Project description:All organisms are constantly exposed to various stresses, necessitating adaptive strategies for survival. In bacteria, the main stress-coping mechanism is the stringent response triggered by the accumulation of “alarmone” (p)ppGpp to arrest proliferation and reprogram transcriptome. While mammalian genomes encode MESH1—the homolog of the (p)ppGpp hydrolase SpoT, current knowledge about its function remains limited. We found MESH1 expression tended to be higher in tumors and associated with poor patient outcomes. Consistently, MESH1 knockdown robustly inhibited proliferation, depleted dNTPs, reduced tumor sphere formation, and retarded xenograft growth. These antitumor phenotypes associated with MESH1 knockdown were accompanied by a significantly altered transcriptome, including the repressed expression of TAZ, a HIPPO coactivator, and proliferative gene. Importantly, TAZ restoration mitigated many anti-growth phenotypes of MESH1 knockdown, including proliferation arrest, reduced sphere formation, tumor growth inhibition, dNTP depletion, and transcriptional changes. Furthermore, TAZ repression was associated with the histone hypo-acetylation at TAZ regulatory loci due to the induction of epigenetic repressors HDAC5 and AHRR. Together, MESH1 knockdown in human cells altered the genome-wide transcriptional patterns and arrested proliferation that mimicked the bacterial stringent response through the epigenetic repression of TAZ expression.
Project description:Promoting rumen development is closely related to the health and efficient growth of ruminants. In the present study, we aimed to assess the impact of YAP1/TAZ on RE proliferation. The transcriptomic expression was analyzed to investigate the potential regulatory networks. The results indicated that GA promoted RE cell proliferation, while VP disrupted RE cell proliferation. The Hippo, Wnt, and calcium signaling pathways were altered in cells following the regulation of YAP1/TAZ. Upon YAP1/TAZ activation through GA, the CCN1/2 increased to promote RE cell proliferation. While when the YAP1/TAZ was inhibited by VP, the BIRC3 decreased to suppress RE cell proliferation. Thus, YAP1/TAZ may be potential targets for regulating RE cell proliferation. These findings broaden our understanding of the role of YAP1/TAZ and their regulators in RE and offer a potential target for promoting rumen development.
Project description:Glioblastoma (GBM) is the most aggressive brain tumor and resistant to current available therapeutics, such as radiation. To improve the clinical efficacy, it is important to understand the cellular mechanisms underlying tumor responses to radiation. Here, we investigated long-term cellular responses of human GBM cells to ionizing radiation. Comparing to the initial response within 12 hours, gene expression modulation at 7 days after radiation is markedly different. While genes related to cell cycle arrest and DNA damage responses are mostly modulated at the initial stage; immune-related genes are specifically affected as the long-term effect. This later response is associated with increased cellular senescence and inhibition of transcriptional coactivator with PDZ-binding motif (TAZ). Mechanistically, TAZ inhibition does not depend on the canonical Hippo pathway, but relies on enhanced degradation mediated by the β-catenin destruction complex in the Wnt pathway. We further showed that depletion of TAZ by RNAi promotes radiation-induced senescence and growth arrest. Pharmacological activation of the β-catenin destruction complex is able to promote radiation-induced TAZ inhibition and growth arrest in these tumor cells. The correlation between senescence and reduced expression of YAP as well as β-catenin also occurs in human gliomas treated by radiation. Collectively, these findings suggested that inhibition of TAZ is involved in radiation-induced senescence and might benefit GBM radiotherapy.
Project description:Here using mouse genetic models and human cancer cells, we show that YAP/TAZ reprogram polyamine metabolism to promote cell proliferation and tumor growth. Mechanistically, YAP/TAZ increases polyamine synthesis mainly through direct upregulation of the major rate-limiting enzyme ornithine decarboxylase 1. We further demonstrate that the polyamine spermidine sustains eukaryotic translation factor 5A (eIF5A) hypusination to support efficient translation of histone demethylase LSD1 that maintains a favored epigenetic status for YAP/TAZ-induced cell proliferation. Furthermore, inhibiting either polyamine synthesis or LSD1 can suppress YAP/TAZ-induced cell proliferation in mouse liver and human cancer cells. Thus our study identifies a YAP/TAZ-polyamine-eIF5A hypusination-LSD1 axis as required for YAP/TAZ-induced cell proliferation and tumor growth and suggests LSD1 as a critical target of polyamine in tumorigenesis.
Project description:Here using mouse genetic models and human cancer cells, we show that YAP/TAZ reprogram polyamine metabolism to promote cell proliferation and tumor growth. Mechanistically, YAP/TAZ increases polyamine synthesis mainly through direct upregulation of the major rate-limiting enzyme ornithine decarboxylase 1. We further demonstrate that the polyamine spermidine sustains eukaryotic translation factor 5A (eIF5A) hypusination to support efficient translation of histone demethylase LSD1 that maintains a favored epigenetic status for YAP/TAZ-induced cell proliferation. Furthermore, inhibiting either polyamine synthesis or LSD1 can suppress YAP/TAZ-induced cell proliferation in mouse liver and human cancer cells. Thus our study identifies a YAP/TAZ-polyamine-eIF5A hypusination-LSD1 axis as required for YAP/TAZ-induced cell proliferation and tumor growth and suggests LSD1 as a critical target of polyamine in tumorigenesis.
Project description:Schwann cell (SC) myelination in the peripheral nervous system is essential for motor function, and uncontrolled SC proliferation occurs in cancer. Here, we show that a dual direct role for Hippo effectors TAZ and YAP in regulation of SC proliferation and myelination through modulating G protein expression and interacting with SOX10, respectively. Developmentally-regulated mutagenesis indicates that TAZ/YAP are critical for SC proliferation yet also required for their differentiation and myelination. Genome-wide occupancy mapping and transcriptome profiling reveal that nuclear TAZ and YAP promote SC proliferation by activating cell cycle regulators, while targeting critical differentiation regulators in cooperation with SOX10 for myelination. We further identified that TAZ targets and represses Gnas, encoding Gαs-protein, which opposes TAZ/YAP activities to decelerate proliferation. Gnas deletion expands SC precursor pools and blocks myelination in the sciatic nerve. Thus, our study revealed that the Hippo/TAZ/YAP and Gαs-protein feedback circuit functions as a fulcrum balancing SC proliferation and differentiation, providing insights into molecular programming of SC lineage progression and homeostasis.
Project description:The Hippo pathway controls the activity of YAP/TAZ transcriptional coactivators through a kinase cascade. Despite the critical role of this pathway in tissue growth and tumorigenesis, it is not fully understood how YAP/TAZ–mediated transcription drives proliferation. By analyzing the effects of inactivating LATS1/2 kinases, the direct upstream inhibitors of YAP/TAZ, on mouse brain development and applying cell-number–normalized transcriptome analysis, we discovered that YAP/TAZ activation causes a global increase in transcription activity, known as hypertranscription, and upregulates many genes associated with increased biosynthetic capacity and proliferation. In contrast, conventional read-depth–normalized RNA-sequencing analysis failed to detect the scope of the transcriptome shift and missed most relevant gene ontologies. Hypertranscription in neural progenitors inhibits differentiation and triggers DNA replication stress, DNA damage, and p53 activation, resulting in massive apoptosis. Our findings reveal the remarkable impact of YAP/TAZ activation on global transcription activity and have important implications for understanding YAP/TAZ function
Project description:The Hippo pathway controls the activity of YAP/TAZ transcriptional coactivators through a kinase cascade. Despite the critical role of this pathway in tissue growth and tumorigenesis, it is not fully understood how YAP/TAZ–mediated transcription drives proliferation. By analyzing the effects of inactivating LATS1/2 kinases, the direct upstream inhibitors of YAP/TAZ, on mouse brain development and applying cell-number–normalized transcriptome analysis, we discovered that YAP/TAZ activation causes a global increase in transcription activity, known as hypertranscription, and upregulates many genes associated with increased biosynthetic capacity and proliferation. In contrast, conventional read-depth–normalized RNA-sequencing analysis failed to detect the scope of the transcriptome shift and missed most relevant gene ontologies. Hypertranscription in neural progenitors inhibits differentiation and triggers DNA replication stress, DNA damage, and p53 activation, resulting in massive apoptosis. Our findings reveal the remarkable impact of YAP/TAZ activation on global transcription activity and have important implications for understanding YAP/TAZ function.
Project description:The Hippo pathway controls the activity of YAP/TAZ transcriptional coactivators through a kinase cascade. Despite the critical role of this pathway in tissue growth and tumorigenesis, it is not fully understood how YAP/TAZ–mediated transcription drives proliferation. By analyzing the effects of inactivating LATS1/2 kinases, the direct upstream inhibitors of YAP/TAZ, on mouse brain development and applying cell-number–normalized transcriptome analysis, we discovered that YAP/TAZ activation causes a global increase in transcription activity, known as hypertranscription, and upregulates many genes associated with increased biosynthetic capacity and proliferation. In contrast, conventional read-depth–normalized RNA-sequencing analysis failed to detect the scope of the transcriptome shift and missed most relevant gene ontologies. Hypertranscription in neural progenitors inhibits differentiation and triggers DNA replication stress, DNA damage, and p53 activation, resulting in massive apoptosis. Our findings reveal the remarkable impact of YAP/TAZ activation on global transcription activity and have important implications for understanding YAP/TAZ function.