Project description:Stat5a and Stat5b proteins are highly homologous with greater than 90% amino acid identity and share binding to the palindromic Stat5 consensus sequence, TTCNNNGAA, but individual roles of each transcription factor in breast cancer have not been thoroughly evaluated. To determine the degree of similarity between transcripts modulated by Stat5a and Stat5b proteins in human breast cancer, we utilized genome-wide transcript profiling to identify genes regulated specifically by Stat5a or Stat5b in response to prolactin. Stat5a or Stat5b was transiently overexpressed using adenoviral gene delivery in MCF7 breast cancer cells followed 16 hr serum starvation and a brief 4 hr exposure to 10nM human prolactin to identify immediate-early transcripts modulated by each transcription factor. Basal activation of Stat5a or Stat5b was not present in cells not stimulated with prolactin. mRNA from each condition was harvested and validated using the Agilent bioanalyzer. cDNA was generated and genome-wide transcript profiling was performed in triplicate using the Affymetrix HuGene 1.0 ST array.
Project description:The transcription factor STAT5 has long been recognized as an important mediator of prolactin induced mammary development during pregnancy. We have used mouse genetics and genome-wide analyses to determine how altering concentrations of STAT5A and STAT5B impacts different target promoters. Examination of genome-wide STAT5A, STAT5B, PolII and H3K4me3 in wild type (AABB) and Stat5a-null (BB) mammary tissues.
Project description:Stat5a and Stat5b proteins are highly homologous with greater than 90% amino acid identity and share binding to the palindromic Stat5 consensus sequence, TTCNNNGAA, but individual roles of each transcription factor in breast cancer have not been thoroughly evaluated. To determine the degree of similarity between transcripts modulated by Stat5a and Stat5b proteins in human breast cancer, we utilized genome-wide transcript profiling to identify genes regulated specifically by Stat5a or Stat5b in response to prolactin.
Project description:The transcription factor STAT5 has long been recognized as an important mediator of prolactin induced mammary development during pregnancy. We have used mouse genetics and genome-wide analyses to determine how altering concentrations of STAT5A and STAT5B impacts different target promoters.
Project description:The hormone, prolactin, has been implicated in breast cancer pathogenesis and regulates chromatin engagement by the transcription factor, STAT5A. STAT5A is known to inducibly bind promoters and cis-regulatory elements genome wide, though the mechanisms by which it exerts specificity and regulation of target gene expression remain enigmatic. We previously identified HDAC6 and HMGN2 as cofactors that facilitate prolactin induced, STAT5A mediated gene expression. Here, multi-condition STAT5A, HDAC6, and HMGN2 ChIP-seq with parallel condition RNA-seq are utilized to reveal the cis-regulatory landscape and cofactor dynamics underlying prolactin stimulated gene expression in breast cancer. We find that prolactin regulated genes are significantly enriched for cis-regulatory elements bound by HDAC6 and HMGN2, and that inducible STAT5A binding at enhancers, rather than promoters, conveys specificity for prolactin regulated genes. The selective HDAC6 inhibitor, ACY-241, blocks prolactin induced STAT5A chromatin engagement at cis-regulatory elements as well as a significant proportion of prolactin stimulated gene expression. We identify functional pathways known to contribute to the development and/or progression of breast cancer that are activated by prolactin and inhibited by ACY-241. Additionally, we find that the DNA sequences underlying shared STAT5A and HDAC6 binding-sites at enhancers are differentially enriched for estrogen response elements (ESR1 and ESR2 motifs) relative to enhancers bound by STAT5A alone. Gene set enrichment analysis identifies significant overlap of ERα regulated genes with genes regulated by prolactin, particularly prolactin regulated genes with promoters or enhancers co-occupied by both STAT5A and HDAC6.
Project description:STAT5A and STAT5B proteins belong to the family of signal transducers and activators of transcription. They are encoded by 2 separate genes with 91% identity in their amino acid sequences. Despite their high degree of conservation, STAT5A and STAT5B exert non-redundant functions, resulting at least in part from differences in target gene activation. To better characterize the differential contribution of STAT5A and STAT5B in gene regulation, we performed single or double knock-down of STAT5A and STAT5B using small interfering RNA. Subsequent gene expression profiling and RT-qPCR analyses of IL-3-stimulated Ba/F3-beta cells led to the identification of putative novel STAT5 target genes. Chromatin immunoprecipitation assays analyzing the corresponding gene loci identified unusual STAT5 binding sites compared to conventional STAT5 responsive elements. Some of the STAT5 targets identified are upregulated in several human cancers, suggesting that they might represent potential oncogenes in STAT5-associated malignancies. Keywords: siRNA-mediated knock-down
Project description:RNA-Seq of immortalized Stat5a-/-, Stat5b-/-, and wildtype BCR/ABLp185+ cell lines was used to identify STAT5A and STAT5B specific target genes.
Project description:Two highly conserved transcription factors STAT5A and STAT5B play an identical role in the intracellular signaling pathway upon cytokine stimulation, while gene deletion experiments have revealed separable and overlapping functions of STAT5. This questions whether the phenotypic differences in the organ development observed in the individual knockout mice result from isoform-specific functions or quantitative differences in the expression levels of each STAT5 isoform among tissues. To elucidate the redundancy and isoform-specificity of STAT5 for development at molecular levels, mice carrying only a single allele of either Stat5a or Stat5b were generated. Both of these mice overcame the lethal anemia observed in Stat5ab-null mice, indicating that development of erythroid cell lineage was totally dependent on the dosage of STAT5. The blocked progression of B cell lineage at the pre-pro B cell stage in Stat5ab-/- mice was rescued in the presence of a single allele of either Stat5a or Stat5b, while the number of total B220+ cells in bone marrow was smaller in Stat5abnull/Stat5b- mice than Stat5abnull/Stat5a- mice. The paucity of alveolar progenitor cells in the Stat5ab-null mammary epithelium was rescued by a single allele of either Stat5a but not Stat5b, suggesting cell-type dependent isoform-specific function. Genome-wide gene expression analyses revealed that different steps of cell lineage progression require different gene sets which expression requires the different isoform of STAT5 in a dose-dependent manner in the mammary epithelium. Taken together, this study demonstrates that dose-dependent isoform specificity of STAT5A and STAT5B controls progression and differentiation of each cell lineage. Six days after observation of a plug, mammary tissues from three of each Stat5a-/- mice, Stat5ab+/null mice, Stat5abnull/Stat5b- and Stat5abnull/Stat5a- mice were collected, frozen in liquid nitrogen, and stored at -70 °C
Project description:Two highly conserved transcription factors STAT5A and STAT5B play an identical role in the intracellular signaling pathway upon cytokine stimulation, while gene deletion experiments have revealed separable and overlapping functions of STAT5. This questions whether the phenotypic differences in the organ development observed in the individual knockout mice result from isoform-specific functions or quantitative differences in the expression levels of each STAT5 isoform among tissues. To elucidate the redundancy and isoform-specificity of STAT5 for development at molecular levels, mice carrying only a single allele of either Stat5a or Stat5b were generated. Both of these mice overcame the lethal anemia observed in Stat5ab-null mice, indicating that development of erythroid cell lineage was totally dependent on the dosage of STAT5. The blocked progression of B cell lineage at the pre-pro B cell stage in Stat5ab-/- mice was rescued in the presence of a single allele of either Stat5a or Stat5b, while the number of total B220+ cells in bone marrow was smaller in Stat5abnull/Stat5b- mice than Stat5abnull/Stat5a- mice. The paucity of alveolar progenitor cells in the Stat5ab-null mammary epithelium was rescued by a single allele of either Stat5a but not Stat5b, suggesting cell-type dependent isoform-specific function. Genome-wide gene expression analyses revealed that different steps of cell lineage progression require different gene sets which expression requires the different isoform of STAT5 in a dose-dependent manner in the mammary epithelium. Taken together, this study demonstrates that dose-dependent isoform specificity of STAT5A and STAT5B controls progression and differentiation of each cell lineage.