Yes-associated Protein Expression Research Articles

ALKBH5 Protects Against Hepatic Ischemia–Reperfusion Injury by Regulating YTHDF1-Mediated YAP Expression

Ischemia/reperfusion (I/R) injury with severe cell death is a major complication involved in liver transplantation and resection. The identification of key regulators improving hepatocyte activity may provide potential strategies to clinically resolve I/R-induced injury. N6-methyladenosine (m6A) RNA modification is essential for tissue homeostasis and pathogenesis. However, the potential involvement of m6A in the regulation of hepatocyte activity and liver injury has not been fully explored. In the present study, we found that hepatocyte AlkB homolog H5 (ALKBH5) levels were decreased both in vivo and in vitro I/R models. Hepatocyte-specific ALKBH5 overexpression effectively attenuated I/R-induced liver necrosis and improved cell proliferation in mice. Mechanistically, ALKBH5-mediated m6A demethylation improved the mRNA stability of YTH N6-methyladenosine RNA-binding protein 1 (YTHDF1), thereby increasing its expression, which consequently promoted the translation of Yes-associated protein (YAP). In conclusion, ALKBH5 is a regulator of hepatic I/R injury that improves hepatocyte repair and proliferation by maintaining YTHDF1 stability and YAP content. The ALKBH5–m6A–YTHDF1–YAP axis represents promising therapeutic targets for hepatic I/R injury to improve the prognosis of liver surgery.

Mesenchymal stem cell-derived exosomal mir-21-5p inhibits YAP1 expression and improves outcomes in myocardial infarction

BackgroundMyocardial infarction (MI) remains a significant global health concern, characterized by cardiomyocyte apoptosis and adverse ventricular remodeling. Nevertheless, the interplay between exosomal miR-21-5p and Yes-associated protein 1 (YAP1) in the context of MI remains unexplored.MethodsRat mesenchymal stem cells (MSCs) and H9c2 cardiomyocytes were cultured, characterized, and instrumental in our experiments. Exosomes were meticulously isolated, and their identity confirmed. The internalization of these exosomes by H9c2 cells was assessed, while RNA and protein expression were quantified using Quantitative Real-Time PCR and Western blot, respectively. MTT assay was implemented for cell viability, and apoptosis was evaluated via flow cytometric analysis. To elucidate gene interactions, we conducted microarray profiling of miRNA expression, dual luciferase reporter assays, and RNA Immunoprecipitation.ResultsMSC-derived exosomes exhibited a remarkable capacity to attenuate hypoxia-induced inflammation and apoptosis in H9c2 cells. Notably, these exosomes significantly upregulated miR-21-5p levels within H9c2 cells, and the abrogation of miR-21-5p function abated their protective effects. Through computational analysis, we unveiled a miR-21-5p binding site in the 3’UTR of YAP1, which directly inhibited YAP1 expression. Importantly, the inhibition of YAP1 effectively reinstated the protective effects of exosomes in cells with impaired exosomal miR-21-5p.ConclusionThis study underscores the pivotal role played by MSC-derived exosomes in safeguarding against MI, primarily by mediating the transfer of miR-21-5p, which targets YAP1 signaling pathways.Clinical trial numberN/A.

Wedelolactone Attenuates Liver Fibrosis and Hepatic Stellate Cell Activation by Suppressing the Hippo Pathway.

Liver fibrosis is a commonly observed pathological phenomenon that occurs during the progression of various types of chronic liver diseases. The Hippo pathway is closely associated with the pathogenesis of liver fibrosis. Previous studies have shown that wedelolactone (WED) has a significant antihepatic fibrosis effect, whereas the target and mechanism underlying WED remain elusive. In this study, we found that WED significantly alleviated liver fibrosis and injury by inhibiting the expression of Yes-associated protein (YAP) and tafazzin (TAZ). In an in vitro model, WED suppressed the activation of hepatic stellate cells (HSCs) induced by transforming growth factor (TGF-β1), as well as the mRNA and protein expression of α-smooth muscle actin (α-SMA), YAP, and TAZ. The allosteric regulation of YAP by WED was confirmed using MD and cellular thermal shift assay. Moreover, specific knockdown or inhibition of YAP did not enhance the suppressive effect of WED on HSC activation or protein expression associated with fibrosis. These findings demonstrated that the administration of WED effectively alleviated liver fibrosis by suppressing the Hippo/YAP/TAZ pathways. In addition, YAP activity may be regulated by WED via allosteric regulation.

Pseudo-3D Topological Alignments Regulate Mechanotransduction and Maturation of Smooth Muscle Cells.

Smooth muscle cells (SMCs) sense and respond to mechanical stimuli in their extracellular microenvironments (ECMs), playing a crucial role in muscle tissue engineering. Increasing evidence from topological cues-mediated mechanotransduction of SMCs in ECMs has suggested some potential underlying mechanisms of how SMC functions and maturation are regulated by their mechanosensing leading to transduction. However, how the expression of yes-associated protein 1 (YAP) influences the phenotypic shift from synthetic to contractile is still controversial. Here, pseudo-3D topological alignments mimicking native muscle tissues are generated using laser-cutter engraving to explore the influence of topological cues on SMC mechanotransduction and maturation. The analysis of topological cue-mediated mechanotransduction and maturation marker expression revealed YAP is involved in mechanotransduction for SMCs cultured on cross-patterned substrates in the presence of cell-cell interactions. Moreover, these SMCs with YAP-linked mechanosensing showed higher expression of calponin, indicating a shift toward contractile phenotypes in vitro and in vivo. Furthermore, it showed skeletal muscle cells has different mechanosensing and maturation mechanisms compared to SMCs, revealing muscle type-dependent different sensing of topological cues, and converting into maturation-associated signaling cascades. This study provides insights into the regulation of SMC mechanotransduction and maturation by topological cues, suggesting the involvement of YAP-linked signaling pathways in this process.

Forkhead box C1 promotes the pathology of osteoarthritis in subchondral bone osteoblasts via the Piezo1/YAP axis

Subchondral bone sclerosis is a key characteristic of osteoarthritis (OA). Prior research has shown that Forkhead box C1 (FoxC1) plays a role in the synovial inflammation of OA, but its specific role in the subchondral bone of OA has not been explored. Our research revealed elevated expression levels of FoxC1 and Piezo1 in OA subchondral bone tissues. Further experiments on OA subchondral bone osteoblasts with FoxC1 or Piezo1 overexpression showed increased cell proliferation activity, expression of Yes-associated Protein 1 (YAP) and osteogenic markers, and secretion of proinflammatory factors. Mechanistically, the overexpression of FoxC1 through Piezo1 activation, in combination with downstream YAP signaling, led to increased levels of alkaline phosphatase (ALP), collagen type 1 (COL1) A1, RUNX2, Osteocalcin, matrix metalloproteinase (MMP) 3, and MMP9 expression. Notably, inhibition of Piezo1 reversed the regulatory function of FoxC1. The binding of FoxC1 to the targeted area (ATATTTATTTA, residues +612 to +622) and the activation of Piezo1 transcription were verified by the dual luciferase assays. Additionally, Reduced subchondral osteosclerosis and microangiogenesis were observed in knee joints from FoxC1-conditional knockout (CKO) and Piezo1-CKO mice, indicating reduced lesions. Collectively, our study reveals the significant involvement of FoxC1 in the pathologic process of OA subchondral bone via the Piezo1/YAP signaling pathway, potentially establishing a novel therapeutic target.

Anti-fibrogenic effect of umbilical cord-derived mesenchymal stem cell-conditioned media in human esophageal fibroblasts.

Esophageal fibrosis can develop due to caustic or radiation injuries. Umbilical cord-derived mesenchymal stem cells (UC-MSCs) are known to mitigate fibrosis in various organs. However, the potential effects of UC-MSCs on human esophageal fibrosis remain underexplored. This study investigated the anti-fibrogenic properties and mechanisms of UC-MSC-derived conditioned media (UC-MSC-CM) on human esophageal fibroblasts (HEFs). HEFs were treated with TGF-β1 and then cultured with UC-MSC-CM, and the expression levels of extracellular matrix (ECM) components, RhoA, myocardin related transcription factor A (MRTF-A), serum response factor (SRF), Yes-associated protein (YAP), and transcriptional coactivator with PDZ-binding motif (TAZ) were measured. UC-MSC-CM suppressed TGF-β1-induced fibrogenic activation in HEFs, as evidenced by the downregulation of ECM. UC-MSC-CM diminished the expression of RhoA, MRTF-A, and SRF triggered by TGF-β1. In TGF-β1-stimulated HEFs, UC-MSC-CM decreased the nuclear localization of MRTF-A and YAP. Additionally, UC-MSC-CM diminished the TGF-β1-induced nuclear expressions of YAP and TAZ, while concurrently enhancing the cytoplasmic presence of phosphorylated YAP. Furthermore, UC-MSC-CM reduced TGF-β1-induced phosphorylation of Smad2. These findings suggest that UC-MSC-CM may inhibit TGF-β1-induced fibrogenic activation in HEFs by targeting the Rho-mediated MRTF/SRF and YAP/TAZ pathways, as well as the Smad2 pathway. This indicates its potential as a stem cell therapy for esophageal fibrosis.

Dihydroartemisinin Inhibits Epithelial-Mesenchymal Transition Progression in Medullary Thyroid Carcinoma Through the Hippo Signaling Pathway Regulated by Interleukin-6.

Dihydroartemisinin (DHA), an artemisinin derivative, can influence certain malignancies' inflammatory response and growth. This study used Cell Counting Kit-8 and Transwell assays to show that DHA suppressed the growth, migration, and invasion of medullary thyroid cancer cells. Furthermore, the authors used enzyme-linked immunosorbent assay, Western blotting, and immunofluorescence to confirm the expression of the transcriptional coactivators Yes-associated protein (YAP)/transcriptional coactivator with a PDZ-binding domain (TAZ) downstream of the Hippo pathway and changes in the expression of the epithelial-mesenchymal transition (EMT) process markers E-cadherin and N-cadherin. These results demonstrate that DHA effectively reduced the expression of interleukin (IL)-6 in medullary thyroid carcinoma (MTC) cells and hindered the EMT process by regulating the Hippo pathway. This regulation was achieved by promoting YAP phosphorylation and inhibiting YAP/TAZ protein expression. Additional activation of the Hippo pathway by GA-017 alleviated the inhibitory effect of DHA on IL-6. Hippo pathway activation led to an increase in the expression of E-cadherin, a marker of EMT. In conclusion, DHA was demonstrated to regulate the Hippo pathway by inhibiting IL-6 secretion, leading to the inhibition of EMT in MTC. These findings provide a theoretical foundation for further exploration of the anticancer mechanisms of DHA and offer valuable insights into its potential clinical application as a combinatorial drug.

Sepsis induces the cardiomyocyte apoptosis and cardiac dysfunction through activation of YAP1/Serpine1/caspase-3 pathway.

Sepsis triggers myocardial injury and dysfunction, leading to a high mortality rate in patients. Cardiomyocyte apoptosis plays a positive regulatory role in septic myocardial injury and dysfunction. However, the mechanism is unclear. Bioinformatics analysis was used to identify differentially expressed genes in septic mice heart and validate key genes and pathways. The correlation of protein-protein and protein-pathway was analyzed. Sequentially, the cecal ligament and puncture (CLP) was used to induce septic mice, followed by Serpine1 inhibitor treatment. Finally, the regulatory relationship of Yes-associated protein1 (YAP1), Serpine1, and caspase-3 was verified in LPS-exposed mouse cardiomyocytes. Bioinformatic analysis found that Serpine1 expression is decreased in septic mice heart tissue and closely related to the HIPPO signaling pathway, while YAP1 is negatively correlated with apoptosis. In vivo, CLP induced a reduction of survival rate, cardiac dysfunction, and an increase in Serpine1 and Cleaved Caspase-3 expression, which could be reversed by a Serpine1 inhibitor. In vitro, LPS induced the mouse cardiomyocytes apoptosis, which could be reversed by Serpine1 inhibitor. Silencing YAP1 and Serpine1 reversed the LPS-induced increase in Serpine1 and Cleaved Caspase-3 expression, but silencing Serpine1 did not affect the LPS-induced YAP1 expression. Sepsis induced mouse cardiomyocytes apoptosis and cardiac dysfunction through activation of YAP1/Serpine1/caspase-3 pathway.

The cytoskeleton dynamics-dependent LINC complex in periodontal ligament stem cells transmits mechanical stress to the nuclear envelope and promotes YAP nuclear translocation

BackgroundPeriodontal ligament stem cells (PDLSCs) are important seed cells in tissue engineering and clinical applications. They are the priority receptor cells for sensing various mechanical stresses. Yes-associated protein (YAP) is a recognized mechanically sensitive transcription factor. However, the role of YAP in regulating the fate of PDLSCs under tension stress (TS) and its underlying mechanism is still unclear.MethodsThe effects of TS on the morphology and fate of PDLSCs were investigated using fluorescence staining, transmission electron microscopy, flow cytometry and quantitative real-time polymerase chain reaction (qRT-PCR). Then qRT-PCR, western blotting, immunofluorescence staining and gene knockdown experiments were performed to investigate the expression and distribution of YAP and its correlation with PDLSCs proliferation. The effects of cytoskeleton dynamics on YAP nuclear translocation were subsequently explored by adding cytoskeleton inhibitors. The effect of cytoskeleton dynamics on the expression of the LINC complex was proved through qRT-PCR and western blotting. After destroying the LINC complex by adenovirus, the effects of the LINC complex on YAP nuclear translocation and PDLSCs proliferation were investigated. Mitochondria-related detections were then performed to explore the role of mitochondria in YAP nuclear translocation. Finally, the in vitro results were verified by constructing orthodontic tooth movement models in Sprague-Dawley rats.ResultsTS enhanced the polymerization and stretching of F-actin, which upregulated the expression of the LINC complex. This further strengthened the pull on the nuclear envelope, enlarged the nuclear pore, and facilitated YAP’s nuclear entry, thus enhancing the expression of proliferation-related genes. In this process, mitochondria were transported to the periphery of the nucleus along the reconstructed microtubules. They generated ATP to aid YAP’s nuclear translocation and drove F-actin polymerization to a certain degree. When the LINC complex was destroyed, the nuclear translocation of YAP was inhibited, which limited PDLSCs proliferation, impeded periodontal tissue remodeling, and hindered tooth movement.ConclusionsOur study confirmed that appropriate TS could promote PDLSCs proliferation and periodontal tissue remodeling through the mechanically driven F-actin/LINC complex/YAP axis, which could provide theoretical guidance for seed cell expansion and for promoting healthy and effective tooth movement in clinical practice.

YAP1 regulates thrombopoiesis by binding to MYH9 in immune thrombocytopenia

AbstractImmune thrombocytopenia (ITP) is a complicated bleeding disease characterized by a sharp platelet reduction. As a dominating element involved in ITP, megakaryocytes (MKs) are responsible for thrombopoiesis. However, the mechanism underlying the dysregulation of thrombopoiesis that occurs in ITP remains unidentified. In this study, we examined the role of Yes-associated protein 1 (YAP1) in thrombopoiesis during ITP. We observed reduced YAP1 expression with cytoskeletal actin misalignment in MKs from patients with ITP. Using an experimental ITP mouse model, we showed that reduced YAP1 expression induced aberrant MK distribution, reduced the percentage of late MKs among the total MKs, and caused submaximal platelet recovery. Mechanistically, YAP1 upregulation by binding of GATA-binding protein 1 to its promoter promoted MK maturation. Phosphorylated YAP1 promoted cytoskeletal activation by binding its WW2 domain to myosin heavy chain 9, thereby facilitating thrombopoiesis. Targeting YAP1 with its activator XMU-MP-1 was sufficient to rescue cytoskeletal defects and thrombopoiesis dysregulation in YAP1+/− mice with ITP and patients. Taken together, these results demonstrate the crucial role of YAP1 in thrombopoiesis, providing potential for the development of diagnostic markers and therapeutic options for ITP.

UBR1 promotes anaplastic thyroid carcinoma progression via stabilizing YAP through monoubiquitylation

Anaplastic thyroid carcinoma (ATC) is a highly aggressive human malignancy without effective treatment. Yes-associated protein (YAP) is a critical effector of the Hippo pathway, which is essential in thyroid carcinogenesis. However, the underlying mechanisms of aberrant YAP expression in ATC are not completely understood. Ubiquitylation-related enzyme siRNA screening identified the ubiquitin protein ligase E3 component n-recognin 1 (UBR1) as a stabilizer of YAP in ATC cells. UBR1 deficiency reduced YAP protein levels and its target gene expression. UBR1 directly interacted with YAP and promoted its monoubiquitylation, competitively suppressing its polyubiquitylation and resulting in extended protein half-life. UBR1 depletion reduced ATC cell proliferation and migration in vitro. Xenograft tumor studies also suggested that UBR1 knockdown suppressed ATC cell growth in vivo. Furthermore, exogenous YAP expression partially reversed the inhibitive effects of UBR1 depletion on ATC cell proliferation and migration. Our studies demonstrated that UBR1 directly interacts with YAP and stabilized it in a monoubiquitylation-dependent manner, consequently promoting ATC tumorigenesis, suggesting that UBR1 might be a potentially therapeutic target for ATC treatment.

Stepwise-targeting and hypoxia-responsive liposome AMVY@NPs carrying siYAP and verteporfin for glioblastoma therapy

BackgroundThe Hippo pathway is a conserved tumour suppressor signalling pathway, and its dysregulation is often associated with abnormal cell growth and tumorigenesis. We previously revealed that the transcriptional coactivator Yes-associated protein (YAP), the key effector of the Hippo pathway, is a molecular target for glioblastoma (GBM), the most common malignant brain tumour. Inhibiting YAP with small interfering RNA (siYAP) or the specific inhibitor verteporfin (VP) can diminish GBM growth to a certain degree.ResultsIn this study, to enhance the anti-GBM effect of siYAP and VP, we designed stepwise-targeting and hypoxia-responsive liposomes (AMVY@NPs), which encapsulate hypoxia-responsive polymetronidazole-coated VP and DOTAP adsorbed siYAP, with angiopep-2 (A2) modification on the surface. AMVY@NPs exhibited excellent blood‒brain barrier crossing, GBM targeting, and hypoxia-responsive and efficient siYAP and VP release properties. By inhibiting the expression and function of YAP, AMVY@NPs synergistically inhibited both the growth and stemness of GBM in vitro. Moreover, AMVY@NPs strongly inhibited the growth of orthotopic U87 xenografts and improved the survival of tumour-bearing mice without adverse effects.ConclusionSpecific targeting of YAP with stepwise-targeting and hypoxia-responsive liposome AMVY@NPs carrying siYAP and VP efficiently inhibited GBM progression. This study provides a valuable drug delivery platform and creative insights for molecular targeted treatment of GBM in the future.

Retinoic acid-induced protein 14 links mechanical forces to Hippo signaling

Cells sense and respond to various mechanical forces from the extracellular matrix primarily by modulating the actin cytoskeleton. Mechanical forces can be translated into biochemical signals in a process called mechanotransduction. Yes-associated protein (YAP) is an effector of Hippo signaling and a mediator of mechanotransduction, but how mechanical forces regulate Hippo signaling is still an open question. We propose that retinoic acid-induced protein 14 (RAI14) responds to mechanical forces and regulates Hippo signaling. RAI14 positively regulates the activity of YAP. RAI14 interacts with NF2, a key component of the Hippo pathway, and the interaction occurs on filamentous actin. When mechanical forces are kept low in cells, NF2 dissociates from RAI14 and filamentous actin, resulting in increased interactions with LATS1 and activation of the Hippo pathway. Clinical data show that tissue stiffness and expression of RAI14 and YAP are upregulated in tumor tissues and that RAI14 is strongly associated with adverse outcome in patients with gastric cancer. Our data suggest that RAI14 links mechanotransduction with Hippo signaling and mediates Hippo-related biological functions such as cancer progression.

CRKL Enhances YAP Signaling through Binding and JNK/JUN Pathway Activation in Liver Cancer.

The Hippo pathway transducers yes-associated protein (YAP) and WW-domain containing transcription regulator 1 (WWTR1/TAZ) are key regulators of liver tumorigenesis, promoting tumor formation and progression. Although the first inhibitors are in clinical trials, targeting the relevant upstream regulators of YAP/TAZ activity could prove equally beneficial. To identify regulators of YAP/TAZ activity in hepatocarcinoma (HCC) cells, we carried out a proximity labelling approach (BioID) coupled with mass spectrometry. We verified CRK-like proto-oncogene adaptor protein (CRKL) as a new YAP-exclusive interaction partner. CRKL is highly expressed in HCC patients, and its expression is associated with YAP activity as well as poor survival prognosis. In vitro experiments demonstrated CRKL-dependent cell survival and the loss of YAP binding induced through actin disruption. Moreover, we delineated the activation of the JNK/JUN pathway by CRKL, which promoted YAP transcription. Our data illustrate that CRKL not only promoted YAP activity through its binding but also through the induction of YAP transcription by JNK/JUN activation. This emphasizes the potential use of targeting the JNK/JUN pathway to suppress YAP expression in HCC patients.

Circ_0002722-induced regulation of YAP promotes platinum resistance in oral squamous cell carcinoma: Implications for verteporfin therapy

Oral squamous cell carcinoma (OSCC) poses a significant public health burden due to its high prevalence and poor prognosis. Platinum resistance is one of the major challenges in OSCC treatment. Yes-associated protein (YAP) has been identified as a pivotal player in OSCC tumorigenesis and progression. Circular RNA (circRNA) has been implicated in chemoresistance in various cancers by regulation the function of microRNA. Nevertheless, the specific mechanisms linking circRNA to YAP expression in OSCC remain poorly understood. In this study, we detected the YAP and circRNA hsa_circ_0002722 (circ_0002722) expression by western blot (WB) and quantitative polymerase chain reaction (qPCR). We found that YAP and circ_0002722 were up-regulated in platinum resistance in OSCC tissues. Furthermore, transfection of circ_0002722 siRNA into platinum-resistant cells revealed that circ_0002722 acted as a regulator of miR-1305, which influenced YAP expression and thereby affected platinum sensitivity. In vivo experiments corroborated the synergistic effects of cisplatin and verteporfin (a YAP inhibitor) in combating platinum resistance. Targeting YAP emerges as a promising therapeutic strategy for addressing platinum resistance in OSCC, with circ_0002722 serving as a potential therapy target and valuable diagnostic marker. These findings shed light on the underlying mechanisms of platinum resistance, paving the way for the development of effective treatment approaches.

Effect of low-intensity pulsed ultrasound on the mineralization of force-treated cementoblasts and orthodontically induced inflammatory root resorption via the Lamin A/C-Yes associated protein axis.

Orthodontic treatment commonly results in orthodontically induced inflammatory root resorption (OIIRR). This condition arises from excessive orthodontic force, which triggerslocal inflammatory responses and impedes cementoblasts' mineralization capacity. Low-intensity pulsed ultrasound (LIPUS) shows potential in reducing OIIRR. However, the precise mechanisms through which LIPUS reduces OIIRR remain unclear. This study aimed to explore the effects and mechanisms of LIPUS on the mineralization of force-treated cementoblasts and its impact on OIIRR. We established a rat OIIRR model and locally administered LIPUS stimulation for 7 and 14 days. We analyzed root resorption volume, osteoclast differentiation, and the expression of osteocalcin and yes-associated protein 1 (YAP1) using micro-computed tomography (micro-CT), hematoxylin and eosin, tartrate-resistant acid phosphatase, immunofluorescence and immunohistochemistry staining. Invitro, we applied compressive force and LIPUS to the immortalized mouse cementoblasts (OCCM30). We assessed mineralization using alkaline phosphatase (ALP) staining, alizarin red staining, real-time quantitative polymerase chain reaction, Western blotting and immunofluorescence staining. In rats, LIPUS reduced OIIRR, as evidenced by micro-CT analysis and histological staining. Invitro, LIPUS enhanced mineralization of force-treated OCCM30 cells, as indicated by ALP and alizarin red staining, upregulated mRNA expression of mineralization-related genes, and increased protein expression of mineralization markers. Mechanistically, LIPUS activated YAP1 signaling via the cytoskeleton-Lamin A/C pathway, supported by immunofluorescence and Western blot analysis. This study demonstrates that LIPUS promotes mineralization in force-treated cementoblasts and reduces OIIRR by activating YAP1 through the cytoskeletal-Lamin A/C signaling pathway. These findings provide fresh insights into how LIPUS benefits orthodontic treatment and suggest potential strategies for preventing and treating OIIRR.

Abstract We070: The role of neutrophil YAP in cardiac inflammation and injury

Background: There is a growing appreciation that neutrophils demonstrate plasticity, not unlike the macrophage, and can modulate both inflammation and repair following organ injury. Neutrophils are rapidly recruited to the heart after acute myocardial infarction (MI) and participate in cardiac inflammation and remodeling. Nevertheless, mechanisms regulating neutrophil function during heart injury remain largely unknown. Research Question/Aim: Previous work demonstrated that Yes-Associated Protein (YAP) regulates macrophage function during heart injury. However, whether YAP regulates neutrophil function in any context, including reperfused MI (I/R), remains unexplored. Approach: We generated neutrophil-specific YAP KO mice (MRP8 Cre ) and subjected them to I/R to elicit inflammation and injury. Cell-based experiments were performed using primary isolated mouse neutrophils. We utilized flow cytometry, single-cell RNAseq, and histological and biochemical assays to investigate underlying mechanisms. Results: Neutrophils isolated from the blood and heart of WT mice subjected to I/R revealed increased YAP expression. Compared to control mice, neutrophil YAP KO hearts had decreased infarct size after 24 hours reperfusion, and better cardiac function after 2 weeks. Single-cell RNAseq of heart leukocytes indicated suppression of inflammatory, migratory, and superoxide production pathways in YAP KO neutrophils. Characterization of neutrophils by flow cytometry indicated a shift toward reparative polarization in YAP KO mice during early reperfusion. Bone marrow-derived neutrophils (BMDNs) from KO mice had attenuated inflammatory gene expression and ROS production compared to control cells. Pharmacological inhibition of YAP using verteporfin produced comparable results. Ongoing experiments are investigating how YAP modulates neutrophil inflammatory function, and will determine the therapeutic potential of targeted YAP inhibition for I/R injury. Conclusion: These results suggest that YAP regulates neutrophil function during I/R injury in the heart and that suppression of neutrophil YAP affords cardioprotection.

Targeting the Hippo/YAP1 signaling pathway in hepatocellular carcinoma: From mechanisms to therapeutic drugs (Review).

The Hippo signaling pathway plays a pivotal role in regulating cell growth and organ size. Its regulatory effects on hepatocellular carcinoma (HCC) encompass diverse aspects, including cell proliferation, invasion and metastasis, tumor drug resistance, metabolic reprogramming, immunomodulatory effects and autophagy. Yes‑associated protein 1 (YAP1), a potent transcriptional coactivator and a major downstream target tightly controlled by the Hippo pathway, is influenced by various molecules and pathways. The expression of YAP1 in different cell types within the liver tumor microenvironment exerts varying effects on tumor outcomes, warranting careful consideration. Therefore, research on YAP1‑targeted therapies merits attention. This review discusses the composition and regulation mechanism of the Hippo/YAP1 signaling pathway and its relationship with HCC, offering insights for future research and cancer prevention strategies.

YAP1 suppression by ZDHHC7 is associated with ferroptosis resistance and poor prognosis in ovarian clear cell carcinoma.

Ovarian clear cell carcinoma (OCCC), which has unique clinical characteristics, arises from benign endometriotic cysts, forming an oxidative stress environment due to excess iron accumulation, and exhibits poor prognosis, particularly in advanced stages owing to resistance to conventional therapeutics. Ferroptosis is an iron-dependent form of programmed cell death induced by lipid peroxidation and controlled by Hippo signaling. We hypothesized that overcoming ferroptosis resistance is an attractive strategy because OCCC acquires oxidative stress resistance during its development and exhibits chemoresistant features indicative of ferroptosis resistance. This study aimed to determine whether OCCC is resistant to ferroptosis and clarify the mechanism underlying resistance. Unlike ovarian high-grade serous carcinoma cells, OCCC cells were exposed to oxidative stress. However, OCCC cells remained unaffected by lipid peroxidation. Cell viability assays revealed that OCCC cells exhibited resistance to the ferroptosis inducer erastin. Moreover, Samroc analysis showed that the Hippo signaling pathway was enriched in OCCC cell lines and clinical samples. Furthermore, patients with low expression of nuclear Yes-associated protein 1(YAP1) exhibited a significantly poor prognosis of OCCC. Moreover, YAP1 activation enhanced ferroptosis in OCCC cell lines. Furthermore, suppression of zinc finger DHHC-type palmitoyltransferase 7 (ZDHHC7) enhanced ferroptosis by activating YAP1 in OCCC cell lines. Mouse xenograft models demonstrated that ZDHHC7 inhibition suppressed tumor growth via YAP1 activation by erastin treatment. In conclusion, YAP1 activation regulated by ZDHHC7 enhanced ferroptosis in OCCC. Thus, overcoming ferroptosis resistance is a potential therapeutic strategy for OCCC.

Potentially actionable targets in synovial sarcoma: A tissue microarray study

BackgroundSynovial sarcoma (SynSa) is one of the most common translocation-related soft tissue sarcomas. Patients with metastatic SynSa have limited treatment options and a very poor prognosis. Several novel experimental therapies are currently being explored in clinical trials, including T cell-based therapies targeting cancer testis antigens such as New York esophageal squamous cell carcinoma 1 (NY-ESO-1) or melanoma-associated antigen A4 (MAGE-A4), and degraders targeting bromodomain-containing protein 9 (BRD9). Preclinical studies investigate inhibitors of Yes associated protein 1 (YAP1), transcriptional co-activator with PDZ-binding motif (TAZ) and inhibitors of chemokine receptor 4 (CXCR4). MethodsWe explored the immunohistochemical expression of these targets using a tissue microarray (TMA) constructed from 91 clinical SynSa samples and correlated these findings with corresponding clinicopathological data. ResultsExpression of MAGE-A4 and NY-ESO-1 was found in 69 % and 56 % of the samples, respectively. NY-ESO-1 was statistically higher expressed in samples from metastatic lesions as compared to samples from primary tumors. Nuclear expression of YAP1 and TAZ was observed in 92 % and 51 % of the samples, respectively. CXCR4 was expressed in the majority of the samples (82 %). BRD9 was highly expressed in all specimens. No prognostic role could be identified for any of the investigated proteins. ConclusionThis study is a comprehensive study providing real-world data on the expression of several actionable proteins in a large proportion of SynSa samples. All evaluated markers were expressed in a clinically meaningful proportion of cases represented in our TMA, supporting the relevance of ongoing preclinical and clinical research with novel agents directed against these targets.