Project description:To better understand the role of Hoxa1 during embryogenesis and gain insight to the transcriptional network controlled by this gene, we carried out a large-scale screening for Hoxa1 downstream targets by performing microarray analysis. Tissue from the rhombomere 3-5 region of wildtype and Hoxa1 null embryos, including neuroectoderm, mesoderm and otic ectoderm was microdissected at the peak of Hoxa1 expression. RNA from wildtype and Hoxa1Δ/Δ samples was hybridized to the Agilent mouse whole genome array.
Project description:To better understand the role of Hoxa1 during embryogenesis and gain insight to the transcriptional network controlled by this gene, we carried out a large-scale screening for Hoxa1 downstream targets by performing microarray analysis. Tissue from the rhombomere 3-5 region of wildtype and Hoxa1 null embryos, including neuroectoderm, mesoderm and otic ectoderm was microdissected at the peak of Hoxa1 expression. RNA from wildtype and Hoxa1Δ/Δ samples was hybridized to the Agilent mouse whole genome array. Tissue from the rhombomere 3-5 region of wildtype and Hoxa1 null embryos, including neuroectoderm, mesoderm and otic ectoderm was microdissected at the peak of Hoxa1 expression (1-6 somite stage).
Project description:The homeobox gene, Hoxa1, has two different isoforms generated by alternative splicing: a full-length homeodomain-containing Hoxa1 (Hoxa1-FL), and a truncated Hoxa1 (Hoxa1-T), that lacks the homeodomain. Oncoretroviral overexpression of wildtype Hoxa1 cDNA (WT-Hoxa1), which generates both Hoxa1 isoforms, in murine hematopoietic stem and progenitor cells (HSPCs) perturbed hematopoiesis, resulting in myelodysplastic syndromes (MDS) in mice. Overexpression of a mutated Hoxa1 cDNA (MUT-Hoxa1) that generates Hoxa1-FL but not Hoxa1-T led to a more severe MDS capable of transforming to secondary acute myeloid leukemia (sAML). Similar to human MDS, DNA damage repair pathways were downregulated in Hoxa1-overexpressing hematopoietic progenitor cells. Conditional knock-in mouse models revealed a Hoxa1-FL dosage-dependent effect on MDS disease severity. Our data reveal that increased expression of Hoxa1-FL in HSPCs is sufficient to initiate MDS in mice. CD34+ cells from up to 50% of patients with MDS had elevated HOXA1-FL expression, highlighting the clinical relevance of our mouse models.
Project description:The homeobox gene, Hoxa1, has two different isoforms generated by alternative splicing: a full-length homeodomain-containing Hoxa1 (Hoxa1-FL), and a truncated Hoxa1 (Hoxa1-T), that lacks the homeodomain. Oncoretroviral overexpression of wildtype Hoxa1 cDNA (WT-Hoxa1), which generates both Hoxa1 isoforms, in murine hematopoietic stem and progenitor cells (HSPCs) perturbed hematopoiesis, resulting in myelodysplastic syndromes (MDS) in mice. Overexpression of a mutated Hoxa1 cDNA (MUT-Hoxa1) that generates Hoxa1-FL but not Hoxa1-T led to a more severe MDS capable of transforming to secondary acute myeloid leukemia (sAML). Similar to human MDS, DNA damage repair pathways were downregulated in Hoxa1-overexpressing hematopoietic progenitor cells. Conditional knock-in mouse models revealed a Hoxa1-FL dosage-dependent effect on MDS disease severity. Our data reveal that increased expression of Hoxa1-FL in HSPCs is sufficient to initiate MDS in mice. CD34+ cells from up to 50% of patients with MDS had elevated HOXA1-FL expression, highlighting the clinical relevance of our mouse models.
Project description:We recently reported an oncogenomics-guided screening approach designed to identify genetic drivers of early stage melanoma metastasis, and in this study we functionally validate the top-scoring candidate, homeobox transcription factor A1 (HOXA1), by demonstrating HOXA1‘s robust effects on melanoma cell invasion, metastasis and tumorigenicity. Transcriptome and pathway profiling analyses of cells expressing HOXA1 reveal up-regulation of factors involved in diverse cytokine pathways that include the TGFβ signaling axis, which we further demonstrate to be required for HOXA1-mediated cell invasion. Transcriptome profiling also informed HOXA1’s ability to potently down-regulate expression of microphthalmia-associated transcription factor (MITF) and other genes required for melanocyte differentiation, suggesting a mechanism by which HOXA1 expression de-differentiates cells into a pro-invasive precursor cell state concomitant with TGFβ activation. Our analysis of publicly available datasets indicate that the HOXA1-induced gene signature successfully categorizes melanoma specimens based on their metastatic potential and, importantly, is capable of stratifying melanoma patient risk for metastasis based on expression in primary tumors.
Project description:We recently reported an oncogenomics-guided screening approach designed to identify genetic drivers of early stage melanoma metastasis, and in this study we functionally validate the top-scoring candidate, homeobox transcription factor A1 (HOXA1), by demonstrating HOXA1‘s robust effects on melanoma cell invasion, metastasis and tumorigenicity. Transcriptome and pathway profiling analyses of cells expressing HOXA1 reveal up-regulation of factors involved in diverse cytokine pathways that include the TGFβ signaling axis, which we further demonstrate to be required for HOXA1-mediated cell invasion. Transcriptome profiling also informed HOXA1’s ability to potently down-regulate expression of microphthalmia-associated transcription factor (MITF) and other genes required for melanocyte differentiation, suggesting a mechanism by which HOXA1 expression de-differentiates cells into a pro-invasive precursor cell state concomitant with TGFβ activation. Our analysis of publicly available datasets indicate that the HOXA1-induced gene signature successfully categorizes melanoma specimens based on their metastatic potential and, importantly, is capable of stratifying melanoma patient risk for metastasis based on expression in primary tumors.
Project description:We recently reported an oncogenomics-guided screening approach designed to identify genetic drivers of early stage melanoma metastasis, and in this study we functionally validate the top-scoring candidate, homeobox transcription factor A1 (HOXA1), by demonstrating HOXA1 robust effects on melanoma cell invasion, metastasis and tumorigenicity. Transcriptome and pathway profiling analyses of cells expressing HOXA1 reveal up-regulation of factors involved in diverse cytokine pathways that include the TGF-beta signaling axis, which we further demonstrate to be required for HOXA1-mediated cell invasion. Transcriptome profiling also informed HOXA1 ability to potently down-regulate expression of microphthalmia-associated transcription factor (MITF) and other genes required for melanocyte differentiation, suggesting a mechanism by which HOXA1 expression de-differentiates cells into a pro-invasive precursor cell state concomitant with TGF-beta activation. Our analysis of publicly available datasets indicate that the HOXA1-induced gene signature successfully categorizes melanoma specimens based on their metastatic potential and, importantly, is capable of stratifying melanoma patient risk for metastasis based on expression in primary tumors. The HOXA1-induced transcription analysis was conducted using RNAs extracted from SkMel30 cells transduced with either control or HOXA1, followed by hybridization of labeled cDNA onto Affymetrix GeneChips (Human Genome U133Plus2.0).
Project description:We recently reported an oncogenomics-guided screening approach designed to identify genetic drivers of early stage melanoma metastasis, and in this study we functionally validate the top-scoring candidate, homeobox transcription factor A1 (HOXA1), by demonstrating HOXA1âs robust effects on melanoma cell invasion, metastasis and tumorigenicity. Transcriptome and pathway profiling analyses of cells expressing HOXA1 reveal up-regulation of factors involved in diverse cytokine pathways that include the TGFβ signaling axis, which we further demonstrate to be required for HOXA1-mediated cell invasion. Transcriptome profiling also informed HOXA1âs ability to potently down-regulate expression of microphthalmia-associated transcription factor (MITF) and other genes required for melanocyte differentiation, suggesting a mechanism by which HOXA1 expression de-differentiates cells into a pro-invasive precursor cell state concomitant with TGFβ activation. Our analysis of publicly available datasets indicate that the HOXA1-induced gene signature successfully categorizes melanoma specimens based on their metastatic potential and, importantly, is capable of stratifying melanoma patient risk for metastasis based on expression in primary tumors. The HOXA1-induced transcription analysis was conducted using RNAs extracted from WM115 cells transduced with either control or HOXA1, followed by hybridization of labeled cDNA onto Affymetrix GeneChips (Human Genome U133Plus2.0).
Project description:High-throughput RNA sequencing (RNA-Seq) has enabled accurate gene discovery and expression estimation, but robust differential analysis of gene and transcript abundances has proven difficult. We present a new algorithm, implemented in the freely available tool Cuffdiff, which integrates transcript-level expression estimation with a method to control for variability across replicate samples. Cuffdiff robustly identifies differentially regulated isoforms and genes and reveals differential splicing or promoter-preference changes. We demonstrate the accuracy of our approach through differential analysis of lung fibroblasts in response to loss of the developmental transcription factor HOXA1 and uncover a critical role for this gene in the maintenance of adult cells. We show that HOXA1 is required for lung fibroblast and HeLa cell cycle progression, and loss of HOXA1 results in significant expression level changes in thousands of individual transcripts, along with isoform switching events in key regulators of the cell cycle. Lung Fibroblasts were transfected with either a HOXA1 directed siRNA pool or a scramble non-targeting siRNA control. RNA was collected 48 hours after transfection and changes in gene expression were assayed for using Agilent microarrays.