Project description:Mammalian genomes are populated with thousands of transcriptional enhancers that orchestrate cell type-specific gene expression programs; however, the potential that there are pre-established enhancers in different functional classes that permit alternative signal-dependent transcriptional responses has remained unexplored. Here we present evidence that cell lineage-specific factors, such as FoxA1, can simultaneously facilitate and restrict key regulated transcription factors, exemplified by the androgen receptor (AR), acting at structurally- and functionally-distinct classes of pre-established enhancers, thus licensing specific signal-activated responses while restricting others. Consequently, FoxA1 down-regulation, an unfavorable prognostic sign in advanced prostate tumors, causes a massive switch in AR binding from one functional class of enhancers to another, with a parallel switch in levels of enhancer-templated non-coding RNAs (eRNAs) revealed by the global run-on assay (GRO-seq), which documents the dramatic reprogramming of the hormonal response. The molecular basis for this switch lies in the release of FoxA1-mediated restriction of AR binding to the new enhancer class with no apparent nucleosome remodeling, which is required for stimulating their eRNA transcription and/or enhancing enhancer:promoter looping and gene activation. Together, these findings reveal a large repository of pre-determined enhancers in the human genome that can be dynamically tuned to induce their transcription and activation of alternative gene expression programs, which may underlie many sequential gene expression events in development or during disease progression. ChIP-Seq, Gro-Seq, and gene expression profiling was performed in LNCaP cells with hormone treatment and siRNA against FoxA1. Gene expression profiling data presented here.
Project description:Mammalian genomes are populated with thousands of transcriptional enhancers that orchestrate cell type-specific gene expression programs; however, the potential that there are pre-established enhancers in different functional classes that permit alternative signal-dependent transcriptional responses has remained unexplored. Here we present evidence that cell lineage-specific factors, such as FoxA1, can simultaneously facilitate and restrict key regulated transcription factors, exemplified by the androgen receptor (AR), acting at structurally- and functionally-distinct classes of pre-established enhancers, thus licensing specific signal-activated responses while restricting others. Consequently, FoxA1 down-regulation, an unfavorable prognostic sign in advanced prostate tumors, causes a massive switch in AR binding from one functional class of enhancers to another, with a parallel switch in levels of enhancer-templated non-coding RNAs (eRNAs) revealed by the global run-on assay (GRO-seq), which documents the dramatic reprogramming of the hormonal response. The molecular basis for this switch lies in the release of FoxA1-mediated restriction of AR binding to the new enhancer class with no apparent nucleosome remodeling, which is required for stimulating their eRNA transcription and/or enhancing enhancer:promoter looping and gene activation. Together, these findings reveal a large repository of pre-determined enhancers in the human genome that can be dynamically tuned to induce their transcription and activation of alternative gene expression programs, which may underlie many sequential gene expression events in development or during disease progression. ChIP-Seq, Gro-Seq, and gene expression profiling was performed in LNCaP cells with hormone treatment and siRNA against FoxA1 ChIP-Seq and Gro-Seq data presented here. Supplementary file GroSeq.denovo.transcripts.hg18.bed represents analysis using GSM686948-GSM686950.
Project description:Mammalian genomes are populated with thousands of transcriptional enhancers that orchestrate cell type-specific gene expression programs; however, the potential that there are pre-established enhancers in different functional classes that permit alternative signal-dependent transcriptional responses has remained unexplored. Here we present evidence that cell lineage-specific factors, such as FoxA1, can simultaneously facilitate and restrict key regulated transcription factors, exemplified by the androgen receptor (AR), acting at structurally- and functionally-distinct classes of pre-established enhancers, thus licensing specific signal-activated responses while restricting others. Consequently, FoxA1 down-regulation, an unfavorable prognostic sign in advanced prostate tumors, causes a massive switch in AR binding from one functional class of enhancers to another, with a parallel switch in levels of enhancer-templated non-coding RNAs (eRNAs) revealed by the global run-on assay (GRO-seq), which documents the dramatic reprogramming of the hormonal response. The molecular basis for this switch lies in the release of FoxA1-mediated restriction of AR binding to the new enhancer class with no apparent nucleosome remodeling, which is required for stimulating their eRNA transcription and/or enhancing enhancer:promoter looping and gene activation. Together, these findings reveal a large repository of pre-determined enhancers in the human genome that can be dynamically tuned to induce their transcription and activation of alternative gene expression programs, which may underlie many sequential gene expression events in development or during disease progression.
Project description:Mammalian genomes are populated with thousands of transcriptional enhancers that orchestrate cell type-specific gene expression programs; however, the potential that there are pre-established enhancers in different functional classes that permit alternative signal-dependent transcriptional responses has remained unexplored. Here we present evidence that cell lineage-specific factors, such as FoxA1, can simultaneously facilitate and restrict key regulated transcription factors, exemplified by the androgen receptor (AR), acting at structurally- and functionally-distinct classes of pre-established enhancers, thus licensing specific signal-activated responses while restricting others. Consequently, FoxA1 down-regulation, an unfavorable prognostic sign in advanced prostate tumors, causes a massive switch in AR binding from one functional class of enhancers to another, with a parallel switch in levels of enhancer-templated non-coding RNAs (eRNAs) revealed by the global run-on assay (GRO-seq), which documents the dramatic reprogramming of the hormonal response. The molecular basis for this switch lies in the release of FoxA1-mediated restriction of AR binding to the new enhancer class with no apparent nucleosome remodeling, which is required for stimulating their eRNA transcription and/or enhancing enhancer:promoter looping and gene activation. Together, these findings reveal a large repository of pre-determined enhancers in the human genome that can be dynamically tuned to induce their transcription and activation of alternative gene expression programs, which may underlie many sequential gene expression events in development or during disease progression.
Project description:Mammalian genomes are populated with thousands of transcriptional enhancers that orchestrate cell-type-specific gene expression programs, but how those enhancers are exploited to institute alternative, signal-dependent transcriptional responses remains poorly understood. Here we present evidence that cell-lineage-specific factors, such as FoxA1, can simultaneously facilitate and restrict key regulated transcription factors, exemplified by the androgen receptor (AR), to act on structurally and functionally distinct classes of enhancer. Consequently, FoxA1 downregulation, an unfavourable prognostic sign in certain advanced prostate tumours, triggers dramatic reprogramming of the hormonal response by causing a massive switch in AR binding to a distinct cohort of pre-established enhancers. These enhancers are functional, as evidenced by the production of enhancer-templated non-coding RNA (eRNA) based on global nuclear run-on sequencing (GRO-seq) analysis, with a unique class apparently requiring no nucleosome remodelling to induce specific enhancer-promoter looping and gene activation. GRO-seq data also suggest that liganded AR induces both transcription initiation and elongation. Together, these findings reveal a large repository of active enhancers that can be dynamically tuned to elicit alternative gene expression programs, which may underlie many sequential gene expression events in development, cell differentiation and disease progression.
Project description:Although stromal cell signaling has been shown to play a significant role in the progression of many cancers, relatively little is known about its importance in modulating ovarian cancer development. The purpose of this study was to investigate the process of stroma activation in human ovarian cancer by molecular analysis of matched sets of cancer and surrounding stroma tissues. RNA microarray profiling of 45 tissue samples was carried out using the Affymetrix (U133 Plus 2.0) gene expression platform. Laser capture microdissection (LCM) was employed to isolate cancer cells from the tumors of ovarian cancer patients (Cepi) and matched sets of surrounding cancer stroma (CS). For controls, ovarian surface epithelial cells (OSE) were isolated from the normal (noncancerous) ovaries and normal stroma (NS). Hierarchical clustering of the microarray data resulted in clear separations between the OSE, Cepi, NS, and CS samples. Expression patterns of genes encoding signaling molecules and compatible receptors in the CS and Cepi samples indicate the existence of two subgroups of cancer stroma (CS) with different propensities to support tumor growth. Our results indicate that functionally significant variability exists among ovarian cancer patients in the ability of the microenvironment to modulate cancer development.
Project description:In primates, C-fibre polymodal nociceptors are broadly classified into two groups based on mechanosensitivity. Here we demonstrate that mechanically sensitive polymodal nociceptors that respond either quickly (QC) or slowly (SC) to a heat stimulus differ in responses to a mild burn, heat sensitization, conductive properties and chemosensitivity. Superficially applied capsaicin and intradermal injection of ?-alanine, an MrgprD agonist, excite vigorously all QCs. Only 40% of SCs respond to ?-alanine, and their response is only half that of QCs. Mechanically insensitive C-fibres (C-MIAs) are ?-alanine insensitive but vigorously respond to capsaicin and histamine with distinct discharge patterns. Calcium imaging reveals that ?-alanine and histamine activate distinct populations of capsaicin-responsive neurons in primate dorsal root ganglion. We suggest that histamine itch and capsaicin pain are peripherally encoded in C-MIAs, and that primate polymodal nociceptive afferents form three functionally distinct subpopulations with ?-alanine responsive QC fibres likely corresponding to murine MrgprD-expressing, non-peptidergic nociceptive afferents.
Project description:AbtractForkhead box A1 (FOXA1) is a pioneer transcription factor that is essential for the normal development of several endoderm-derived organs, including the prostate gland1,2. FOXA1 is frequently mutated in hormone-receptor-driven prostate, breast, bladder and salivary-gland tumours3-8. However, it is unclear how FOXA1 alterations affect the development of cancer, and FOXA1 has previously been ascribed both tumour-suppressive9-11 and oncogenic12-14 roles. Here we assemble an aggregate cohort of 1,546 prostate cancers and show that FOXA1 alterations fall into three structural classes that diverge in clinical incidence and genetic co-alteration profiles, with a collective prevalence of 35%. Class-1 activating mutations originate in early prostate cancer without alterations in ETS or SPOP, selectively recur within the wing-2 region of the DNA-binding forkhead domain, enable enhanced chromatin mobility and binding frequency, and strongly transactivate a luminal androgen-receptor program of prostate oncogenesis. By contrast, class-2 activating mutations are acquired in metastatic prostate cancers, truncate the C-terminal domain of FOXA1, enable dominant chromatin binding by increasing DNA affinity and-through TLE3 inactivation-promote metastasis driven by the WNT pathway. Finally, class-3 genomic rearrangements are enriched in metastatic prostate cancers, consist of duplications and translocations within the FOXA1 locus, and structurally reposition a conserved regulatory element-herein denoted FOXA1 mastermind (FOXMIND)-to drive overexpression of FOXA1 or other oncogenes. Our study reaffirms the central role of FOXA1 in mediating oncogenesis driven by the androgen receptor, and provides mechanistic insights into how the classes of FOXA1 alteration promote the initiation and/or metastatic progression of prostate cancer. These results have direct implications for understanding the pathobiology of other hormone-receptor-driven cancers and rationalize the co-targeting of FOXA1 activity in therapeutic strategies.
Project description:Epigenetic regulation of gene enhancer elements is important for establishing and maintaining the identity of cells. Gene enhancer elements are thought to exist in either active or poised states distinguishable by chromatin features, but a complete understanding of the regulation of enhancers is lacking. Here, by using mouse embryonic stem cells and their differentiated derivatives, as well as terminally differentiated cells, we report the coexistence of multiple, defined classes of enhancers that serve distinct cellular functions. Specifically, we found that active enhancers can be subclassified based on varying levels of H3K4me1, H3K27ac, and H3K36me3 and the pSer2/5 forms of RNA polymerase II. The abundance of these histone modifications positively correlates with the expression of associated genes and cellular functions consistent with the identity of the cell type. Poised enhancers can also be subclassified based on presence or absence of H3K27me3 and H3K9me3, conservation, genomic location, expression levels of associated genes, and predicted function of associated genes. These findings not only refine the repertoire of histone modifications at both active and poised gene enhancer elements but also raise the possibility that enhancers associated with distinct cellular functions are partitioned based on specific combinations of histone modifications.