Cheung, K. | bioRxiv Science

bioRxiv2019

Androgen-regulated transcription of ESRP2 drives alternative splicing patterns in prostate cancer

Prostate is the most frequent cancer in men. Prostate cancer progression is driven by androgen steroid hormones, and delayed by androgen deprivation therapy (ADT). Androgens control transcription by stimulating androgen receptor (AR) activity, yet also control pre-mRNA splicing through less clear mechanisms. Here we find androgens regulate splicing through AR-mediated transcriptional control of the epithelial-specific splicing regulator ESRP2. Both ESRP2 and its close paralog ESRP1 are highly expressed in primary prostate cancer. Androgen stimulation induces splicing switches in many endogenous ESRP2-controlled mRNA isoforms, including a key splicing switch in the metastatic regulator FLNB which is associated with disease relapse. ESRP2 expression in clinical prostate cancer is repressed by ADT, which may thus inadvertently dampen epithelial splice programmes. Supporting this, FLNB splicing was reciprocally switched by the AR antagonist bicalutamide (Casodex(R)). Our data reveal a new mechanism of splicing control in prostate cancer with important implications for metastatic disease progression.\n\nKey pointsO_LITranscriptional regulation of ESRP2 by the androgen receptor controls splice isoform patterns in prostate cancer cells.\nC_LIO_LISplicing switches regulated by the androgen-ESRP2 axis include a splice isoform in the FLNB gene that is a known metastatic driver.\nC_LIO_LIBoth ESRP1 and ESRP2 are highly expressed in prostate cancer tissue.\nC_LIO_LIEctopic expression of ESRP1 and 2 inhibits prostate cancer cell growth.\nC_LIO_LIBy repressing ESRP2 expression androgen deprivation therapy (ADT) may dampen epithelial splicing programmes to inadvertently prime disease progression towards metastasis.\nC_LI

molecular biology↗

bioRxiv2019

Spaniel: analysis and interactive sharing of Spatial Transcriptomics data

Spatial Transcriptomics allows the sequencing of the complete transcriptomes from barcoded regions of intact tissue. The technology has the potential to answer a wide range of biological questions concerning cellular function, but analysis of the data presents a number of challenges which are not met by existing analysis tools. Here we present Spaniel, an R package providing a framework for analysing and sharing Spatial Transcriptomics data.

bioinformatics↗

bioRxiv2019

DNA hypomethylation during MSC chondrogenesis occurs predominantly at enhancer regions

SummaryRegulation of transcription occurs in a cell type specific manner by epigenetic mechanisms including DNA methylation and histone modifications. Methylation changes during stem cell differentiation may play a key role in lineage specification. We sought to characterise DNA methylation changes during chondrogenesis of mesenchymal stem cells (MSCs) in order to further our understanding of epigenetic regulation in chondrocytes. The consequences of which has potential to improve cartilage generation for tissue engineering purposes and also to provide context for observed methylation changes in cartilage diseases such as osteoarthritis. We identified significant DNA hypomethylation during chondrogenesis including changes at many key cartilage gene loci. Importantly characterisation of significant CpG loci indicated their predominant localisation to enhancer regions. Comparison with adult cartilage and other tissue methylation profiles identified chondrocyte-specific regulatory regions. Taken together we have associated methylation at many CpGs with the chondrocyte phenotype.\n\nAbstractRegulation of transcription is determined in a cell type specific manner by epigenetic mechanisms including DNA methylation and histone modifications. Methylation changes during stem cell differentiation may play a role in lineage specification. Multipotent mesenchymal stem cell (MSC) differentiation into chondrocytes not only serves as a model for chondrocyte development but also provides an important source of cartilage for tissue engineering purposes. We sought to characterise DNA methylation changes during chondrogenesis to further understanding of epigenetic regulation but to also provide context for the changes identified during disease.\n\nDNA cytosine methylation changes during human MSC differentiation into chondrocytes were measured by Infinium 450K methylation array. Methylation changes at gene loci were contrasted with gene expression changes. Chromatin states of significant methylation loci were interpreted by intersection with chondrogenesis histone modification ChlP-seq data. Chondrogenic and cartilage specific hypomethylation was utilised in order to identify a chondrocyte methylome. Articular cartilage and tissue panel DNA methylation was compared and alterations during osteoarthritis cartilage disease classified.\n\nSignificant DNA hypomethylation was identified following chondrogenic differentiation of MSCs including changes at many key cartilage gene loci. Highly upregulated genes during chondrogenesis were more likely to exhibit a reduction in DNA methylation. Characterisation of significant CpG loci indicated their predominant localisation in CpG poor regions which importantly are most likely to correspond to enhancer regions. Methylation level at certain CpGs following chondrogenesis corresponds to the level found in adult cartilage.\n\nTaken together, considerable demethylation changes to the epigenetic landscape occur during MSC chondrogenesis especially at sites marked by enhancer modifications. Comparison with other tissues, including healthy and OA cartilage, associates CpGs to the chondrocyte phenotype and provides context for changes in disease.

genomics↗