The Hippo pathway in intestinal regeneration and disease

The Prognostic Biomarker RAB7A Promotes Growth and Metastasis of Liver Cancer Cells by Regulating Glycolysis and YAP1 Activation

Activating transcription factor 6 (ATF6) and its downstream genes are involved in progression of hepatocellular carcinoma (HCC). Herein, we demonstrated that sulfhydration of Ras-related protein Rab-7a (RAB7A) was regulated by ATF6. High expression of RAB7A indicated poor prognosis of HCC patients. RAB7A overexpression contributed to proliferation, colony formation, migration, and invasion of HepG2 and Hep3B cells. Furthermore, we found that RAB7A enhanced aerobic glycolysis in HepG2 cells, indicating a higher degree of tumor malignancy. Mechanistically, RAB7A suppressed Yes-associated protein 1 (YAP1) binding to 14-3-3 and conduced to YAP1 nuclear translocation and activation, promoting its downstream gene expression, thereby promoting growth and metastasis of liver cancer cells. In addition, knocking down RAB7A attenuated the progression of orthotopic liver tumors in mice. These findings illustrate the important role of RAB7A in regulating HCC progression. Thus, RAB7A may be a potential innovative target for HCC treatment.

Hippo kinases Mst1 and Mst2 maintain NK cell homeostasis by orchestrating metabolic state and transcriptional activity

Natural killer (NK) cells play a crucial role in immune response against viral infections and tumors. However, further investigation is needed to better understand the key molecules responsible for determining the fate and function of NK cells. In this study, we made an important discovery regarding the involvement of the Hippo kinases Mst1 and Mst2 as novel regulators in maintaining mouse NK cell homeostasis. The presence of high Mst1 and Mst2 (Mst1/2) activity in NK cells is essential for their proper development, survival and function in a canonical Hippo signaling independent mode. Mechanistically, Mst1/2 induce cellular quiescence by regulating the processes of proliferation and mitochondrial metabolism, thereby ensuring the development and survival of NK cells. Furthermore, Mst1/2 effectively sense IL-15 signaling and facilitate the activation of pSTAT3-TCF1, which contributes to NK cell homeostasis. Overall, our investigation highlights the crucial role of Mst1/2 as key regulators in metabolic reprogramming and transcriptional regulation for mouse NK cell survival and function, emphasizing the significance of cellular quiescence during NK cell development and functional maturation.

The hippo-YAP1/HIF-1α pathway mediates arsenic-induced renal fibrosis

Epidemiological evidence reveals that arsenic increases the risk of chronic kidney disease (CKD) in humans, but its mechanism of action has so far been unclear. Fibrosis is the manifestation of end-stage renal disease. Hypoxia is recognized as a vital event accompanying the progression of renal fibrosis. KM mice were exposed to 0, 20, 40, and 80 mg/L NaAsO2 for 12 weeks. HK-2 cells were treated with 1 μM NaAsO2 for 4 weeks. The results showed that arsenic increased the expression of hypoxia-inducible factor 1α (HIF-1α) (P < 0.05), which is involved in inorganic arsenic-induced renal fibrosis. The Hippo signaling pathway is the upstream signal of HIF-1α and the kinase cascade of Large tumor suppressor kinase 1 (LATS1) and Yes-associated protein 1 (YAP1) is the heart of the Hippo pathway. Our results showed that protein expressions of LATS1 and phosphorylated YAP1 were decreased, and dephosphorylated YAP1 expression increased in arsenic-treated mouse kidneys and human HK-2 cells (P < 0.05). Our research manifested that arsenic treatment suppressed the Hippo signaling and induced high expression of YAP1 into the nucleus. We also found that YAP1 was involved in arsenic-induced renal fibrosis by forming a complex with HIF-1α and maintaining HIF-1α stability. Our findings indicate that YAP1 is a potential target for molecular-based therapy for arsenic-mediated renal fibrosis.

Preparation of polyclonal antibodies to chicken P62 protein and its application in nephropathogenic infectious bronchitis virus-infected chickens

p62, also known as SQSTM1, has been shown to be closely related to the coronavirus. However, it remains unclear on the relationship between p62 and NIBV infection. Moreover, there are no available antibodies against the chicken p62 protein. Thus, this study aimed to prepare p62 polyclonal antibody and investigate the correlation between the p62 protein and NIBV infection. Here, PET-32a-p62 prokaryotic fusion expression vector was constructed for prokaryotic protein expression, and then p62 polyclonal antibody was prepared by immunizing rabbits. Lastly, these antibodies were then utilized in Western blotting (WB), immunohistochemistry (IHC), and immunofluorescence (IF) assays. The results showed that we successfully prepared chicken p62 polyclonal antibody. Meanwhile, WB and IF demonstrated that the expression of p62 showed a trend of first increase and then decrease after NIBV infection. IHC showed that the expression of p62 in the spleen, lung, kidney, bursa of Fabricius and trachea of chickens infected with NIBV in 11 dpi was significantly higher than that of normal chickens. Taken together, this study successfully prepared a polyclonal antibody for chicken p62 protein and confirmed its application and expression in chickens, as well as the expression of p62 in tissues after NIBV infection.

Endometrial stem cell-derived exosomes repair cisplatin-induced premature ovarian failure via Hippo signaling pathway

Stem cells have been documented as a new therapeutic method for ovarian injuries such as premature ovarian failure (POF). However, effects of exosomes (Exos) derived from human endometrial stem cells (EnSCs) on diminished ovarian failure remain to be carefully elucidated. Our study aims to investigate the mechanisms of EnSC-Exos in the recovery of the cisplatin-induced granulosa cell injury model in vitro or POF mouses model in vivo and whether the Hippo signaling pathway is involved in the regulation. In this study, we established successful construction of the cisplatin-induced granulosa cell injury model and evaluated Hippo signaling pathway activation in cisplatin-damaged granulosa cells (GCs). Furthermore, laser scanning confocal microscope and immunofluorescence demonstrated that EnSC-Exos can be transferred to cisplatin-damaged GCs to decrease apoptosis. In addition, the enhanced expression of YAP at the protein level as well as YAP/TEAD target genes, such as CTGF, ANKRD1, and the increase of YAP into the nucleus in immunofluorescence staining after the addition of EnSC-Exos to cisplatin-damaged GCs confirmed the suppression of Hippo signaling pathway. While in vivo, EnSC-Exos successfully remedied POF in a mouse model. Collectively, our findings suggest that chemotherapy-induced POF was associated with the activating of Hippo signaling pathway. Human EnSC-Exos significantly elevated the proliferation of ovarian GCs and the ovarian function by regulating Hippo signaling pathway. These findings provide new insights for further understanding of EnSC-Exos in the recovery of ovary function.

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

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

Nuclear Localization of Yes-Associated Protein Is Associated With Tumor Progression in Cutaneous Melanoma

Yes-associated protein (YAP), an effector molecule of the Hippo signaling pathway, is expressed at high levels in cutaneous melanoma. However, the role of YAP in melanoma progression according to cellular localization is poorly understood. Tissues from 140 patients with invasive melanoma were evaluated by immunohistochemistry. Flow cytometry, western blotting, viability assays, wound healing assays, verteporfin treatment, and xenograft assays were conducted using melanoma cell lines B16F1 and B16F10 subjected to YapS127A transfection and siYap knockdown. Nuclear YAP localization was identified in 63 tumors (45.0%) and was more frequent than cytoplasmic YAP in acral lentiginous and nodular subtypes (P = .007). Compared with cytoplasmic YAP melanomas, melanomas with nuclear YAP had higher mitotic activity (P = .016), deeper invasion (P < .001), and more frequently metastasized to lymph nodes (P < .001) and distant organs (P < .001). Patients with nuclear YAP melanomas had poorer disease-free survival (P < .001) and overall survival (P < .001). Nuclear YAP was an independent risk factor for distant metastasis (hazard ratio: 3.206; 95% CI, 1.032-9.961; P = .044). Proliferative ability was decreased in siYapB16F1 (P < .001) and siYapB16F10 (P = .001) cells and increased in YapS127AB16F1 (P = .003) and YapS127AB16F10 (P = .002) cells. Cell cycle analysis demonstrated relative G1 retention in siYapB16F1 (P < .001) and siYapB16F10 (P < .001) cells and S retention in YapS127AB16F1 cells (P = .008). Wound healing assays showed that Yap knockdown inhibited cell invasion (siYapB16F1, P = .001; siYapB16F10, P < .001), whereas nuclear YAP promoted it (YapS127AB16F, P < .001; YapS127AB16F1, P = .017). Verteporfin, a direct YAP inhibitor, reduced cellular proliferation in B16F1 (P = .003) and B16F10 (P < .001) cells. Proliferative effects of nuclear YAP were confirmed in xenograft mice (P < .001). In conclusion, nuclear YAP in human melanomas showed subtype specificity and correlated with proliferative activity and proinvasiveness. It is expected that YAP becomes a useful prognostic marker, and its inhibition may be a potential therapy for melanoma patients.

Colonic crypt stem cell functions are controlled by tight junction protein claudin-7 through Notch/Hippo signaling

The tight junction protein claudin-7 is essential for tight junction function and intestinal homeostasis. Cldn7 deletion in mice leads to an inflammatory bowel disease-like phenotype exhibiting severe intestinal epithelial damage, weight loss, inflammation, mucosal ulcerations, and epithelial hyperplasia. Claudin-7 has also been shown to be involved in cancer metastasis and invasion. Here, we test our hypothesis that claudin-7 plays an important role in regulating colonic intestinal stem cell function. Conditional knockout of Cldn7 in the colon led to impaired epithelial cell differentiation, hyperproliferative epithelium, a decrease in active stem cells, and dramatically altered gene expression profiles. In 3D colonoid culture, claudin-7-deficient crypts were unable to survive and form spheroids, emphasizing the importance of claudin-7 in stem cell survival. Inhibition of the Hippo pathway or activation of Notch signaling partially rescued the defective stem cell behavior. Concurrent Notch activation and Hippo inhibition resulted in restored colonoid survival, growth, and differentiation to the level comparable to those of wild-type derived crypts. In this study, we highlight the essential role of claudin-7 in regulating Notch and Hippo signaling-dependent colonic stem cell functions, including survival, self-renewal, and differentiation. These new findings may shed light on potential avenues to explore for drug development in colorectal cancer.

Hippo/YAP1 promotes osteoporotic mice bone defect repair via the activating of Wnt signaling pathway

BACKGROUND

This study is to investigate the role and mechanism of Hippo/YAP1 in the repair of osteoporotic bone defects in aged mice, both in vivo and in vitro.

METHODS

We investigated the expression differences of the Hippo signaling in young and aged individuals both in vivo and in vitro. By manipulating the expression of Lats1/2 and Yap1, we investigated the role of Hippo/YAP1 in regulating osteogenic differentiation in aged BMSCs. In vivo, by intervening in the local and systemic expression of Lats1/2 and Yap1 respectively, we sought to demonstrate whether Hippo/YAP1 promotes the repair of bone defects in aged osteoporotic conditions. Finally, we delved into the underlying mechanisms of Hippo/YAP1 in regulating osteogenic differentiation.

RESULTS

We observed differences in the expression of the Hippo signaling between young and aged individuals. After knocking out Lats1/2 in aged BMSCs, we observed that the upregulation of endogenous YAP1 promotes cellular osteogenic differentiation and proliferation capacity. Through interference with Yap1 expression, we provided strong evidence for the role of Hippo/YAP1 in promoting osteogenic differentiation in aged BMSCs. In vivo, we confirmed that Hippo/YAP1 promotes the repair of bone defects in aging osteoporosis. Moreover, we discovered an interaction relationship among YAP1, β-catenin, and TEAD1.

CONCLUSION

This study elucidates the role of Hippo/YAP1 in promoting the repair of osteoporotic bone defects in aged mice. Mechanistically, YAP1 functions by activating the Wnt/β-catenin pathway, and this process is not independent of TEAD1.

Pasteurella multocida activates Rassf1-Hippo-Yap pathway to induce pulmonary epithelial apoptosis

Pasteurella multocida is an opportunistic zoonotic pathogen that primarily causes fatal respiratory diseases, such as pneumonia and respiratory syndromes. However, the precise mechanistic understanding of how P. multocida disrupts the epithelial barrier in mammalian lung remains largely unknown. In this study, using unbiased RNA-seq analysis, we found that the evolutionarily conserved Hippo-Yap pathway was dysregulated after P. multocida infection. Given the complexity of P. multocida infection associated with lung injury and systemic inflammatory processes, we employed a combination of cell culture models, mouse models, and rabbit models to investigate the dynamics of the Hippo-Yap pathway during P. multocida infection. Our findings reveal that P. multocida infection activates the Hippo-Yap pathway both in vitro and in vivo, by upregulating the upstream factors p-Mst1/2, p-Lats1, and p-Yap, and downregulating the downstream effectors Birc5, Cyr61, and Slug. Conversely, pharmacological inhibition of the Hippo pathway by XMU-MP-1 significantly rescued pulmonary epithelial cell apoptosis in vitro and reduced lung injury, systemic inflammation, and mouse mortality in vivo. Mechanistic studies revealed that P. multocida induced up-regulation of Rassf1 expression, and Rassf1 enhanced Hippo-Yap pathway through phosphorylation. Accordingly, in vitro knockdown of Rassf1 significantly enhanced Yap activity and expression of Yap downstream factors and reduced apoptosis during P. multocida infection. P. multocida-infected rabbit samples also showed overexpression of Rassf1, p-Lats1, and p-Yap, suggesting that P. multocida activates the Rassf1-Hippo-Yap pathway. These results elucidate the pathogenic role of the Rassf1-Hippo-Yap pathway in P. multocida infection and suggest that this pathway has the potential to be a drug target for the treatment of pasteurellosis.

Hippo cooperates with p53 to maintain foregut homeostasis and suppress the malignant transformation of foregut basal progenitor cells

Basal progenitor cells serve as a stem cell pool to maintain the homeostasis of the epithelium of the foregut, including the esophagus and the forestomach. Aberrant genetic regulation in these cells can lead to carcinogenesis, such as squamous cell carcinoma (SCC). However, the underlying molecular mechanisms regulating the function of basal progenitor cells remain largely unknown. Here, we use mouse models to reveal that Hippo signaling is required for maintaining the homeostasis of the foregut epithelium and cooperates with p53 to repress the initiation of foregut SCC. Deletion of Mst1/2 in mice leads to epithelial overgrowth in both the esophagus and forestomach. Further molecular studies find that Mst1/2-deficiency promotes epithelial growth by enhancing basal cell proliferation in a Yes-associated protein (Yap)-dependent manner. Moreover, Mst1/2 deficiency accelerates the onset of foregut SCC in a carcinogen-induced foregut SCC mouse model, depending on Yap. Significantly, a combined deletion of Mst1/2 and p53 in basal progenitor cells sufficiently drives the initiation of foregut SCC. Therefore, our studies shed light on the collaborative role of Hippo signaling and p53 in maintaining squamous epithelial homeostasis while suppressing malignant transformation of basal stem cells within the foregut.

Prognostic analysis of Yes-associated protein 1 in patients with colorectal cancer. A systematic review and meta-analysis

BACKGROUND

colorectal cancer (CRC) is the most common carcinoma worldwide, but a lack of effective prognostic markers limits clinical diagnosis and treatment. Yes-associated protein 1 (YAP1) is an effector of the HIPPO-pathway, which plays a critical role in cancer development and prognosis, including CRC. However, previous reports have suggested that it plays a dual role in CRC.

METHODS

a meta-analysis using RevMan 5.4 and Stata 14.0 was performed to evaluate the relationship between YAP1 and clinical outcomes of CRC, after searching for eligible studies in the PubMed, Web of Science and Embase databases. Online datasets GEPIA and LOGpc were also used to calculate survival results and for comparison with the meta-analysis results. Besides, "DESeq" packages were used for the expression analysis of YAP1 from the TCGA dataset.

RESULTS

YAP1 was overexpressed in the cancer tissues when compared to normal tissues in patients with CRC from the TCGA database (p = 0.000164) and GEPIA database. A total of 10 studies involving 2305 patients from the literature were selected. Pooled HR indicated that overexpression of YAP1 was associated with poor clinical outcomes (HR = 1.70, 95 % CI: 1.28-2.26, p = 0.0003). Subgroup analysis showed a clear correlation between overexpression of YAP1 and worse survival rate in Chinese patients (HR = 1.94, 95 % CI: 1.40-2.69, p = 0.0001), nuclear YAP1 overexpression (HR = 2.07, 95 % CI: 1.29-3.31, p = 0.003), 60 months of follow-up (HR = 1.89, 95 % CI: 1.30-2.73, p = 0.0008), IHC test (HR = 1.65, 95 % CI: 1.17-2.33, p = 0.005), IHC combined with other tests (HR = 1.77, 95 % CI: 1.13-2.77, p = 0.01) and multivariate analysis (HR = 1.70, 95 % CI: 1.24-2.31, p = 0.0009). Nevertheless, disease-free survival (DFS) showed no significant results in the patients with CRC in our meta-analysis (HR = 1.38, 95 % CI: 0.51-3.75, p = 0.52) as well as in the GEPIA and LOGpc databases. Meanwhile, YAP1 overexpression was also significantly associated with worse overall survival (OS) in GSE17536, GSE40967, GSE29623 and GSE71187.

CONCLUSION

YAP1 overexpression is common in CRC tissues. Overexpression of YAP1 in CRC patients, particularly in the nucleus, might be related to shorter OS, maybe in the early stages. YAP1 could serve as a potential predictor of poor prognosis in CRC.

Mechanisms of Immune Sensing of DNA Damage

Genomic stability relies on a multifaceted and evolutionarily conserved DNA damage response (DDR). In multicellular organisms, an integral facet of the DDR involves the activation of the immune system to eliminate cells with persistent DNA damage. Recent research has shed light on a complex array of nucleic acid sensors crucial for innate immune activation in response to oncogenic stress-associated DNA damage, a process vital for suppressing tumor formation. Yet, these immune sensing pathways may also be co-opted to foster tolerance of chromosomal instability, thereby driving cancer progression. This review aims to provide an updated overview of how the innate immune system detects and responds to DNA damage. An improved understanding of the regulatory intricacies governing this immune response may uncover new avenues for cancer prevention and therapeutic intervention.

YAP represses intestinal inflammation through epigenetic silencing of JMJD3

BACKGROUND

Epigenetics plays an important role in the pathogenesis of inflammatory bowel disease (IBD). Some studies have reported that YAP is involved in inflammatory response and can regulate target genes through epigenetic modifications. JMJD3, a histone H3K27me3 demethylase, is associated with some inflammatory diseases. In this study, we investigated the role of YAP in the development of IBD and the underlying epigenetic mechanisms.

RESULTS

YAP expression was significantly increased in both in vitro and in vivo colitis models as well as in patients with IBD. Epithelial-specific knockout of YAP aggravates disease progression in dextran sodium sulfate (DSS)-induced murine colitis. In the TNF-α-activated cellular inflammation model, YAP knockdown significantly increased JMJD3 expression. Coimmunoprecipitation experiments showed that YAP and EZH2 bind to each other, and chromatin immunoprecipitation-PCR (ChIP-PCR) assay indicated that silencing of YAP or EZH2 decreases H3K27me3 enrichment on the promoter of JMJD3. Finally, administration of the JMJD3 pharmacological inhibitor GSK-J4 alleviated the progression of DSS-induced murine colitis.

CONCLUSION

Our findings elucidate an epigenetic mechanism by which YAP inhibits the inflammatory response in colitis through epigenetic silencing of JMJD3 by recruiting EZH2.

The underlying mechanisms of DNA methylation in high salt memory in hypertensive vascular disease

This study demonstrates the effect and DNA methylation-related mechanisms of a high-salt diet and salt memory-induced hypertension and vasculopathy. Thirty Sprague Dawley rats were randomly divided into a control (CON) group (n = 6) and a modeling group (n = 24). A 12% NaCl solution (1 mL/100 g) was intragastrically administered for 60 consecutive days for modeling. An increase in blood pressure up to 140 mmHg was considered successful modeling. Twelve of fifteen successfully modeled rats were randomly selected and divided into a High Salt Diet (HSD) group and a High Salt Memory (HSM) group (n = 6). Rats in HSD group were intragastrically administered a 12% NaCl solution, while rats in HSM group were administered a 3% NaCl solution twice a day for 30 days. At the end of the intervention, blood pressure and the serum levels of ET-1, NO, TNF-α and IL-1β were measured. RRBS-heavy sulfite sequencing technology was selected for DNA methylation analysis. The systolic blood pressure of rats in the HSD group and HSM group was significantly higher than that in the CON group. Compared with those in the CON group, the serum levels of ET-1 in the HSM group and the serum levels of NO in the HSD group and HSM group were significantly increased. The methylation level of the CON group was lower than that of the HSD group and the HSM group, and there was no significant difference between the HSD group and the HSM group. The methylation level of Myoz3 was downregulated in the HSD group and HSM group. The methylation level of Fgd3 were upregulated in HSD group and downregulated in the HSM group. The methylation levels of AC095693.1, Adamts3, PDGFA and PDGFRα were downregulated in the HSD group and upregulated in the HSM group. According to the GO database, the differentially methylated genes were significantly enriched in the coordination of cell function, genetic development, and RNA transcription. There were three main metabolic pathways that were enriched in the differentially expressed genes between the groups: the PI3K-Akt signaling pathway, MAPK signaling pathway, and Hippo signaling pathway. Excessive salt intake may cause hypertension and vascular damage, and this damage may continue after the reduction of salt intake. Therefore, salt memory phenomenon exists, and this memory effect may be correlated with the levels of DNA methylation.

YAP1 expression in colorectal cancer confers the aggressive phenotypes via its target genes

Yes-associated protein1 (YAP1), a downstream effector of the Hippo pathway, is over-expressed in several types of malignancies. We analyzed retrospectively the TCGA database using 447 colorectal cancer (CRC) samples to determine the correlation between YAP1 expression level and CRC patient prognosis. YAP1-enforced expressed CRC cell lines were constructed using the lentivirus particles containing a YAP1 insert. YAP1 was highly expressed in CRC cancerous tissues and is associated with distant metastasis of CRC patients. Kaplan - Meier analysis indicated that CRC patients with a higher YAP1 expression group (n = 104) had worse disease-free survival (DFS) and overall survival (OS) than lower YAP1 expression group (n = 343) (p = 0.008 and p = 0.022). Univariate and multivariate analysis indicated that the elevated YAP1 expression predicted the aggressive phenotype and was an independent indicator for OS and DFS of CRC patients. YAP1 over-expression in CRC cells enhanced their migration and invasion significantly which can be reversed by AXL, CTGF, or CYR61 interference. The study suggested that YAP1 affected the prognosis of CRC patients and controlled the abilities of invasion and migration of CRC cells via its target genes AXL, CTGF, and CYR61.

Regulation of Hippo-YAP/CTGF signaling by combining an HDAC inhibitor and 5-fluorouracil in gastric cancer cells

Histone deacetylase (HDAC) inhibitors diminish carcinogenesis, metastasis, and cancer cell proliferation by inducing death in cancer cells. Tissue regeneration and organ development are highly dependent on the Hippo signaling pathway. Targeting the dysregulated hippo pathway is an excellent approach for cancer treatment. According to the results of this study, the combination of panobinostat, a histone deacetylase inhibitor, and 5-fluorouracil (5-FU), a chemotherapy drug, can act synergistically to induce apoptosis in gastric cancer cells. The combination of panobinostat and 5-FU was more effective in inhibiting cell viability than either treatment alone by elevating the protein levels of cleaved PARP and cleaved caspase-9. By specifically targeting E-cadherin, vimentin, and MMP-9, the combination of panobinostat and 5-FU significantly inhibited cell migration. Additionally, panobinostat significantly increased the anticancer effects of 5-FU by activating Hippo signaling (Mst 1 and 2, Sav1, and Mob1) and inhibiting the Akt signaling pathway. As a consequence, there was a decrease in the amount of Yap protein. The combination therapy of panobinostat with 5-FU dramatically slowed the spread of gastric cancer in a xenograft animal model by deactivating the Akt pathway and supporting the Hippo pathway. Since combination treatment exhibits much higher anti-tumor potential than 5-FU alone, panobinostat effectively potentiates the anti-tumor efficacy of 5-FU. As a result, it is believed that panobinostat and 5-FU combination therapy will be useful as supplemental chemotherapy in the future.

YAP-mediated trophoblast dysfunction: the common pathway underlying pregnancy complications

Yes-associated protein (YAP) is a pivotal regulator in cellular proliferation, survival, differentiation, and migration, with significant roles in embryonic development, tissue repair, and tumorigenesis. At the maternal-fetal interface, emerging evidence underscores the importance of precisely regulated YAP activity in ensuring successful pregnancy initiation and progression. However, despite the established association between YAP dysregulation and adverse pregnancy outcomes, insights into the impact of aberrant YAP levels in fetal-derived, particularly trophoblast cells, and the ensuing dysfunction at the maternal-fetal interface remain limited. This review comprehensively examines YAP expression and its regulatory mechanisms in trophoblast cells throughout pregnancy. We emphasize its integral role in placental development and maternal-fetal interactions and delve into the correlations between YAP dysregulation and pregnancy complications. A nuanced understanding of YAP's functions during pregnancy could illuminate intricate molecular mechanisms and pave the way for innovative prevention and treatment strategies for pregnancy complications. Video Abstract.

Impaired Expression of the Salvador Homolog-1 Gene Is Associated with the Development and Progression of Colorectal Cancer

Salvador homolog-1 (SAV1) is a component of the Hippo pathway that regulates tissue growth and homeostasis by affecting diverse cell processes, including apoptosis, cell division, and differentiation. The aberrant expression of Hippo pathway components has been observed in various human cancers. This study aimed to examine the expression level of the SAV1 gene in colorectal cancer (CRC) and its prognostic value and associations with tumor progression. We obtained matched pairs of tumor tissue and non-cancerous mucosa of the large intestine from 94 CRC patients as well as 40 colon biopsies of healthy subjects collected during screening colonoscopy. The tissue samples and CRC cell lines were quantified for SAV1 mRNA levels using the quantitative polymerase chain reaction method, while SAV1 protein expression was estimated in the paired tissues of CRC patients using immunohistochemistry. The average level of SAV1 mRNA was decreased in 93.6% of the tumor tissues compared to the corresponding non-cancerous tissues and biopsies of healthy colon mucosa. A downregulated expression of SAV1 mRNA was also noted in the CRC cell lines. Although the average SAV1 immunoreactivity was increased in the CRC samples compared to the non-cancerous tissues, a decreased immunoreactivity of the SAV1 protein in the tumor specimens was associated with lymph node involvement and higher TNM disease stage and histological grade. The results of our study suggest that the impaired expression of SAV1 is involved in CRC progression.

Shenhuang plaster enhances intestinal anastomotic healing in rabbits through activation of the TGF-β and Hippo/YAP signaling pathways

Although many efforts have been made to improve management strategies and diagnostic methods in the past several decades, the prevention of anastomotic complications, such as anastomotic leaks and strictures, remain a major clinical challenge. Therefore, new molecular pathways need to be identified that regulate anastomotic healing, and to design new treatments for patients after anastomosis to reduce the occurrence of complications. Rabbits were treated with a MST1/2 inhibitor XMU-XP-1, a Chinese medicine formula Shenhuang plaster (SHP) or a control vehicle immediately after surgery. The anastomotic burst pressure, collagen deposition, and hydroxyproline concentration were evaluated at 3 and 7 days after the surgery, and qRT-PCR and western-blot analyses were used to characterize mRNA and protein expression levels. Both XMU-XP-1 and SHP significantly increased anastomotic burst pressure, collagen deposition, and the concentration of hydroxyproline in intestinal anastomotic tissue at postoperative day 7 (POD 7). Importantly, SHP could induce TGF-β1 expression, which activated its downstream target Smad-2 to activate the TGF-β1 signaling pathway. Moreover, SHP reduced the phosphorylation level of YAP and increased its active form, and treatment with verteporfin, a YAP-TEAD complex inhibitor, significantly suppressed the effects induced by SHP during anastomotic tissue healing. This study demonstrated that activation of the Hippo-YAP pathway enhances anastomotic healing, and that SHP enhances both the TGF-β1/Smad and YAP signaling pathways to promote rabbit anastomotic healing after surgery. These results suggest that SHP could be used to treat patients who underwent anastomosis to prevent the occurrence of anastomotic complications.

Regulation and signaling pathways in cancer stem cells: implications for targeted therapy for cancer

Cancer stem cells (CSCs), initially identified in leukemia in 1994, constitute a distinct subset of tumor cells characterized by surface markers such as CD133, CD44, and ALDH. Their behavior is regulated through a complex interplay of networks, including transcriptional, post-transcriptional, epigenetic, tumor microenvironment (TME), and epithelial-mesenchymal transition (EMT) factors. Numerous signaling pathways were found to be involved in the regulatory network of CSCs. The maintenance of CSC characteristics plays a pivotal role in driving CSC-associated tumor metastasis and conferring resistance to therapy. Consequently, CSCs have emerged as promising targets in cancer treatment. To date, researchers have developed several anticancer agents tailored to specifically target CSCs, with some of these treatment strategies currently undergoing preclinical or clinical trials. In this review, we outline the origin and biological characteristics of CSCs, explore the regulatory networks governing CSCs, discuss the signaling pathways implicated in these networks, and investigate the influential factors contributing to therapy resistance in CSCs. Finally, we offer insights into preclinical and clinical agents designed to eliminate CSCs.

Slowed Intestinal Transit Induced by Less Mucus in Intestinal Goblet Cell Piezo1-Deficient Mice through Impaired Epithelial Homeostasis

Mucus secreted by goblet cells (GCs) may play an important role in intestinal transit function. Our previous study found that Piezo1 protein is essential for GC function; however, the effect of GC Piezo1 on intestinal transit function is unclear. Our study aimed to investigate the effect of Piezo1 in GCs on intestinal transit and the potential mechanism. We compared intestinal mucus, fecal form, intestinal transit time, intestinal epithelial cell composition, and stem cell function in WT and GC-specific Piezo1-deficient (Piezo1ΔGC) mice. Our results revealed a correlation between mucus and intestinal transit: the less mucus there was, the slower the intestinal transit. Piezo1 deficiency in GCs led to decreased mucus synthesis and also disrupted the ecological niche of colon stem cells (CSCs). Through organoid culture, we found that the capacity of proliferation and differentiation in Piezo1ΔGC mouse CSCs was significantly decreased, which also led to a reduced source of GCs. Further studies found that the reduced Wnt and Notch signals in colon crypts might be the potential mechanism. These results indicated the importance of GC Piezo1 in intestinal transit function, which acts by maintaining the homeostasis of intestinal epithelial cells and mucus.

Exosomal circEZH2_005, an intestinal injury biomarker, alleviates intestinal ischemia/reperfusion injury by mediating Gprc5a signaling

Intestinal ischemia/reperfusion (I/R) injury is a severe clinical condition without optimal diagnostic markers nor clear molecular etiological insights. Plasma exosomal circular RNAs (circRNAs) are valuable biomarkers and therapeutic targets for various diseases, but their role in intestinal I/R injury remains unknown. Here we screen the expression profile of circRNAs in intestinal tissue exosomes collected from intestinal I/R mice and identify circEZH2_005 as a significantly downregulated exosomal circRNA. In parallel, circEZH2_005 is also reduced in the plasma of clinical cardiac surgery patients who developed postoperative intestinal I/R injury. Exosomal circEZH2_005 displays a significant diagnostic value for intestinal injury induced by I/R. Mechanistically, circEZH2_005 is highly expressed in intestinal crypt cells. CircEZH2_005 upregulation promotes the proliferation of Lgr5+ stem cells by direct interaction with hnRNPA1, and enhanced Gprc5a stability, thereby alleviating I/R-induced intestinal mucosal damage. Hence, exosomal circEZH2_005 may serve as a biomarker for intestinal I/R injury and targeting the circEZH2_005/hnRNPA1/Gprc5a axis may be a potential therapeutic strategy for intestinal I/R injury.

O-GlcNAcylation: A Crucial Regulator in Cancer-Associated Biological Events

O-GlcNAcylation, a recently discovered post-translational modification of proteins, plays a crucial role in regulating protein structure and function, and is closely associated with multiple diseases. Research has shown that O-GlcNAcylation is abnormally upregulated in most cancers, promoting disease progression. To elucidate the roles of O-GlcNAcylation in cancer, this review summarizes various cancer-associated biological events regulated by O-GlcNAcylation and the corresponding signaling pathways. This work may provide insights for future studies on the function or underlying mechanisms of O-GlcNAcylation in cancer.

The Hippo signaling pathway contributes to the 2,5-Hexadion-induced apoptosis of ovarian granulosa cells

Although n-hexane can induce ovarian damage by inducing ovarian granulosa cell (GC) apoptosis, the mechanism underlying this induction of apoptosis has not been fully elucidated. In this study, rat ovarian GCs were exposed to different concentrations of 2,5-hexanedione (2,5-HD) (the main metabolite of n-hexane) in vitro to observe apoptosis, and the mechanism was further explored via mRNA microarray analysis. Hoechst 33258 staining and flow cytometry suggested that the apoptosis rate of ovarian GC apoptosis was significantly increased in the 2,5-HD-treated group. Subsequently, microarray analysis revealed that a total of 5677 mRNAs were differentially expressed, and further GO and KEGG analyses revealed that the differentially expressed genes were significantly enriched in many signaling pathways, including the Hippo pathway. A total of 7 differentially expressed genes that function upstream of the Hippo signaling pathway (Nf2, Wwc1, Ajuba, Llgl1, Dlg3, Rassf6 and Rassf1) were selected to confirm the microarray results by qRT-PCR, and the expression of these genes did change. Subsequently, the expression of key effector genes (Yap1, Mst1 and Lats1) and target genes (Ctgf and Puma) of the Hippo signaling was measured, and the results suggested that the mRNA and protein levels of Yap1, Mst1, Lats1, and Ctgf were significantly decreased while those of Puma were significantly increased after 2,5-HD treatment. Further CO-IP analysis suggested that the interaction between YAP1 and TEAD was significantly reduced after 2,5-HD treatment, while the interaction between YAP1 and P73 was not affected. In summary, during the 2,5-HD-induced apoptosis of ovarian GCs, the Hippo signaling pathway is inhibited, and downregulation of the pro-proliferation gene Ctgf and upregulated of the pro-apoptosis gene Puma are important. Decreased Ctgf expression was associated with decreased binding of YAP1 to TEAD. However, increased PUMA expression was not associated with YAP1 binding to P73.

Reduced smooth muscle-fibroblasts transformation potentially decreases intestinal wound healing and colitis-associated cancer in ageing mice

Cancer and impaired tissue wound healing with ageing are closely related to the quality of life of the elderly population. Given the increased incidence of cancer and the population ageing trend globally, it is very important to explore how ageing impairs tissue wound healing and spontaneous cancer. In a murine model of DSS-induced acute colitis and AOM/DSS-induced colitis-associated cancer (CAC), we found ageing significantly decreases intestinal wound healing and simultaneous CAC initiation, although ageing does not affect the incidence of AOM-induced, sporadic non-inflammatory CRC. Mechanistically, reduced fibroblasts were observed in the colitis microenvironment of ageing mice. Through conditional lineage tracing, an important source of fibroblasts potentially derived from intestinal smooth muscle cells (ISMCs) was identified orchestrating intestinal wound healing and CAC initiation in young mice. However, the number of transformed fibroblasts from ISMCs significantly decreased in ageing mice, accompanied by decreased intestinal wound healing and decreased CAC initiation. ISMCs-fibroblasts transformation in young mice and reduction of this transformation in ageing mice were also confirmed by ex-vivo intestinal muscular layer culture experiments. We further found that activation of YAP/TAZ in ISMCs is required for the transformation of ISMCs into fibroblasts. Meanwhile, the reduction of YAP/TAZ activation in ISMCs during intestinal wound healing was observed in ageing mice. Conditional knockdown of YAP/TAZ in ISMCs of young mice results in reduced fibroblasts in the colitis microenvironment, decreased intestinal wound healing and decreased CAC initiation, similar to the phenotype of ageing mice. In addition, the data from intestine samples derived from inflammatory bowel disease (IBD) patients show that activation of YAP/TAZ also occurs in ISMCs from these patients. Collectively, our work reveals an important role of the ageing stromal microenvironment in intestinal wound healing and CAC initiation. Furthermore, our work also identified a potential source of fibroblasts involved in colitis and CAC.

Mammalian Intestinal Development and Differentiation-The State of the Art

The development of the mammalian intestine, from its earliest origins as a morphologically uniform sheet of endoderm cells during gastrulation into the complex organ system that is essential for the life of the organism, is a truly fascinating process. During midgestation development, reciprocal interactions between endoderm-derived epithelium and mesoderm-derived mesenchyme enable villification, or the conversion of a radially symmetric pseudostratified epithelium into the functional subdivision of crypts and villi. Once a mature crypt-villus axis is established, proliferation and differentiation of new epithelial cells continue throughout life. Spatially localized signals including the wingless and Int-1, fibroblast growth factor, and Hippo systems, among others, ensure that new cells are being born continuously in the crypt. As cells exit the crypt compartment, a gradient of bone morphogenetic protein signaling limits proliferation to allow for the specification of multiple mature cell types. The first major differentiation decision is dependent on Notch signaling, which specifies epithelial cells into absorptive and secretory lineages. The secretory lineage is subdivided further into Paneth, goblet, tuft, and enteroendocrine cells via a complex network of transcription factors. Although some of the signaling molecules are produced by epithelial cells, critical components are derived from specialized crypt-adjacent mesenchymal cells termed telocytes, which are marked by Forkhead box l1, GLI Family Zinc Finger 1, and platelet-derived growth factor receptor α. The crucial nature of these processes is evidenced by the multitude of intestinal disorders such as colorectal cancer, short-bowel syndrome, and inflammatory bowel disease, which all reflect perturbations of the development and/or differentiation of the intestine.

The Hippo Pathway Effectors YAP/TAZ-TEAD Oncoproteins as Emerging Therapeutic Targets in the Tumor Microenvironment

Various cancer cell-associated intrinsic and extrinsic inputs act on YAP/TAZ proteins to mediate the hyperactivation of the TEAD transcription factor-based transcriptome. This YAP/TAZ-TEAD activity can override the growth-limiting Hippo tumor-suppressor pathway that maintains normal tissue homeostasis. Herein, we provide an integrated summary of the contrasting roles of YAP/TAZ during normal tissue homeostasis versus tumor initiation and progression. In addition to upstream factors that regulate YAP/TAZ in the TME, critical insights on the emerging functions of YAP/TAZ in immune suppression and abnormal vasculature development during tumorigenesis are illustrated. Lastly, we discuss the current methods that intervene with the YAP/TAZ-TEAD oncogenic signaling pathway and the emerging applications of combination therapies, gut microbiota, and epigenetic plasticity that could potentiate the efficacy of chemo/immunotherapy as improved cancer therapeutic strategies.

MOB kinase activator 1A acts as an oncogene by targeting PI3K/AKT/mTOR in ovarian cancer

BACKGROUND

To illuminate the precise roles of MOB Kinase Activator 1 A (MOB1A) in the development of ovarian cancer (OC).

METHODS

MOB1A expression and clinical data of OC were obtained from the public database on gene expression and proteomics. Meanwhile, verification of expression was carried out in Gene Expression Omnibus, the Human Protein Atlas, and OC cell lines. The prognosis of MOB1A was explored in the Kaplan-Meier plotter. RNA interference and lentivirus vectors were applied to construct knockdown and overexpressed cell models. Changes in the malignant behaviors of OC cells were detected by cholecystokinin octopeptide cell counting kit, wound healing, colony formation assay, transwell, flow cytometry assays, and in vivo experiments. Changes in proteins in the PI3K and autophagy-related makers were detected by western blot analysis.

RESULTS

The expression of MOB1A was significantly upregulated and accompanied by an inferior survival rate in OC. Knockdown of MOB1A inhibited the proliferation, invasion, migration, and cell cycle of OC cells, whereas induced cell autophagy. MOB1A upregulation had the opposite effects. In addition, bioinformatics analysis and western blot experiments showed that MOB1A plays an important role in the PI3K/AKT/mTOR pathway.

CONCLUSIONS

Our findings indicated that MOB1A is highly expressed and related to poor prognosis in OC. MOB1A plays a role in promoting the malignant biological behavior of tumor cells through PI3K/AKT/mTOR signaling pathway.

The role of Hippo pathway in ovarian development

The follicle is the functional unit of the ovary, whereby ovarian development is largely dependent on the development of the follicles themselves. The activation, growth, and progression of follicles are modulated by a diverse range of factors, including reproductive endocrine system and multiple signaling pathways. The Hippo pathway exhibits a high degree of evolutionary conservation between both Drosophila and mammalian systems, and is recognized for its pivotal role in regulating cellular proliferation, control of organ size, and embryonic development. During the process of follicle development, the components of the Hippo pathway show temporal and spatial variations. Recent clinical studies have shown that ovarian fragmentation can activate follicles. The mechanism is that the mechanical signal of cutting triggers actin polymerization. This process leads to the disruption of the Hippo pathway and subsequently induces the upregulation of downstream CCN and apoptosis inhibitors, thereby promoting follicle development. Thus, the Hippo pathway plays a crucial role in both the activation and development of follicles. In this article, we focused on the development and atresia of follicles and the function of Hippo pathway in these processes. Additionally, the physiological effects of Hippo pathway in follicle activation are also explored.

Modulation of stem cell fate in intestinal homeostasis, injury and repair

The mammalian intestinal epithelium constitutes the largest barrier against the external environment and makes flexible responses to various types of stimuli. Epithelial cells are fast-renewed to counteract constant damage and disrupted barrier function to maintain their integrity. The homeostatic repair and regeneration of the intestinal epithelium are governed by the Lgr5⁺ intestinal stem cells (ISCs) located at the base of crypts, which fuel rapid renewal and give rise to the different epithelial cell types. Protracted biological and physicochemical stress may challenge epithelial integrity and the function of ISCs. The field of ISCs is thus of interest for complete mucosal healing, given its relevance to diseases of intestinal injury and inflammation such as inflammatory bowel diseases. Here, we review the current understanding of the signals and mechanisms that control homeostasis and regeneration of the intestinal epithelium. We focus on recent insights into the intrinsic and extrinsic elements involved in the process of intestinal homeostasis, injury, and repair, which fine-tune the balance between self-renewal and cell fate specification in ISCs. Deciphering the regulatory machinery that modulates stem cell fate would aid in the development of novel therapeutics that facilitate mucosal healing and restore epithelial barrier function.

CircSTK3 drives the metastasis of colorectal cancer by regulating epithelial-mesenchymal transition

Circular RNAs (circRNAs) play crucial roles in malignancies. We aimed to delineate the functions and clinical importance of dysregulated circRNAs in colorectal cancer (CRC). We determined the circRNA expression profile from five CRC and paired adjacent normal tissues using circRNA microarray. We found that a novel circRNA, hsa_circ_0004592 (named circSTK3), was significantly upregulated in CRC tissues and correlated with decreased survival. Loss- and gain-of-function assays revealed that circSTK3 promoted the migration and invasion but not proliferation of cells. Whole genome expression microarray identified potential downstream targets and the regulatory networks of circSTK3; Gene Ontology analysis confirmed circSTK3 involvement in the CRC metastasis phenotype. Abnormal circSTK3 expression affected a subset of genes associated with CRC metastasis and triggered epithelial-mesenchymal transition programming, maintaining a tumor-promoting signature. Moreover, circSTK3 was transcriptionally regulated by CTCF. These findings reveal the functional and prognostic roles of circSTK3 and expose circRNAs as key players in metastasis.

WWP2 drives the progression of gastric cancer by facilitating the ubiquitination and degradation of LATS1 protein

BACKGROUND

Large tumor suppressor kinase 1 (LATS1), one of the predominant components of the Hippo pathway, has been characterized as a key player controlling the proliferation and invasion of cancer cells, including gastric cancer (GC) cells. However, the mechanism by which the functional stability of LATS1 is modulated has yet to be elucidated.

METHODS

Online prediction tools, immunohistochemistry and western blotting assays were used to explore the expression of WW domain-containing E3 ubiquitin ligase 2 (WWP2) in GC cells and tissues. Gain- and loss-of-function assays, as well as rescue experiments were performed to determine the role of the WWP2-LATS1 axis in cell proliferation and invasion. Additionally, the mechanisms involving WWP2 and LATS1 were assessed by coimmunoprecipitation (Co-IP), immunofluorescence, cycloheximide and in vivo ubiquitination assays.

RESULTS

Our results demonstrate a specific interaction between LATS1 and WWP2. WWP2 was markedly upregulated and correlated with disease progression and a poor prognosis in GC patients. Moreover, ectopic WWP2 expression facilitated the proliferation, migration and invasion of GC cells. Mechanistically, WWP2 interacts with LATS1, resulting in its ubiquitination and subsequent degradation, leading to increased transcriptional activity of YAP1. Importantly, LATS1 depletion abolished the suppressive effects of WWP2 knockdown on GC cells. Furthermore, WWP2 silencing attenuated tumor growth by regulating the Hippo-YAP1 pathway in vivo.

CONCLUSIONS

Our results define the WWP2-LATS1 axis as a critical regulatory mechanism of the Hippo-YAP1 pathway that promotes GC development and progression. Video Abstract.

Irradiation-Induced Intestinal Injury is Associated With Disorders of Bile Acids Metabolism

PURPOSE

Intestinal injury commonly occurs in radiation therapy, but its pathogenesis is not well understood. The relationship between irradiation-induced intestinal injury and bile acids (BAs) metabolism remains elusive. This study intends to clarify the role of BAs metabolism in irradiation-induced intestinal injury and the potential for supplementation with BAs to alleviate this injury.

MATERIALS AND METHODS

BAs metabolomic analysis of fecal pellets from normal and 12 Gy γ-ray total abdominal irradiation (TAI) treated mice was performed. The effects of a crude bile extract (BAmix) or lithocholic acid (LCA) on mice exposed to 12 Gy γ-ray TAI were determined by analyzing weight loss, colon length, villus length, crypt number, and the expression of leucine-rich repeat-containing G protein-coupled receptor 5 (Lgr5) and yes-associated protein 1 (YAP1). The effects of BAmix or LCA on intestinal organoids after 4 Gy irradiation were analyzed. ELISA assay was applied to test IL-1β, IL-6 and TNF-α levels in mouse intestine. The expression changes of G protein-coupled receptor 1 (TGR5) and YAP1 in the colonic mucosa of patients with radiation-induced intestinal injury were determined by IHC.

RESULTS

The relative abundance of secondary BAs was decreased while the relative abundance of primary BAs was increased in irradiated mice, and LCA was the most obvious change. BAmix and LCA alleviated irradiation-induced intestinal injury in a mouse model, as reflected by reduced body weight loss, longer colon, higher villus, more crypts, and increased Lgr5 expression. In intestinal organoids, BAmix and LCA enhanced newborn crypts formation after irradiation. LCA treatment improved the expression of TGR5 and YAP1 in mouse intestinal crypts. LCA has potential to reduce the inflammation levels in irradiated mice. Additionally, the expression levels of TGR5 and YAP1 in the colonic mucosa of patients with radiation enteritis were also significantly decreased.

CONCLUSIONS

Radiation-induced intestinal injury is associated with disorders of BAs metabolism, and treatment with LCA had a protective effect against radiation-induced intestinal injury in mice by modulating TGR5 and YAP1.

Deciphering Potential Role of Hippo Signaling Pathway in Breast Cancer: A Comprehensive Review

Breast cancer is a heterogeneous disease and a leading malignancy around the world. It is a vital cause of untimely mortality among women. Drug resistance is the major challenge for effective cancer therapeutics. In contrast, cancer stem cells (CSCs) are one of the reasons for drug resistance, tumor progression, and metastasis. The small population of CSCs present in each tumor has the ability of self-renewal, differentiation, and tumorigenicity. CSCs are often identified and enriched using a variety of cell surface markers (CD44, CD24, CD133, ABCG2, CD49f, LGR5, SSEA-3, CD70) that exert their functions by different regulatory networks, i.e., Notch, Wnt/β-catenin, hedgehog (Hh), and Hippo signaling pathways. Particularly the Hippo signaling pathway is the emerging and very less explored cancer stem cell pathway. Here, in this review, the Hippo signaling molecules are elaborated with respect to their ability of stemness as epigenetic modulators and how these molecules can be targeted for better cancer treatment and to overcome drug resistance.

USP36 facilitates esophageal squamous carcinoma progression via stabilizing YAP

Esophageal squamous carcinoma (ESCC) is the major subtype of esophageal cancer in China, accounting for 90% of cases. Recent studies revealed that abnormalities in the Hippo/YAP axis are pervasive in ESCC and are recognized as the important driver of ESCC progression. Since the activity of Hippo signaling is controlled by phosphorylation cascade, it is a mystery why the major effector YAP is still over-activated when the cascade is inhibited. Several studies suggested that in addition to phosphorylation, other protein modifications such as ubiquitination also play important roles in manipulating Hippo/YAP signaling activity. Since YAP protein stability is controlled via an appropriate balance between E3 ubiquitin ligases and deubiquitinases, we performed deubiquitinase siRNA screening and identified USP36 as a deubiquitinase significantly related to Hippo/YAP signaling activity and ESCC progression. USP36 expression was elevated in ESCC samples and correlated with poor differentiation. USP36 expression was correlated with YAP protein levels in ESCC samples. Molecular studies demonstrated that USP36 associated with the YAP protein and enhanced YAP protein stability by blocking the K48-linked polyubiquitination of YAP. In conclusion, our study revealed a novel deubiquitinase in regulating Hippo signaling in ESCC, which could be an encouraging drug target for Hippo-driven ESCC.

N6-Methyladenosine Modification of CIRCKRT17 Initiated by METTL3 Promotes Osimertinib Resistance of Lung Adenocarcinoma by EIF4A3 to Enhance YAP1 Stability

BACKGROUND

Circular RNAs (circRNAs) play a key role in regulating the drug resistance of numerous human tumors. However, whether circKRT17 involves in the osimertinib resistance of lung adenocarcinoma (LUAD) remains undetermined.

METHODS

Relative mRNA/circRNA and protein levels were detected by qRT-PCR and western blotting. Localization of circKRT17 and YAP1 was determined by FISH and immunofluorescence staining. Cell growth and apoptosis were evaluated using colony formation, EdU assays, and flow cytometry. The N6-methyladenosine (m6A) modification was analyzed by MeRIP. The interplay between EIF4A3 and circKRT17 or YAP1 was verified by RNA pull-down or/and RIP assays. Subcutaneous tumor growth was monitored in nude mice, and Ki-67 and TUNEL staining were carried out to evaluate cell proliferation and apoptosis, respectively.

RESULTS

CircKRT17 and METTL3 were elevated in osimertinib-insensitive LUAD tissues and cells. Knockdown of circKRT 17 and METTL3 increased the sensitivity of LUAD cells to osimertinib. Knockdown of METTL3 decreased the expression of circKRT17 by inhibiting m6A modification. CircKRT17 promoted the stability and nuclear transportation of YAP1 by recruiting EIF4A3 in LUAD cells. Overexpression of YAP1 abolished the impacts of circKRT17 knockdown on the osimertinib sensitivity of LUAD cells. CircKRT17 knockdown increased the repressive effects of osimertinib on tumor growth in vivo by inhibiting YAP1 signaling.

CONCLUSION

METTL3 initiated the m6A modification of circKRT17, thus promoting osimertinib resistance of LUAD by enhancing YAP1 stability through EIF4A4 recruitment.

The Hippo signalling pathway and its implications in human health and diseases

As an evolutionarily conserved signalling network, the Hippo pathway plays a crucial role in the regulation of numerous biological processes. Thus, substantial efforts have been made to understand the upstream signals that influence the activity of the Hippo pathway, as well as its physiological functions, such as cell proliferation and differentiation, organ growth, embryogenesis, and tissue regeneration/wound healing. However, dysregulation of the Hippo pathway can cause a variety of diseases, including cancer, eye diseases, cardiac diseases, pulmonary diseases, renal diseases, hepatic diseases, and immune dysfunction. Therefore, therapeutic strategies that target dysregulated Hippo components might be promising approaches for the treatment of a wide spectrum of diseases. Here, we review the key components and upstream signals of the Hippo pathway, as well as the critical physiological functions controlled by the Hippo pathway. Additionally, diseases associated with alterations in the Hippo pathway and potential therapies targeting Hippo components will be discussed.

A review on mechanobiology of cell adhesion networks in different stages of sporadic colorectal cancer to explain its tumorigenesis

Sporadic colorectal cancer (CRC) is strongly linked to extraneous factors, like poor diet and lifestyle, but not to inherent factors like familial genetics. The changes at the epigenomics and signalling pathways are known across the sporadic CRC stages. The catch is that temporal information of the onset, the feedback loop, and the crosstalk of signalling and noise are still unclear. This makes it challenging to diagnose and treat colon cancer effectively with no relapse. Various microbial cells and native cells of the colon, contribute to sporadic CRC development. These cells secrete autocrine and paracrine for their bioenergetics and communications with other cell types. Imbalances of the biochemicals affect the epithelial lining of colon. One side of this epithelial lining is interfacing the dense colon tissue, while the other side is exposed to microbiota and excrement from the lumen. Hence, the epithelial lining is prone to tumorigenesis due to the influence of both biochemical and mechanical cues from its complex surrounding. The role of physical transformations in tumorigenesis have been limitedly discussed. In this context, cellular and tissue structures, and force transductions are heavily regulated by cell adhesion networks. These networks include cell anchoring mechanism to the surrounding, cell structural integrity mechanism, and cell effector molecules. This review will focus on the progression of the sporadic CRC stages that are governed by the underlaying cell adhesion networks within the epithelial cells. Additionally, current and potential technologies and therapeutics that target cell adhesion networks for treatments of sporadic CRC will be incorporated.

Loss of Mst1/2 activity promotes non-mitotic hair cell generation in the neonatal organ of Corti

Mammalian sensory hair cells (HCs) have limited capacity for regeneration, which leads to permanent hearing loss after HC death. Here, we used in vitro RNA-sequencing to show that the Hippo signaling pathway is involved in HC damage and self-repair processes. Turning off Hippo signaling through Mst1/2 inhibition or Yap overexpression induces YAP nuclear accumulation, especially in supporting cells, which induces supernumerary HC production and HC regeneration after injury. Mechanistically, these effects of Hippo signaling work synergistically with the Notch pathway. Importantly, the supernumerary HCs not only express HC markers, but also have cilia structures that are able to form neural connections to auditory regions in vivo. Taken together, regulating Hippo suggests new strategies for promoting cochlear supporting cell proliferation, HC regeneration, and reconnection with neurons in mammals.

Targeting the Hippo Pathway in Gastric Cancer and Other Malignancies in the Digestive System: From Bench to Bedside

The Hippo pathway is an evolutionally conserved signaling cascade that controls organ size and tissue regeneration under physiological conditions, and its aberrations have been well studied to promote tumor initiation and progression. Dysregulation of the Hippo tumor suppressor signaling frequently occurs in gastric cancer (GC) and other solid tumors and contributes to cancer development through modulating multiple aspects, including cell proliferation, survival, metastasis, and oncotherapy resistance. In the clinic, Hippo components also possess diagnostic and prognostic values for cancer patients. Considering its crucial role in driving tumorigenesis, targeting the Hippo pathway may greatly benefit developing novel cancer therapies. This review summarizes the current research progress regarding the core components and regulation of the Hippo pathway, as well as the mechanism and functional roles of their dysregulation in gastrointestinal malignancies, especially in GC, and discusses the therapeutic potential of targeting the Hippo pathway against cancers.

Tiny Drosophila intestinal stem cells, big power

The signaling pathways are highly conserved between Drosophila and mammals concerning intestinal development, regeneration, and disease. The powerful genetic tools of Drosophila make it a valuable and convenient alternative to answer basic biological questions that can not be addressed using mammalian models. In this review, we discuss recent advances in how we use fly midgut to answer the following key questions: (1) How intestine stem cell niches are established; (2) which factors control asymmetric division of stem cells; (3) how intestinal cells interact with environmental factors, such as tissue damage, microbiota, and diet; (4) how to screen aging/cancer-related factors or drugs by fly intestine stem cells.

CAF-derived exosomal WEE2-AS1 facilitates colorectal cancer progression via promoting degradation of MOB1A to inhibit the Hippo pathway

Cancer-associated fibroblasts (CAFs) are the most abundant stromal components in the tumor microenvironment (TME) and closely involved in tumor progression. However, the precise biological functions and molecular mechanisms of CAFs in the TME have yet to be understood. Here, we demonstrate that WEE2-AS1 is highly expressed in the CAF-derived small extracellular vesicles (sEVs). Moreover, WEE2-AS1 is markedly higher in plasma sEVs of CRC patients than in healthy subjects and its high level predicts advanced pathological staging and poor survival. Then, we conducted a series of in vitro and in vivo experiments. Elevated expression of WEE2-AS1 in sEVs increases CRC cell proliferation in vitro. Importantly, aberrant CAF-sEVs^WEE2-AS1 leads to tumor formation and progression in BALB/c nude mice and promotes AOM/DSS-induced tumorigenesis. Mechanistically, WEE2-AS1 functions as a modular scaffold for the MOB1A and E3 ubiquitin-protein ligase praja2 complexes, leading to MOB1A degradation via the ubiquitin-proteasome pathway. The Hippo pathway is then inhibited and more YAP are transported into the nucleus, where they activate downstream gene transcription. Together, our data reveal that CAF-sEVs^WEE2-AS1 interacts with MOB1A, promotes degradation of MOB1A, inhibits the Hippo pathway, and facilitates the growth of CRC cells. Hence, exosomal WEE2-AS1 may be a promising therapeutic target and circulating biomarker for CRC diagnosis and prognosis.

YAP1-TEAD1 mediates the perineural invasion of prostate cancer cells induced by cancer-associated fibroblasts

Perineural invasion (PNI) driven by the tumor microenvironment (TME) has emerged as a key pattern of metastasis of prostate cancer (PCa), while its underlying mechanism is still elusive. Here, we identified increased CAFs and YAP1 expression levels in patients with metastatic PCa. In the cultured PCa cell line LNCaP, co-culture with cancer-associated fibroblasts (CAFs) could upregulate YAP1 protein expression. Either ectopic overexpression of YAP1 or co-culture with CAFs could promote the infiltration of LNCaPs towards dorsal root ganglia (DRG). This effect could be blocked using an YAP1 inhibitor. In vivo, overexpression of YAP1 could increase PNI in a mouse model of sciatic nerve tumor invasion. Mechanistically, TEAD1 binds to the NGF promotor and YAP1/TEAD1 activates its transcription and consequently increases NGF secretion. In turn, PCa cells treated with CM from CAFs or stable YAP1 overexpression can stimulate DRG to secrete CCL2. The epithelial-to-mesenchymal transition (EMT) of PCa cells is thus activated via CCL2/CCR2. Overall, our data demonstrate that CAFs can activate YAP1/TEAD1 signaling and increase the secretion of NGF, therefore promoting PCa PNI. In addition, EMT induced by PNI suggests a feedback loop is present between neurons and PCa cells.

Helminths revive to survive

Helminth parasites are well known to have co-evolved a diverse arsenal of immunomodulatory factors to aid their persistence following infection. In this issue, Karo-Atar et al. (2022. J. Exp. Med.https://doi.org/10.1084/jem.20212311) demonstrate that products released by the gut-dwelling helminth Heligmosomoides polygyrus barkeri modify intestinal stem cells into a "revival" state, which is associated with a loss of helminth-expelling secretory cell types from the epithelium.

The role of intestinal stem cell within gut homeostasis: Focusing on its interplay with gut microbiota and the regulating pathways

Intestinal stem cells (ISCs) play an important role in maintaining intestinal homeostasis via promoting a healthy gut barrier. Within the stem cell niche, gut microbiota linking the crosstalk of dietary influence and host response has been identified as a key regulator of ISCs. Emerging insights from recent research reveal that ISC and gut microbiota interplay regulates epithelial self-renewal. This article reviews the recent knowledge on the key role of ISC in their local environment (stem cell niche) associating with gut microbiota and their metabolites as well as the signaling pathways. The current progress of intestinal organoid culture is further summarized. Subsequently, the key challenges and future directions are discussed.

CEP63 upregulates YAP1 to promote colorectal cancer progression through stabilizing RNA binding protein FXR1

Abnormal regulation of centrosome components can induce chromosome instability and tumorigenesis. Centrosomal protein 63 (CEP63) is a vital member for assembling centrosome. Yet, the involvement of CEP63 in cancer pathogenesis remains unclear. Here we identify CEP63 as an important mediator for RNA-binding proteins (RBPs) to facilitate regulation on their RNA targets in colorectal cancer (CRC). We demonstrate that CEP63 protein is upregulated in a large cohort of colorectal cancer tissues and predicts poor prognosis, and USP36 is identified for stabilizing CEP63 by enhancing its K48-dependent deubiquitination. CEP63 overexpression promotes the proliferation and tumor growth of CRC cells in vitro and in vivo. Furthermore, we find that CEP63 can promote cancer stem-like cell properties by enhancing YAP1 expression through binding with and inhibiting the K63-ubiquitylation degradation of RBP FXR1 in CRC cells. Importantly, we further verify that the KH domain of FXR1 is necessary for the interaction between CEP63 and FXR1. Moreover, microtube motor proteins can form a complex with CEP63 and FXR1 to mediate the regulation of FXR1 on RNA targets. Additionally, we also confirm that CEP63 can bind and regulate multiple RBPs. In conclusion, our findings unveil an unrecognized CEP63/RBPs/RNA axis that CEP63 may perform as an adapter facilitating the formation of RBPs complex to regulate RNA progression and discover the role of CEP63 involved in signal transduction and RNA regulation, providing potential therapeutic target for CRC patients.

Multiscale light-sheet organoid imaging framework

Organoids provide an accessible in vitro system to mimic the dynamics of tissue regeneration and development. However, long-term live-imaging of organoids remains challenging. Here we present an experimental and image-processing framework capable of turning long-term light-sheet imaging of intestinal organoids into digital organoids. The framework combines specific imaging optimization combined with data processing via deep learning techniques to segment single organoids, their lumen, cells and nuclei in 3D over long periods of time. By linking lineage trees with corresponding 3D segmentation meshes for each organoid, the extracted information is visualized using a web-based “Digital Organoid Viewer” tool allowing combined understanding of the multivariate and multiscale data. We also show backtracking of cells of interest, providing detailed information about their history within entire organoid contexts. Furthermore, we show cytokinesis failure of regenerative cells and that these cells never reside in the intestinal crypt, hinting at a tissue scale control on cellular fidelity.

Live imaging of organoid growth remains a challenge: it requires long-term imaging of several samples simultaneously and dedicated analysis pipelines. Here the authors report an experimental and image processing framework to turn long-term light-sheet imaging of intestinal organoids into digital organoids.

Therapeutic Effect of Melatonin in Premature Ovarian Insufficiency: Hippo Pathway Is Involved

Objective

Premature ovarian insufficiency (POI) is a female reproductive disorder of unknown etiology with no definite pathogenesis. Melatonin (MT) is an endogenous hormone synthesized mainly by pineal cells and has strong endogenous effects in regulating ovarian function. To systematically explore the pharmacological mechanism of MT on POI therapy, a literature review approach was conducted at the signaling pathways level.

Methods

Relevant literatures were searched and downloaded from databases, including PubMed and China National Knowledge Infrastructure, using the keywords “premature ovarian insufficiency,” “Hippo signaling pathways,” and “melatonin.” The search criteria were from 2010 to 2022. Text mining was also performed.

Results

MT is involved in the regulation of Hippo signaling pathway in a variety of modes and has been correlated with ovarian function.

Conclusions

The purpose of this review is to summarize the research progress of Hippo signaling pathways and significance of MT in POI, the potential crosstalk between MT and Hippo signaling pathways, and the prospective therapy.

Cancer Stem Cells and Circulatory Tumor Cells Promote Breast Cancer Metastasis

Breast cancer (BC) is a highly metastatic, pathological cancer that significantly affects women worldwide. The mortality rate of BC is related to its heterogeneity, aggressive phenotype, and metastasis. Recent studies have highlighted that the tumor microenvironment (TME) is critical for the interplay between metastasis mediators in BC. BC stem cells, tumor-derived exosomes, circulatory tumor cells (CTCs), and signaling pathways dynamically remodel the TME and promote metastasis. This review examines the cellular and molecular mechanisms governing the epithelial to mesenchymal transition (EMT) that facilitate metastasis. This review also discusses the role of cancer stem cells (CSCs), tumor-derived exosomes, and CTs in promoting BC metastasis. Furthermore, the review emphasizes major signaling pathways that mediate metastasis in BC. Finally, the interplay among CSCs, exosomes, and CTCs in mediating metastasis have been highlighted. Therefore, understanding the molecular cues that mediate the association of CSCs, exosomes, and CTCs in TME helps to optimize systemic therapy to target metastatic BC.