Project description:Aberrant activation of Hedgehog (HH) signaling has been identified as a key etiologic factor of many human malignancies. Signal strength, target gene specificity, and oncogenic activity of HH signaling profoundly depend on interactions with other pathways such as epidermal growth factor receptor-mediated signaling which has been shown to cooperate with HH/GLI in basal cell carcinoma and pancreatic cancer. We demonstrate that the human medulloblastoma cell line Daoy possesses a fully inducible endogenous HH pathway. Treatment of Daoy cells with Sonic Hedgehog or Smoothened agonist induced expression of GLI1 protein and prevented processing of GLI3 to its repressor form. To study interactions between HH- and EGF-induced signaling in greater detail, time-resolved measurements were carried out and analyzed on the transcriptomic as well as proteomic level. Daoy cells responded to the co-treatment by downregulating GLI1, PTCH, and HHIP on the transcript level which was also seen when Amphiregulin (AREG) was used instead of EGF. The finding that EGFR signaling silences proteins acting as negative regulators of HH signaling is firstly described here as a novel crosstalk mechanism. Furthermore, combined EGFR/HH signaling maintains high GLI1 protein levels contrasting its downregulation on the transcript level. On the other hand, high level synergism was observed with respect to a strong and significant upregulation of numerous canonical EGF-targets with putative tumor-promoting properties such as MMP7, VEGFA, and IL-8. In conclusion, synergistic effects between EGFR and HH signaling can selectively induce a switch from a canonical HH/GLI profile to a modulated specific target gene profile pointing to more wide-spread, yet context-dependent, interactions between HH/GLI and growth factor receptor signaling in human malignancies. To study interactions between HH- and EGF-induced signaling, time-resolved measurements were carried out over a period of 24 h at 14 different time points after stimulation by EGF with and without additional stimulation by SHH. Furthermore, as a control, cells without any stimulation by EGF and SHH (control) and cells in the presents of SHH were analyzed. Overall, three biological replicates of 60 different treatment/timepoints were analyzed yielding 180 different samples.
Project description:Aberrant activation of Hedgehog (HH) signaling has been identified as a key etiologic factor of many human malignancies. Signal strength, target gene specificity, and oncogenic activity of HH signaling profoundly depend on interactions with other pathways such as epidermal growth factor receptor-mediated signaling which has been shown to cooperate with HH/GLI in basal cell carcinoma and pancreatic cancer. We demonstrate that the human medulloblastoma cell line Daoy possesses a fully inducible endogenous HH pathway. Treatment of Daoy cells with Sonic Hedgehog or Smoothened agonist induced expression of GLI1 protein and prevented processing of GLI3 to its repressor form. To study interactions between HH- and EGF-induced signaling in greater detail, time-resolved measurements were carried out and analyzed on the transcriptomic as well as proteomic level. Daoy cells responded to the co-treatment by downregulating GLI1, PTCH, and HHIP on the transcript level which was also seen when Amphiregulin (AREG) was used instead of EGF. The finding that EGFR signaling silences proteins acting as negative regulators of HH signaling is firstly described here as a novel crosstalk mechanism. Furthermore, combined EGFR/HH signaling maintains high GLI1 protein levels contrasting its downregulation on the transcript level. On the other hand, high level synergism was observed with respect to a strong and significant upregulation of numerous canonical EGF-targets with putative tumor-promoting properties such as MMP7, VEGFA, and IL-8. In conclusion, synergistic effects between EGFR and HH signaling can selectively induce a switch from a canonical HH/GLI profile to a modulated specific target gene profile pointing to more wide-spread, yet context-dependent, interactions between HH/GLI and growth factor receptor signaling in human malignancies.
Project description:The goal of this study was to profile the total proteome and transcriptome of the established medulloblastoma cell lines, Daoy and UW228, using label-free nano-LC-MS/MS-based quantitative proteomics and high-throughput RNA sequencing (RNA-Seq), coupled with pathway analysis to identify differentially expressed genes, proteins and signaling pathways with potential as prognostic markers. A total of 14250 and 12870 transcripts were detected for Daoy and UW228, respectively. Proteomic profiling identified 2630 and 1235 proteins in Daoy and UW228, representing 18% and 10% of detected transcripts, respectively. Interestingly, Daoy proteome included >50% unique proteins, while almost 90% of proteins expressed by UW228 were commonly expressed in Daoy. Differential expression of a number of adhesion, cytoskeletal and signaling molecules were observed between the two cell lines. Upregulation of a number of proteins and enrichment of key signaling pathways, including WNT, Sonic hedgehog (SHH) and integrin signaling pathways, were uniquely observed in MB cell lines, in particular in Daoy.
Project description:Circular RNAs have largely emerged as novel regulators of human biology, including brain function and cancer development. On the other hand, the Hedgehog pathway has established roles in regulating biological processes, including tumorigenesis. Here, the circular RNA transcriptome, in the context of Hedgehog signaling activation of medulloblastoma Daoy and human embryonic palatal mesenchyme HEPM cells, was determined.
Project description:Purpose: The response to Hedgehog signaling in the limb is driven by GLI bound enhancers and the majority of Hh targets in the developing limb bud are regulated solely by the activity of GLI-repressor. Currently we do not have a comprehensive understanding of how GLI bound enhancers respond Hedgehog signaling. The goal of this study is to identify how GLI bound enhancers are regulated by Hedgehog signaling and specifically by GLI-repressor. Methods: Histone modification ChIP-sequencing was done in Embryonic day 10.5 limb buds from control and Shh null embryos to identify histone modifications that change in response to Hedgehog signaling. We also did a comparative analysis of histone modificaiton response to Hedgehog stimulation in NIH3T3 cells to assess tissue specificity of GLI bound enhancer response to Hedgehog signaling. Results: We found that Hedgehog signaling specifically regulates the acetylation status of Histone 3 lysine 27 at a subset of GLI binding regions. These regions correlate with both known Hedgehog target genes in the limb bud and with characterized enhancers in the limb. This set of Hedgehog responsive GLI bound enhancers demonstrate enhanced tissue specificity.
Project description:Aberrant sonic hedeghog signaling is implicated in the development of various cancer entities such as medulloblastoma. The canonical signaling cascade has been studied for years. Activation of GLI transcription factors was revealed as the driving force upon pathway activation. Phosphorylation by Proteinkinase A, Casein Kinase 1 and Glycogen Synthase Kinase 3 β has been found to influence the degradation of the GLI transcription factors. However, the deeper role of phosphorylation in the signal transduction remains unclear. We, therefore, applied comprehensive HPLC-MS/MS based phosphoproteomics to reveal phosphorylation dynamics underlying the chemical activation and inhibition of sonic hedgehog signaling in human medulloblastoma cells. Human medulloblastoma cells were treated with SAG (Hh pathway induction) and Vismodegib (Hh pathway inhibition) for 5 and 15 minutes. Our phosphoproteomic profiling revealed a central role of phosphorylation in the regulation of ciliary assembly, trafficking and signal transduction after 5 minutes treatment. ERK/MAPK signaling besides protein kinase A signaling and mTOR signaling were differentially regulated. Activation of Polo-like kinase 1 and inhibtion of Caseinkinase 2A1 was characteristic for Vismodegib treatment while SAG treatment induced Aurora kinase A activity. Distinctive phosphorylation of central players of sonic Hh signaling such as Smoothened, SUFU, Gli2 and Gli3 was obtained after 15 minutes treatment.
Project description:Purpose: The response to Hedgehog signaling in the limb is driven by GLI bound enhancers and the majority of Hh targets in the developing limb bud are regulated solely by the activity of GLI-repressor. Currently, we do not have a comprehensive understanding of how GLI bound enhancers respond to Hedgehog signaling. The goal of this study is to identify how GLI bound enhancers are regulated by Hedgehog signaling and specifically by GLI-repressor. Methods: ATAC-seq was done in embryonic day 10.5 posterior limb buds from control and Shh-null embryos to identify GLI enhancers that change chromatin accessibility in response to Hedgehog signaling. Results: We found that Hedgehog signaling regulates the chromatin accessibility of a subset of GLI binding regions. This subset of GLI bound enhancers has reduced accessibility in the absence of Hedgehog signaling and largely overlaps with GLI enhancers that also have reduced H3K27ac in the absence of Hedgehog signaling.
Project description:Regulation of the Hedgehog pathway activity may be supported by coactivators and corepresors of its main effectors- Gli transcription factors. While activation processes are well studied, repression mechanisms remain elusive. We identified chromatin remodelling complex Hira to interact with Gli3R protein, showed that its loss-of-function changes Hh pathway activity, and examined possible mechanism behind the observed effect. We also established that Hira influences the viability and migratory abilities of Hh-dependent medulloblastoma Daoy cells. Our study paves the way for a better understanding of processes involved in Hh pathway regulation and Hh-dependent carcinogenesis. This work was supported by grant from the National Science Centre (NCN): PRELUDIUM 2022/45/N/NZ3/02113.
Project description:Regulation of the Hedgehog pathway activity may be supported by coactivators and corepresors of its main effectors- Gli transcription factors. While activation processes are well studied, repression mechanisms remain elusive. We identified chromatin remodelling complex Hira to interact with Gli3R protein, showed that its loss-of-function changes Hh pathway activity, and examined possible mechanism behind the observed effect. We also established that Hira influences the viability and migratory abilities of Hh-dependent medulloblastoma Daoy cells. Our study paves the way for a better understanding of processes involved in Hh pathway regulation and Hh-dependent carcinogenesis. This work was supported by grant from the National Science Centre (NCN): PRELUDIUM 2022/45/N/NZ3/02113.
Project description:Cellular signaling pathways rely on posttranslational modifications (PTMs) to finely regulate protein functions, particularly transcription factors. The Hedgehog (Hh) signaling cascade, crucial for embryonic development and tissue homeostasis, is susceptible to aberrations that lead to developmental anomalies and various cancers. At the core of Hh signaling are Gli proteins, whose dynamic balance between activator (GliA) and repressor (GliR) states shapes cellular outcomes. Phosphorylation, orchestrated by multiple kinases, is pivotal in regulating Gli activity. While kinases in this context have been extensively studied, the role of protein phosphatases, particularly Protein Phosphatase 2A (PP2A), remains less explored. This study unveils a novel role for the B'' gamma subunit of PP2A, PPP2R3C, in Hh signaling regulation. PPP2R3C interacts with Gli proteins, and its disruption reduces Hedgehog pathway activity. Moreover, we establish a connection between PPP2R3C and MEKK1 kinase in Gli protein phosphorylation, underscoring the intricate interplay between kinases and phosphatases in Hh signaling pathway. This study sheds light on the previously understudied role of protein phosphatases in Hh signaling and provides insights into their significance in cellular regulation.