The Hippo pathway: regulators and regulations

Exploring Degradation of Intrinsically Disordered Protein Yes-Associated Protein Induced by Proteolysis TArgeting Chimeras

Yes-associated protein (YAP) is a key oncogene in the Hippo tumor suppression pathway, historically challenging to target due to its intrinsically disordered nature. Leveraging recent advances in high-throughput screening that identified several YAP binders, we employed proteolysis-targeting chimera technology to develop a series of YAP degraders. Utilizing NSC682769, a known YAP binder, linked with VHL ligand 2 or pomalidomide via diverse linkers, we synthesized degraders including YZ-6. This degrader not only recruits the E3 ligase VHL for the rapid and sustained degradation of YAP but also effectively inhibits its nuclear localization, curtailing YAP/TEAD-mediated transcription in cancer cell lines such as NCI-H226 and Huh7. This dual action significantly diminishes YAP's oncogenic activity, contributing to the potent antiproliferative effects observed both in vitro and in a Huh7 xenograft mouse model. These results underscore the potential of PROTAC-mediated YAP degradation as a strategy for treating YAP-driven cancers.

Regulation of Hippo/YAP axis in colon cancer progression by the deubiquitinase JOSD1

Colon cancer is a prevalent malignancy, while recent studies revealed the dys-regulation of Hippo signaling as the important driver for colon cancer progression. Several studies have indicated that post-translational modifications on YAP play crucial roles in both Hippo signaling activity and cancer progression. This raises a puzzling question about why YAP/TAZ, an auto-inhibitory pathway, is frequently over-activated in colon cancer, despite the suppressive cascade of Hippo signaling remaining operational. The protein stability of YAP is subject to a tiny balance between ubiquitination and deubiquitination processes. Through correlation analysis of DUBs (deubiquitinases) expression and Hippo target gene signature in colon cancer samples, we found JOSD1 as a critical deubiquitinase for Hippo signaling and colon cancer progression. JOSD1 could facilitate colon cancer progression and in colon cancer, inhibition of JOSD1 via shRNA has been demonstrated to impede tumorigenesis. Furthermore, molecular mechanism studies have elucidated that JOSD1 enhances the formation of the Hippo/YAP transcriptome by impeding K48-linked polyubiquitination on YAP. ChIP assays have shown that YAP binds to JOSD1's promoter region, promoting its gene transcription. These results suggest that JOSD1 is involved in both activating and being targeted by the Hippo signaling pathway in colon cancer. Consequently, a positive regulatory loop between JOSD1 and Hippo signaling has been identified, underscoring their interdependence during colon cancer progression. Thus, targeting JOSD1 may represent a promising therapeutic approach for managing colon cancer.

Hippo signaling pathway regulates Ebola virus transcription and egress

Filovirus-host interactions play important roles in all stages of the virus lifecycle. Here, we identify LATS1/2 kinases and YAP, key components of the Hippo pathway, as critical regulators of EBOV transcription and egress. Specifically, we find that when YAP is phosphorylated by LATS1/2, it localizes to the cytoplasm (Hippo "ON") where it sequesters VP40 to prevent egress. In contrast, when the Hippo pathway is "OFF", unphosphorylated YAP translocates to the nucleus where it transcriptionally activates host genes and promotes viral egress. Our data reveal that LATS2 indirectly modulates filoviral VP40-mediated egress through phosphorylation of AMOTp130, a positive regulator of viral egress, but more surprisingly that LATS1/2 kinases directly modulate EBOV transcription by phosphorylating VP30, an essential regulator of viral transcription. In sum, our findings highlight the potential to exploit the Hippo pathway/filovirus axis for the development of host-oriented countermeasures targeting EBOV and related filoviruses.

Stem Cell Division and Its Critical Role in Mammary Gland Development and Tumorigenesis: Current Progress and Remaining Challenges

The origin of breast cancer (BC) has traditionally been a focus of medical research. It is widely acknowledged that BC originates from immortal mammary stem cells and that these stem cells participate in two division modes: symmetric cell division (SCD) and asymmetrical cell division (ACD). Although both of these modes are key to the process of breast development and their imbalance is closely associated with the onset of BC, the molecular mechanisms underlying these phenomena deserve in-depth exploration. In this review, we first outline the molecular mechanisms governing ACD/SCD and analyze the role of ACD/SCD in various stages of breast development. We describe that the changes in telomerase activity, the role of polar proteins, and the stimulation of ovarian hormones subsequently lead to two distinct consequences: breast development or carcinogenesis. Finally, gene mutations, abnormalities in polar proteins, modulation of signal-transduction pathways, and alterations in the microenvironment disrupt the balance of BC stem cell division modes and cause BC. Important regulatory factors such as mammalian Inscuteable mInsc, Numb, Eya1, PKCα, PKCθ, p53, and IL-6 also play significant roles in regulating pathways of ACD/SCD and may constitute key targets for future research on stem cell division, breast development, and tumor therapy.

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.

Synergistic effect of PAK and Hippo pathway inhibitor combination in NF2-deficient Schwannoma

Neurofibromatosis type 2 is a genetic disorder that results in the formation and progressive growth of schwannomas, ependymomas, and/or meningiomas. The NF2 gene encodes the Merlin protein, which links cell cortical elements to the actin cytoskeleton and regulates a number of key enzymes including Group I p21-activated kinases (PAKs), the Hippo-pathway kinase LATS, and mTORC. While PAK1 and PAK2 directly bind Merlin and transmit proliferation and survival signals when Merlin is mutated or absent, inhibition of Group 1 PAKs alone has not proven sufficient to completely stop the growth of NF2-deficient meningiomas or schwannomas in vivo, suggesting the need for a second pathway inhibitor. As the Hippo pathway is also activated in NF2-deficient cells, several inhibitors of the Hippo pathway have recently been developed in the form of YAP-TEAD binding inhibitors. These inhibitors prevent activation of pro-proliferation and anti-apoptotic Hippo pathway effectors. In this study, we show that PAK inhibition slows cell proliferation while TEAD inhibition promotes apoptotic cell death. Finally, we demonstrate the efficacy of PAK and TEAD inhibitor combinations in several NF2-deficient Schwannoma cell lines.

Endothelial LATS2 is a suppressor of bone marrow fibrosis

Myelofibrosis and osteosclerosis are fibrotic diseases disrupting bone marrow function that occur in various leukemias but also in response to non-malignant alterations in hematopoietic cells. Here we show that endothelial cell-specific inactivation of the Lats2 gene, encoding Hippo kinase large tumor suppressor kinase 2, or overexpression of the downstream effector YAP1 induce myofibroblast formation and lead to extensive fibrosis and osteosclerosis, which impair bone marrow function and cause extramedullary hematopoiesis in the spleen. Mechanistically, loss of LATS2 induces endothelial-to-mesenchymal transition, resulting in increased expression of extracellular matrix and secreted signaling molecules. Changes in endothelial cells involve increased expression of serum response factor target genes, and, strikingly, major aspects of the LATS2 mutant phenotype are rescued by inactivation of the Srf gene. These findings identify the endothelium as a driver of bone marrow fibrosis, which improves understanding of myelofibrotic and osteosclerotic diseases, for which drug therapies are currently lacking.

Peroxisomal cholesterol metabolism regulates yap-signaling, which maintains intestinal epithelial barrier function and is altered in Crohn's disease

Intestinal epithelial cells line the luminal surface to establish the intestinal barrier, where the cells play essential roles in the digestion of food, absorption of nutrients and water, protection from microbial infections, and maintaining symbiotic interactions with the commensal microbial populations. Maintaining and coordinating all these functions requires tight regulatory signaling, which is essential for intestinal homeostasis and organismal health. Dysfunction of intestinal epithelial cells, indeed, is linked to gastrointestinal disorders such as irritable bowel syndrome, inflammatory bowel disease, and gluten-related enteropathies. Emerging evidence suggests that peroxisome metabolic functions are crucial in maintaining intestinal epithelial cell functions and intestinal epithelium regeneration and, therefore, homeostasis. Here, we investigated the molecular mechanisms by which peroxisome metabolism impacts enteric health using the fruit fly Drosophila melanogaster and murine model organisms and clinical samples. We show that peroxisomes control cellular cholesterol, which in turn regulates the conserved yes-associated protein-signaling and contributes to intestinal epithelial structure and epithelial barrier function. Moreover, analysis of intestinal organoid cultures derived from biopsies of patients affected by Crohn's Disease revealed that the dysregulation of peroxisome number, excessive cellular cholesterol, and inhibition of Yap-signaling are markers of disease and could be novel diagnostic and/or therapeutic targets for treating Crohn's Disease. Our studies provided mechanistic insights on peroxisomal signaling in intestinal epithelial cell functions and identified cholesterol as a novel metabolic regulator of yes-associated protein-signaling in tissue homeostasis.

Breast cancer drug resistance: Decoding the roles of Hippo pathway crosstalk

The most significant factors that lead to cancer-related death in breast cancer (BC) patients include drug resistance, migration, invasion, and metastasis. Several signaling pathways are involved in the development of BC. The different types of BC are initially sensitive to chemotherapy, and drug resistance can occur through multiple molecular mechanisms. Regardless of developing targeted Therapy, due to the heterogenic nature and complexity of drug resistance, it is a major clinical challenge with the low survival rate in BC patients. The deregulation of several signaling pathways, particularly the Hippo pathway (HP), is one of the most recent findings about the molecular mechanisms of drug resistance in BC, which are summarized in this review. Given that HP is one of the recent cancer research hotspots, this review focuses on its implication in BC drug resistance. Unraveling the different molecular basis of HP through its crosstalk with other signaling pathways, and determining the effectiveness of HP inhibitors can provide new insights into possible therapeutic strategies for overcoming chemoresistance in BC.

Remote coupling of electrical and mechanical cues by diurnal photothermal irradiation synergistically promotes bone regeneration

Recapitulating the natural extracellular physical microenvironment has emerged as a promising method for tissue regeneration, as multiple physical interventions, including ultrasound, thermal and electrical therapy, have shown great potential. However, simultaneous coupling of multiple physical cues to highly bio-mimick natural characteristics for improved tissue regeneration still remains formidable. Coupling of intrinsic electrical and mechanical cues has been regarded as an effective way to modulate tissue repair. Nevertheless, precise and convenient manipulation on coupling of mechano-electrical signals within extracellular environment to facilitate tissue regeneration remains challengeable. Herein, a photothermal-sensitive piezoelectric membrane was designed for simultaneous integration of electrical and mechanical signals in response to NIR irradiation. The high-performance mechano-electrical coupling under NIR exposure synergistically triggered the promotion of osteogenic differentiation of stem cells and enhances bone defect regeneration by increasing cellular mechanical sensing, attachment, spreading and cytoskeleton remodeling. This study highlights the coupling of mechanical signals and electrical cues for modulation of osteogenesis, and sheds light on alternative bone tissue engineering therapies with multiple integrated physical cues for tissue repair.

The circadian gene ARNTL2 promotes nasopharyngeal carcinoma invasiveness and metastasis through suppressing AMOTL2-LATS-YAP pathway

Metastasis is the major culprit of treatment failure in nasopharyngeal carcinoma (NPC). Aryl hydrocarbon receptor nuclear translocator like 2 (ARNTL2), a core circadian gene, plays a crucial role in the development of various tumors. Nevertheless, the biological role and mechanism of ARNTL2 are not fully elucidated in NPC. In this study, ARNTL2 expression was significantly upregulated in NPC tissues and cells. Overexpression of ARNTL2 facilitated NPC cell migration and invasion abilities, while inhibition of ARNTL2 in similarly treated cells blunted migration and invasion abilities in vitro. Consistently, in vivo xenograft tumor models revealed that ARNTL2 silencing reduced nude mice inguinal lymph node and lung metastases, as well as tumor growth. Mechanistically, ARNTL2 negatively regulated the transcription expression of AMOTL2 by directly binding to the AMOTL2 promoter, thus reducing the recruitment and stabilization of AMOTL2 to LATS1/2 kinases, which strengthened YAP nuclear translocation by suppressing LATS-dependent YAP phosphorylation. Inhibition of AMOTL2 counteracted the effects of ARNTL2 knockdown on NPC cell migration and invasion abilities. These findings suggest that ARNTL2 may be a promising therapeutic target to combat NPC metastasis and further supports the crucial roles of circadian genes in cancer development.

The molecular crosstalk of the hippo cascade in breast cancer: A potential central susceptibility

The incidence of breast cancer is perpetually growing globally, and it remains a major public health problem and the leading cause of mortality in women. Though the aberrant activities of the Hippo pathway have been reported to be associated with cancer, constructive knowledge of the pathway connecting the various elements of breast cancer remains to be elucidated. The Hippo transducers, yes-associated protein (YAP) and transcriptional co-activator with PDZ binding motif (TAZ), are reported to be either tumor suppressors, oncogenes, or independent prognostic markers in breast cancer. Thus, there is further need for an explicative evaluation of the dilemma with this molecular contribution of Hippo transducers in modulating breast malignancy. In this review, we summarize the intricate crosstalk of the Hippo pathway in different aspects of breast malignancy, including stem-likeness, cellular signaling, metabolic adaptations, tumor microenvironment, and immune responses. The collective data shows that Hippo transducers play an indispensable role in mammary tumor formation, progression, and dissemination. However, the cellular functions of YAP/TAZ in tumorigenesis might be largely dependent on the mechanical and biophysical cues they interact with, as well as on the cell phenotype. This review provides a glimpse into the plausible biological contributions of the cascade to the inward progression of breast carcinoma and suggests potential therapeutic prospects.

NEDD8 enhances Hippo signaling by mediating YAP1 neddylation

The Hippo-YAP signaling pathway plays a central role in many biological processes such as regulating cell fate, organ size, and tissue growth, and its key components are spatiotemporally expressed and posttranslationally modified during these processes. Neddylation is a posttranslational modification that involves the covalent attachment of NEDD8 to target proteins by NEDD8-specific E1-E2-E3 enzymes. Whether neddylation is involved in Hippo-YAP signaling remains poorly understood. Here, we provide evidence supporting the critical role of NEDD8 in facilitating the Hippo-YAP signaling pathway by mediating neddylation of the transcriptional coactivator yes-associated protein 1 (YAP1). Overexpression of NEDD8 induces YAP1 neddylation and enhances YAP1 transactivity, but inhibition of neddylation suppresses YAP1 transactivity and attenuates YAP1 nuclear accumulation. Furthermore, inhibition of YAP1 signaling promotes MLN4924-induced ovarian granulosa cells apoptosis and disruption of nedd8 in zebrafish results in downregulation of yap1-activated genes and upregulation of yap1-repressed genes. Further assays show that the xiap ligase promotes nedd8 conjugates to yap1 and that yap1 neddylation. In addition, we identify lysine 159 as a major neddylation site on YAP1. These findings reveal a novel mechanism for neddylation in the regulation of Hippo-YAP signaling.

A humanized Anti-YKL-40 antibody inhibits tumor development

Drugs specifically targeting YKL-40, an over-expressed gene (CHI3L1) in various diseases remain developed. The current study is to create a humanized anti-YKL-40 neutralizing antibody and characterize its potentially therapeutic signature. We utilized in silico CDR-grafting bioinformatics to replace the complementarity determining regions (CDRs) of human IgG1 with mouse CDRs of our previously established anti-YKL-40 antibody (mAY). In fifteen candidates (VL1-3/VH1-5) of heavy and light chain variable region combination, one antibody L3H4 named Rosazumab demonstrated strong binding affinity with YKL-40 (KD = 4.645 × 10-8 M) and high homology with human IgG (80 %). In addition, we established different overlapping amino acid peptides of YKL-40 and found that Rosazumab specifically bound to residues K337, K342, and R344, the KR-rich functional domain of YKL-40. Rosazumab inhibited migration and tube formation of YKL-40-expressing tumor cells and induced tumor cell apoptosis. Mechanistically, Rosazumab induced interaction of N-cadherin with β-catenin and activation of downstream MST1/RASSF1/Histone H2B axis, leading to chromosomal DNA breakage and cell apoptosis. Treatment of xenografted tumor mice with Rosazumab twice a week for 4 weeks inhibited tumor growth and angiogenesis, but induced tumor apoptosis. Rosazumab injected in mice distributed to blood, tumor, and other multiple organs, but did not impact in function or structure of liver and kidney, indicating non-detectable toxicity in vivo. Collectively, the study is the first one to demonstrate that a humanized YKL-40 neutralizing antibody offers a valuable means to block tumor development.

An agonist of the adenosine A2A receptor, CGS21680, promotes corneal epithelial wound healing via the YAP signalling pathway

BACKGROUND AND PURPOSE

The adenosine A2A receptor (A2AR) is involved in various physiological and pathological processes in the eye; however, the role of the A2AR signalling in corneal epithelial wound healing is not known. Here, the expression, therapeutic effects and signalling mechanism of A2AR in corneal epithelial wound healing were investigated using the A2AR agonist CGS21680.

EXPERIMENTAL APPROACH

A2AR localization and expression during wound healing in the murine cornea were determined by immunofluorescence staining, quantitative reverse transcription polymerase chain reaction (RT-qPCR) and western blotting. The effect of CGS21680 on corneal epithelial wound healing in the lesioned corneal and cultured human corneal epithelial cells (hCECs) by modulating cellular proliferation and migration was critically evaluated. The role of Hippo-YAP signalling in mediating the CGS21680 effect on wound healing by pharmacological inhibition of YAP signalling was explored.

KEY RESULTS

A2AR expression was up-regulated after corneal epithelial injury. Topical administration of CGS21680 dose-dependently promoted corneal epithelial wound healing in the injured corneal epithelium by promoting cellular proliferation. Furthermore, CGS21680 accelerated the cellular proliferation and migration of hCECs in vitro. A2AR activation promoted early up-regulation and later down-regulation of YAP signalling molecules, and pharmacological inhibition of YAP signalling reverted CGS21680-mediated wound healing effect in vivo and in vitro.

CONCLUSION AND IMPLICATIONS

A2AR activation promotes wound healing by enhancing cellular proliferation and migration through the YAP signalling pathway. A2ARs play an important role in the maintenance of corneal epithelium integrity and may represent a novel therapeutic target for facilitating corneal epithelial wound healing.

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.

Sirtuin 5-mediated deacetylation of TAZ at K54 promotes melanoma development

PURPOSE

Nuclear accumulation of YAP/TAZ promotes tumorigenesis in several cancers, including melanoma. Although the mechanisms underlying the nuclear retention of YAP are known, those underlying the retention of TAZ remain unclear. Our study investigates a novel acetylation/deacetylation switch in TAZ, governing its subcellular localization in melanoma tumorigenesis.

METHODS

Immunoprecipitation/Western blot assessed TAZ protein interactions and acetylation. SIRT5 activity was quantified with enzyme-linked immunosorbent assay. Immunofluorescence indicated TAZ nuclear localization. TEAD transcriptional activity was measured through luciferase reporter assays. ChIP detected TAZ binding to the CTGF promoter. Transwell and wound healing assays quantified melanoma cell invasiveness and migration. Metastasis was evaluated using a mouse model via tail vein injections. Clinical relevance was explored via immunohistochemical staining of patient tumors.

RESULTS

CBP facilitated TAZ acetylation at K54 in response to epidermal growth factor stimulation, while SIRT5 mediated deacetylation. Acetylation correlated with phosphorylation, regulating TAZ's binding with LATS2 or TEAD. TAZ K54 acetylation enhanced its S89 phosphorylation, promoting cytosolic retention via LATS2 interaction. SIRT5-mediated deacetylation enhanced TAZ-TEAD interaction and nuclear retention. Chromatin IP showed SIRT5-deacetylated TAZ recruited to CTGF promoter, boosting transcriptional activity. In a mouse model, SIRT5 overexpression induced melanoma metastasis to lung tissue following the injection of B16F10 melanocytes via the tail vein, and this effect was prevented by verteporfin treatment.

CONCLUSIONS

Our study revealed a novel mechanism of TAZ nuclear retention regulated by SIRT5-mediated K54 deacetylation and demonstrated the significance of TAZ deacetylation in CTGF expression. This study highlights the potential implications of the SIRT5/TAZ axis for treating metastatic melanoma.

YAP in development and disease: Navigating the regulatory landscape from retina to brain

The distinctive role of Yes-associated protein (YAP) in the nervous system has attracted widespread attention. This comprehensive review strategically uses the retina as a vantage point, embarking on an extensive exploration of YAP's multifaceted impact from the retina to the brain in development and pathology. Initially, we explore the crucial roles of YAP in embryonic and cerebral development. Our focus then shifts to retinal development, examining in detail YAP's regulatory influence on the development of retinal pigment epithelium (RPE) and retinal progenitor cells (RPCs), and its significant effects on the hierarchical structure and functionality of the retina. We also investigate the essential contributions of YAP in maintaining retinal homeostasis, highlighting its precise regulation of retinal cell proliferation and survival. In terms of retinal-related diseases, we explore the epigenetic connections and pathophysiological regulation of YAP in diabetic retinopathy (DR), glaucoma, and proliferative vitreoretinopathy (PVR). Lastly, we broaden our exploration from the retina to the brain, emphasizing the research paradigm of "retina: a window to the brain." Special focus is given to the emerging studies on YAP in brain disorders such as Alzheimer's disease (AD) and Parkinson's disease (PD), underlining its potential therapeutic value in neurodegenerative disorders and neuroinflammation.

A PAK family kinase and the Hippo/Yorkie pathway modulate WNT signaling to functionally integrate body axes during regeneration

Successful regeneration of missing tissues requires seamless integration of positional information along the body axes. Planarians, which regenerate from almost any injury, use conserved, developmentally important signaling pathways to pattern the body axes. However, the molecular mechanisms which facilitate cross talk between these signaling pathways to integrate positional information remain poorly understood. Here, we report a p21-activated kinase (smed-pak1) which functionally integrates the anterior-posterior (AP) and the medio-lateral (ML) axes. pak1 inhibits WNT/β-catenin signaling along the AP axis and, functions synergistically with the β-catenin-independent WNT signaling of the ML axis. Furthermore, this functional integration is dependent on warts and merlin-the components of the Hippo/Yorkie (YKI) pathway. Hippo/YKI pathway is a critical regulator of body size in flies and mice, but our data suggest the pathway regulates body axes patterning in planarians. Our study provides a signaling network integrating positional information which can mediate coordinated growth and patterning during planarian regeneration.

TAZ is involved in breast cancer cell migration via regulating actin dynamics

Background

Cancer metastasis is dependent on cell migration. Several mechanisms, including epithelial-to-mesenchymal transition (EMT) and actin fiber formation, could be involved in cancer cell migration. As a downstream effector of the Hippo signaling pathway, transcriptional coactivator with PDZ-binding motif (TAZ) is recognized as a key mediator of the metastatic ability of breast cancer cells. We aimed to examine whether TAZ affects the migration of breast cancer cells through the regulation of EMT or actin cytoskeleton.

Methods

MCF-7 and MDA-MB-231 cells were treated with siRNA to attenuate TAZ abundance. Transwell migration assay and scratch wound healing assay were performed to study the effects of TAZ knockdown on cancer cell migration. Fluorescence microscopy was conducted to examine the vinculin and phalloidin. Semiquantitative immunoblotting and quantitative real-time PCR were performed to study the expression of small GTPases and kinases. Changes in the expression of genes associated with cell migration were examined through next-generation sequencing.

Results

TAZ-siRNA treatment reduced TAZ abundance in MCF-7 and MDA-MB-231 breast cancer cells, which was associated with a significant decrease in cell migration. TAZ knockdown increased the expression of fibronectin, but it did not exhibit the typical pattern of EMT progression. TGF-β treatment in MDA-MB-231 cells resulted in a reduction in TAZ and an increase in fibronectin levels. However, it paradoxically promoted cell migration, suggesting that EMT is unlikely to be involved in the decreased migration of breast cancer cells in response to TAZ suppression. RhoA, a small Rho GTPase protein, was significantly reduced in response to TAZ knockdown. This caused a decrease in the expression of the Rho-dependent downstream pathway, i.e., LIM kinase 1 (LIMK1), phosphorylated LIMK1/2, and phosphorylated cofilin, leading to actin depolymerization. Furthermore, myosin light chain kinase (MLCK) and phosphorylated MLC2 were significantly decreased in MDA-MB-231 cells with TAZ knockdown, inhibiting the assembly of stress fibers and focal adhesions.

Conclusion

TAZ knockdown inhibits the migration of breast cancer cells by regulating the intracellular actin cytoskeletal organization. This is achieved, in part, by reducing the abundance of RhoA and Rho-dependent downstream kinase proteins, which results in actin depolymerization and the disassembly of stress fibers and focal adhesions.

Varroa destructor parasitism and Deformed wing virus infection in honey bees are linked to peroxisome-induced pathways

The ectoparasitic mite Varroa destructor transmits and triggers viral infections that have deleterious effects on honey bee colonies worldwide. We performed a manipulative experiment in which worker bees collected at emergence were exposed to Varroa for 72 h, and their proteomes were compared with those of untreated control bees. Label-free quantitative proteomics identified 77 differentially expressed A. mellifera proteins (DEPs). In addition, viral proteins were identified by orthogonal analysis, and most importantly, Deformed wing virus (DWV) was found at high levels/intensity in Varroa-exposed bees. Pathway enrichment analysis suggested that the main pathways affected included peroxisomal metabolism, cyto-/exoskeleton reorganization, and cuticular proteins. Detailed examination of individual DEPs revealed that additional changes in DEPs were associated with peroxisomal function. In addition, the proteome data support the importance of TGF-β signaling in Varroa-DWV interaction and the involvement of the mTORC1 and Hippo pathways. These results suggest that the effect of DWV on bees associated with Varroa feeding results in aberrant autophagy. In particular, autophagy is selectively modulated by peroxisomes, to which the observed proteome changes strongly corresponded. This study complements previous research with different study designs and suggests the importance of the peroxisome, which plays a key role in viral infections.

Role of microRNA-363 during tumor progression and invasion

Recent progresses in diagnostic and therapeutic methods have significantly improved prognosis in cancer patients. However, cancer is still considered as one of the main causes of human deaths in the world. Late diagnosis in advanced tumor stages can reduce the effectiveness of treatment methods and increase mortality rate of cancer patients. Therefore, investigating the molecular mechanisms of tumor progression can help to introduce the early diagnostic markers in these patients. MicroRNA (miRNAs) has an important role in regulation of pathophysiological cellular processes. Due to their high stability in body fluids, they are always used as the non-invasive markers in cancer patients. Since, miR-363 deregulation has been reported in a wide range of cancers, we discussed the role of miR-363 during tumor progression and metastasis. It has been reported that miR-363 has mainly a tumor suppressor function through the regulation of transcription factors, apoptosis, cell cycle, and structural proteins. MiR-363 also affected the tumor progression via regulation of various signaling pathways such as WNT, MAPK, TGF-β, NOTCH, and PI3K/AKT. Therefore, miR-363 can be introduced as a probable therapeutic target as well as a non-invasive diagnostic marker in cancer patients.

An effective two-stage NMBzA-induced rat esophageal tumor model revealing that the FAT-Hippo-YAP1 axis drives the progression of ESCC

Rat model of N-nitrosomethylbenzylamine (NMBzA)-induced esophageal squamous cell carcinoma (ESCC) is routinely used to study ESCC initiation, progression and new therapeutic strategies. However, the model is time-consuming and malignant tumor incidences are low. Here, we report the usage of multi-kinase inhibitor sorafenib as a tumor promoter to establish an efficient two-stage NMBzA-induced rat ESCC carcinogenesis model, resulting in increments of tumor incidences and shortened tumor formation times. By establishing the model and applying whole-genome sequencing, we discover that benign papillomas and malignant ESCCs harbor most of the "driver" events found in rat ESCCs (e.g. recurrent mutations in Ras family, the Hippo and Notch pathways and histone modifier genes) and the mutational landscapes of rat and human ESCCs overlap extensively. We generate tumor cell lines derived from NMBzA-induced papillomas and ESCCs, showing that papilloma cells retain more characteristics of normal epithelial cells than carcinoma cells, especially their exhibitions of normal rat cell karyotypes and inabilities of forming tumors in immunodeficient mice. Three-dimensional (3-D) organoid cultures and single cell RNA sequencing (scRNA-seq) indicate that, when compared to control- and papilloma-organoids, ESCC-organoids display salient abnormalities at tissue and single-cell levels. Multi-omic analyses indicate that NMBzA-induced rat ESCCs are accompanied by progressive hyperactivations of the FAT-Hippo-YAP1 axis and siRNA or inhibitors of YAP1 block the growth of rat ESCCs. Taken together, these studies provide a framework of using an effective rat ESCC model to investigate multilevel functional genomics of ESCC carcinogenesis, which justify targeting YAP1 as a therapeutic strategy for ESCC.

Pulsed Low-Intensity Focused Ultrasound (LIFU) Activation of Ovarian Follicles

Objective: A biological system's internal morphological structure or function can be changed as a result of the mechanical effect of focused ultrasound. Pulsed low-intensity focused ultrasound (LIFU) has mechanical effects that might induce follicle development with less damage to ovarian tissue. The potential development of LIFU as a non-invasive method for the treatment of female infertility is being considered, and this study sought to explore and confirm that LIFU can activate ovarian follicles. Results: We found a 50% increase in ovarian weight and in the number of mature follicles on the ultrasound-stimulated side with pulsed LIFU and intraperitoneal injection of 10 IU PMSG in 10-day-old rats. After ultrasound stimulation, the PCOS-like rats had a decrease in androgen levels, restoration of regular estrous cycle and increase in the number of mature follicles and corpora lutea, and the ratio of M1 and M2 type macrophages was altered in antral follicles of PCOS-like rats, consequently promoting further development and maturation of antral follicles. Conclusion: LIFU treatment could trigger actin changes in ovarian cells, which might disrupt the Hippo signal pathway to promote follicle formation, and the mechanical impact on the ovaries of PCOS-like rats improved antral follicle development.

A LATS2 and ALKBH5 positive feedback loop supports their oncogenic roles

N(6)-methyladenosine (m6A) critically regulates RNA dynamics in various biological processes. The m6A demethylase ALKBH5 promotes tumorigenesis of glioblastoma, while the intricate web that orchestrates its regulation remains enigmatic. Here, we discover that cell density affects ALKBH5 subcellular localization and m6A dynamics. Mechanistically, ALKBH5 is phosphorylated by the large tumor suppressor kinase 2 (LATS2), preventing its nuclear export and enhancing protein stability. Furthermore, phosphorylated ALKBH5 reciprocally erases m6A from LATS2 mRNA, thereby stabilizing this transcript. Unexpectedly, LATS2 depletion suppresses glioblastoma stem cell self-renewal independent of yes-associated protein activation. Additionally, deficiency in either LATS2 or ALKBH5 phosphorylation impedes tumor progression in mouse xenograft models. Moreover, high levels of LATS2 expression and ALKBH5 phosphorylation are associated with tumor malignancy in patients with gliomas. Collectively, our study unveils an oncogenic positive feedback loop between LATS2 and ALKBH5, revealing a non-canonical branch of the Hippo pathway for RNA processing and suggesting potential anti-cancer interventions.

NIBR-LTSi is a selective LATS kinase inhibitor activating YAP signaling and expanding tissue stem cells in vitro and in vivo

The YAP/Hippo pathway is an organ growth and size regulation rheostat safeguarding multiple tissue stem cell compartments. LATS kinases phosphorylate and thereby inactivate YAP, thus representing a potential direct drug target for promoting tissue regeneration. Here, we report the identification and characterization of the selective small-molecule LATS kinase inhibitor NIBR-LTSi. NIBR-LTSi activates YAP signaling, shows good oral bioavailability, and expands organoids derived from several mouse and human tissues. In tissue stem cells, NIBR-LTSi promotes proliferation, maintains stemness, and blocks differentiation in vitro and in vivo. NIBR-LTSi accelerates liver regeneration following extended hepatectomy in mice. However, increased proliferation and cell dedifferentiation in multiple organs prevent prolonged systemic LATS inhibition, thus limiting potential therapeutic benefit. Together, we report a selective LATS kinase inhibitor agonizing YAP signaling and promoting tissue regeneration in vitro and in vivo, enabling future research on the regenerative potential of the YAP/Hippo pathway.

Regulation of hippo signaling mediated apoptosis by Rauvolfia tetraphylla in triple-negative breast cancer

Rauvolfia tetraphylla is an essential medicinal plant that has been widely used in traditional medicine for various disease treatments. However, the tumor suppressor activity of R. tetraphylla and its phytocompounds were not explored against triple-negative breast cancer. The current research investigated the impact of R. tetraphylla methanolic extract (RTE) and its isolated compounds Ajmaline (RTC1) and Reserpine (RTC2) on triple-negative breast cancer cell line (MDA-MB-231) focusing on anti-proliferative effects. Our study imparts that RTE and RTC2 showed promising cytotoxic effects compared to RTC1. So further experiments have proceeded with RTE and RTC2, to evaluate its proliferation, migration, and apoptotic effect. The result shows around 80% of cells were observed in the G0/G1 phase in cell cycle analysis indicating the cell cycle inhibition and duel staining clearly showed the apoptotic effect. The migration of cells after the scratch was 60.45% observed in control and 90% in treated cells showing the inhibition of migration. ROS distribution was intense compared to control indicating the increased ROS stress in treated cells. Both RTE and RTC2-treated cells showed the potential to suppress proliferation and induce apoptotic change by upregulating BAX and MST-1 and suppressing Bcl2, LATS-1, and YAP, proving that deregulation of YAP resulting in the blockage of TEAD-YAP complex and inhibit proliferation. Therefore, R. tetraphylla extract and its isolated compounds were demonstrated to find its ability to act against MDA-MB-231 and these findings will help adjudicate it as a therapeutic drug against experimental triple-negative breast cancer.

FTO attenuates the cytotoxicity of cisplatin in KGN granulosa cell-like tumour cells by regulating the Hippo/YAP1 signalling pathway

Premature ovarian failure (POF) is a devastating condition for women under 40 years old. Chemotherapy, especially the use of cisplatin, has been demonstrated to promote the apoptosis of granulosa cells in primary and secondary follicles, leading to POF. Our previous studies demonstrated that fat mass- and obesity-associated (FTO) plays an essential role in protecting granulosa cells from cisplatin-induced cytotoxicity. Various studies have suggested that the Hippo/YAP signalling pathway plays a significant role in regulating cell apoptosis and proliferation. Additionally, YAP1 is the main downstream target of the Hippo signalling pathway and is negatively regulated by the Hippo signalling pathway. However, whether the Hippo/YAP signalling pathway is involved in the protective effect of FTO on granulosa cells has not been determined. In this study, we found that after cisplatin treatment, the apoptosis of granulosa cells increased in a concentration-dependent manner, accompanied by the downregulation of FTO and YAP1. Furthermore, overexpression of FTO decreased cisplatin-induced granulosa cell apoptosis, inhibited the Hippo/YAP kinase cascade-induced phosphorylation of YAP1, and promoted the entry of YAP1 into the nucleus. The downstream targets of YAP1 (CTGF, CYR61, and ANKRD1) were also increased. Si-RNA-mediated downregulation of FTO promoted cisplatin-induced granulosa cell apoptosis, activated the Hippo/YAP kinase cascade, and inhibited the YAP1 entry into the nucleus. These effects were completely reversed by the small molecule inhibitor of YAP1-verteporfin (VP). Taken together, these data suggested that FTO-YAP1 plays a positive role in regulating the proliferation of injured granulosa cells induced by cisplatin.

YAP/TAZ as Molecular Targets in Skeletal Muscle Atrophy and Osteoporosis

Skeletal muscles and bones are closely connected anatomically and functionally. Age-related degeneration in these tissues is associated with physical disability in the elderly and significantly impacts their quality of life. Understanding the mechanisms of age-related musculoskeletal tissue degeneration is crucial for identifying molecular targets for therapeutic interventions for skeletal muscle atrophy and osteoporosis. The Hippo pathway is a recently identified signaling pathway that plays critical roles in development, tissue homeostasis, and regeneration. The Yes-associated protein (YAP) and transcriptional coactivator with PDZ-binding motif (TAZ) are key downstream effectors of the mammalian Hippo signaling pathway. This review highlights the fundamental roles of YAP and TAZ in the homeostatic maintenance and regeneration of skeletal muscles and bones. YAP/TAZ play a significant role in stem cell function by relaying various environmental signals to stem cells. Skeletal muscle atrophy and osteoporosis are related to stem cell dysfunction or senescence triggered by YAP/TAZ dysregulation resulting from reduced mechanosensing and mitochondrial function in stem cells. In contrast, the maintenance of YAP/TAZ activation can suppress stem cell senescence and tissue dysfunction and may be used as a basis for the development of potential therapeutic strategies. Thus, targeting YAP/TAZ holds significant therapeutic potential for alleviating age-related muscle and bone dysfunction and improving the quality of life in the elderly.

The alveolus: Our current knowledge of how the gas exchange unit of the lung is constructed and repaired

The mammalian lung completes its last step of development, alveologenesis, to generate sufficient surface area for gas exchange. In this process, multiple cell types that include alveolar epithelial cells, endothelial cells, and fibroblasts undergo coordinated cell proliferation, cell migration and/or contraction, cell shape changes, and cell-cell and cell-matrix interactions to produce the gas exchange unit: the alveolus. Full functioning of alveoli also involves immune cells and the lymphatic and autonomic nervous system. With the advent of lineage tracing, conditional gene inactivation, transcriptome analysis, live imaging, and lung organoids, our molecular understanding of alveologenesis has advanced significantly. In this review, we summarize the current knowledge of the constituents of the alveolus and the molecular pathways that control alveolar formation. We also discuss how insight into alveolar formation may inform us of alveolar repair/regeneration mechanisms following lung injury and the pathogenic processes that lead to loss of alveoli or tissue fibrosis.

From pixels to phenotypes: Integrating image-based profiling with cell health data as BioMorph features improves interpretability

Cell Painting assays generate morphological profiles that are versatile descriptors of biological systems and have been used to predict in vitro and in vivo drug effects. However, Cell Painting features extracted from classical software such as CellProfiler are based on statistical calculations and often not readily biologically interpretable. In this study, we propose a new feature space, which we call BioMorph, that maps these Cell Painting features with readouts from comprehensive Cell Health assays. We validated that the resulting BioMorph space effectively connected compounds not only with the morphological features associated with their bioactivity but with deeper insights into phenotypic characteristics and cellular processes associated with the given bioactivity. The BioMorph space revealed the mechanism of action for individual compounds, including dual-acting compounds such as emetine, an inhibitor of both protein synthesis and DNA replication. Overall, BioMorph space offers a biologically relevant way to interpret the cell morphological features derived using software such as CellProfiler and to generate hypotheses for experimental validation.

Hippo cell signaling and HS-proteoglycans regulate tissue form and function, age-dependent maturation, extracellular matrix remodeling, and repair

This review examined how Hippo cell signaling and heparan sulfate (HS)-proteoglycans (HSPGs) regulate tissue form and function. Despite being a nonweight-bearing tissue, the brain is regulated by Hippo mechanoresponsive cell signaling pathways during embryonic development. HS-proteoglycans interact with growth factors, morphogens, and extracellular matrix components to regulate development and pathology. Pikachurin and Eyes shut (Eys) interact with dystroglycan to stabilize the photoreceptor axoneme primary cilium and ribbon synapse facilitating phototransduction and neurotransduction with bipolar retinal neuronal networks in ocular vision, the primary human sense. Another HSPG, Neurexin interacts with structural and adaptor proteins to stabilize synapses and ensure specificity of neural interactions, and aids in synaptic potentiation and plasticity in neurotransduction. HSPGs also stabilize the blood-brain barrier and motor neuron basal structures in the neuromuscular junction. Agrin and perlecan localize acetylcholinesterase and its receptors in the neuromuscular junction essential for neuromuscular control. The primary cilium is a mechanosensory hub on neurons, utilized by YES associated protein (YAP)-transcriptional coactivator with PDZ-binding motif (TAZ) Hippo, Hh, Wnt, transforming growth factor (TGF)-β/bone matrix protein (BMP) receptor tyrosine kinase cell signaling. Members of the glypican HSPG proteoglycan family interact with Smoothened and Patched G-protein coupled receptors on the cilium to regulate Hh and Wnt signaling during neuronal development. Control of glycosyl sulfotransferases and endogenous protease expression by Hippo TAZ YAP represents a mechanism whereby the fine structure of HS-proteoglycans can be potentially modulated spatiotemporally to regulate tissue morphogenesis in a similar manner to how Hippo signaling controls sialyltransferase expression and mediation of cell-cell recognition, dysfunctional sialic acid expression is a feature of many tumors.

Hippo-YAP/TAZ signaling in breast cancer: Reciprocal regulation of microRNAs and implications in precision medicine

Breast cancer is a molecularly heterogeneous disease and the most common female malignancy. In recent years, therapy approaches have evolved to accommodate molecular diversity, with a focus on more biologically based therapies to minimize negative consequences. To regulate cell fate in human breast cells, the Hippo signaling pathway has been associated with the alpha subtype of estrogen receptors. This pathway regulates tissue size, regeneration, and healing, as well as the survival of tissue-specific stem cells, proliferation, and apoptosis in a variety of organs, allowing for cell differentiation. Hippo signaling is mediated by the kinases MST1, MST2, LATS1, and LATS2, as well as the adaptor proteins SAV1 and MOB. These kinases phosphorylate the downstream effectors of the Hippo pathway, yes-associated protein (YAP), and transcriptional coactivator with PDZ-binding motif (TAZ), suppressing the expression of their downstream target genes. The Hippo signaling pathway kinase cascade plays a significant role in all cancers. Understanding the principles of this kinase cascade would prevent the occurrence of breast cancer. In recent years, small noncoding RNAs, or microRNAs, have been implicated in the development of several malignancies, including breast cancer. The interconnections between miRNAs and Hippo signaling pathway core proteins in the breast, on the other hand, remain poorly understood. In this review, we focused on highlighting the Hippo signaling system, its key parts, its importance in breast cancer, and its regulation by miRNAs and other related pathways.

Small cells - big issues: biological implications and preclinical advancements in small cell lung cancer

Current treatment guidelines refer to small cell lung cancer (SCLC), one of the deadliest human malignancies, as a homogeneous disease. Accordingly, SCLC therapy comprises chemoradiation with or without immunotherapy. Meanwhile, recent studies have made significant advances in subclassifying SCLC based on the elevated expression of the transcription factors ASCL1, NEUROD1, and POU2F3, as well as on certain inflammatory characteristics. The role of the transcription regulator YAP1 in defining a unique SCLC subset remains to be established. Although preclinical analyses have described numerous subtype-specific characteristics and vulnerabilities, the so far non-existing clinical subtype distinction may be a contributor to negative clinical trial outcomes. This comprehensive review aims to provide a framework for the development of novel personalized therapeutic approaches by compiling the most recent discoveries achieved by preclinical SCLC research. We highlight the challenges faced due to limited access to patient material as well as the advances accomplished by implementing state-of-the-art models and methodologies.

Epigenetic drug screening for trophoblast syncytialization reveals a novel role for MLL1 in regulating fetoplacental growth

BACKGROUND

Abnormal placental development is a significant factor contributing to perinatal morbidity and mortality, affecting approximately 5-7% of pregnant women. Trophoblast syncytialization plays a pivotal role in the establishment and maturation of the placenta, and its dysregulation is closely associated with several pregnancy-related disorders, including preeclampsia and intrauterine growth restriction. However, the underlying mechanisms and genetic determinants of syncytialization are largely unknown.

METHODS

We conducted a systematic drug screen using an epigenetic compound library to systematically investigate the epigenetic mechanism essential for syncytialization, and identified mixed lineage leukemia 1 (MLL1), a histone 3 lysine 4 methyltransferase, as a crucial regulator of trophoblast syncytialization. BeWo cells were utilized to investigate the role of MLL1 during trophoblast syncytialization. RNA sequencing and CUT&Tag were further performed to search for potential target genes and the molecular pathways involved. Human placenta tissue was used to investigate the role of MLL1 in TEA domain transcription factor 4 (TEAD4) expression and the upstream signaling during syncytialization. A mouse model was used to examine whether inhibition of MLL1-mediated H3K4me3 regulated placental TEAD4 expression and fetoplacental growth.

RESULTS

Genetic knockdown of MLL1 or pharmacological inhibition of the MLL1 methyltransferase complex (by MI-3454) markedly enhanced syncytialization, while overexpression of MLL1 inhibited forskolin (FSK)-induced syncytiotrophoblast formation. In human placental villous tissue, MLL1 was predominantly localized in the nuclei of cytotrophoblasts. Moreover, a notable upregulation in MLL1 expression was observed in the villus tissue of patients with preeclampsia compared with that in the control group. Based on RNA sequencing and CUT&Tag analyses, depletion of MLL1 inhibited the Hippo signaling pathway by suppressing TEAD4 expression by modulating H3K4me3 levels on the TEAD4 promoter region. TEAD4 overexpression significantly reversed the FSK-induced or MLL1 silencing-mediated trophoblast syncytialization. Additionally, decreased hypoxia-inducible factor 1A (HIF1A) enrichment at the MLL1 promoter was observed during syncytialization. Under hypoxic conditions, HIF1A could bind to and upregulate MLL1, leading to the activation of the MLL1/TEAD4 axis. In vivo studies demonstrated that the administration of MI-3454 significantly enhanced fetal vessel development and increased the thickness of the syncytial layer, thereby supporting fetoplacental growth.

CONCLUSIONS

These results revealed a novel epigenetic mechanism underlying the progression of syncytialization with MLL1, and suggest potential avenues for identifying new therapeutic targets for pregnancy-related disorders.

The Han:SPRD Rat: A Preclinical Model of Polycystic Kidney Disease

Autosomal Dominant Polycystic Kidney Disease (ADPKD) stands as the most prevalent hereditary renal disorder in humans, ultimately culminating in end-stage kidney disease. Animal models carrying mutations associated with polycystic kidney disease have played an important role in the advancement of ADPKD research. The Han:SPRD rat model, carrying an R823W mutation in the Anks6 gene, is characterized by cyst formation and kidney enlargement. The mutated protein, named Samcystin, is localized in cilia of tubular epithelial cells and seems to be involved in cystogenesis. The homozygous Anks6 mutation leads to end-stage renal disease and death, making it a critical factor in kidney development and function. This review explores the utility of the Han:SPRD rat model, highlighting its phenotypic similarity to human ADPKD. Specifically, we discuss its role in preclinical trials and its importance for investigating the pathogenesis of the disease and developing new therapeutic approaches.

Activation of the melanocortin-1 receptor attenuates neuronal apoptosis after traumatic brain injury by upregulating Merlin expression

Traumatic brain injury (TBI) is a common disease worldwide with high mortality and disability rates. Besides the primary mechanical injury, the secondary injury associated with TBI can also induce numerous pathological changes, such as brain edema, nerve apoptosis, and neuroinflammation, which further aggravates neurological dysfunction and even causes the death due to the primary injury. Among them, neuronal apoptosis is a key link in the injury. Melanocortin-1 receptor (MC1R) is a G protein coupled receptor, belonging to the melanocortin receptor family. Studies have shown that activation of MC1R inhibits oxidative stress and apoptosis, and confers neuroprotective effects against various neurological diseases. Merlin is a protein product of the NF2 gene, which is widely expressed in the central nervous system (CNS) of mice, rats, and humans. Studies have indicated that Merlin is associated with MC1R. In this study, we explored the anti-apoptotic effects and potential mechanisms of MC1R. A rat model of TBI was established through controlled cortical impact. The MC1R-specific agonist Nle4-D-Phe7-α-Melanocyte (NDP-MSH) and the inhibitor MSG-606 were employed to explore the effects of MC1R and Merlin following TBI and investigated the associated mechanisms. The results showed that the expression levels of MC1R and Merlin were upregulated after TBI, and activation of MC1R promoted Merlin expression. Further, we found that MC1R activation significantly improved neurological dysfunction and reduced brain edema and neuronal apoptosis induced by TBI in rats. Mechanistically, its neuroprotective function and anti-apoptotic were partly associated with MC1R activation. In conclusion, we demonstrated that MC1R activation after TBI may inhibit apoptosis and confer neuroprotection by upregulating the expression of Merlin.

Skp2: A critical molecule for ubiquitination and its role in cancer

The ubiquitin-proteasome system (UPS) is a multi-step process that serves as the primary pathway for protein degradation within cells. UPS activity also plays a crucial role in regulating various life processes, including the cell cycle, signal transduction, DNA repair, and others. The F-box protein Skp2, a crucial member of the UPS, plays a central role in the development of various diseases. Skp2 controls cancer cell growth and drug resistance by ubiquitinating modifications to a variety of proteins. This review emphasizes the multifaceted role of Skp2 in a wide range of cancers and the mechanisms involved, highlighting the potential of Skp2 as a therapeutic target in cancer. Additionally, we describe the impactful influence exerted by Skp2 in various other diseases beyond cancer.

The scaffold protein AXIN1: gene ontology, signal network, and physiological function

AXIN1, has been initially identified as a prominent antagonist within the WNT/β-catenin signaling pathway, and subsequently unveiled its integral involvement across a diverse spectrum of signaling cascades. These encompass the WNT/β-catenin, Hippo, TGFβ, AMPK, mTOR, MAPK, and antioxidant signaling pathways. The versatile engagement of AXIN1 underscores its pivotal role in the modulation of developmental biological signaling, maintenance of metabolic homeostasis, and coordination of cellular stress responses. The multifaceted functionalities of AXIN1 render it as a compelling candidate for targeted intervention in the realms of degenerative pathologies, systemic metabolic disorders, cancer therapeutics, and anti-aging strategies. This review provides an intricate exploration of the mechanisms governing mammalian AXIN1 gene expression and protein turnover since its initial discovery, while also elucidating its significance in the regulation of signaling pathways, tissue development, and carcinogenesis. Furthermore, we have introduced the innovative concept of the AXIN1-Associated Phosphokinase Complex (AAPC), where the scaffold protein AXIN1 assumes a pivotal role in orchestrating site-specific phosphorylation modifications through interactions with various phosphokinases and their respective substrates.

A transcriptomic examination of encased rotifer embryos reveals the developmental trajectory leading to long-term dormancy; are they "animal seeds"?

BACKGROUND

Organisms from many distinct evolutionary lineages acquired the capacity to enter a dormant state in response to environmental conditions incompatible with maintaining normal life activities. Most studied organisms exhibit seasonal or annual episodes of dormancy, but numerous less studied organisms enter long-term dormancy, lasting decades or even centuries. Intriguingly, many planktonic animals produce encased embryos known as resting eggs or cysts that, like plant seeds, may remain dormant for decades. Herein, we studied a rotifer Brachionus plicatilis as a model planktonic species that forms encased dormant embryos via sexual reproduction and non-dormant embryos via asexual reproduction and raised the following questions: Which genes are expressed at which time points during embryogenesis? How do temporal transcript abundance profiles differ between the two types of embryos? When does the cell cycle arrest? How do dormant embryos manage energy?

RESULTS

As the molecular developmental kinetics of encased embryos remain unknown, we employed single embryo RNA sequencing (CEL-seq) of samples collected during dormant and non-dormant embryogenesis. We identified comprehensive and temporal transcript abundance patterns of genes and their associated enriched functional pathways. Striking differences were uncovered between dormant and non-dormant embryos. In early development, the cell cycle-associated pathways were enriched in both embryo types but terminated with fewer nuclei in dormant embryos. As development progressed, the gene transcript abundance profiles became increasingly divergent between dormant and non-dormant embryos. Organogenesis was suspended in dormant embryos, concomitant with low transcript abundance of homeobox genes, and was replaced with an ATP-poor preparatory phase characterized by very high transcript abundance of genes encoding for hallmark dormancy proteins (e.g., LEA proteins, sHSP, and anti-ROS proteins, also found in plant seeds) and proteins involved in dormancy exit. Surprisingly, this period appeared analogous to the late maturation phase of plant seeds.

CONCLUSIONS

The study highlights novel divergent temporal transcript abundance patterns between dormant and non-dormant embryos. Remarkably, several convergent functional solutions appear during the development of resting eggs and plant seeds, suggesting a similar preparatory phase for long-term dormancy. This study accentuated the broad novel molecular features of long-term dormancy in encased animal embryos that behave like "animal seeds".

Impact of De Novo Cholesterol Biosynthesis on the Initiation and Progression of Breast Cancer

Cholesterol (CHOL) is a multifaceted lipid molecule. It is an essential structural component of cell membranes, where it cooperates in regulating the intracellular trafficking and signaling pathways. Additionally, it serves as a precursor for vital biomolecules, including steroid hormones, isoprenoids, vitamin D, and bile acids. Although CHOL is normally uptaken from the bloodstream, cells can synthesize it de novo in response to an increased requirement due to physiological tissue remodeling or abnormal proliferation, such as in cancer. Cumulating evidence indicated that increased CHOL biosynthesis is a common feature of breast cancer and is associated with the neoplastic transformation of normal mammary epithelial cells. After an overview of the multiple biological activities of CHOL and its derivatives, this review will address the impact of de novo CHOL production on the promotion of breast cancer with a focus on mammary stem cells. The review will also discuss the effect of de novo CHOL production on in situ and invasive carcinoma and its impact on the response to adjuvant treatment. Finally, the review will discuss the present and future therapeutic strategies to normalize CHOL biosynthesis.

Stem Cell-Based Hair Cell Regeneration and Therapy in the Inner Ear

Hearing loss has become increasingly prevalent and causes considerable disability, thus gravely burdening the global economy. Irreversible loss of hair cells is a main cause of sensorineural hearing loss, and currently, the only relatively effective clinical treatments are limited to digital hearing equipment like cochlear implants and hearing aids, but these are of limited benefit in patients. It is therefore urgent to understand the mechanisms of damage repair in order to develop new neuroprotective strategies. At present, how to promote the regeneration of functional hair cells is a key scientific question in the field of hearing research. Multiple signaling pathways and transcriptional factors trigger the activation of hair cell progenitors and ensure the maturation of newborn hair cells, and in this article, we first review the principal mechanisms underlying hair cell reproduction. We then further discuss therapeutic strategies involving the co-regulation of multiple signaling pathways in order to induce effective functional hair cell regeneration after degeneration, and we summarize current achievements in hair cell regeneration. Lastly, we discuss potential future approaches, such as small molecule drugs and gene therapy, which might be applied for regenerating functional hair cells in the clinic.

Pharmacological inhibition of CLK2 activates YAP by promoting alternative splicing of AMOTL2

Yes-associated protein (YAP), the downstream effector of the evolutionarily conserved Hippo pathway, promotes cellular proliferation and coordinates certain regenerative responses in mammals. Small molecule activators of YAP may, therefore, display therapeutic utility in treating disease states involving insufficient proliferative repair. From a high-throughput chemical screen of the comprehensive drug repurposing library ReFRAME, here we report the identification of SM04690, a clinical stage inhibitor of CLK2, as a potent activator of YAP-driven transcriptional activity in cells. CLK2 inhibition promotes alternative splicing of the Hippo pathway protein AMOTL2, producing an exon-skipped gene product that can no longer associate with membrane-bound proteins, resulting in decreased phosphorylation and membrane localization of YAP. This study reveals a novel mechanism by which pharmacological perturbation of alternative splicing inactivates the Hippo pathway and promotes YAP-dependent cellular growth.

Biallelic ANKS6 null variants cause notable extrarenal phenotypes in a nephronophthisis patient and lead to hepatobiliary abnormalities by YAP1 deficiency

The ankyrin repeat and sterile alpha motif domain containing 6 (ANKS6) gene, encoding an inversin compartment protein of the primary cilium, was recently reported as a pathogenic gene of nephronophthisis (MIM PS256100). Extrarenal manifestations are frequently observed in this disease, however, potential genotype-phenotype correlations and the underlying mechanisms remain poorly understood. Here we described an infant with kidney failure, hepatobiliary abnormalities, and heart disease, in whom whole exome sequencing identified compound heterozygous variants in ANKS6, including a novel nonsense variant p.Trp458* and a recurrent splicing variant c.2394+1G > A. mRNA expression studies showed that the splicing variant caused aberrant mRNA splicing with exon 13 skipping and the biallelic variants were predicted to cause loss of ANKS6 function. We systematically characterized the clinical and genetic spectra of the disease and revealed that biallelic null variants in ANKS6 cause more severe kidney disease and more extrarenal manifestations, thus establishing a clear genotype-phenotype correlation for the disease. Further evaluations showed that ANKS6 deficiency reduced YAP1 expression in the patient's bile duct epithelium and ANKS6 promotes YAP1 transcriptional activity in a dose-dependent manner, indicating that loss of ANKS6 function causes hepatobiliary abnormalities through YAP1 deficiency during biliary morphogenesis and development, which may offer new therapeutic targets.

α-Catenin acetylation is essential for its stability and blocks its tumor suppressor effects in breast cancer through Yap1

α-Catenin plays a critical role in tissue integrity, repair, and embryonic development. However, the post-translational modifications of α-catenin and the correlative roles in regulating cancer progression remain unclear. Here, we report that α-catenin is acetylated by p300, and identify three acetylation sites, K45, K866, and K881. Conversely, α-catenin acetylation can be reversed by deacetylase HDAC6. Mechanistically, α-catenin acetylation releases the transcriptional coactivator Yes-associated protein 1 (Yap1) by blocking the interaction between α-catenin and Yap1, and promotes the accumulation of Yap1 in the nucleus. Through this mechanism, acetylation weakens the capacity of α-catenin to inhibit breast cancer cell proliferation and tumor growth in mice. Meanwhile, we show that CDDP induces acetylation of α-catenin, and acetylated α-catenin resists the apoptosis under CDDP conditions. Additionally, acetylation inhibits the proteasome-dependent degradation of α-catenin, thus enhancing the stability of α-catenin for storage. Taken together, our results demonstrate that α-catenin can be acetylated, an event that is key for the subcellular distribution of Yap1 and subsequent facilitation of breast tumorigenesis.

Coagulation factor VIIa enhances programmed death-ligand 1 expression and its stability in breast cancer cells to promote breast cancer immune evasion

BACKGROUND

Immunotherapy for breast cancer has not gained significant success. Coagulation factor VIIa (FVIIa)-tissue factor (TF) mediated activation of protease-activated receptor 2 (PAR2) is shown to promote metastasis and secretion of the immune-modulatory cytokines but the role of FVIIa in cancer immunology is still not well understood.

OBJECTIVES

Here, we aim to investigate whether FVIIa protects breast cancer cells from CD8 T-cell-mediated killing.

METHODS

Peripheral blood mononuclear cell-derived CD8 T cells were cocultured with vehicle or FVIIa pretreated MDAMB468 cells. The proliferation and activity of CD8 T cells were measured by flow cytometry and ELISA. An allograft model, using wild-type or TF/PAR2-deleted 4T1 cells, was employed to determine the effect of FVIIa on breast cancer immune evasion in vivo.

RESULTS

Here, we demonstrate that TF-FVIIa induces programmed death-ligand 1 (PD-L1) in breast cancer cells by activating PAR2. PAR2 activation triggers large tumor suppressor kinase 1 (LATS1) inactivation leading to loss of yes-associated protein (YAP)/transcriptional coactivator with PDZ-binding motif (TAZ) phosphorylation and subsequent nuclear localization of YAP/TAZ. YAP/TAZ inhibition reduces PD-L1 expression and increases CD8 T-cell activity. We further demonstrate that, apart from transcriptional induction of PD-L1, PAR2 activation also increases PD-L1 stability by enhancing its glycosylation through N-glycosyltransferases STT3A and STT3B.

CONCLUSION

In a mouse model of breast cancer, tumor cell-specific PAR2 depletion leads to PD-L1 downregulation and increases anti-PD-1 immunotherapy efficacy. In conclusion, we showed that FVIIa-mediated signaling cascade in cancer cells serves as a tumor intrinsic mechanism of immunosuppression to promote cancer immune evasion.

Tolfenamic acid negatively regulates YAP and TAZ expression in human cancer cells

Several diseases are associated with improper regulation of the Hippo pathway, which plays an important role in cell proliferation and cancer metastasis. Overactivation of the YAP and TAZ proteins accelerates cell proliferation, invasion, and migration during tumorigenesis. Tolfenamic acid (TA) is a non-steroidal anti-inflammatory drug (NSAID) that exhibits activity against various types of cancer. In this study, we observed that TA decreased YAP and TAZ protein levels in cancer cells. TA increased the phosphorylation of YAP and TAZ, leading to the degradation of YAP and TAZ in the cytoplasm and nucleus. TA predominantly affected multiple phosphodegron sites in the YAP and TAZ and lowered 14-3-3β protein expression, causing YAP and TAZ to enter the ubiquitination pathway. Proteins that affect YAP and TAZ regulation, such as NAG-1 and several YAP/TAZ E3 ligases, were not involved in TA-mediated YAP/TAZ degradation. In summary, our results indicate that TA affects phosphodegron sites on YAP/TAZ, demonstrating a novel effect of TA in tumorigenesis.

TOR Complex 1: Orchestrating Nutrient Signaling and Cell Cycle Progression

The highly conserved TOR signaling pathway is crucial for coordinating cellular growth with the cell cycle machinery in eukaryotes. One of the two TOR complexes in budding yeast, TORC1, integrates environmental cues and promotes cell growth. While cells grow, they need to copy their chromosomes, segregate them in mitosis, divide all their components during cytokinesis, and finally physically separate mother and daughter cells to start a new cell cycle apart from each other. To maintain cell size homeostasis and chromosome stability, it is crucial that mechanisms that control growth are connected and coordinated with the cell cycle. Successive periods of high and low TORC1 activity would participate in the adequate cell cycle progression. Here, we review the known molecular mechanisms through which TORC1 regulates the cell cycle in the budding yeast Saccharomyces cerevisiae that have been extensively used as a model organism to understand the role of its mammalian ortholog, mTORC1.

Interaction of de novo cholesterol biosynthesis and Hippo signaling pathway in ductal carcinoma in situ (DCIS)-comparison with the corresponding normal breast epithelium

Background

Ductal carcinoma in situ (DCIS) is a non-obligate precursor to invasive breast cancer. However, if left untreated, about 50% of DCIS progress. Preventing such a progression is of paramount importance. Cumulative evidence indicated that the mevalonate cascade, the core of cholesterol biosynthesis, contributes to the regulation of the Hippo signaling pathway providing the isoprenoids required for GTPase activation, the nuclear accumulation of the Yes-associated protein (YAP)/transcriptional coactivator with PDZ-binding motif (TAZ) coactivator, and the subsequent gene transcription and that the disruption of this cooperation associated with tumor progression.

Methods

In this in silico study, we investigated whether such a disruption occurred already during the transformation of the normal mammary epithelium into DCIS. To this aim, we interrogated a publicly available dataset, and we explored the interrelationship of the genes involved in the de novo cholesterol biosynthesis and the association with those coding for the core components of the Hippo signaling pathway in a set of patient-matched samples of DCIS and corresponding histologically normal (HN) epithelium.

Results

Most genes involved in cholesterol biosynthesis were more expressed in DCIS than in the corresponding HN epithelium. This differential expression was associated with a substantial change in their correlation profile. In particular, 3-hydroxy-3-methylglutaryl coenzyme-A reductase (HMGCR) and INSIG1 lost the positive association shown in the HN epithelium, and their negative association with LSS switched to a positive one. Also, GGPS1, which plays a crucial role in isoprenoids production, significantly changed its correlation profile. The positive association between GGPS1 and HMGCR or INSIG1 disappeared, whereas the positive association with SQLE, which drives the irreversible commitment to cholesterol, switched to a negative one in DCIS.

Conclusions

Present findings corroborated the hypothesis that a dysfunctional mevalonate pathway possibly concurs with DCIS development by leading to abnormal production of isoprenoids, which in turn activate GTPases and promote YAP/TAZ nuclear translocation, and suggested the safe and low-cost treatment with statins as the possible winning strategy to contrast this metabolic dysfunction.

miR-3133 inhibits gastrointestinal cancer progression through activation of Hippo and p53 signalling pathways via multi-targets

BACKGROUND

Malignant cell growth and chemoresistance, the main obstacles in treating gastrointestinal cancer (GIC), rely on the Hippo and p53 signalling pathways. However, the upstream regulatory mechanisms of these pathways remain complex and poorly understood.

METHODS

Immunohistochemistry (IHC), western blot and RT-qPCR were used to analyse the expression of RNF146, miR-3133 and key components of Hippo and p53 pathway. CCK-8, colony formation, drug sensitivity assays and murine xenograft models were used to investigate the effect of RNF146 and miR-3133 in GIC. Further exploration of the upstream regulatory mechanism was performed using bioinformatics analysis, dual-luciferase reporter gene, immunoprecipitation assays and bisulfite sequencing PCR (BSP).

RESULTS

Clinical samples, in vitro and in vivo experiments demonstrated that RNF146 exerts oncogenic effects in GIC by regulating the Hippo pathway. Bioinformatics analysis identified a novel miRNA, miR-3133, as an upstream regulatory factor of RNF146. fluorescence in situ hybridization and RT-qPCR assays revealed that miR-3133 was less expressed in gastrointestinal tumour tissues and was associated with adverse pathological features. Functional assays and animal models showed that miR-3133 promoted the proliferation and chemotherapy sensitivity of GIC cells. miR-3133 affected YAP1 protein expression by targeting RNF146, AGK and CUL4A, thus activating the Hippo pathway. miR-3133 inhibited p53 protein degradation and extended p53's half-life by targeting USP15, SPIN1. BSP experiments confirmed that miR-3133 promoter methylation is an important reason for its low expression.

CONCLUSION

miR-3133 inhibits GIC progression by activating the Hippo and p53 signalling pathways via multi-targets, including RNF146, thereby providing prognostic factors and valuable potential therapeutic targets for GIC.