs surrounding the phosphorylated residues were analyzed using the motif-x algorithm. Western blot analysis was performed to verify the differential expression of p-FLNC, its predicted kinase and the related signaling pathway. The results of the bioinformatic analysis were validated by immunohistochemical staining of clinical specimens.

Results

In total, 3373 proteins and 12,183 peptides, including 3232 phosphorylated proteins and 11,358 phosphorylated peptides, were identified and quantified. Twenty-three significantly differentially expressed phosphoproteins were identified in the comparison between the IL-6 and Lob groups, and p-FLNC ranked second among these phosphoproteins. GO and KEGG analyses revealed the pivotal role of mitogen-activated protein kinase signaling in drug resistance induced by rhIL-6. Four motifs, namely, -SPxxK-, -RxxSP-, -SP-, and -SPK-, demonstrated higher expression in the IL-6 group than in the Lob group. The western blot analysis results verified the higher expression of p-FLNC, AKT1, and p-ERK and the lower expression of p-JNK in the IL-6 group than in the Con and Lob groups. The immunohistochemical staining results showed that p-FLNC, AKT1 and p-ERK1/2 were highly expressed in platinum-resistant clinical specimens but weakly expressed in platinum-sensitive specimens, and platinum-resistant osteosarcoma specimens demonstrated weak expression of p-JNK.

Conclusions

This phosphoproteomic study is the first to reveal the signature associated with rhIL-6 intervention before lobaplatin treatment in human osteosarcoma cells. p-FLNC, AKT1, and MAPK signaling contributes to resistance to lobaplatin in osteosarcoma SaOS-2 cells and may represent molecular targets to overcome osteosarcoma chemoresistance.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12935-021-02286-z.

Glycogen accumulation and phase separation drives liver tumor initiation

Glucose consumption is generally increased in tumor cells to support tumor growth. Interestingly, we report that glycogen accumulation is a key initiating oncogenic event during liver malignant transformation. We found that glucose-6-phosphatase (G6PC) catalyzing the last step of glycogenolysis is frequently downregulated to augment glucose storage in pre-malignant cells. Accumulated glycogen undergoes liquid-liquid phase separation, which results in the assembly of the Laforin-Mst1/2 complex and consequently sequesters Hippo kinases Mst1/2 in glycogen liquid droplets to relieve their inhibition on Yap. Moreover, G6PC or another glycogenolysis enzyme-liver glycogen phosphorylase (PYGL) deficiency in both human and mice results in glycogen storage disease along with liver enlargement and tumorigenesis in a Yap-dependent manner. Consistently, elimination of glycogen accumulation abrogates liver growth and cancer incidence, whereas increasing glycogen storage accelerates tumorigenesis. Thus, we concluded that cancer-initiating cells adapt a glycogen storing mode, which blocks Hippo signaling through glycogen phase separation to augment tumor incidence.

Interferon induction held captive in tumor cells

Unusual nucleic acids activate innate immunity and may be present in transformed cells. Meng et al. (2021) find that cancer-associated mutations in NF2 turn this tumor suppressor into a potent antagonist of DNA- and RNA-induced innate immune signaling.

Activation of Yes-Associated Protein/PDZ-Binding Motif Pathway Contributes to Endothelial Dysfunction and Vascular Inflammation in AngiotensinII Hypertension

Yes-associated protein (YAP) and its associated coactivator of PDZ-binding motif (TAZ) are co-transcriptional regulators and down effectors of the Hippo signaling pathway. Recent studies have shown that the Hippo/YAP signaling pathway may play a role in mediating vascular homeostasis. This study investigated the role of YAP/TAZ in endothelial dysfunction and vascular inflammation in angiotensin (Ang)II hypertensive mice. The infusion of AngII (1.1 mg/kg/day by mini-pump) for 3 weeks induced the activation of YAP/TAZ, manifested by decreased cytosolic phosphor-YAP and phosphor-TAZ, and increased YAP/TAZ nuclear translocation, which were prevented by YAP/TAZ inhibitor verteporfin. AngII significantly increased systolic blood pressure (SBP), macrophage infiltration, and expressions of proinflammatory cytokines, and impaired endothelial function in the aorta of the mice. Treatment with verteporfin improved endothelial function and reduced vascular inflammation with a mild reduction in SBP. AngII also induced YAP/TAZ activation in human umbilical vein endothelial cells in vitro, which were prevented by LB-100, an inhibitor of protein phosphatase 2A (PP2A, a major dephosphorylase). Treatment with LB-100 reversed AngII-induced proinflammatory cytokine expression and impairment of phosphor-eNOS expression in vitro. Our results suggest that AngII induces YAP/TAZ activation via PP2A-dependent dephosphorylation, which may contribute to the impairment of endothelial function and the induction of vascular inflammation in hypertension. YAP/TAZ may be a new target for hypertensive vascular injury.

YAP inhibition promotes endothelial cell differentiation from pluripotent stem cell through EC master transcription factor FLI1

Endothelial cells (ECs) derived from pluripotent stem cells (PSCs) provide great resource for vascular disease modeling and cell-based regeneration therapy. However, the molecular mechanisms of EC differentiation are not completely understood. In this study, we checked transcriptional profile by microarray and found Hippo pathway is changed and the activity of YAP decreased during mesoderm-mediated EC differentiation from human embryonic stem cells (hESCs). Knockdown of YAP in hESCs promoted both mesoderm and EC differentiation indicating by mesodermal- or EC-specific marker gene expression increased both in mRNA and protein level. In contrast, overexpression of YAP inhibited mesoderm and EC differentiation. Microarray data showed that several key transcription factors of EC differentiation, such as FLI1, ERG, SOX17 are upregulated. Interestingly, knockdown YAP enhanced the expression of these master transcription factors. Bioinformation analysis revealed that TEAD, a YAP binds transcription factors, might regulate the expression of EC master TFs, including FLI1. Luciferase assay confirmed that YAP binds to TEAD1, which would inhibit FLI1 expression. Finally, FLI1 overexpression rescued the effects of YAP overexpression-mediated inhibition of EC differentiation. In conclusion, we revealed the inhibitory effects of YAP on EC differentiation from PSCs, and YAP inhibition might promote expression of master TFs FLI1 for EC commitment through interacting with TEAD1, which might provide an idea for EC differentiation and vascular regeneration via manipulating YAP signaling.

Dura cells in the etiopathogenesis of Crouzon syndrome: the effects of FGFR2 mutations in the dura cells on the proliferation of osteoblasts through the hippo/YAP mediated transcriptional regulation pathway

BACKGROUND

FGFR2 (fibroblast growth factor receptor 2) mutations are implicated in the etiopathogenesis of syndromic craniosynostosis, and C278F- or C342Y-FGFR2 mutations can lead to Crouzon syndrome. The dura mater exerts crucial effects in the regulation of cranial suture development. However, the underlying mechanisms of these biological processes are rarely studied. This research explored and analyzed the biological function of FGFR2 overexpressed by dura cells on cranial osteoblasts.

METHODS

Dura cells and cranial osteoblasts from C57BL/6 mice aged 6 days were obtained and cultured respectively. Lentivirus-FGFR2 constructs were engineered with C278F- and C342Y-FGFR2 mutations. The dura cells were infected with the constructs and co-cultured with osteoblasts in a trans-well system. Four experimental groups were established, namely the Oste group, the Oste+Dura-vector group, the Oste+Dura-C278F group, and the Oste+Dura-C342Y group. FACS, CCK8, and EdU assays were used to evaluate the osteoblast proliferation levels. Western blot and RT-qPCR were used to measure the expressions of the factors related to proliferation, differentiation, and apoptosis. Furthermore, the expression levels of the key factors in the Hippo/YAP-PI3K-AKT proliferation pathway were measured and analyzed. Finally, rescue experiments were performed with an RNA interfering assay.

RESULTS

The proliferation and differentiation levels of the osteoblasts in the Oste+Dura-C278F and Oste+Dura-C342Y groups were significantly up-regulated, but the apoptosis levels in the four groups were not significantly different. The YAP, TEADs1-4, p-PI3K, and p-AKT1 expressions in the mutant FGFR2 groups were higher than the corresponding expressions in the control groups, and the results of the rescue experiments showed a reverse expression tendency, which further confirmed the effects of the FGFR2 mutations in the dura cells on the proliferation of the osteoblasts and the underlying possible mechanisms.

CONCLUSION

Our studies suggest that the Crouzon mutations (C278F- and C342Y-) of FGFR2 in dura cells can enhance osteoblast proliferation and differentiation and might influence the pathogenesis of craniosynostosis by affecting the Hippo/YAP-PI3K-AKT proliferation signaling pathway.

The Balance between Differentiation and Terminal Differentiation Maintains Oral Epithelial Homeostasis

Simple Summary

Oral cancer affecting the oral cavity represents the most common cancer of the head and neck region. Oral cancer develops in a multistep process in which normal cells gradually accumulate genetic and epigenetic modifications to evolve into a malignant disease. Mortality for oral cancer patients is high and morbidity has a significant long-term impact on the health and wellbeing of affected individuals, typically resulting in facial disfigurement and a loss of the ability to speak, chew, taste, and swallow. The limited scope to which current treatments are able to control oral cancer underlines the need for novel therapeutic strategies. This review highlights the molecular differences between oral cell proliferation, differentiation and terminal differentiation, defines terminal differentiation as an important tumour suppressive mechanism and establishes a rationale for clinical investigation of differentiation-paired therapies that may improve outcomes in oral cancer.

Abstract

The oral epithelium is one of the fastest repairing and continuously renewing tissues. Stem cell activation within the basal layer of the oral epithelium fuels the rapid proliferation of multipotent progenitors. Stem cells first undergo asymmetric cell division that requires tightly controlled and orchestrated differentiation networks to maintain the pool of stem cells while producing progenitors fated for differentiation. Rapidly expanding progenitors subsequently commit to advanced differentiation programs towards terminal differentiation, a process that regulates the structural integrity and homeostasis of the oral epithelium. Therefore, the balance between differentiation and terminal differentiation of stem cells and their progeny ensures progenitors commitment to terminal differentiation and prevents epithelial transformation and oral squamous cell carcinoma (OSCC). A recent comprehensive molecular characterization of OSCC revealed that a disruption of terminal differentiation factors is indeed a common OSCC event and is superior to oncogenic activation. Here, we discuss the role of differentiation and terminal differentiation in maintaining oral epithelial homeostasis and define terminal differentiation as a critical tumour suppressive mechanism. We further highlight factors with crucial terminal differentiation functions and detail the underlying consequences of their loss. Switching on terminal differentiation in differentiated progenitors is likely to represent an extremely promising novel avenue that may improve therapeutic interventions against OSCC.

Long noncoding RNAs: fine-tuners hidden in the cancer signaling network

With the development of sequencing technology, a large number of long non-coding RNAs (lncRNAs) have been identified in addition to coding genes. LncRNAs, originally considered as junk RNA, are dysregulated in various types of cancer. Although protein-coding signaling pathways underlie various biological activities, and abnormal signal transduction is a key trigger and indicator for tumorigenesis and cancer progression, lncRNAs are sparking keen interest due to their versatile roles in fine-tuning signaling pathways. We are just beginning to scratch the surface of lncRNAs. Therefore, despite the fact that lncRNAs drive malignant phenotypes from multiple perspectives, in this review, we focus on important signaling pathways modulated by lncRNAs in cancer to demonstrate an up-to-date understanding of this emerging field.

Targeted inhibition of YAP/TAZ alters the biological behaviours of keloid fibroblasts

Abnormal activation of fibroblasts plays a crucial role in keloid development. However, the mechanism of fibroblast activation remains to be determined. YAP/TAZ are key molecules in the Hippo signalling pathway that promote cell proliferation and inhibit apoptosis. Here, we show that keloid fibroblasts have higher levels of YAP/TAZ mRNA and proteins on primary culture. Targeted knockdown of endogenous YAP or TAZ significantly inhibited cell proliferation, reduced cell migration, induced cell apoptosis and down-regulated collagen1a1 production by keloid fibroblasts. Moreover, we demonstrate that verteporfin, an inhibitor of YAP/TAZ, has similar but stronger inhibitory effects on fibroblasts compared to YAP/TAZ knockdown. Our study provides evidence that YAP/TAZ may be involved in the pathogenesis of keloids. Targeted inhibition of YAP/TAZ could change the biological behaviours of fibroblasts and can potentially be used as therapy for keloids.

Specific Deletion of the FHA Domain Containing SLMAP3 Isoform in Postnatal Myocardium Has No Impact on Structure or Function

Sarcolemmal membrane-associated proteins (SLMAPs) belong to the superfamily of tail-anchored membrane proteins known to regulate diverse biological processes, including protein trafficking and signal transduction. Mutations in SLMAP have been linked to Brugada and defective sodium channel Nav1.5 shuttling. The SLMAP gene is alternatively spliced to generate numerous isoforms, broadly defined as SLMAP1 (~35 kDa), SLMAP2 (~45 kDa) and SLMAP3 (~80–95 kDa), which are highly expressed in the myocardium. The SLMAP3 isoform exhibits ubiquitous expression carrying an FHA domain and is believed to negatively regulate Hippo signaling to dictate cell growth/death and differentiation. Using the αMHC-MerCreMer-flox system to target the SLMAP gene, we specifically deleted the SLMAP3 isoform in postnatal mouse hearts without any changes in the expression of SLMAP1/SLMAP2 isoforms. The in vivo analysis of mice with SLMAP3 cardiac deficiency revealed no significant changes to heart structure or function in young or aged mice without or with isoproterenol-induced stress. SLMAP3-deficient hearts revealed no obvious differences in cardiac size, function or hypertrophic response. Further, the molecular analysis indicated that SLMAP3 loss had a minor impact on sodium channel (Nav1.5) expression without affecting cardiac electrophysiology in postnatal myocardium. Surprisingly, the loss of SLMAP3 did not impact Hippo signaling in postnatal myocardium. We conclude that the FHA domain-containing SLMAP3 isoform has no impact on Hippo signaling or sodium channels in postnatal myocardium, which is able to function and respond normally to stress in its absence. Whether SLMAP1/SMAP2 isoforms can compensate for the loss of SLMAP3 in the affairs of the postnatal heart remains to be determined.

Synthetic molecules targeting yes associated protein activity as chemotherapeutics against cancer

The Hippo signaling pathway extorts several signals that concomitantly target the activity of transcriptional cofactor yes associated protein (YAP). YAP is a key regulator that elicits signature gene expression by coupling with transcriptional enhanced associate domain (TEAD) family of transcriptional factors. The YAP-TEAD complex via target gene expression gets associated with the development, proliferation, and progression of cancerous cells. Moreover, YAP adorns cells with several oncogenic traits such as inhibition of apoptosis, enhanced proliferation, drug resistance, and immune response suppression, which later became associated with various diseases, particularly cancer. Therefore, inhibition of the YAP activity is an appealing and viable therapeutic target for cancer treatment. This review highlights the recent advances in existing and novel synthetic therapeutics targeting YAP inhibition and regulation. The synthetically produced YAP^D93A belonging to cyclic peptides and DC-TEADin02 and vinyl sulfonamide class of compounds are the most potent compounds to inhibit the YAP-TEAD expression by targeting protein-protein interaction (IC₅₀  = 25 nM) and palmitate binding central pocket of TEAD (IC₅₀  = 197 nM), respectively. On the other hand, Chlorpromazine belonging to phenothiazines class has the least potential to suppress YAP via proteasomal degradation (cell viability value of <20% at 40 µM).

Polyploidy in development and tumor models in Drosophila

Polyploidy, a cell status defined as more than two sets of genomic DNA, is a conserved strategy across species that can increase cell size and biosynthetic production, but the functional aspects of polyploidy are nuanced and vary across cell types. Throughout Drosophila developmental stages (embryo, larva, pupa and adult), polyploid cells are present in numerous organs and help orchestrate development while contributing to normal growth, well-being and homeostasis of the organism. Conversely, increasing evidence has shown that polyploid cells are prevalent in Drosophila tumors and play important roles in tumor growth and invasiveness. Here, we summarize the genes and pathways involved in polyploidy during normal and tumorigenic development, the mechanisms underlying polyploidization, and the functional aspects of polyploidy in development, homeostasis and tumorigenesis in the Drosophila model.

Effects of YAP1 and SFRP2 overexpression on the biological behavior of colorectal cancer cells and their molecular mechanisms

Background

Colorectal cancer (CRC) is one of the most common malignancies worldwide and has a high mortality rate. With the development of tumor molecular biology, more and more attention is being paid to the mechanisms of cell pathways in colorectal carcinogenesis, such as the Hippo/Yes-associated protein 1 (YAP1) and Wnt/β-catenin signaling pathways. The abnormal expression of YAP1 and β-catenin have been reported in CRC, and can lead to excessive cell proliferation, and eventually, tumor formation. Secreted frizzled-related protein 2 (SFRP2) levels have been found to be decreased in a variety of cancers, and SFRP2 is an antagonist that binds directly to Wnt signal. At present, the molecular basis of colorectal tumors is still not fully understood. In the present study, we sought to identify the molecular mechanisms underlying YAP1 and SFRP2 in the development of CRC.

Methods

We constructed CRC cell lines that stably overexpressed YAP1 and SFRP2 using lentivirus packaging and cell infection. The levels of expression of the proteins were evaluated by western blot and immunofluorescence assays. Protein complex immunoprecipitation (Co-IP) was used to detect the interaction between YAP1, SFRP2, and β-catenin. The functional roles of YAP1 and SFRP2 in CRC was determined by a Cell Counting Kit-8 (CCK8) proliferation assay and flow cytometric apoptosis assay.

Results

The data of the present study showed that the overexpression of SFRP2 promoted the expression of YAP1 and β-catenin protein, and the overexpression of YAP1 promoted the expression of β-catenin protein. YAP1 overexpression promoted cell proliferation, while SFRP2 overexpression inhibited cell proliferation and promoted cell apoptosis.

Conclusions

Our findings showed that the expression of YAP1, SFRP2, and β-catenin is correlated in CRC cells. The Hippo pathway and Wnt pathway interact with each other in the pathogenesis of CRC, and YAP1 and SFRP2 are involved in the formation and development of CRC.

Targeting the Hippo pathway in heart repair

The Hippo pathway is an evolutionarily and functionally conserved signaling pathway that controls organ size by regulating cell proliferation, apoptosis, and differentiation. Emerging evidence has shown that the Hippo pathway plays critical roles in cardiac development, homeostasis, disease, and regeneration. Targeting the Hippo pathway has tremendous potential as a therapeutic strategy for treating intractable cardiovascular diseases such as heart failure. In this review, we summarize the function of the Hippo pathway in the heart. Particularly, we highlight the posttranslational modification of Hippo pathway components, including the core kinases LATS1/2 and their downstream effectors YAP/TAZ, in different contexts, which has provided new insights and avenues in cardiac research.

Mechanisms of Fibroblast Activation and Myocardial Fibrosis: Lessons Learned from FB-Specific Conditional Mouse Models

Heart failure (HF) is a leading cause of morbidity and mortality across the world. Cardiac fibrosis is associated with HF progression. Fibrosis is characterized by the excessive accumulation of extracellular matrix components. This is a physiological response to tissue injury. However, uncontrolled fibrosis leads to adverse cardiac remodeling and contributes significantly to cardiac dysfunction. Fibroblasts (FBs) are the primary drivers of myocardial fibrosis. However, until recently, FBs were thought to play a secondary role in cardiac pathophysiology. This review article will present the evolving story of fibroblast biology and fibrosis in cardiac diseases, emphasizing their recent shift from a supporting to a leading role in our understanding of the pathogenesis of cardiac diseases. Indeed, this story only became possible because of the emergence of FB-specific mouse models. This study includes an update on the advancements in the generation of FB-specific mouse models. Regarding the underlying mechanisms of myocardial fibrosis, we will focus on the pathways that have been validated using FB-specific, in vivo mouse models. These pathways include the TGF-β/SMAD3, p38 MAPK, Wnt/β-Catenin, G-protein-coupled receptor kinase (GRK), and Hippo signaling. A better understanding of the mechanisms underlying fibroblast activation and fibrosis may provide a novel therapeutic target for the management of adverse fibrotic remodeling in the diseased heart.

Expression Profiles and Potential Functions of Long Non-Coding RNAs in the Heart of Mice With Coxsackie B3 Virus-Induced Myocarditis

Aims

Long non-coding RNAs (lncRNAs) are critical regulators of viral infection and inflammatory responses. However, the roles of lncRNAs in acute myocarditis (AM), especially fulminant myocarditis (FM), remain unclear.

Methods

FM and non-fulminant myocarditis (NFM) were induced by coxsackie B3 virus (CVB3) in different mouse strains. Then, the expression profiles of the lncRNAs in the heart tissues were detected by sequencing. Finally, the patterns were analyzed by Pearson/Spearman rank correlation, Kyoto Encyclopedia of Genes and Genomes, and Cytoscape 3.7.

Results

First, 1,216, 983, 1,606, and 2,459 differentially expressed lncRNAs were identified in CVB3-treated A/J, C57BL/6, BALB/c, and C3H mice with myocarditis, respectively. Among them, 88 lncRNAs were commonly dysregulated in all four models. Quantitative real-time polymerase chain reaction analyses further confirmed that four out of the top six commonly dysregulated lncRNAs were upregulated in all four models. Moreover, the levels of ENSMUST00000188819, ENSMUST00000199139, and ENSMUST00000222401 were significantly elevated in the heart and spleen and correlated with the severity of cardiac inflammatory infiltration. Meanwhile, 923 FM-specific dysregulated lncRNAs were detected, among which the levels of MSTRG.26098.49, MSTRG.31307.11, MSTRG.31357.2, and MSTRG.32881.28 were highly correlated with LVEF.

Conclusion

Expression of lncRNAs is significantly dysregulated in acute myocarditis, which may play different roles in the progression of AM.

Interplay Between Notch and YAP/TAZ Pathways in the Regulation of Cell Fate During Embryo Development

Cells in growing tissues receive both biochemical and physical cues from their microenvironment. Growing evidence has shown that mechanical signals are fundamental regulators of cell behavior. However, how physical properties of the microenvironment are transduced into critical cell behaviors, such as proliferation, progenitor maintenance, or differentiation during development, is still poorly understood. The transcriptional co-activators YAP/TAZ shuttle between the cytoplasm and the nucleus in response to multiple inputs and have emerged as important regulators of tissue growth and regeneration. YAP/TAZ sense and transduce physical cues, such as those from the extracellular matrix or the actomyosin cytoskeleton, to regulate gene expression, thus allowing them to function as gatekeepers of progenitor behavior in several developmental contexts. The Notch pathway is a key signaling pathway that controls binary cell fate decisions through cell-cell communication in a context-dependent manner. Recent reports now suggest that the crosstalk between these two pathways is critical for maintaining the balance between progenitor maintenance and cell differentiation in different tissues. How this crosstalk integrates with morphogenesis and changes in tissue architecture during development is still an open question. Here, we discuss how progenitor cell proliferation, specification, and differentiation are coordinated with morphogenesis to construct a functional organ. We will pay special attention to the interplay between YAP/TAZ and Notch signaling pathways in determining cell fate decisions and discuss whether this represents a general mechanism of regulating cell fate during development. We will focus on research carried out in vertebrate embryos that demonstrate the important roles of mechanical cues in stem cell biology and discuss future challenges.

Imipramine impedes glioma progression by inhibiting YAP as a Hippo pathway independent manner and synergizes with temozolomide

Patients with malignant glioma often suffered from depression, which leads to an increased risk of detrimental outcomes. Imipramine, an FDA‐approved tricyclic antidepressant, has been commonly used to relieve depressive symptoms in the clinic. Recently, imipramine has been reported to participate in the suppression of tumour progression in several human cancers, including prostate cancer, colon cancer and lymphomas. However, the effect of imipramine on malignant glioma is largely unclear. Here, we show that imipramine significantly retarded proliferation of immortalized and primary glioma cells. Mechanistically, imipramine suppressed tumour proliferation by inhibiting yes‐associated protein (YAP), a recognized oncogene in glioma, independent of Hippo pathway. In addition to inhibiting YAP transcription, imipramine also promoted the subcellular translocation of YAP from nucleus into cytoplasm. Consistently, imipramine administration significantly reduced orthotopic tumour progression and prolonged survival of tumour‐bearing mice. Moreover, exogenous overexpression of YAP partially restored the inhibitory effect of imipramine on glioma progression. Most importantly, compared with imipramine or temozolomide (TMZ) monotherapy, combination therapy with imipramine and TMZ exhibited enhanced inhibitory effect on glioma growth both in vitro and in vivo, suggesting the synergism of both agents. In conclusion, we found that tricyclic antidepressant imipramine impedes glioma progression by inhibiting YAP. In addition, combination therapy with imipramine and TMZ may potentially serve as promising anti‐glioma regimens, thus predicting a broad prospect of clinical application.

Long-Term Hypoxia Maintains a State of Dedifferentiation and Enhanced Stemness in Fetal Cardiovascular Progenitor Cells

Early-stage mammalian embryos survive within a low oxygen tension environment and develop into fully functional, healthy organisms despite this hypoxic stress. This suggests that hypoxia plays a regulative role in fetal development that influences cell mobilization, differentiation, proliferation, and survival. The long-term hypoxic environment is sustained throughout gestation. Elucidation of the mechanisms by which cardiovascular stem cells survive and thrive under hypoxic conditions would benefit cell-based therapies where stem cell survival is limited in the hypoxic environment of the infarcted heart. The current study addressed the impact of long-term hypoxia on fetal Islet-1+ cardiovascular progenitor cell clones, which were isolated from sheep housed at high altitude. The cells were then cultured in vitro in 1% oxygen and compared with control Islet-1+ cardiovascular progenitor cells maintained at 21% oxygen. RT-PCR, western blotting, flow cytometry, and migration assays evaluated adaptation to long term hypoxia in terms of survival, proliferation, and signaling. Non-canonical Wnt, Notch, AKT, HIF-2α and Yap1 transcripts were induced by hypoxia. The hypoxic niche environment regulates these signaling pathways to sustain the dedifferentiation and survival of fetal cardiovascular progenitor cells.

Verteporfin suppresses osteosarcoma progression by targeting the Hippo signaling pathway

Verteporfin (VP) is a specific inhibitor of yes-associated protein 1 (YAP1) that suppresses tumor progression by inhibiting YAP1 expression. The present study aimed to determine the inhibitory effect of VP on osteosarcoma and the underlying mechanism of its anticancer effects. Cell viability, cell cycle and apoptosis and cell migration and invasion were analyzed using the MTT assay, flow cytometry, wound healing assay and Transwell assay, respectively. Expressions of YAP1 and TEA domain transcription factor 1 (TEAD1) were measured using reverse transcription-quantitative PCR and western blotting, while their interaction was identified by the co-immunoprecipitation assay. In vivo mouse xenograft experiments were performed to evaluate the effect of VP on osteosarcoma growth. The results demonstrated that YAP1 and TEAD1 were highly expressed in osteosarcoma cells and tissues, whereas VP significantly downregulated the expression levels of YAP1 and TEAD1 in the osteosarcoma cell line Saos-2 compared with those in untreated control cells. In addition, compared with those in the control group, VP suppressed the viability, migration and invasion, induced cell cycle arrest in the G1 phase and promoted apoptosis in Saos-2 cells. In addition, VP inhibited mouse xenograft tumor growth in vivo compared with that observed in the control group. Notably, VP downregulated the levels of CYR61 expression in Saos-2 cells, whereas CYR61 overexpression mitigated the inhibitory effects of VP on osteosarcoma cells, as indicated by the increased viability and reduced apoptotic rates in Saos-2 cells overexpressing CYR61 compared with those in the control group. In summary, VP suppressed osteosarcoma by downregulating the expression of YAP1 and TEAD1. Additionally, CYR61 may mediate the effects of VP on osteosarcoma progression.

The Hippo pathway: an emerging role in urologic cancers

The Hippo pathway controls several biological processes, including cell growth, differentiation, motility, stemness, cell contact, immune cell maturation, organ size, and tumorigenesis. The Hippo pathway core kinases MST1/2 and LATS1/2 in mammals phosphorylate and inactivate YAP1 signaling. Increasing evidence indicates that loss of MST1/2 and LATS1/2 function is linked to the biology of many cancer types with poorer outcomes, likely due to the activation of oncogenic YAP1/TEAD signaling. Therefore, there is a renewed interest in blocking the YAP1/TEAD functions to prevent cancer growth. This review introduces the Hippo pathway components and examines their role and therapeutic potentials in prostate, kidney, and bladder cancer.

Stabilization of Motin family proteins in NF2-deficient cells prevents full activation of YAP/TAZ and rapid tumorigenesis

Germline alterations of the NF2 gene cause neurofibromatosis type 2, a syndrome manifested with benign tumors, and Nf2 deletion in mice also results in slow tumorigenesis. As a regulator of the Hippo signaling pathway, NF2 induces LATS1/2 kinases and consequently represses YAP/TAZ. YAP/TAZ oncoproteins are also inhibited by motin family proteins (Motins). Here, we show that the Hippo signaling is fine-tuned by Motins in a NF2-dependent manner, in which NF2 recruits E3 ligase RNF146 to facilitate ubiquitination and subsequent degradation of Motins. In the absence of NF2, Motins robustly accumulate to restrict full activation of YAP/TAZ and prevent rapid tumorigenesis. Hence, NF2 deficiency not only activates YAP/TAZ by inhibiting LATS1/2 but also stabilizes Motins to keep YAP/TAZ activity in check. The upregulation of Motins upon NF2 deletion serves as a strategy for avoiding uncontrolled perturbation of the Hippo signaling and may contribute to the benign nature of most NF2-mutated tumors.

Yap Promotes Noncanonical Wnt Signals From Cardiomyocytes for Heart Regeneration

[Figure: see text].

YAP/TAZ maintain the proliferative capacity and structural organization of radial glial cells during brain development

The Hippo pathway regulates the development and homeostasis of many tissues and in many species. It controls the activity of two paralogous transcriptional coactivators, YAP and TAZ (YAP/TAZ). Although previous studies have established that aberrant YAP/TAZ activation is detrimental to mammalian brain development, whether and how endogenous levels of YAP/TAZ activity regulate brain development remain unclear. Here, we show that during mammalian cortical development, YAP/TAZ are specifically expressed in apical neural progenitor cells known as radial glial cells (RGCs). The subcellular localization of YAP/TAZ undergoes dynamic changes as corticogenesis proceeds. YAP/TAZ are required for maintaining the proliferative potential and structural organization of RGCs, and their ablation during cortical development reduces the numbers of cortical projection neurons and causes the loss of ependymal cells, resulting in hydrocephaly. Transcriptomic analysis using sorted RGCs reveals gene expression changes in YAP/TAZ-depleted cells that correlate with mutant phenotypes. Thus, our study has uncovered essential functions of YAP/TAZ during mammalian brain development and revealed the transcriptional mechanism of their action.

Wogonin Induces Cell Cycle Arrest and Apoptosis of Hepatocellular Carcinoma Cells by Activating Hippo Signalling

OBJECTIVE

The current study aimed to illustrate whether wogonin influences HCC cell cycle progression and apoptosis by regulating Hippo signaling. <P> Methods: The effects of wogonin on HCC cell viability, cell cycle progression and apoptosis were analyzed by utilizing CCK-8 and flow cytometry. RNA-seq was employed to analyze the expression profiles between wogonin-treated and control HCC cells, and the selected RNA-seq transcripts were validated by reverse transcription-quantitative real-time polymerase chain reaction (RT-qPCR). Immunofluorescence staining was performed to detect the distribution of YAP/TAZ in the nucleus and cytoplasm in HCC cells. Western blotting and human apoptosis array were performed to examine the expression of the indicated genes. <P> Results: We demonstrated that wogonin induced cell cycle arrest and apoptosis of HCC cell lines SMMC7721 and HCCLM3. RNA-seq analysis showed enrichment in genes associated with cell cycle progression and apoptosis following incubation with wogonin in HCC cells, and the pathways analysis further identified that Hippo signaling pathways highly altered in wogonin-treated cells. Specifically, wogonin increased the phosphorylation of MOB1 and LATS1, promoted translocation of endogenous YAP and TAZ from the nucleus to the cytoplasm, and facilitated phosphorylation of YAP and TAZ. Notably, overexpression of YAP or TAZ partially abrogated the wogonin-mediated HCC cell cycle arrest and apoptosis, and reversed wogonin-mediated suppression of Claspin. <P> Conclusion: Wogonin induced HCC cell cycle arrest and apoptosis probably by activating MOB1-LATS1 signaling to inhibit the activation of YAP and TAZ, and then decrease the expression of Claspin, suggesting that the understanding of the molecular mechanisms underlying wogonin-induced cell cycle arrest and apoptosis may be useful in HCC therapeutics.

The Hippo pathway uses different machinery to control cell fate and organ size

The Hippo pathway is a conserved signaling network that regulates organ growth and cell fate. One such cell fate decision is that of R8 photoreceptor cells in the Drosophila eye, where Hippo specifies whether cells sense blue or green light. We show that only a subset of proteins that control organ growth via the Hippo pathway also regulate R8 cell fate choice, including the STRIPAK complex, Tao, Pez, and 14-3-3 proteins. Furthermore, key Hippo pathway proteins were primarily cytoplasmic in R8 cells rather than localized to specific membrane domains, as in cells of growing epithelial organs. Additionally, Warts was the only Hippo pathway protein to be differentially expressed between R8 subtypes, while central Hippo pathway proteins were expressed at dramatically lower levels in adult and pupal eyes than in growing larval eyes. Therefore, we reveal several important differences in Hippo signaling in the contexts of organ growth and cell fate.

Identifying cancer patient subgroups by finding co-modules from the driver mutation profiles and downstream gene expression profiles

Identifying cancer subtypes shed new light on effective personalized cancer medicine, future therapeutic strategies and minimizing treatment-related costs. Recently, there are many clustering methods have been proposed in categorizing cancer patients. However, these methods still fail to fully use the prior known biological information in the model designing process to improve precision and efficiency. It is acknowledged that the driver gene always regulates its downstream genes in the net-work to perform a certain function. By analyzing the known clinic cancer subtype data, we found some special co-pathways between the driver genes and the downstream genes in the cancer patients of the same subgroup. Hence, we proposed a novel model named DDCMNMF(Driver and Downstream gene Co-Module Assisted Multiple Non-negative Matrix Factorization model) that first stratify cancer sub-types by identifying co-modules of driver genes and downstream genes. We applied our model on lung and breast cancer datasets and compared it with the other four state-of-the-art models. The final results show that our model could identify the cancer subtypes with high compactness and separateness and achieve a high degree of consistency with the known cancer subtypes. The survival time analysis further proves the significant clinical characteristic of identified cancer subgroups by our model.

Cellular feedback dynamics and multilevel regulation driven by the hippo pathway

The Hippo pathway is a dynamic cellular signalling nexus that regulates differentiation and controls cell proliferation and death. If the Hippo pathway is not precisely regulated, the functionality of the upstream kinase module is impaired, which increases nuclear localisation and activity of the central effectors, the transcriptional co-regulators YAP and TAZ. Pathological YAP and TAZ hyperactivity consequently cause cancer, fibrosis and developmental defects. The Hippo pathway controls an array of fundamental cellular processes, including adhesion, migration, mitosis, polarity and secretion of a range of biologically active components. Recent studies highlight that spatio-temporal regulation of Hippo pathway components are central to precisely controlling its context-dependent dynamic activity. Several levels of feedback are integrated into the Hippo pathway, which is further synergized with interactors outside of the pathway that directly regulate specific Hippo pathway components. Likewise, Hippo core kinases also ‘moonlight’ by phosphorylating multiple substrates beyond the Hippo pathway and thereby integrates further flexibility and robustness in the cellular decision-making process. This topic is still in its infancy but promises to reveal new fundamental insights into the cellular regulation of this therapeutically important pathway. We here highlight recent advances emphasising feedback dynamics and multilevel regulation of the Hippo pathway with a focus on mitosis and cell migration, as well as discuss potential productive future research avenues that might reveal novel insights into the overall dynamics of the pathway.

Autotransplantation of the ovarian cortex after in-vitro activation for infertility treatment: a shortened procedure

STUDY QUESTION

Is it possible to establish a new in-vitro activation (IVA) protocol for infertility treatment?

SUMMARY ANSWER

A new IVA procedure is an efficient and easily performed approach for infertility treatment of patients with diminished ovarian reserve (DOR).

WHAT IS KNOWN ALREADY

IVA of primordial follicles with or without stimulators has been developed to treat patients with primary ovarian insufficiency (POI) successfully. However, the efficiency of the procedure is still very low. There is a requirement to optimize the protocol with increased efficiency for clinical application.

STUDY DESIGN, SIZE, DURATION

Newborn mouse ovaries were used to establish a new 1-h IVA protocol with the mechanistic target of rapamycin (mTOR) stimulator phosphatidic acid (PA, 200 µM) and the phosphatidylinositol-3-kinase (PI3K) stimulator 740Y-P (250 µg/ml); a prospective observational cohort study in POI patients was performed on 15 POI patients and 3 poor ovarian response (POR) patients in three different centers of reproductive medicine in China.

PARTICIPANTS/MATERIALS, SETTING, METHODS

One-third of ovarian cortex was removed and processed into bigger strips (1 × 1 cm2, 1-2 mm thickness). Strips were then sutured back after treatment. The new approach only requires one laparoscopic surgery.

MAIN RESULTS AND THE ROLE OF CHANCE

Follicular activation and development increased in cultured mouse and human ovarian tissues after 1 h of stimulator treatment. Compared with tiny ovarian cortex pieces (1 × 1 mm2), large ovarian strips (1 × 1 cm2) showed the lowest apoptotic signals after incubation. We applied the orthotropic transplantation procedure with large strips in the clinic, and 9 of 15 POI patients showed at least one-wave follicular growth during the monitoring period. One patient was reported with one healthy delivery after natural conception and another patient with a healthy singleton delivery after IVF. All the contacted patients (n = 13) responded with no side effects on their health 2-4 years after IVA procedure.

LIMITATIONS, REASONS FOR CAUTION

Further clinical trials with a large number of well-defined patients are required to compare different IVA protocols. A long-term follow-up system should be set up to monitor patient's health in the future cohort study.

WIDER IMPLICATIONS OF THE FINDINGS

By using stimulators, the findings in the study provide a more efficient IVA protocol for the treatment of patients with DOR. It requires only one laparoscopic surgery and thus minimizes patients' discomfort and costs. This strategy could be useful for patients diagnosed with POI and desire pregnancy as soon as possible after the operation.

STUDY FUNDING/COMPETING INTEREST(S)

This work was supported by the National Key Research and Development Program of China (2018YFC1003703 and 2018YFC1004203); the National Natural Science Foundation of China (81871221); Co-construction of Provincial Department (201601006). The authors have no conflict of interest to disclose.

TRIAL REGISTRATION NUMBER

ChiCTR2000030872.

Binary pan-cancer classes with distinct vulnerabilities defined by pro- or anti-cancer YAP/TEAD activity

Cancer heterogeneity impacts therapeutic response, driving efforts to discover over-arching rules that supersede variability. Here, we define pan-cancer binary classes based on distinct expression of YAP and YAP-responsive adhesion regulators. Combining informatics with in vivo and in vitro gain- and loss-of-function studies across multiple murine and human tumor types, we show that opposite pro- or anti-cancer YAP activity functionally defines binary YAP^on or YAP^off cancer classes that express or silence YAP, respectively. YAP^off solid cancers are neural/neuroendocrine and frequently RB1^-/-, such as retinoblastoma, small cell lung cancer, and neuroendocrine prostate cancer. YAP silencing is intrinsic to the cell of origin, or acquired with lineage switching and drug resistance. The binary cancer groups exhibit distinct YAP-dependent adhesive behavior and pharmaceutical vulnerabilities, underscoring clinical relevance. Mechanistically, distinct YAP/TEAD enhancers in YAP^off or YAP^on cancers deploy anti-cancer integrin or pro-cancer proliferative programs, respectively. YAP is thus pivotal across cancer, but in opposite ways, with therapeutic implications.

Liquid-liquid phase separation in human health and diseases

Emerging evidence suggests that liquid-liquid phase separation (LLPS) represents a vital and ubiquitous phenomenon underlying the formation of membraneless organelles in eukaryotic cells (also known as biomolecular condensates or droplets). Recent studies have revealed evidences that indicate that LLPS plays a vital role in human health and diseases. In this review, we describe our current understanding of LLPS and summarize its physiological functions. We further describe the role of LLPS in the development of human diseases. Additionally, we review the recently developed methods for studying LLPS. Although LLPS research is in its infancy-but is fast-growing-it is clear that LLPS plays an essential role in the development of pathophysiological conditions. This highlights the need for an overview of the recent advances in the field to translate our current knowledge regarding LLPS into therapeutic discoveries.

A case of metastatic NUT carcinoma with prolonged response on gemcitabine and nab-paclitaxel

BACKGROUND

NUT carcinoma is an aggressive malignancy characterized by translocations in the NUTM1 gene. There are currently no consensus treatment recommendations for NUT carcinomas.

METHODS

Here, we describe the case of a previously healthy male diagnosed with NUT carcinoma after presenting with sinus pressure, found to have a sinonasal mass and distant metastatic disease in the lungs. While pathologic evaluation and immunohistochemistry were consistent with NUT carcinoma, initial genomic profiling did not demonstrate a NUTM1 translocation.

RESULTS

Whole transcriptomic RNA sequencing of the tumor revealed a YAP1-NUTM1 fusion. Based on an in vitro drug sensitivity screen, the patient was treated with gemcitabine and nab-paclitaxel, achieving a partial response that persisted for 9 months.

CONCLUSIONS

Unbiased transcriptomic sequencing may identify previously uncharacterized NUTM1 fusion partners. Gemcitabine and nab-paclitaxel is a well-tolerated combination chemotherapy regimen and could offer a novel treatment approach for NUT carcinoma.

Transcriptional regulation of miR-30a by YAP impacts PTPN13 and KLF9 levels and Schwann cell proliferation

The Hippo pathway is a key regulatory pathway that is tightly regulated by mechanical cues such as tension, pressure, and contact with the extracellular matrix and other cells. At the distal end of the pathway is the yes-associated protein (YAP), a well-characterized transcriptional regulator. Through binding to transcription factors such as the TEA Domain TFs (TEADs) YAP regulates expression of several genes involved in cell fate, proliferation and death decisions. While the function of YAP as direct transcriptional regulator has been extensively characterized, only a small number of studies examined YAP function as a regulator of gene expression via microRNAs. We utilized bioinformatic approaches, including chromatin immunoprecipitation sequencing and RNA-Seq, to identify potential new targets of YAP regulation and identified miR-30a as a YAP target gene in Schwann cells. We find that YAP binds to the promoter and regulates the expression of miR-30a. Moreover, we identify several YAP-regulated genes that are putative miR-30a targets and focus on two of these, protein tyrosine pohosphatase non-receptor type 13 (PTPN13) and Kruppel like factor 9. We find that YAP regulation of Schwann cell proliferation and death is mediated, to a significant extent, through miR-30a regulation of PTPN13 in Schwann cells. These findings identify a new regulatory function by YAP, mediated by miR-30a, to downregulate expression of PTPN13 and Kruppel like factor 9. These studies expand our understanding of YAP function as a regulator of miRNAs and illustrate the complexity of YAP transcriptional functions.

Genome-wide association studies of preweaning growth and in vivo carcass composition traits in Esme sheep

Sheep are considered as a major contributor of global food security. Moreover, sheep preweaning growth traits as well as in vivo carcass composition traits such as ultrasonic measurements of Longissimus dorsi muscle depth (UMD) and back-fat thickness (UFD) are crucially important indicators of meat yield and hot carcass composition. Despite their relative importance for productivity and profitability of a sheep production system, detected QTL for these traits are quite scarce. Therefore, we implemented GWAS for these traits using animal mixed model-based association approach provided by GenABEL in Esme sheep. Three genome-wide and 14 individual chromosome-wide associated SNPs were discovered. As a result, ESRP1, LOC105613082, ZNF641, DUSP5, TEAD1, SMOX, PTPRT, RALYL, POM121C, PHIP, LOC101106051, ZIM3, PEG3, TRPC7, FBXL4, LOC105610397, LOC105616489 and DNAAF2 were suggested as candidates. Some of the discovered genes and involved pathways were already annotated to contribute growth and development in various species including human, mice and cattle. All in all, the results of this study are expected to strongly contribute to shed a light on the underlying molecular mechanisms behind growth and carcass composition traits, with potential implications on studies aiming faster genetic improvement, targeted low-resolution SNP panel designs and genome-editing studies.

The two sides of Hippo pathway in cancer

The Hippo signaling pathway was originally characterized by genetic studies in Drosophila to regulate tissue growth and organ size, and the core components of this pathway are highly conserved in mammals. Studies over the past two decades have revealed critical physiological and pathological functions of the Hippo tumor-suppressor pathway, which is tightly regulated by a broad range of intracellular and extracellular signals. These properties enable the Hippo pathway to serve as an important controller in organismal development and adult tissue homeostasis. Dysregulation of the Hippo signaling has been observed in many cancer types, suggesting the possibility of cancer treatment by targeting the Hippo pathway. The general consensus is that Hippo has tumor suppressor function. However, growing evidence also suggests that the function of the Hippo pathway in malignancy is cancer context dependent as recent studies indicating tumor promoting function of LATS. This article surveys the Hippo pathway signaling mechanisms and then reviews both the tumor suppressing and promoting function of this pathway. A comprehensive understanding of the dual roles of the Hippo pathway in cancer will benefit future therapeutic targeting of the Hippo pathway for cancer treatment.

A self-amplifying loop of YAP and SHH drives formation and expansion of heterotopic ossification

Heterotopic ossification (HO) occurs as a common complication after injury or in genetic disorders. The mechanisms underlying HO remain incompletely understood, and there are no approved prophylactic or secondary treatments available. Here, we identify a self-amplifying, self-propagating loop of Yes-associated protein (YAP)-Sonic hedgehog (SHH) as a core molecular mechanism underlying diverse forms of HO. In mouse models of progressive osseous heteroplasia (POH), a disease caused by null mutations in GNAS, we found that Gnas^-/- mesenchymal cells secreted SHH, which induced osteoblast differentiation of the surrounding wild-type cells. We further showed that loss of Gnas led to activation of YAP transcription activity, which directly drove Shh expression. Secreted SHH further induced YAP activation, Shh expression, and osteoblast differentiation in surrounding wild-type cells. This self-propagating positive feedback loop was both necessary and sufficient for HO expansion and could act independently of Gnas in fibrodysplasia ossificans progressiva (FOP), another genetic HO, and nonhereditary HO mouse models. Genetic or pharmacological inhibition of YAP or SHH abolished HO in POH and FOP and acquired HO mouse models without affecting normal bone homeostasis, providing a previously unrecognized therapeutic rationale to prevent, reduce, and shrink HO.

The Yin and Yang of tumour-derived extracellular vesicles in tumour immunity

Extracellular vesicles (EVs) are small particles that are naturally released from various types of cells. EVs contain a wide variety of cellular components, such as proteins, nucleic acids, lipids and metabolites, which facilitate intercellular communication in diverse biological processes. In the tumour microenvironment, EVs have been shown to play important roles in tumour progression, including immune system-tumour interactions. Although previous studies have convincingly demonstrated the immunosuppressive functions of tumour-derived EVs, some studies have suggested that tumour-derived EVs can also stimulate host immunity, especially in therapeutic conditions. Recent studies have revealed the heterogeneous nature of EVs with different structural and biological characteristics that may account for the divergent functions of EVs in tumour immunity. In this review article, we provide a brief summary of our current understanding of tumour-derived EVs in immune activation and inhibition. We also highlight the emerging utility of EVs in the diagnosis and treatment of cancers and discuss the potential clinical applications of tumour-derived EVs.

YAP/TEAD4-induced KIF4A contributes to the progression and worse prognosis of esophageal squamous cell carcinoma

Aberrant expression of kinesin family member 4A (KIF4A), which is associated with tumor progression, has been reported in several types of cancer. However, its expression and the underlying molecular mechanisms regulating the transcription of KIF4A in esophageal squamous cell carcinoma (ESCC) remain largely unclear. Here, we found that high KIF4A expression was positively correlated with tumor stage and poor prognosis in ESCC patients. KIF4A silencing significantly inhibited the growth and migration of ESCC cells, arrested cell cycle, and induced apoptosis. Interestingly, KIF4A expression was positively related to the expression of YAP in human ESCC tissues. YAP knockdown or disrupting YAP/TEAD4 interaction by verteporfin repressed KIF4A expression. Also, KIF4A knockdown significantly inhibited the cell growth induced by YAP overexpression. Mechanistically, YAP activated KIF4A transcriptional expression by TEAD4-mediated direct binding to KIF4A promoter. Finally, KIF4A knockdown and verteporfin treatment synergistically inhibited tumor growth in xenograft models. Together, these results indicated that KIF4A, a novel target gene of YAP/TEAD4, may be a progression and prognostic biomarker of ESCC. Targeting drugs for KIF4A combined with YAP inhibitor may be a novel therapeutic strategy for ESCC.

A novel role of Hippo-Yap/TAZ signaling pathway in lymphatic vascular development

The lymphatic vasculature plays important role in regulating fluid homeostasis, intestinal lipid absorption, and immune surveillance in humans. Malfunction of lymphatic vasculature leads to several human diseases. Understanding the fundamental mechanism in lymphatic vascular development not only expand our knowledge, but also provide a new therapeutic insight. Recently, Hippo-YAP/TAZ signaling pathway, a key mechanism of organ size and tissue homeostasis, has emerged as a critical player that regulate lymphatic specification, sprouting, and maturation. In this review, we discuss the mechanistic regulation and pathophysiological significant of Hippo pathway in lymphatic vascular development.

Proliferation Increasing Genetic Engineering in Human Corneal Endothelial Cells: A Literature Review

The corneal endothelium is the inner layer of the cornea. Despite comprising only a monolayer of cells, dysfunction of this layer renders millions of people visually impaired worldwide. Currently, corneal endothelial transplantation is the only viable means of restoring vision for these patients. However, because the supply of corneal endothelial grafts does not meet the demand, many patients remain on waiting lists, or are not treated at all. Possible alternative treatment strategies include intracameral injection of human corneal endothelial cells (HCEnCs), biomedical engineering of endothelial grafts and increasing the HCEnC density on grafts that would otherwise have been unsuitable for transplantation. Unfortunately, the limited proliferative capacity of HCEnCs proves to be a major bottleneck to make these alternatives beneficial. To tackle this constraint, proliferation enhancing genetic engineering is being investigated. This review presents the diverse array of genes that have been targeted by different genetic engineering strategies to increase the proliferative capacity of HCEnCs and their relevance for clinical and research applications. Together these proliferation-related genes form the basis to obtain a stable and safe supply of HCEnCs that can tackle the corneal endothelial donor shortage.

Hippo-YAP signaling in digestive system tumors

The Hippo pathway is an evolutionally conserved pathway and plays an important role in regulating tissue hemostasis and organ size control. Deregulation of the Hippo pathway is implicated in various human digestive system tumors. The past two decades have witnessed the discovery and elucidation of key signaling components and molecular mechanisms of the Hippo pathway. Among these, the signaling transducers YAP/TAZ are in the center of this complex network to sense and respond to extracellular cues such as cell contact, matrix stiffness and growth factors. In this review, we summarize the biological and clinical significance of Hippo-YAP signaling in the digestive system tumors, and explore the novel therapeutic strategies for targeting Hippo-YAP signaling.

Identification of TAZ-Dependent Breast Cancer Vulnerabilities Using a Chemical Genomics Screening Approach

Breast cancer stem cells (BCSCs) represent a subpopulation of tumor cells that can self-renew and generate tumor heterogeneity. Targeting BCSCs may ameliorate therapy resistance, tumor growth, and metastatic progression. However, the origin and molecular mechanisms underlying their cellular properties are poorly understood. The transcriptional coactivator with PDZ-binding motif (TAZ) promotes mammary stem/progenitor cell (MaSC) expansion and maintenance but also confers stem-like traits to differentiated tumor cells. Here, we describe the rapid generation of experimentally induced BCSCs by TAZ-mediated reprogramming of human mammary epithelial cells, hence allowing for the direct analysis of BCSC phenotypes. Specifically, we establish genetically well-defined TAZ-dependent (TAZ_DEP) and -independent (TAZ_IND) cell lines with cancer stem cell (CSC) traits, such as self-renewal, variable resistance to chemotherapeutic agents, and tumor seeding potential. TAZ_DEP cells were associated with the epithelial to mesenchymal transition, embryonic, and MaSC signature genes. In contrast, TAZ_IND cells were characterized by a neuroendocrine transdifferentiation transcriptional program associated with Polycomb repressive complex 2 (PRC2). Mechanistically, we identify Cyclin D1 (CCND1) as a critical downstream effector for TAZ-driven tumorigenesis. Overall, our results reveal a critical TAZ-CCND1-CDK4/CDK6 signaling axis, suggesting novel therapeutic approaches to eliminate both BCSCs and therapy-resistant cancer cells.

TEAD family transcription factors in development and disease

The balance between stem cell potency and lineage specification entails the integration of both extrinsic and intrinsic cues, which ultimately influence gene expression through the activity of transcription factors. One example of this is provided by the Hippo signalling pathway, which plays a central role in regulating organ size during development. Hippo pathway activity is mediated by the transcriptional co-factors Yes-associated protein (YAP) and transcriptional co-activator with PDZ-binding motif (TAZ), which interact with TEA domain (TEAD) proteins to regulate gene expression. Although the roles of YAP and TAZ have been intensively studied, the roles played by TEAD proteins are less well understood. Recent studies have begun to address this, revealing that TEADs regulate the balance between progenitor self-renewal and differentiation throughout various stages of development. Furthermore, it is becoming apparent that TEAD proteins interact with other co-factors that influence stem cell biology. This Primer provides an overview of the role of TEAD proteins during development, focusing on their role in Hippo signalling as well as within other developmental, homeostatic and disease contexts.

TLR4 signalling via Piezo1 engages and enhances the macrophage mediated host response during bacterial infection

TLR4 signaling plays key roles in the innate immune response to microbial infection. Innate immune cells encounter different mechanical cues in both health and disease to adapt their behaviors. However, the impact of mechanical sensing signals on TLR4 signal-mediated innate immune response remains unclear. Here we show that TLR4 signalling augments macrophage bactericidal activity through the mechanical sensor Piezo1. Bacterial infection or LPS stimulation triggers assembly of the complex of Piezo1 and TLR4 to remodel F-actin organization and augment phagocytosis, mitochondrion-phagosomal ROS production and bacterial clearance and genetic deficiency of Piezo1 results in abrogation of these responses. Mechanistically, LPS stimulates TLR4 to induce Piezo1-mediated calcium influx and consequently activates CaMKII-Mst1/2-Rac axis for pathogen ingestion and killing. Inhibition of CaMKII or knockout of either Mst1/2 or Rac1 results in reduced macrophage bactericidal activity, phenocopying the Piezo1 deficiency. Thus, we conclude that TLR4 drives the innate immune response via Piezo1 providing critical insight for understanding macrophage mechanophysiology and the host response.

Signaling pathways in cancer-associated fibroblasts and targeted therapy for cancer

To flourish, cancers greatly depend on their surrounding tumor microenvironment (TME), and cancer-associated fibroblasts (CAFs) in TME are critical for cancer occurrence and progression because of their versatile roles in extracellular matrix remodeling, maintenance of stemness, blood vessel formation, modulation of tumor metabolism, immune response, and promotion of cancer cell proliferation, migration, invasion, and therapeutic resistance. CAFs are highly heterogeneous stromal cells and their crosstalk with cancer cells is mediated by a complex and intricate signaling network consisting of transforming growth factor-beta, phosphoinositide 3-kinase/AKT/mammalian target of rapamycin, mitogen-activated protein kinase, Wnt, Janus kinase/signal transducers and activators of transcription, epidermal growth factor receptor, Hippo, and nuclear factor kappa-light-chain-enhancer of activated B cells, etc., signaling pathways. These signals in CAFs exhibit their own special characteristics during the cancer progression and have the potential to be targeted for anticancer therapy. Therefore, a comprehensive understanding of these signaling cascades in interactions between cancer cells and CAFs is necessary to fully realize the pivotal roles of CAFs in cancers. Herein, in this review, we will summarize the enormous amounts of findings on the signals mediating crosstalk of CAFs with cancer cells and its related targets or trials. Further, we hypothesize three potential targeting strategies, including, namely, epithelial-mesenchymal common targets, sequential target perturbation, and crosstalk-directed signaling targets, paving the way for CAF-directed or host cell-directed antitumor therapy.