Project description:Postnatal period of development is critical for mammalian tissues and is coordinated through precise activation of genetic programs that govern differentiation, growth and maturation. Here, we describe a cell type- and developmental stage-specific program of alternative splicing that drives sequential replacement of fetal-to-adult protein isoforms in the mouse liver. Using deep transcriptome analysis of loss- & gain-of-function models we identified Epithelial Splicing regulatory protein 2 (ESRP2) as the major regulator for these developmental splicing decisions. Targeted deletion of ESRP2 in mice resulted in the failure of fetal-to-adult switch in splicing for hundreds of RNA transcripts that encode proteins involved in functional competence of hepatocytes. To delineate its role in activation of adult splicing program, we generated transgenic mice with tetracycline-inducible and hepatocyte-specific expression of ESRP2. Remarkably, premature expression of ESRP2 in the livers of newborn pups forced an earlier-than-normal onset of adult splicing program. To determine the in vivo ESRP2 RNA binding landscape within hepatocytes, we used CRISPR-Cas9 technology to FLAG-tag the endogenous locus of ESRP2 in mice and performed FLAG-eCLIP to identify genomewide binding sites. We identified ESRP2 as a regulator of miR-122 levels in hepatocytes, wherein this axis balances the polyploidization and proliferation states in postnatal hepatocytes.
Project description:A defining feature of the mammalian liver is polyploidy, a numerical change in the entire complement of chromosomes. The first step of polyploidization involves cell division with failed cytokinesis. Although polyploidy is common, affecting ~90% of hepatocytes in mice and 50% in humans, the specialized role played by polyploid cells in liver homeostasis and disease remains poorly understood. The goal of this study was to identify novel signals that regulate polyploidization, and we focused on microRNAs (miRNAs). First, to test whether miRNAs could regulate hepatic polyploidy we examined livers from Dicer1 liver-specific knockout mice, which are devoid of mature miRNAs. Loss of miRNAs resulted in a 3-fold reduction in binucleate hepatocytes, indicating that miRNAs regulate polyploidization. Secondly, we surveyed age-dependent expression of miRNAs in wild-type mice and identified a subset of miRNAs, including miR-122, that is differentially expressed at 2-3 weeks, a period when extensive polyploidization occurs. Next, we examined Mir122 knockout mice and observed profound, life-long depletion of polyploid hepatocytes, proving that miR-122 is required for complete hepatic polyploidization. Moreover, the polyploidy defect in Mir122 knockout mice was ameliorated by adenovirus-mediated over-expression of miR-122, underscoring the critical role miR-122 plays in polyploidization. Finally, we identified direct targets of miR-122 (Cux1, Rhoa, Iqgap1, Mapre1, Nedd4l and Slc25a34) that regulate cytokinesis. Inhibition of each target induced cytokinesis failure and promoted hepatic binucleation. Conclusion: Our data demonstrate that miR-122 is both necessary and sufficient in liver polyploidization. Among the different signals that have been associated with hepatic polyploidy, miR-122 is the first liver-specific signal identified. These studies will serve as the foundation for future work investigating miR-122 in liver maturation, homeostasis and disease. Livers from C57Bl/6 mice were isolated at defined ages: embryonic day 15.5 (n=3; mixed gender), 2 weeks (n=3; male), 3 weeks (n=3, male) and 7 weeks (n=3; male). Differential miRNA expression was assessed using the nCounter Mouse miRNA Expression Assay Kit (nanoString).
Project description:A defining feature of the mammalian liver is polyploidy, a numerical change in the entire complement of chromosomes. The first step of polyploidization involves cell division with failed cytokinesis. Although polyploidy is common, affecting ~90% of hepatocytes in mice and 50% in humans, the specialized role played by polyploid cells in liver homeostasis and disease remains poorly understood. The goal of this study was to identify novel signals that regulate polyploidization, and we focused on microRNAs (miRNAs). First, to test whether miRNAs could regulate hepatic polyploidy we examined livers from Dicer1 liver-specific knockout mice, which are devoid of mature miRNAs. Loss of miRNAs resulted in a 3-fold reduction in binucleate hepatocytes, indicating that miRNAs regulate polyploidization. Secondly, we surveyed age-dependent expression of miRNAs in wild-type mice and identified a subset of miRNAs, including miR-122, that is differentially expressed at 2-3 weeks, a period when extensive polyploidization occurs. Next, we examined Mir122 knockout mice and observed profound, life-long depletion of polyploid hepatocytes, proving that miR-122 is required for complete hepatic polyploidization. Moreover, the polyploidy defect in Mir122 knockout mice was ameliorated by adenovirus-mediated over-expression of miR-122, underscoring the critical role miR-122 plays in polyploidization. Finally, we identified direct targets of miR-122 (Cux1, Rhoa, Iqgap1, Mapre1, Nedd4l and Slc25a34) that regulate cytokinesis. Inhibition of each target induced cytokinesis failure and promoted hepatic binucleation. Conclusion: Our data demonstrate that miR-122 is both necessary and sufficient in liver polyploidization. Among the different signals that have been associated with hepatic polyploidy, miR-122 is the first liver-specific signal identified. These studies will serve as the foundation for future work investigating miR-122 in liver maturation, homeostasis and disease.
Project description:Alternative splicing greatly expands the proteomic diversity but its functional impact is often unclear. Here, we identify a highly conserved and temporally coordinated cell-type-specific splicing program, which is activated in part by ESRP2 during postnatal liver development. Consistent with failure of many neonatal-to-adult splicing transitions, Esrp2 null mice exhibit persistent expression of fetal markers and loss of mature hepatocyte characteristics. Conversely, ectopic expression of ESRP2 in immature mouse or human hepatocytes results in a reciprocal switch in splicing. Our findings define an essential role for ESRP2 in generation of conserved repertoires of adult splice isoforms that facilitate postnatal liver maturation. Mouse liver RNA was isolated with Trizol (Invitrogen). Hi-Seq libraries were prepared and paired-end 100bp Illumina sequencing was performed on mouse liver samples from different developmental stages.
Project description:Alternative splicing greatly expands the proteomic diversity but its functional impact is often unclear. Here, we identify a highly conserved and temporally coordinated cell-type-specific splicing program, which is activated in part by ESRP2 during postnatal liver development. Consistent with failure of many neonatal-to-adult splicing transitions, Esrp2 null mice exhibit persistent expression of fetal markers and loss of mature hepatocyte characteristics. Conversely, ectopic expression of ESRP2 in immature mouse or human hepatocytes results in a reciprocal switch in splicing. Our findings define an essential role for ESRP2 in generation of conserved repertoires of adult splice isoforms that facilitate postnatal liver maturation.
Project description:In order to study the effect of polyploidization on gene expression in the leaves of Eucalyptus urophylla, triploid obtained by sexual polyploidization and its diploid control were used as materials, and leaves at different growth stages of different ploidies were collected for transcriptome sequencing.
Project description:Near-haploid chromosome numbers have been found in less than 1% of cytogenetically reported tumors, but seem to be more common in certain neoplasms including the malignant cartilage-producing tumor chondrosarcoma. By a literature survey of published karyotypes from chondrosarcomas we could confirm that loss of chromosomes resulting in hyperhaploid-hypodiploid cells is common and that these cells may polyploidize. Sixteen chondrosarcomas were investigated by single nucleotide polymorphism (SNP) array and the majority displayed SNP patterns indicative of a hyperhaploid-hypodiploid origin, with or without subsequent polyploidization. Except for chromosomes 5, 7, 19, 20 and 21, autosomal loss of heterozygosity was commonly found, resulting from chromosome loss and subsequent duplication of monosomic chromosomes giving rise to uniparental disomy. Additional gains, losses and rearrangements of genetic material, and even repeated rounds of polyploidization, may affect chondrosarcoma cells resulting in highly complex karyotypes. Loss of chromosomes and subsequent polyploidization was not restricted to a particular chondrosarcoma subtype and, although commonly found in chondrosarcoma, binucleated cells did not seem to be involved in these events.
Project description:We found that PTC undergo polyploidization immediately after AKI induced by ischemia. To identify the mechanism controlling polyploidization of PTC, we generated single-cell RNA sequencing (scRNAseq) datasets from healthy mouse kidneys, 2 and 30 days after ischemia reperfusion injury. We found that polyploid PTC become hypertrophic and undergo polyploidization in a YAP1-related manner. In particular, YAP1 controls polyploidization of PTC via E2f7, E2f8 and Akt1. We confirmed these findings by knocking-down those genes in vitro.
Project description:Tumor-specific alternative splicing is implicated in the progression of cancer, including clear cell renal cell carcinoma (ccRCC). Using ccRCC RNA-sequencing data from The Cancer Genome Atlas, we found that epithelial splicing regulatory protein 2 (ESRP2), one of the key regulators of alternative splicing in epithelial cells, is expressed in ccRCC. ESRP2 mRNA expression did not correlate with the overall survival rate of ccRCC patients, but the expression of some ESRP-target exons correlated with the good prognosis and with the expression of Arkadia (also known as RNF111) in ccRCC. Arkadia physically interacted with ESRP2, induced polyubiquitination, and modulated its splicing function. Arkadia and ESRP2 suppressed ccRCC tumor growth in a coordinated manner. Lower expression of Arkadia correlated with advanced tumor stages and poor outcomes in ccRCC patients. This study thus reveals a novel tumor-suppressive role of the Arkadia-ESRP2 axis in ccRCC. Expression of mRNA in a ccRCC cell line OS-RC-2 under the knockdown of Arkadia or ESRP2. Knock-down of ESRP2 was confirmed by RT-PCR because of low expression of ESRP2 which resulted in non-quantitative FPKM value.
Project description:Polyploidization as the consequence of 2n gamete formation is a prominent mechanism in plant evolution. Studying its effects on the genome and its expression has both basic and applied interest. We crossed two diploid (2n=2x=16) M. sativa plants, a subsp. falcata seed parent and a coerulea x falcata pollen parent that produce a mixture of n and 2n eggs and pollen, respectively. Such cross produced full-sib diploid and tetraploid (2n=4x=32) progenies, the latter being the result of bilateral sexual polyploidization (BSP). These unique materials allowed us to investigate the effects of BSP, and separating the effect of intraspecific hybridization from those of polyploidization by comparing 2x with 4x full sib progeny plants. SSR marker segregation demonstrated tetrasomic inheritance for all chromosomes but one, demonstrating that these neotetraploids are true autotetraploids. BSP brought about increased biomass, earlier flowering, higher seed set and weight, larger leaves with larger cells. Microarray analyses with M. truncatula gene chips showed that several hundred genes, related to diverse metabolic functions, changed their expression level as a consequence of polyploidization. In addition, cytosine methylation increased in 2x but not in 4x hybrids. Our results indicate that sexual polyploidization induce significant transcriptional novelty, possibly mediated in part by DNA methylation, and phenotypic novelty that can be at the base of improved adaptation and reproductive success of tetraploid M. sativa with respect to its diploid progenitor. These polyploidy-induced changes may have promoted the adoption of tetraploid alfalfa in agriculture.