The Hippo Signaling Pathway in Development and Disease

Complex interplay between RAS GTPases and RASSF effectors regulates subcellular localization of YAP

RAS GTPases bind effectors to convert upstream cues to changes in cellular function. Effectors of classical H/K/NRAS are defined by RBD/RA domains which recognize the GTP-bound conformation of these GTPases, yet the specificity of RBD/RAs for over 160 RAS superfamily proteins remains poorly explored. We have systematically mapped interactions between BRAF and four RASSF effectors, the largest family of RA-containing proteins, with all RAS, RHO and ARF small GTPases. 39 validated complexes reveal plasticity in RASSF binding, while BRAF demonstrates tight specificity for classical H/K/NRAS. Complex between RASSF5 and diverse RAS GTPases at the plasma membrane can activate Hippo signalling and sequester YAP in the cytosol. RASSF8 undergoes liquid-liquid phase separation and resides in YAP-associated membraneless condensates, which also engage several RAS and RHO GTPases. The poorly studied RASSF3 has been identified as a first potential effector of mitochondrial MIRO proteins, and its co-expression with these GTPases impacts mitochondria and peroxisome distribution. These data reveal the complex nature of GTPase-effector interactions and show their systematic elucidation can reveal completely novel and biologically relevant cellular processes.

Assembling a Hippo: the evolutionary emergence of an animal developmental signaling pathway

Decades of work in developmental genetics has given us a deep mechanistic understanding of the fundamental signaling pathways underlying animal development. However, little is known about how these pathways emerged and changed over evolutionary time. Here, we review our current understanding of the evolutionary emergence of the Hippo pathway, a conserved signaling pathway that regulates tissue size in animals. This pathway has deep evolutionary roots, emerging piece by piece in the unicellular ancestors of animals, with a complete core pathway predating the origin of animals. Recent functional studies in close unicellular relatives of animals and early-branching animals suggest an ancestral function of the Hippo pathway in cytoskeletal regulation, which was subsequently co-opted to regulate proliferation and animal tissue size.

Mapping spatially resolved transcriptomes in human and mouse pulmonary fibrosis

Idiopathic pulmonary fibrosis (IPF) is a progressive lung disease with poor prognosis and limited treatment options. Efforts to identify effective treatments are thwarted by limited understanding of IPF pathogenesis and poor translatability of available preclinical models. Here we generated spatially resolved transcriptome maps of human IPF (n = 4) and bleomycin-induced mouse pulmonary fibrosis (n = 6) to address these limitations. We uncovered distinct fibrotic niches in the IPF lung, characterized by aberrant alveolar epithelial cells in a microenvironment dominated by transforming growth factor beta signaling alongside predicted regulators, such as TP53 and APOE. We also identified a clear divergence between the arrested alveolar regeneration in the IPF fibrotic niches and the active tissue repair in the acutely fibrotic mouse lung. Our study offers in-depth insights into the IPF transcriptional landscape and proposes alveolar regeneration as a promising therapeutic strategy for IPF.

Zinc finger protein 367 exerts a cancer-promoting role in small cell lung cancer by influencing the CIT/LATS2/YAP signaling cascade

A remarkable cancer-related role of zinc finger protein 367 (ZNF367) has been demonstrated in multiple malignancies. However, whether ZNF367 has a role in small-cell lung cancer (SCLC) remains unexplored. The purpose of this work was to explore the potential role and mechanism of ZNF367 in SCLC. In silico analysis using the Gene Expression Omnibus (GEO) dataset revealed high levels of the ZNF367 transcript in SCLC. Examination of clinical tissues confirmed the significant abundance of ZNF367 in SCLC tissues compared with adjacent non-malignant tissues. The genetic depletion of ZNF367 in SCLC cells led to remarkable alterations in cell proliferation, the cell cycle, colony formation and chemosensitivity. Mechanistically, ZNF367 was shown to regulate the activation of yes-associated protein (YAP) associated with the up-regulation of phosphorylated large tumour suppressor kinase 2 (LATS2). Further investigation revealed that ZNF367 affected the LATS2-YAP cascade by regulating the expression of citron kinase (CIT). Re-expression of constitutively active YAP diminished the tumour-inhibiting function of ZNF367 depletion. Xenograft experiments confirmed the tumour-inhibiting effect of ZNF367 depletion in vivo. In summary, our results demonstrate that the inhibition of ZNF367 displays anticancer effects in SCLC by inhibiting YAP activation, suggesting it as a potential druggable oncogenic target.

ARID1A restrains EMT and stemness of ovarian cancer cells through the Hippo pathway

Genes encoding subunits of SWI/SNF (BAF) chromatin‑remodeling complexes are recurrently mutated in a broad array of tumor types, and among the subunits, ARID1A is the most frequent target with mutations. In the present study, it was reported that ARID1A inhibits the epithelial‑mesenchymal transition (EMT) and stemness of ovarian cancer cells, accompanied by reduced cell viability, migration and colony formation, suggesting that ARID1A acts as a tumor suppressor in ovarian cancer. Mechanistically, ARID1A exerts its inhibitory effects on ovarian cancer cells by activating the Hippo signaling pathway. Conversely, the overexpression of a gain‑of‑function transcriptional co‑activator with PDZ‑binding motif (TAZ) mutant (TAZ‑Ser89) effectively reverses the effects induced by ARID1A. In addition, activation of Hippo signaling apparently upregulates ARID1A protein expression, whereas ectopic expression of TAZ‑Ser89 results in the markedly decreased ARID1A levels, indicating a feedback of ARID1A‑TAZ in regulating ovarian cancer cell EMT and stemness. Thus, the present study uncovered the role of ARID1A through the Hippo/TAZ pathway in modulating EMT and stemness of ovarian cancer cells, and providing with evidence that TAZ inhibitors could effectively prevent initiation and metastasis of ovarian cancer cases where ARID1A is lost or mutated.

Angiomotin family proteins in the Hippo signaling pathway

The Motin family proteins (Motins) are a class of scaffolding proteins consisting of Angiomotin (AMOT), AMOT-like protein 1 (AMOTL1), and AMOT-like protein 2 (AMOTL2). Motins play a pivotal role in angiogenesis, tumorigenesis, and neurogenesis by modulating multiple cellular signaling pathways. Recent findings indicate that Motins are components of the Hippo pathway, a signaling cascade involved in development and cancer. This review discusses how Motins are integrated into the Hippo signaling network, as either upstream regulators or downstream effectors, to modulate cell proliferation and migration. The repression of YAP/TAZ by Motins contributes to growth inhibition, whereas subcellular localization of Motins and their interactions with actin fibers are critical in regulating cell migration. The net effect of Motins on cell proliferation and migration may contribute to their diverse biological functions.

FGF2 promotes the proliferation of injured granulosa cells in premature ovarian failure via Hippo-YAP signaling pathway

Young women undergoing anticancer treatment are at risk of premature ovarian failure (POF). Endometrial-derived stem cells (EnSCs) have demonstrated significant therapeutic potential for treating ovarian insufficiency, although the underlying mechanisms remain to be fully understood. This study aims to further investigate the therapeutic effects of EnSCs, particularly through the paracrine action of fibroblast growth factor 2 (FGF2), on POF. The findings show that exogenous FGF2 enhances the survival of ovarian granulosa cells damaged by cisplatin. FGF2 stimulates the proliferation of these damaged cells by suppressing the Hippo signaling pathway and activating YAP expression. In vivo experiments also revealed that FGF2 treatment significantly improves ovarian reserve and endocrine function in mice with POF. These results suggest that FGF2 can boost the proliferative capacity of damaged ovarian granulosa cells through the Hippo-YAP signaling pathway, providing a theoretical foundation for using EnSCs and FGF2 in clinical treatments for POF.

The OsMOB1A-OsSTK38 kinase complex phosphorylates CYCLIN C, controlling grain size and weight in rice

Grain size and weight are crucial yield-related traits in rice (Oryza sativa). Although certain key genes associated with rice grain size and weight have been successfully cloned, the molecular mechanisms underlying grain size and weight regulation remain elusive. Here, we identified a molecular pathway regulating grain size and weight in rice involving the MPS ONE BINDER KINASE ACTIVATOR-LIKE 1A-SERINE/THREONINE-PROTEIN KINASE 38-CYCLIN C (OsMOB1A-OsSTK38-OsCycC) module. OsSTK38 is a nuclear Dbf2-related kinase that positively regulates grain size and weight by coordinating cell proliferation and expansion in the spikelet hull. OsMOB1A interacts with and enhances the autophosphorylation of OsSTK38. Specifically, the critical role of the OsSTK38 S322 site in its kinase activity is highlighted. Furthermore, OsCycC, a component of the Mediator complex, was identified as a substrate of OsSTK38, with enhancement by OsMOB1A. Notably, OsSTK38 phosphorylates the T33 site of OsCycC. The phosphorylation of OsCycC by OsSTK38 influenced its interaction with the transcription factor KNOTTED-LIKE HOMEOBOX OF ARABIDOPSIS THALIANA 7 (OsKNAT7). Genetic analysis confirmed that OsMOB1A, OsSTK38, and OsCycC function in a common pathway to regulate grain size and weight. Taken together, our findings revealed a connection between the Hippo signaling pathway and the cyclin-dependent kinase module in eukaryotes. Moreover, they provide insights into the molecular mechanisms linked to yield-related traits and propose innovative breeding strategies for high-yielding varieties.

Role of Mitogen-Activated Protein Kinase Kinase Kinase Kinase 4 Signaling in Liver and Metabolic Diseases

MAP4K4 is a serine/threonine protein kinase belonging to the germinal center kinase subgroup of sterile 20 protein family of kinases. MAP4K4 has been involved in regulating multiple biologic processes and a plethora of pathologies, including systemic inflammation, cardiovascular diseases, cancers, and metabolic and hepatic diseases. Recently, multiple reports have indicated the upregulation of MAP4K4 expression and signaling in hyperglycemia and liver diseases. This review provides an overview of our current knowledge of MAP4K4 structure and expression, as well as its regulation and signaling, specifically in metabolic and hepatic diseases. Reviewing these promising studies will enrich our understanding of MAP4K4 signaling pathways and, in the future, will help us design innovative therapeutic interventions against metabolic and liver diseases using MAP4K4 as a target. SIGNIFICANCE STATEMENT: Although most studies on the involvement of MAP4K4 in human pathologies are related to cancers, only recently its role in liver and other metabolic diseases is beginning to unravel. This mini review discusses recent advancements in MAP4K4 biology within the context of metabolic dysfunction and comprehensively characterizes MAP4K4 as a clinically relevant therapeutic target against liver and metabolic diseases.

Modulating cell stiffness for improved vascularization: leveraging the MIL-53(fe) for improved interaction of titanium implant and endothelial cell

Vascularization plays a significant role in promoting the expedited process of bone regeneration while also enhancing the stability and viability of artificial bone implants. Although titanium alloy scaffolds were designed to mimic the porous structure of human bone tissues to facilitate vascularization in bone repair, their biological inertness restricted their broader utilization. The unique attribute of Metal-organic framework (MOF) MIL-53(Fe), known as "breathing", can facilitate the efficient adsorption of extracellular matrix proteins and thus provide the possibility for efficient interaction between scaffolds and cell adhesion molecules, which helps improve the bioactivity of the titanium alloy scaffolds. In this study, MIL-53(Fe) was synthesized in situ on the scaffold after hydrothermal treatment. The MIL-53(Fe) endowed the scaffold with superior protein absorption ability and preferable biocompatibility. The scaffolds have been shown to possess favorable osteogenesis and angiogenesis inducibility. It was indicated that MIL-53(Fe) modulated the mechanotransduction process of endothelial cells and induced increased cell stiffness by promoting the adsorption of adhesion-mediating extracellular matrix proteins to the scaffold, such as laminin, fibronectin, and perlecan et al., which contributed to the activation of the endothelial tip cell phenotype at sprouting angiogenesis. Therefore, this study effectively leveraged the intrinsic "breathing" properties of MIL-53 (Fe) to enhance the interaction between titanium alloy scaffolds and vascular endothelial cells, thereby facilitating the vascularization inducibility of the scaffold, particularly during the sprouting angiogenesis phase. This study indicates that MIL-53(Fe) coating represents a promising strategy to facilitate accelerated and sufficient vascularization and uncovers the scaffold-vessel interaction from a biomechanical perspective.

Investigating underlying molecular mechanisms, signaling pathways, emerging therapeutic approaches in pancreatic cancer

Pancreatic adenocarcinoma, a clinically challenging malignancy constitutes a significant contributor to cancer-related mortality, characterized by an inherently poor prognosis. This review aims to provide a comprehensive understanding of pancreatic adenocarcinoma by examining its multifaceted etiologies, including genetic mutations and environmental factors. The review explains the complex molecular mechanisms underlying its pathogenesis and summarizes current therapeutic strategies, including surgery, chemotherapy, and emerging modalities such as immunotherapy. Critical molecular pathways driving pancreatic cancer development, including KRAS, Notch, and Hedgehog, are discussed. Current therapeutic strategies, including surgery, chemotherapy, and radiation, are discussed, with an emphasis on their limitations, particularly in terms of postoperative relapse. Promising research areas, including liquid biopsies, personalized medicine, and gene editing, are explored, demonstrating the significant potential for enhancing diagnosis and treatment. While immunotherapy presents promising prospects, it faces challenges related to immune evasion mechanisms. Emerging research directions, encompassing liquid biopsies, personalized medicine, CRISPR/Cas9 genome editing, and computational intelligence applications, hold promise for refining diagnostic approaches and therapeutic interventions. By integrating insights from genetic, molecular, and clinical research, innovative strategies that improve patient outcomes can be developed. Ongoing research in these emerging fields holds significant promise for advancing the diagnosis and treatment of this formidable malignancy.

The Drosophila Hippo pathway transcription factor Scalloped and its co-factors alter each other's chromatin binding dynamics and transcription in vivo

The Hippo pathway is an important regulator of organ growth and cell fate. The major mechanism by which Hippo is known to control transcription is by dictating the nucleo-cytoplasmic shuttling rate of Yorkie, a transcription co-activator, which promotes transcription with the DNA binding protein Scalloped. The nuclear biophysical behavior of Yorkie and Scalloped, and whether this is regulated by the Hippo pathway, remains unexplored. Using multiple live-imaging modalities on Drosophila tissues, we found that Scalloped interacts with DNA on a broad range of timescales, and enrichment of Scalloped at sites of active transcription is mediated by longer DNA dwell times. Further, Yorkie increased Scalloped's DNA dwell time, whereas the repressors Nervous fingers 1 (Nerfin-1) and Tondu-domain-containing growth inhibitor (Tgi) decreased it. Therefore, the Hippo pathway influences transcription not only by controlling nuclear abundance of Yorkie but also by modifying the DNA binding kinetics of the transcription factor Scalloped.

YAP/TAZ, beta-catenin, and TGFb pathway activation in medical plasma-induced wound healing in diabetic mice

INTRODUCTION

Hippo is a signaling pathway that is evolutionarily conserved and plays critical roles in wound healing and tissue regeneration. Disruption of the transcriptional activity of both Hippo-associated factors, the yes-associated protein (YAP), and the transcriptional co-activator with PDZ binding motif (TAZ) has been associated with cardiovascular diseases, fibrosis, and cancer. This makes the Hippo pathway an appealing target for therapeutic interventions.

OBJECTIVES

Prior research has indicated that medical gas plasma promotes wound healing by delivering a combination of reactive species directly to the affected areas. However, the involvement of YAP/TAZ and other signaling pathways in diabetic wound healing remains unexplored.

METHODS

To this extent, ear wounds were generated and treated with gas plasma in streptozotocin (STZ)-induced diabetic mice. Transcriptome profiling at two wound healing stages (days 9 and 20 post-wounding) was performed in female and male mice. Additionally, we employed gene and protein expression analyses, utilizing immunohistological and -chemical staining of various targets as well as quantitative PCR and Western blot analysis.

RESULTS

Gas plasma treatment accelerated healing by increasing re-epithelialization and modifying extracellular matrix components. Transcriptomic profiling charting the major alterations in gene expression following plasma treatment was followed by a validation of several targets using transcriptional and translational quantification as well as localization analyses.

CONCLUSION

Our study evaluated the cellular regulation of essential targets of the Hippo and related pathways such as YAP/TAZ, β-catenin, tumor growth factor β, and oxidative stress signaling after plasma treatment. The activation of genes, pathways, and their regulators is an attractive therapeutic aim for a therapeutic intervention in dermal skin repair in diabetic diseases using medical gas plasmas.

Cell signaling and transcriptional regulation of osteoblast lineage commitment, differentiation, bone formation, and homeostasis

The initiation of osteogenesis primarily occurs as mesenchymal stem cells undergo differentiation into osteoblasts. This differentiation process plays a crucial role in bone formation and homeostasis and is regulated by two intricate processes: cell signal transduction and transcriptional gene expression. Various essential cell signaling pathways, including Wnt, BMP, TGF-β, Hedgehog, PTH, FGF, Ephrin, Notch, Hippo, and Piezo1/2, play a critical role in facilitating osteoblast differentiation, bone formation, and bone homeostasis. Key transcriptional factors in this differentiation process include Runx2, Cbfβ, Runx1, Osterix, ATF4, SATB2, and TAZ/YAP. Furthermore, a diverse array of epigenetic factors also plays critical roles in osteoblast differentiation, bone formation, and homeostasis at the transcriptional level. This review provides an overview of the latest developments and current comprehension concerning the pathways of cell signaling, regulation of hormones, and transcriptional regulation of genes involved in the commitment and differentiation of osteoblast lineage, as well as in bone formation and maintenance of homeostasis. The paper also reviews epigenetic regulation of osteoblast differentiation via mechanisms, such as histone and DNA modifications. Additionally, we summarize the latest developments in osteoblast biology spurred by recent advancements in various modern technologies and bioinformatics. By synthesizing these insights into a comprehensive understanding of osteoblast differentiation, this review provides further clarification of the mechanisms underlying osteoblast lineage commitment, differentiation, and bone formation, and highlights potential new therapeutic applications for the treatment of bone diseases.

Sheep litter size heredity basis using genome-wide selective analysis

Sheep are important herbivorous domestic animal globally, and the Chinese indigenous sheep breed has a multitude of economically significant variations due to the diverse geographical and ecological conditions. In particular, certain native breeds exhibit a visible high litter size phenotype due to the selection pressure of natural and artificial for thousands of years, offering an ideal animal model for investigating sheep's fecundity. In this study, selective signal analysis was performed on public whole-genome sequencing data from 60 sheep across eight breeds to identify candidate genes related to litter size. Results revealed that a total of 34,065,017 single-nucleotide polymorphisms (SNPs) were identified from all sheep, and 65 candidate genes (CDGs) were pinpointed from the top 1% of interacted windows and SNPs between the pairwise fixation index (FST, >0.149543) and cross-population extended haplotype homozygosity (XP-EHH, >0.701551). A total of 41 CDGs (e.g. VRTN, EYA2 and MCPH1) were annotated to 576 GO terms, of which seven terms were directly linked to follicular and embryonic development (e.g. TBXT, BMPR1B, and BMP2). In addition, 73 KEGG pathways were enriched by 21 CDGs (e.g. ENTPD5, ABCD4 and RXFP2), mainly related to Hippo (TCF4, BMPR1B and BMP2), TGF-β (BMPR1B and BMP2), PI3K-Akt (ITGB4, IL4R and PPP2R5A) and Jak-STAT signalling pathways (IL20RA and IL4R). Notably, a series of CDGs was under strong selection in sheep with high litter size traits. These findings result could improve the comprehension of the genetic underpinnings of sheep litter size. Furthermore, it provides valuable CDGS for future molecular breeding.

A novel ARHGAP family gene signature for survival prediction in glioma patients

ARHGAP family genes are often used as glioma oncogenic factors, and their mechanism of action remains unexplained. Our research entailed a thorough examination of the immune microenvironment and enrichment pathways across various glioma subtypes. A distinctive 6-gene signature was developed employing the CGGA cohort, leading to insights into the disparities in clinical characteristics, mutation patterns, and immune cell infiltration among distinct risk categories. Additionally, a unique nomogram was established, grounded on ARHGAPs, with DCA curves illustrating the model's prospective clinical utility in guiding therapeutic strategies. Emphasizing the role of ARHGAP30, integral to our model, its impact on glioma severity and the credibility of our risk assessment model were substantiated through RT-qPCR, Western blot analysis, and cellular functional assays. We identified 6 ARHGAP family genes associated with glioma prognosis. Analysis using the Kaplan-Meier method indicated a correlation between elevated risk levels and adverse outcomes in glioma patients. The risk score, linked with tumour staging and IDH mutation status, emerged as an independent factor predicting prognosis. Patients in the high-risk category exhibited increased immune cell infiltration, enhanced tumour mutational burden, more pronounced expression of immune checkpoint genes, and a better response to ICB therapy. A nomogram, integrating the risk score with the pathological features of glioma patients, was developed. DCA analysis and cellular studies confirmed the model's potential to improve clinical treatment outcomes for patients. A novel ARHGAP family gene signature reveals the prognosis of glioma.

Diverse functions of SOX9 in liver development and homeostasis and hepatobiliary diseases

The liver is the central organ for digestion and detoxification and has unique metabolic and regenerative capacities. The hepatobiliary system originates from the foregut endoderm, in which cells undergo multiple events of cell proliferation, migration, and differentiation to form the liver parenchyma and ductal system under the hierarchical regulation of transcription factors. Studies on liver development and diseases have revealed that SRY-related high-mobility group box 9 (SOX9) plays an important role in liver embryogenesis and the progression of hepatobiliary diseases. SOX9 is not only a master regulator of cell fate determination and tissue morphogenesis, but also regulates various biological features of cancer, including cancer stemness, invasion, and drug resistance, making SOX9 a potential biomarker for tumor prognosis and progression. This review systematically summarizes the latest findings of SOX9 in hepatobiliary development, homeostasis, and disease. We also highlight the value of SOX9 as a novel biomarker and potential target for the clinical treatment of major liver diseases.

STK3 higher expression association with clinical characteristics in intrinsic subtypes of breast cancer invasive ductal carcinoma patients

PURPOSE

STK3 has a central role in maintaining cell homeostasis, proliferation, growth, and apoptosis. Previously, we investigated the functional link between STK3/MST2, and estrogen receptor in MCF-7 breast cancer cells. To expand the investigation, this study evaluated STK3's higher expression and associated genes in breast cancer intrinsic subtypes using publicly available data.

METHODS

The relationship between clinical pathologic features and STK3 high expression was analyzed using descriptive and multivariate analysis.

RESULTS

Increased STK3 expression in breast cancer was significantly associated with higher pathological cancer stages, and a different expression level was observed in the intrinsic subtypes of breast cancer. Kaplan-Meier analysis showed that breast cancer with high STK3 had a lower survival rate in IDC patients than that with low STK3 expression (p < 0.05). The multivariate analysis unveiled a strong correlation between STK3 expression and the survival rate among IDC patients, demonstrating hazard ratios for lower expression. In the TCGA dataset, the hazard ratio was 0.56 (95% CI 0.34-0.94, p = 0.029) for patients deceased with tumor, and 0.62 (95% CI 0.42-0.92, p = 0.017) for all deceased patients. Additionally, in the METABRIC dataset, the hazard ratio was 0.76 (95% CI 0.64-0.91, p = 0.003) for those deceased with tumor. From GSEA outcomes 7 gene sets were selected based on statistical significance (FDR < 0.25 and p < 0.05). Weighted Sum model (WSM) derived top 5% genes also have higher expression in basal and lower in luminal A in association with STK3.

CONCLUSION

By introducing a novel bioinformatics approach that combines GSEA and WSM, the study successfully identified the top 5% of genes associated with higher expression of STK3.

ENO1 contributes to the gemcitabine resistance of pancreatic cancer through the YAP1 signaling pathway

Pancreatic cancer (PC), a leading cause of cancer-related deaths, has a 5-year survival rate of approximately 10%. α-Enolase (ENO1) is a junction channel protein involved in tumor cell apoptosis and chemoresistance. However, the role of ENO1 in PC remains unclear. The expression and prognosis of ENO1 levels were determined in PC using public databases based on The Cancer Genome Atlas (TCGA) data sets. Cell viability, half maximal inhibitory concentration (IC50), autophagy, apoptosis, and autophagy markers were examined using cell counting kit-8 (CCK-8), transmission electron microscope, flow cytometry assays, and immunoblot, respectively. Using the Gene Expression Omnibus (GEO) and TCGA data sets, we found that ENO1 was significantly enriched in PC tumor tissues, and high expression levels of ENO1 were associated with an unfavorable prognosis. Whereas ENO1 silencing suppressed proliferation, autophagy, and induced cell apoptosis in PC cells, and inhibited tumor growth in vivo. Mechanistically, knockdown of ENO1 enhanced cellular cytotoxicity of gemcitabine (GEM), as well as reducing the expression of yes-associated protein 1 (YAP1), a major downstream effector of the Hippo pathway in vitro. YAP1 promoted autophagy and protected PC cells from GEM-induced apoptotic cell death. Furthermore, YAP1 overexpression attenuated the inhibition effects of ENO1 silencing. Our results suggest that ENO1 overexpression promotes cell growth and tumor progression by increasing the expression of YAP1 in PC. Further studies are required to understand the detailed mechanisms between ENO1 and YAP1 in PC.

Crosstalk between CAFs and tumour cells in head and neck cancer

Head and neck squamous cell carcinomas (HNSCCs) are amongst the most aggressive, complex, and heterogeneous malignancies. The standard of care treatments for HNC patients include surgery, radiotherapy, chemotherapy, or their combination. However, around 50% do not benefit while suffering severe toxic side effects, costing the individuals and society. Decades have been spent to improve HNSCC treatment outcomes with only limited success. Much of the research in HNSCC treatment has focused on understanding the genetics of the HNSCC malignant cells, but it has become clear that tumour microenvironment (TME) plays an important role in the progression as well as treatment response in HNSCC. Understanding the crosstalk between cancer cells and TME is crucial for inhibiting progression and treatment resistance. Cancer-associated fibroblasts (CAFs), the predominant component of stroma in HNSCC, serve as the primary source of extra-cellular matrix (ECM) and various pro-tumoral composites in TME. The activation of CAFs in HNSCC is primarily driven by cancer cell-secreted molecules, which in turn induce phenotypic changes, elevated secretive status, and altered ECM production profile. Concurrently, CAFs play a pivotal role in modulating the cell cycle, stemness, epithelial-mesenchymal transition (EMT), and resistance to targeted and chemoradiotherapy in HNSCC cells. This modulation occurs through interactions with secreted molecules or direct contact with the ECM or CAF. Co-culture and 3D models of tumour cells and other TME cell types allows to mimic the HNSCC tumour milieu and enable modulating tumour hypoxia and reprograming cancer stem cells (CSC). This review aims to provide an update on the development of HNSCC tumour models comprising CAFs to obtain better understanding of the interaction between CAFs and tumour cells, and for providing preclinical testing platforms of current and combination with emerging therapeutics.

YAP condensates are highly organized hubs

YAP/TEAD signaling is essential for organismal development, cell proliferation, and cancer progression. As a transcriptional coactivator, how YAP activates its downstream target genes is incompletely understood. YAP forms biomolecular condensates in response to hyperosmotic stress, concentrating transcription-related factors to activate downstream target genes. However, whether YAP forms condensates under other signals, how YAP condensates organize and function, and how YAP condensates activate transcription in general are unknown. Here, we report that endogenous YAP forms sub-micron scale condensates in response to Hippo pathway regulation and actin cytoskeletal tension. YAP condensates are stabilized by the transcription factor TEAD1, and recruit BRD4, a coactivator that is enriched at active enhancers. Using single-particle tracking, we found that YAP condensates slowed YAP diffusion within condensate boundaries, a possible mechanism for promoting YAP target search. These results reveal that YAP condensate formation is a highly regulated process that is critical for YAP/TEAD target gene expression.

Targeting the Hippo Pathway in Cutaneous Melanoma

Melanoma is the most aggressive form of skin cancer. In the advanced stage of development, it is resistant to currently available therapeutic modalities. Increased invasiveness and metastatic potential depend on several proteins involved in various signal transduction pathways. Hippo signaling plays a vital role in malignant transformation. Dysfunctions of the Hippo pathway initiate the expression of tumor growth factors and are associated with tumor growth and metastasis formation. This review summarizes the recent achievements in studying the role of the Hippo pathway in melanoma pathogenesis and points to the potential specific targets for anti-melanoma therapy.

Molecular pathways and targeted therapies in head and neck cancers pathogenesis

The substantial heterogeneity exhibited by head and neck cancer (HNC), encompassing diverse cellular origins, anatomical locations, and etiological contributors, combined with the prevalent late-stage diagnosis, poses significant challenges for clinical management. Genomic sequencing endeavors have revealed extensive alterations in key signaling pathways that regulate cellular proliferation and survival. Initiatives to engineer therapies targeting these dysregulated pathways are underway, with several candidate molecules progressing to clinical evaluation phases, including FDA approval for agents like the EGFR-targeting monoclonal antibody cetuximab for K-RAS wild-type, EGFR-mutant HNSCC treatment. Non-coding RNAs (ncRNAs), owing to their enhanced stability in biological fluids and their important roles in intracellular and intercellular signaling within HNC contexts, are now recognized as potent biomarkers for disease management, catalyzing further refined diagnostic and therapeutic strategies, edging closer to the personalized medicine desideratum. Enhanced comprehension of the genomic and immunological landscapes characteristic of HNC is anticipated to facilitate a more rigorous assessment of targeted therapies benefits and limitations, optimize their clinical deployment, and foster innovative advancements in treatment approaches. This review presents an update on the molecular mechanisms and mutational spectrum of HNC driving the oncogenesis of head and neck malignancies and explores their implications for advancing diagnostic methodologies and precision therapeutics.

G6PD and ACSL3 are synthetic lethal partners of NF2 in Schwann cells

Neurofibromatosis Type II (NFII) is a genetic condition caused by loss of the NF2 gene, resulting in activation of the YAP/TAZ pathway and recurrent Schwann cell tumors, as well as meningiomas and ependymomas. Unfortunately, few pharmacological options are available for NFII. Here, we undertake a genome-wide CRISPR/Cas9 screen to search for synthetic-lethal genes that, when inhibited, cause death of NF2 mutant Schwann cells but not NF2 wildtype cells. We identify ACSL3 and G6PD as two synthetic-lethal partners for NF2, both involved in lipid biogenesis and cellular redox. We find that NF2 mutant Schwann cells are more oxidized than control cells, in part due to reduced expression of genes involved in NADPH generation such as ME1. Since G6PD and ME1 redundantly generate cytosolic NADPH, lack of either one is compatible with cell viability, but not down-regulation of both. Since genetic deficiency for G6PD is tolerated in the human population, G6PD could be a good pharmacological target for NFII.

The RNF214-TEAD-YAP signaling axis promotes hepatocellular carcinoma progression via TEAD ubiquitylation

RNF214 is an understudied ubiquitin ligase with little knowledge of its biological functions or protein substrates. Here we show that the TEAD transcription factors in the Hippo pathway are substrates of RNF214. RNF214 induces non-proteolytic ubiquitylation at a conserved lysine residue of TEADs, enhances interactions between TEADs and YAP, and promotes transactivation of the downstream genes of the Hippo signaling. Moreover, YAP and TAZ could bind polyubiquitin chains, implying the underlying mechanisms by which RNF214 regulates the Hippo pathway. Furthermore, RNF214 is overexpressed in hepatocellular carcinoma (HCC) and inversely correlates with differentiation status and patient survival. Consistently, RNF214 promotes tumor cell proliferation, migration, and invasion, and HCC tumorigenesis in mice. Collectively, our data reveal RNF214 as a critical component in the Hippo pathway by forming a signaling axis of RNF214-TEAD-YAP and suggest that RNF214 is an oncogene of HCC and could be a potential drug target of HCC therapy.

Blockade of a novel MAP4K4-LATS2-SASH1-YAP1 cascade inhibits tumorigenesis and metastasis in luminal breast cancer

Novel components in the noncanonical Hippo pathway that mediate the growth, metastasis, and drug resistance of breast cancer (BC) cells need to be identified. Here, we showed that expression of SAM and SH3 domain-containing protein 1 (SASH1) is negatively correlated with expression of mitogen-activated protein kinase kinase kinase kinase 4 (MAP4K4) in a subpopulation of patients with luminal-subtype BC. Downregulated SASH1 and upregulated MAP4K4 synergistically regulated the proliferation, migration, and invasion of luminal-subtype BC cells. The expression of LATS2, SASH1, and YAP1 and the phosphorylation of YAP1 were negatively regulated by MAP4K4, and LATS2 then phosphorylated SASH1 to form a novel MAP4K4-LATS2-SASH1-YAP1 cascade. Dephosphorylation of Yes1 associated transcriptional regulator (YAP1), YAP1/TAZ nuclear translocation, and downstream transcriptional regulation of YAP1 were promoted by the combined effects of ectopic MAP4K4 expression and SASH1 silencing. Targeted inhibition of MAP4K4 blocked proliferation, cell migration, and ER signaling both in vitro and in vivo. Our findings reveal a novel MAP4K4-LATS2-SASH1-YAP1 phosphorylation cascade, a noncanonical Hippo pathway that mediates ER signaling, tumorigenesis, and metastasis in breast cancer. Targeted intervention with this noncanonical Hippo pathway may constitute a novel alternative therapeutic approach for endocrine-resistant BC.

Preventive effects of Ramelteon on bleomycin-induced pulmonary fibrosis in mice

Pulmonary fibrosis (PF) is a devastating lung disease that leads to impaired lung function and ultimately death. Several studies have suggested that melatonin, a hormone involved in regulating sleep-wake cycles, may be effective in improving PF. Ramelteon, an FDA-approved melatonin receptor agonist, has shown promise in exerting an anti-PF effect similar to melatonin. However, further investigations are required for illuminating the extent on its therapeutic benefits and the underlying molecular mechanisms. In this work, a mouse lung fibrosis model was built through intratracheal administration of bleomycin (BLM). Subsequently, the mice were administrated Ramelteon for a duration of 3 weeks to explore its efficacy and mechanism of action. Additionally, we utilized a TGF-β1-induced MRC-5 cell model to further investigate the molecular mechanism underlying ramelteon's effects. Functionally, Ramelteon partially abrogated TGF-β1-induced pulmonary fibrosis and reduced fibroblast proliferation, extracellular matrix deposition, and differentiation into myofibroblasts. In vivo experiments, ramelteon attenuated BLM-induced pulmonary fibrosis and collagen deposition. Mechanistically, ramelteon exerts its beneficial effect by alleviating translocation and expression of YAP1, a core component of Hippo pathway, from cytoplasm to nucleus; however, overexpression of YAP1 reversed this effect. In conclusion, our findings indicate that ramelteon can improve PF by regulating Hippo pathway and may become a potential candidate as a therapy to PF.

LATS2 condensates organize signalosomes for Hippo pathway signal transduction

Biomolecular condensates have been proposed to mediate cellular signaling transduction. However, the mechanism and functional consequences of signal condensates are not well understood. Here we report that LATS2, the core kinase of the Hippo pathway, responds to F-actin cytoskeleton reduction and forms condensates. The proline-rich motif (PRM) of LATS2 mediates its condensation. LATS2 partitions with the main components of the Hippo pathway to assemble a signalosome for LATS2 activation and for its stability by physically compartmentalizing from E3 ligase FBXL16 complex-dependent degradation, which in turn mediates yes-associated protein (YAP)-transcriptional coactivator with PDZ-binding motif (TAZ) recruitment and inactivation. This oncogenic FBXL16 complex blocks LATS2 condensation by binding to the PRM region to promote its degradation. Disruption of LATS2 condensation leads to tumor progression. Thus, our study uncovers that the signalosomes assembled by LATS2 condensation provide a compartmentalized and reversible platform for Hippo signaling transduction and protein stability, which have potential implications in cancer diagnosis and therapeutics.

Reactivating Hippo by drug compounds to suppress gastric cancer and enhance chemotherapy sensitivity

The Hippo signaling pathway plays an essential role in organ size control and tumorigenesis. Loss of Hippo signal and hyper-activation of the downstream oncogenic YAP signaling are commonly observed in various types of cancers. We previously identified STRN3-containing PP2A phosphatase as a negative regulator of MST1/2 kinases (i.e., Hippo) in gastric cancer (GC), opening the possibility of selectively targeting the PP2Aa-STRN3-MST1/2 axis to recover Hippo signaling against cancer. Here, we further discovered 1) disulfiram (DSF), an FDA-approved drug, which can similarly block the binding of STRN3 to PP2A core enzyme and 2) CX-6258 (CX), a chemical inhibitor, that can disrupt the interaction between STRN3 and MST1/2, both allowing reactivation of Hippo activity to inhibit GC. More importantly, we found these two compounds, via an MST1/2 kinase-dependent manner, inhibit DNA repair to sensitize GC towards chemotherapy. In addition, we identified thiram, a structural analog of DSF, can function similarly to inhibit cancer cell proliferation or enhance chemotherapy sensitivity. Interestingly, inclusion of copper ion enhanced such effects of DSF and thiram on GC treatment. Overall, this work demonstrated that pharmacological targeting of the PP2Aa-STRN3-MST1/2 axis by drug compounds can potently recover Hippo signal for tumor treatment.

Tead4 and Tfap2c generate bipotency and a bistable switch in totipotent embryos to promote robust lineage diversification

The mouse and human embryo gradually loses totipotency before diversifying into the inner cell mass (ICM, future organism) and trophectoderm (TE, future placenta). The transcription factors TFAP2C and TEAD4 with activated RHOA accelerate embryo polarization. Here we show that these factors also accelerate the loss of totipotency. TFAP2C and TEAD4 paradoxically promote and inhibit Hippo signaling before lineage diversification: they drive expression of multiple Hippo regulators while also promoting apical domain formation, which inactivates Hippo. Each factor activates TE specifiers in bipotent cells, while TFAP2C also activates specifiers of the ICM fate. Asymmetric segregation of the apical domain reconciles the opposing regulation of Hippo signaling into Hippo OFF and the TE fate, or Hippo ON and the ICM fate. We propose that the bistable switch established by TFAP2C and TEAD4 is exploited to trigger robust lineage diversification in the developing embryo.

Signaling pathways in liver cancer: pathogenesis and targeted therapy

Liver cancer remains one of the most prevalent malignancies worldwide with high incidence and mortality rates. Due to its subtle onset, liver cancer is commonly diagnosed at a late stage when surgical interventions are no longer feasible. This situation highlights the critical role of systemic treatments, including targeted therapies, in bettering patient outcomes. Despite numerous studies on the mechanisms underlying liver cancer, tyrosine kinase inhibitors (TKIs) are the only widely used clinical inhibitors, represented by sorafenib, whose clinical application is greatly limited by the phenomenon of drug resistance. Here we show an in-depth discussion of the signaling pathways frequently implicated in liver cancer pathogenesis and the inhibitors targeting these pathways under investigation or already in use in the management of advanced liver cancer. We elucidate the oncogenic roles of these pathways in liver cancer especially hepatocellular carcinoma (HCC), as well as the current state of research on inhibitors respectively. Given that TKIs represent the sole class of targeted therapeutics for liver cancer employed in clinical practice, we have particularly focused on TKIs and the mechanisms of the commonly encountered phenomena of its resistance during HCC treatment. This necessitates the imperative development of innovative targeted strategies and the urgency of overcoming the existing limitations. This review endeavors to shed light on the utilization of targeted therapy in advanced liver cancer, with a vision to improve the unsatisfactory prognostic outlook for those patients.

Lats1 and Lats2 regulate YAP and TAZ activity to control the development of mouse Sertoli cells

Recent reports suggest that the Hippo signaling pathway regulates testis development, though its exact roles in Sertoli cell differentiation remain unknown. Here, we examined the functions of the main Hippo pathway kinases, large tumor suppressor homolog kinases 1 and 2 (Lats1 and Lats2) in developing mouse Sertoli cells. Conditional inactivation of Lats1/2 in Sertoli cells resulted in the disorganization and overgrowth of the testis cords, the induction of a testicular inflammatory response and germ cell apoptosis. Stimulated by retinoic acid 8 (STRA8) expression in germ cells additionally suggested that germ cells may have been preparing to enter meiosis prior to their loss. Gene expression analyses of the developing testes of conditional knockout animals further suggested impaired Sertoli cell differentiation, epithelial-to-mesenchymal transition, and the induction of a specific set of genes associated with Yes-associated protein (YAP) and transcriptional coactivator with PDZ-binding motif (TAZ)-mediated integrin signaling. Finally, the involvement of YAP/TAZ in Sertoli cell differentiation was confirmed by concomitantly inactivating Yap/Taz in Lats1/2 conditional knockout model, which resulted in a partial rescue of the testicular phenotypic changes. Taken together, these results identify Hippo signaling as a crucial pathway for Sertoli cell development and provide novel insight into Sertoli cell fate maintenance.

The Hippo pathway terminal effector TAZ/WWTR1 mediates oxaliplatin sensitivity in p53 proficient colon cancer cells

YAP and TAZ, the Hippo pathway terminal transcriptional activators, are frequently upregulated in cancers. In tumor cells, they have been mainly associated with increased tumorigenesis controlling different aspects from cell cycle regulation, stemness, or resistance to chemotherapies. In fewer cases, they have also been shown to oppose cancer progression, including by promoting cell death through the action of the p73/YAP transcriptional complex, in particular after chemotherapeutic drug exposure. Using HCT116 cells, we show here that oxaliplatin treatment led to core Hippo pathway down-regulation and nuclear accumulation of TAZ. We further show that TAZ was required for the increased sensitivity of HCT116 cells to oxaliplatin, an effect that appeared independent of p73, but which required the nuclear relocalization of TAZ. Accordingly, Verteporfin and CA3, two drugs affecting the activity of YAP and TAZ, showed antagonistic effects with oxaliplatin in co-treatments. Importantly, using several colorectal cell lines, we show that the sensitizing action of TAZ to oxaliplatin is dependent on the p53 status of the cells. Our results support thus an early action of TAZ to sensitize cells to oxaliplatin, consistent with a model in which nuclear TAZ in the context of DNA damage and p53 activity pushes cells towards apoptosis.

The Hippo kinases control inflammatory Hippo signaling and restrict bacterial infection in phagocytes

The Hippo kinases MST1 and MST2 initiate a highly conserved signaling cascade called the Hippo pathway that limits organ size and tumor formation in animals. Intriguingly, pathogens hijack this host pathway during infection, but the role of MST1/2 in innate immune cells against pathogens is unclear. In this report, we generated Mst1/2 knockout macrophages to investigate the regulatory activities of the Hippo kinases in immunity. Transcriptomic analyses identified differentially expressed genes (DEGs) regulated by MST1/2 that are enriched in biological pathways, such as systemic lupus erythematosus, tuberculosis, and apoptosis. Surprisingly, pharmacological inhibition of the downstream components LATS1/2 in the canonical Hippo pathway did not affect the expression of a set of immune DEGs, suggesting that MST1/2 control these genes via alternative inflammatory Hippo signaling. Moreover, MST1/2 may affect immune communication by influencing the release of cytokines, including TNFα, CXCL10, and IL-1ra. Comparative analyses of the single- and double-knockout macrophages revealed that MST1 and MST2 differentially regulate TNFα release and expression of the immune transcription factor MAF, indicating that the two homologous Hippo kinases individually play a unique role in innate immunity. Notably, both MST1 and MST2 can promote apoptotic cell death in macrophages upon stimulation. Lastly, we demonstrate that the Hippo kinases are critical factors in mammalian macrophages and single-cell amoebae to restrict infection by Legionella pneumophila, Escherichia coli, and Pseudomonas aeruginosa. Together, these results uncover non-canonical inflammatory Hippo signaling in macrophages and the evolutionarily conserved role of the Hippo kinases in the anti-microbial defense of eukaryotic hosts.

IMPORTANCE

Identifying host factors involved in susceptibility to infection is fundamental for understanding host-pathogen interactions. Clinically, individuals with mutations in the MST1 gene which encodes one of the Hippo kinases experience recurrent infection. However, the impact of the Hippo kinases on innate immunity remains largely undetermined. This study uses mammalian macrophages and free-living amoebae with single- and double-knockout in the Hippo kinase genes and reveals that the Hippo kinases are the evolutionarily conserved determinants of host defense against microbes. In macrophages, the Hippo kinases MST1 and MST2 control immune activities at multiple levels, including gene expression, immune cell communication, and programmed cell death. Importantly, these activities controlled by MST1 and MST2 in macrophages are independent of the canonical Hippo cascade that is known to limit tissue growth and tumor formation. Together, these findings unveil a unique inflammatory Hippo signaling pathway that plays an essential role in innate immunity.

The AAA-ATPase Ter94 regulates wing size in Drosophila by suppressing the Hippo pathway

Insect wing development is a fascinating and intricate process that involves the regulation of wing size through cell proliferation and apoptosis. In this study, we find that Ter94, an AAA-ATPase, is essential for proper wing size dependently on its ATPase activity. Loss of Ter94 enables the suppression of Hippo target genes. When Ter94 is depleted, it results in reduced wing size and increased apoptosis, which can be rescued by inhibiting the Hippo pathway. Biochemical experiments reveal that Ter94 reciprocally binds to Mer, a critical upstream component of the Hippo pathway, and disrupts its interaction with Ex and Kib. This disruption prevents the formation of the Ex-Mer-Kib complex, ultimately leading to the inactivation of the Hippo pathway and promoting proper wing development. Finally, we show that hVCP, the human homolog of Ter94, is able to substitute for Ter94 in modulating Drosophila wing size, underscoring their functional conservation. In conclusion, Ter94 plays a positive role in regulating wing size by interfering with the Ex-Mer-Kib complex, which results in the suppression of the Hippo pathway.

Amplification of Hippo Signaling Pathway Genes Is Governed and Implicated in the Serous Subtype-Specific Ovarian Carcino-Genesis

Among women, ovarian cancer ranks as the fifth most common cause of cancer-related deaths. This study examined the impact of Hippo signaling pathway on ovarian carcinogenesis. Therefore, the signatures related to Hippo signaling pathway were derived from the molecular signatures database (MSigDB) and were used for further analysis. The Z score-based pathway activation scoring method was employed to investigate the expression patterns of these signatures in the mRNA expression profiles of ovarian cancer cohorts. Compared to other subtype tumors, the results of this study show that the Hippo signaling pathway signatures are dysregulated prominently in serous subtype-specific ovarian carcinogenesis. A receiver operating characteristic (ROC) curve-based results of the Hippo gene set, yes-associated protein 1 (YAP1), and mammalian sterile 20-like kinases 1 (MST1) genes can predict the serous subtype tumors by higher specificity and sensitivity with significant areas under the curve values also further reconfirmed these signaling dysregulations. Moreover, these gene sets were studied further for mutation analysis in the profile of high-grade serous ovarian adenocarcinoma in the cBioPortal database. The OncoPrint results reveal that these Hippo signaling pathway genes are amplified highly during the grade three and stage third or fourth of serous type ovarian tumors. In addition, the results of the Dependency Map (DepMap) plot also clearly show that these genes are amplified significantly across the ovarian cancer cell lines. Finally, overall survival (OS) curve plot investigations also revealed that these gene expressions show poor survival patterns linked to highly expressed conditions in serous subtypes of ovarian cancer patients with significant p-values (p < 0.05). Thus, the current finding would help to develop the targeted therapies treatment for serous subtype ovarian carcinogenesis.

Interplay of RAP2 GTPase and the cytoskeleton in Hippo pathway regulation

The Hippo signaling is instrumental in regulating organ size, regeneration, and carcinogenesis. The cytoskeleton emerges as a primary Hippo signaling modulator. Its structural alterations in response to environmental and intrinsic stimuli control Hippo signaling pathway activity. However, the precise mechanisms underlying the cytoskeleton regulation of Hippo signaling are not fully understood. RAP2 GTPase is known to mediate the mechanoresponses of Hippo signaling via activating the core Hippo kinases LATS1/2 through MAP4Ks and MST1/2. Here we show the pivotal role of the reciprocal regulation between RAP2 GTPase and the cytoskeleton in Hippo signaling. RAP2 deletion undermines the responses of the Hippo pathway to external cues tied to RhoA GTPase inhibition and actin cytoskeleton remodeling, such as energy stress and serum deprivation. Notably, RhoA inhibitors and actin disruptors fail to activate LATS1/2 effectively in RAP2-deficient cells. RNA sequencing highlighted differential regulation of both actin and microtubule networks by RAP2 gene deletion. Consistently, Taxol, a microtubule-stabilizing agent, was less effective in activating LATS1/2 and inhibiting cell growth in RAP2 and MAP4K4/6/7 knockout cells. In summary, our findings position RAP2 as a central integrator of cytoskeletal signals for Hippo signaling, which offers new avenues for understanding Hippo regulation and therapeutic interventions in Hippo-impaired cancers.

Natural compounds targeting YAP/TAZ axis in cancer: Current state of art and challenges

Cancer has become a burgeoning global healthcare concern marked by its exponential growth and significant economic ramifications. Though advancements in the treatment modalities have increased the overall survival and quality of life, there are no definite treatments for the advanced stages of this malady. Hence, understanding the diseases etiologies and the underlying molecular complexities, will usher in the development of innovative therapeutics. Recently, YAP/TAZ transcriptional regulation has been of immense interest due to their role in development, tissue homeostasis and oncogenic transformations. YAP/TAZ axis functions as coactivators within the Hippo signaling cascade, exerting pivotal influence on processes such as proliferation, regeneration, development, and tissue renewal. In cancer, YAP is overexpressed in multiple tumor types and is associated with cancer stem cell attributes, chemoresistance, and metastasis. Activation of YAP/TAZ mirrors the cellular "social" behavior, encompassing factors such as cell adhesion and the mechanical signals transmitted to the cell from tissue structure and the surrounding extracellular matrix. Therefore, it presents a significant vulnerability in the clogs of tumors that could provide a wide window of therapeutic effectiveness. Natural compounds have been utilized extensively as successful interventions in the management of diverse chronic illnesses, including cancer. Owing to their capacity to influence multiple genes and pathways, natural compounds exhibit significant potential either as adjuvant therapy or in combination with conventional treatment options. In this review, we delineate the signaling nexus of YAP/TAZ axis, and present natural compounds as an alternate strategy to target cancer.

Regulation of myocardial glucose metabolism by YAP/TAZ signaling

The heart utilizes glucose and its metabolites as both energy sources and building blocks for cardiac growth and survival under both physiological and pathophysiological conditions. YAP/TAZ, transcriptional co-activators of the Hippo pathway, are key regulators of cell proliferation, survival, and metabolism in many cell types. Increasing lines of evidence suggest that the Hippo-YAP/TAZ signaling pathway is involved in the regulation of both physiological and pathophysiological processes in the heart. In particular, YAP/TAZ play a critical role in mediating aerobic glycolysis, the Warburg effect, in cardiomyocytes. Here, we summarize what is currently known about YAP/TAZ signaling in the heart by focusing on the regulation of glucose metabolism and its functional significance.

The tumor suppressor NF2 modulates TEAD4 stability and activity in Hippo signaling via direct interaction

As an output effector of the Hippo signaling pathway, the TEAD transcription factor and co-activator YAP play crucial functions in promoting cell proliferation and organ size. The tumor suppressor NF2 has been shown to activate LATS1/2 kinases and interplay with the Hippo pathway to suppress the YAP-TEAD complex. However, whether and how NF2 could directly regulate TEAD remains unknown. We identified a direct link and physical interaction between NF2 and TEAD4. NF2 interacted with TEAD4 through its FERM domain and C-terminal tail and decreased the protein stability of TEAD4 independently of LATS1/2 and YAP. Furthermore, NF2 inhibited TEAD4 palmitoylation and induced the cytoplasmic translocation of TEAD4, resulting in ubiquitination and dysfunction of TEAD4. Moreover, the interaction with TEAD4 is required for NF2 function to suppress cell proliferation. These findings reveal an unanticipated role of NF2 as a binding partner and inhibitor of the transcription factor TEAD, shedding light on an alternative mechanism of how NF2 functions as a tumor suppressor through the Hippo signaling cascade.

Potential therapeutic strategy for cancer: Multi-dimensional cross-talk between circRNAs and parental genes

In many ways, circular RNAs (circRNAs) have been demonstrated to be crucial in the onset and advancement of cancer throughout the last ten years and have become a new focus of intense research in the field of RNAs. Accumulating studies have demonstrated that circRNAs can regulate parental gene expression via a variety of biological pathways. Furthermore, research into the complex interactions between circRNAs and their parental genes will shed light on their biological roles and open up new avenues for circRNAs' potential clinical translational uses. However, to date, multi-dimensional cross-talk between circRNAs and parental genes have not been systematically elucidated. Particularly intriguing is circRNA's exploration of tumor targeting, and potential therapeutic uses based on the parental gene regulation perspective. Here, we discuss their biogenesis, take a fresh look at the molecular mechanisms through which circRNAs control the expression of their parental genes in cancer. We further highlight We further highlight the latest circRNA clinical translational applications, including prognostic diagnostic markers, cancer vaccines, gDNA, and so on. Demonstrating the potential benefits and future applications of circRNA therapy.

MST1/2 exerts a pivotal role in inducing neuroinflammation and Coxsackievirus-A10 replication by interacting with innate immunity

Coxsackievirus-A10 (CV-A10), responsible for the hand, foot and mouth disease (HFMD) pandemic, could cause serious central nervous system (CNS) complications. The underlying molecular basis of CV-A10 and host interactions inducing neuropathogenesis is still unclear. The Hippo signaling pathway, historically known for a dominator of organ development and homeostasis, has recently been implicated as an immune regulator. However, its role in host defense against CV-A10 has not been investigated. Herein, it was found that CV-A10 proliferated in HMC3 cells and promoted the release of inflammatory cytokines. Moreover, pattern recognition receptors (PRRs)-mediated pathways, including TLR3-TRIF-TRAF3-TBK1-NF-κB axis, RIG-I/MDA5-MAVS-TRAF3-TBK1-NF-κB axis and TLR7-MyD88-IRAK1/IRAK4-TRAF6-TAK1-NF-κB axis, were examined to be elevated under CV-A10 infection. Meanwhile, it was further uncovered that Hippo signaling pathway was inhibited in HMC3 cells with CV-A10 infection. Previous studies have been reported that there exist complex relations between innate immune and Hippo signaling pathway. Then, plasmids of knockdown and overexpression of MST1/2 were transfected into HMC3 cells. Our results showed that MST1/2 suppressed the levels of inflammatory cytokines via interacting with TBK1 and IRAK1, and also enhanced virus production via restricting IRF3 and IFN-β expressions. Overall, these data obviously pointed out that CV-A10 accelerated the formation of neuroinflammation by the effect of the Hippo pathway on the PRRs-mediated pathway, which delineates a negative immunoregulatory role for MST1/2 in CV-A10 infection and the potential for this pathway to be pharmacologically targeted to treat CV-A10.

Non-coding RNAs as regulators of the Hippo pathway in cardiac development and cardiovascular disease

Cardiovascular diseases pose a serious threat to human health. The onset of cardiovascular diseases involves the comprehensive effects of multiple genes and environmental factors, and multiple signaling pathways are involved in regulating the occurrence and development of cardiovascular diseases. The Hippo pathway is a highly conserved signaling pathway involved in the regulation of cell proliferation, apoptosis, and differentiation. Recently, it has been widely studied in the fields of cardiovascular disease, cancer, and cell regeneration. Non-coding RNA (ncRNAs), which are important small molecules for the regulation of gene expression in cells, can directly target genes and have diverse regulatory functions. Recent studies have found that ncRNAs interact with Hippo pathway components to regulate myocardial fibrosis, cardiomyocyte proliferation, apoptosis, and hypertrophy and play an important role in cardiovascular disease. In this review, we describe the mode of action of ncRNAs in regulating the Hippo pathway, provide new ideas for further research, and identify molecules involved in the mechanism of action of ncRNAs and the Hippo pathway as potential therapeutic targets, with the aim of finding new modes of action for the treatment and prevention of cardiovascular diseases.

Premature endocycling of Drosophila follicle cells causes pleiotropic defects in oogenesis

Endocycling cells grow and repeatedly duplicate their genome without dividing. Cells switch from mitotic cycles to endocycles in response to developmental signals during the growth of specific tissues in a wide range of organisms. The purpose of switching to endocycles, however, remains unclear in many tissues. Additionally, cells can switch to endocycles in response to conditional signals, which can have beneficial or pathological effects on tissues. However, the impact of these unscheduled endocycles on development is underexplored. Here, we use Drosophila ovarian somatic follicle cells as a model to examine the impact of unscheduled endocycles on tissue growth and function. Follicle cells normally switch to endocycles at mid-oogenesis. Inducing follicle cells to prematurely switch to endocycles resulted in the lethality of the resulting embryos. Analysis of ovaries with premature follicle cell endocycles revealed aberrant follicular epithelial structure and pleiotropic defects in oocyte growth, developmental gene amplification, and the migration of a special set of follicle cells known as border cells. Overall, these findings reveal how unscheduled endocycles can disrupt tissue growth and function to cause aberrant development.

Transcriptional regulation of cancer stem cell: regulatory factors elucidation and cancer treatment strategies

Cancer stem cells (CSCs) were first discovered in the 1990s, revealing the mysteries of cancer origin, migration, recurrence and drug-resistance from a new perspective. The expression of pluripotent genes and complex signal regulatory networks are significant features of CSC, also act as core factors to affect the characteristics of CSC. Transcription is a necessary link to regulate the phenotype and potential of CSC, involving chromatin environment, nucleosome occupancy, histone modification, transcription factor (TF) availability and cis-regulatory elements, which suffer from ambient pressure. Especially, the expression and activity of pluripotent TFs are deeply affected by both internal and external factors, which is the foundation of CSC transcriptional regulation in the current research framework. Growing evidence indicates that regulating epigenetic modifications to alter cancer stemness is effective, and some special promoters and enhancers can serve as targets to influence the properties of CSC. Clarifying the factors that regulate CSC transcription will assist us directly target key stem genes and TFs, or hinder CSC transcription through environmental and other related factors, in order to achieve the goal of inhibiting CSC and tumors. This paper comprehensively reviews the traditional aspects of transcriptional regulation, and explores the progress and insights of the impact on CSC transcription and status through tumor microenvironment (TME), hypoxia, metabolism and new meaningful regulatory factors in conjunction with the latest research. Finally, we present opinions on omnidirectional targeting CSCs transcription to eliminate CSCs and address tumor resistance.

SIRT7 promotes Hippo/YAP activation and cancer cell proliferation in hepatocellular carcinoma via suppressing MST1

Abnormal activation of the oncogene YAP in the Hippo pathway is a major feature in liver cancer and inactivation of MST1/2 has been shown to be responsible for the overactivation of YAP that led to tumorigenesis. However, mechanisms underlying MST1/2 dysregulation remain poorly understood. RNA-seq analysis and genome (KEGG) pathway enrichment analysis were used to identify genes and pathways that were regulated by SIRT7. qRT-PCR, ChIP, and luciferase assay were used to investigate transcriptional regulation. Mass spectrometry, co-immunoprecipitation and immunoprecipitation were used to exam protein-protein interaction and post-transcriptional modification. A xenograft mouse model was used to confirm the effect of SIRT7 and SIRT7 inhibitors on hepatocellular carcinoma (HCC) proliferation in vivo. We found that SIRT7 suppresses MST1 by both transcriptional regulation and post-transcriptional modification, which in turn promotes YAP nuclear localization and transcriptional activation in liver cancer. Mechanistically, we revealed that SIRT7 suppresses MST1 transcription by binding to the MST1 promoter and inducing H3K18 deacetylation in its promoter region. In addition, SIRT7 directly binds to and deacetylates MST1, which primes acetylation-dependent MST1 ubiquitination and protein degradation. In clinical samples, we confirmed a negative correlation between SIRT7 and MST1 protein levels, and high SIRT7 expression correlated with elevated YAP expression and nuclear localization. In addition, SIRT7 specific inhibitor 2800Z sufficiently inhibited HCC growth by disrupting the SIRT7/MST1/YAP axis. Our data thus revealed the previously undescribed function of SIRT7 in regulating the Hippo pathway in HCC and further proved that targeting SIRT7 might provide novel therapeutic options for the treatment of liver cancer.

OptoREACT: Optogenetic Receptor Activation on Nonengineered Human T Cells

Optogenetics is a versatile and powerful tool for the control and analysis of cellular signaling processes. The activation of cellular receptors by light using optogenetic switches usually requires genetic manipulation of cells. However, this considerably limits the application in primary, nonengineered cells, which is crucial for the study of physiological signaling processes and for controlling cell fate and function for therapeutic purposes. To overcome this limitation, we developed a system for the light-dependent extracellular activation of cell surface receptors of nonengineered cells termed OptoREACT (Optogenetic Receptor Activation) based on the light-dependent protein interaction of A. thaliana phytochrome B (PhyB) with PIF6. In the OptoREACT system, a PIF6-coupled antibody fragment binds the T cell receptor (TCR) of Jurkat or primary human T cells, which upon illumination is bound by clustered phytochrome B to induce receptor oligomerization and activation. For clustering of PhyB, we either used tetramerization by streptavidin or immobilized PhyB on the surface of cells to emulate the interaction of a T cell with an antigen-presenting cell. We anticipate that this extracellular optogenetic approach will be applicable for the light-controlled activation of further cell surface receptors in primary, nonengineered cells for versatile applications in fundamental and applied research.

PICK1 links KIBRA and AMPA receptors in coiled-coil-driven supramolecular complexes

The human memory-associated protein KIBRA regulates synaptic plasticity and trafficking of AMPA-type glutamate receptors, and is implicated in multiple neuropsychiatric and cognitive disorders. How KIBRA forms complexes with and regulates AMPA receptors remains unclear. Here, we show that KIBRA does not interact directly with the AMPA receptor subunit GluA2, but that PICK1, a key regulator of AMPA receptor trafficking, can serve as a bridge between KIBRA and GluA2. We identified structural determinants of KIBRA-PICK1-AMPAR complexes by investigating interactions and cellular expression patterns of different combinations of KIBRA and PICK1 domain mutants. We find that the PICK1 BAR domain, a coiled-coil structure, is sufficient for interaction with KIBRA, whereas mutation of the BAR domain disrupts KIBRA-PICK1-GluA2 complex formation. In addition, KIBRA recruits PICK1 into large supramolecular complexes, a process which requires KIBRA coiled-coil domains. These findings reveal molecular mechanisms by which KIBRA can organize key synaptic signaling complexes.

TEAD1 is crucial for developmental myelination, Remak bundles, and functional regeneration of peripheral nerves

Previously we showed that the hippo pathway transcriptional effectors, YAP and TAZ, are essential for Schwann cells (SCs) to develop, maintain and regenerate myelin . Although TEAD1 has been implicated as a partner transcription factor, the mechanisms by which it mediates YAP/TAZ regulation of SC myelination are unclear. Here, using conditional and inducible knockout mice, we show that TEAD1 is crucial for SCs to develop and regenerate myelin. It promotes myelination by both positively and negatively regulating SC proliferation, enabling Krox20/Egr2 to upregulate myelin proteins, and upregulating the cholesterol biosynthetic enzymes FDPS and IDI1. We also show stage-dependent redundancy of TEAD1 and that non-myelinating SCs have a unique requirement for TEAD1 to enwrap nociceptive axons in Remak bundles. Our findings establish TEAD1 as a major partner of YAP/TAZ in developmental myelination and functional nerve regeneration and as a novel transcription factor regulating Remak bundle integrity.