Project description:Sox9 is a transcription factor expressed in most solid tumors. However, the molecular mechanisms underlying Sox9 function during tumorigenesis remain unclear. Here, using a genetic mouse model of basal cell carcinoma (BCC), the most frequent cancer in human, we show that Sox9 is expressed from the earliest step of tumor formation in a Wnt/β-catenin dependent manner. Deletion of Sox9 together with the constitutive activation of Hedgehog (HH) signaling completely prevents BCC formation and leads to a progressive loss of oncogene expressing cells. Transcriptional profiling of oncogene expressing cells with Sox9 deletion, combined with in vivo ChIP-sequencing uncovers a cancer-specific gene network regulated by Sox9 that promotes stemness, extracellular matrix (ECM) deposition and cytoskeleton remodeling while repressing epidermal differentiation. Our study identifies the molecular mechanisms regulated by Sox9 that links tumor initiation and invasion. Sox9 ChIP-seq analysis in K14CreER SmoM2 cells.
Project description:A comprehensive analysis of Sox9 binding profiles in developing chondrocytes identified marked enrichment of an AP-1-like motif (Ohba et al. 2015). Here, we have explored the functional interplay between Sox9 and AP-1 in mammalian chondrocyte development. Among AP-1 family members, Jun and Fosl2 were highly expressed within prehypertrophic and early hypertrophic chondrocytes. Chromatin immunoprecipitation followed by DNA sequencing (ChIP-seq) showed a striking overlap in Jun- and Sox9-bound regions throughout the chondrocyte genome, a reflection of direct binding of each factor to target motifs in shared enhancers, and physical interactions of AP-1 with Sox9. In vitro expression analysis indicates that direct co-binding of Sox9 and AP-1 at target motifs enhanced target gene expression, while protein-protein interactions suppressed AP-1- and Sox9-driven transcription. Analysis of prehypertrophic chondrocyte removal of Sox9 demonstrated Sox9 was essential for hypertrophic chondrocyte development, while in vitro and ex vivo analyses showed AP-1 promotes chondrocyte hypertrophy. Sox9 and Jun co-bound and co-activated a Col10a1 enhancer in Sox9 and AP-1 motif-dependent manners consistent with their combined action promoting hypertrophic gene expression. Together, the data support a model where AP-1-family members promote Sox9-action in the transition of chondrocytes to a terminal hypertrophic program. Intersection of ChIP-seq data from Sox9 and AP-1 factor Jun, RNA-seq data from developing rib chondrocytes and Col10a1mCherry positive hypertrophic chondrocytes in neonatal mice to uncover regulation of Sox9 by AP-1 factors during chondrocyte hypertrophy.
Project description:Sox9 is a transcription factor expressed in most solid tumors. However, the molecular mechanisms underlying Sox9 function during tumorigenesis remain unclear. Here, using a genetic mouse model of basal cell carcinoma (BCC), the most frequent cancer in human, we show that Sox9 is expressed from the earliest step of tumor formation in a Wnt/β-catenin dependent manner. Deletion of Sox9 together with the constitutive activation of Hedgehog (HH) signaling completely prevents BCC formation and leads to a progressive loss of oncogene expressing cells. Transcriptional profiling of oncogene expressing cells with Sox9 deletion, combined with in vivo ChIP-sequencing uncovers a cancer-specific gene network regulated by Sox9 that promotes stemness, extracellular matrix (ECM) deposition and cytoskeleton remodeling while repressing epidermal differentiation. Our study identifies the molecular mechanisms regulated by Sox9 that links tumor initiation and invasion.
Project description:A comprehensive analysis of Sox9 binding profiles in developing chondrocytes identified marked enrichment of an AP-1-like motif (Ohba et al. 2015). Here, we have explored the functional interplay between Sox9 and AP-1 in mammalian chondrocyte development. Among AP-1 family members, Jun and Fosl2 were highly expressed within prehypertrophic and early hypertrophic chondrocytes. Chromatin immunoprecipitation followed by DNA sequencing (ChIP-seq) showed a striking overlap in Jun- and Sox9-bound regions throughout the chondrocyte genome, a reflection of direct binding of each factor to target motifs in shared enhancers, and physical interactions of AP-1 with Sox9. In vitro expression analysis indicates that direct co-binding of Sox9 and AP-1 at target motifs enhanced target gene expression, while protein-protein interactions suppressed AP-1- and Sox9-driven transcription. Analysis of prehypertrophic chondrocyte removal of Sox9 demonstrated Sox9 was essential for hypertrophic chondrocyte development, while in vitro and ex vivo analyses showed AP-1 promotes chondrocyte hypertrophy. Sox9 and Jun co-bound and co-activated a Col10a1 enhancer in Sox9 and AP-1 motif-dependent manners consistent with their combined action promoting hypertrophic gene expression. Together, the data support a model where AP-1-family members promote Sox9-action in the transition of chondrocytes to a terminal hypertrophic program.
Project description:Although oncogenicity of the stem cell regulator SOX9 has been implicated in many solid tumors, its role in lymphomagenesis remains largely unknown. In this study, we showed that SOX9 is overexpressed preferentially in a subset of diffuse large B-cell lymphomas (DLBCL) harboring IGH-BCL2 translocations. SOX9 positivity in DLBCL correlates with advanced stage of disease. Silencing of SOX9 decreased cell proliferation, induced G1/S arrest and increased apoptosis of DLBCL cells, both in vitro and in vivo. Whole transcriptome analysis and CHIP-seq assays identified DHCR24, a terminal enzyme in cholesterol biosynthesis, as a direct target of SOX9, which promotes cholesterol synthesis by increasing DHCR24 expression. Enforced expression of DHCR24 was capable of rescuing the phenotypes associated with SOX9 knockdown in DLBCL cells. In DLBCL cell line xenograft models, SOX9 knockdown resulted in lower DHCR24 level, reduced cholesterol content and decreased tumor load. Pharmacological inhibition of cholesterol synthesis also inhibited DLBCL xenograft tumorigenesis, the reduction of which is more pronounced in DLBCL cell line with higher SOX9 expression, suggesting that it may be addicted to cholesterol. In summary, our study demonstrates that SOX9 can drive lymphomagenesis through DHCR24 and the cholesterol biosynthesis pathway. This SOX9-DHCR24-cholesterol 3 biosynthesis axis may serve as a novel treatment target for DLBCL.
Project description:In mammals, gonadal differentiation is the first step of sex determination, and the transcription factor Sox9 promotes testis differentiation. Here we used the XY Sox9flox/flox; Sf1:creTr/+ mouse model and show that the lack of Sox9 expression induces a full sex reversal of E13.5 XY Sox9flox/flox; Sf1:creTr/+ gonads compared to XY Sox9flox/flox. Keywords: gonads gene expression profiling in WT and Sox9flox/flox; Sf1:creTr/+ mice 3 WT versus 3 Sox9flox/flox; Sf1:creTr/+ mice.
Project description:Sox9 is a transcription factor expressed in most solid tumors. However, the molecular mechanisms underlying Sox9 function during tumorigenesis remain unclear. Here, using a genetic mouse model of basal cell carcinoma (BCC), the most frequent cancer in human, we show that Sox9 is expressed from the earliest step of tumor formation in a Wnt/β-catenin dependent manner. Deletion of Sox9 together with the constitutive activation of Hedgehog (HH) signaling completely prevents BCC formation and leads to a progressive loss of oncogene expressing cells. Transcriptional profiling of oncogene expressing cells with Sox9 deletion, combined with in vivo ChIP-sequencing uncovers a cancer-specific gene network regulated by Sox9 that promotes stemness, extracellular matrix (ECM) deposition and cytoskeleton remodeling while repressing epidermal differentiation. Our study identifies the molecular mechanisms regulated by Sox9 that links tumor initiation and invasion.
Project description:We compared Sox9-association at chondrocyte targets to a broad catalogue of regulatory indicators of chromatin organization and transcriptional activity to determine Sox9’s direct regulatory actions in normal developing chondrocytes. Sox9-associated regions resolve into two distinct regulatory categories. Class I regions closely associate with transcriptional start sites (TSSs). Their targets reflect general regulators of basal cell activities that Sox9 engages indirectly though a likely association with the basal transcriptional complex. In contrast, Class II regions outside of the local TSS domains highlight evolutionarily conserved, active enhancers directing expression of chondrocyte specific target genes, though DNA binding of Sox9-dimers at target sites with sub-optimal binding affinity. The level of associated chondrocyte gene expression correlates with the number of enhancer modules around the target gene and grouping into super-enhancer clusters. Comparison of Sox9 programs between neural crest and mesoderm-derived chondrocytes points to similar modes of chondrocyte specification in distinct chondrocyte lineages. These data provide the first insight into mammalian Sox family actions at the genome scale in the vivo setting. The resulting enhancer sets provide a key resource for further dissection of the regulatory programs of mammalian chondrogenesis. Incorportation of ChIP-seq data of Sox9 and histone modification marks for chromatin status together with micorarray gene expression profiling in neonatal mice chondrocytes to uncover Sox9 regulatory system. Overexpression of Sox9 with a control of EGFP in human fibroblasts to identify the direct targets of Sox9 regulatory system
Project description:Introduction: In addition to the well-known cartilage extracellular matrix-related expression of Sox9, we demonstrated that chondrogenic differentiation of progenitor cells is driven by a sharply defined bi-phasic expression of Sox9: an immediate early and a late (extracellular matrix associated) phase expression. In this study we aimed to determine what biological processes are driven by Sox9 during this early phase of chondrogenic differentiation. Materials: Sox9 expression in ATDC5 cells was knocked-down by siRNA transfection at the day before chondrogenic differentiation or at day 6 of differentiation. Samples were harvested at 2 hours, and 7 days of differentiation. The transcriptomes (RNA-seq approach) and proteomes (Label-free proteomics approach) were compared using pathway and network analyses. Total protein translational capacity was evaluated with the SuNSET assay, active ribosomes with polysome profiling and ribosome modus with bicistronic reporter assays. Results: Early Sox9 knockdown severely inhibited chondrogenic differentiation weeks later. Sox9 expression during the immediate early phase of ATDC5 chondrogenic differentiation regulated the expression of ribosome biogenesis factors and ribosomal protein subunits. This was accompanied by decreased translational capacity following Sox9 knockdown, and this correlated to lower amounts of active mono- and polysomes. Moreover, cap- versus IRES-mediated translation was altered by Sox9 knockdown. Sox9 overexpression was able to induce reciprocal effects to the Sox9 knockdown. Conclusion: Here we identified an essential new function for Sox9 during early chondrogenic differentiation. A role for Sox9 in regulation of ribosome amount, activity and/or composition may be crucial in preparation for the demanding proliferative phase and subsequent cartilage extracellular matrix-production of chondroprogenitors in the growth plate in vivo.
Project description:Although oncogenicity of the stem cell regulator SOX9 has been implicated in many solid tumors, its role in lymphomagenesis remains largely unknown. In this study, we showed that SOX9 is overexpressed preferentially in a subset of diffuse large B-cell lymphomas (DLBCL) harboring IGH-BCL2 translocations. SOX9 positivity in DLBCL correlates with advanced stage of disease. Silencing of SOX9 decreased cell proliferation, induced G1/S arrest and increased apoptosis of DLBCL cells, both in vitro and in vivo. Whole transcriptome analysis and CHIP-seq assays identified DHCR24, a terminal enzyme in cholesterol biosynthesis, as a direct target of SOX9, which promotes cholesterol synthesis by increasing DHCR24 expression. Enforced expression of DHCR24 was capable of rescuing the phenotypes associated with SOX9 knockdown in DLBCL cells. In DLBCL cell line xenograft models, SOX9 knockdown resulted in lower DHCR24 level, reduced cholesterol content and decreased tumor load. Pharmacological inhibition of cholesterol synthesis also inhibited DLBCL xenograft tumorigenesis, the reduction of which is more pronounced in DLBCL cell line with higher SOX9 expression, suggesting that it may be addicted to cholesterol. In summary, our study demonstrates that SOX9 can drive lymphomagenesis through DHCR24 and the cholesterol biosynthesis pathway. This SOX9-DHCR24-cholesterol 3 biosynthesis axis may serve as a novel treatment target for DLBCL.