Project description:Primary murine fetal liver cells were freshly isolated from day e14.5 livers and then sorted for successive differentiation stages by Ter119 and CD71 surface expression (ranging from double-negative CFU-Es to Ter-119 positive enucleated erythrocytes) [Zhang, et al. Blood. 2003 Dec 1; 102(12):3938-46]. RNA isolated from each freshly isolated, stage-sorted population was reverse-transcribed, labelled, and then hybridized onto 3' oligo Affymetrix arrays. Important erythroid specific genes as well as the proteins that regulate them were elucidated through this profiling based on coexpression and differential expression patterns as well as by extracting specific GO categories of genes (such as DNA-binding proteins). Abstract (submitted paper): rationale for expression profiling Gene-targeting experiments report that the homeodomain-interacting protein kinases 1 and 2, Hipk1 and Hipk2, are essential but redundant in hematopoietic developmentâbecause Hipk1/Hipk2 double-deficient animals exhibit severe defects in hematopoiesis and vasculogenesis while the single knockouts do not. These serine-threonine kinases phosphorylate, and consequently modify the functions of, several important hematopoietic transcription factors and cofactors. Here we show that Hipk2 knockdown alone plays a significant role in terminal fetal liver erythroid differentiation. Hipk1 and Hipk2 are highly induced during primary mouse fetal liver erythropoiesis. Specific knockdown of Hipk2 inhibits terminal erythroid cell proliferationâexplained in part by impaired cell cycle progression as well as increased apoptosisâand terminal enucleation as well as the accumulation of hemoglobin. Hipk2 knockdown also reduces the transcription of many genes involved in proliferation and apoptosis as well as important, erythroid-specific genes involved in hemoglobin biosynthesisâsuch as alpha-globin and mitoferrin 1âdemonstrating that Hipk2 plays an important role in some but not all aspects of normal terminal erythroid differentiation.

Project description:Mammals express thousands of long noncoding (lnc) RNAs, a few of which are shown to function in tissue development. However, the entire repertoire of lncRNAs and the extent to which they regulate biological processes in different tissues and species are not defined. Indeed, most lncRNAs are not conserved between species, raising questions about function. We used RNA-Seq to identify lncRNAs in primary murine fetal liver erythroblasts expressing the lineage marker TER119, megakaryocytes (CD41+) cultured from embryonic day (E) 14.5 murine fetal liver and megakaryocyte erythroid progenitors (MEPs) isolated from mouse bone marrow. We identified 683 and 594 polyadenylated lncRNAs expressed in red blood cell (erythroid) precursors of mice and humans, respectively. More than one half of erythroid lncRNAs are un-annotated, emphasizing the opportunity for new discovery through studies of specialized cell types. We analyzed the expression of these identified lncRNAs in several hematopoietic compartments using a custom microarray to identify erythroid-specific lncRNAs that were robustly expressed in both fetal liver and adult erythroid cells as targets for knockdown. Over 90% of fetal liver erythroid lncRNAs detected using RNA-seq were expressed in adult erythroblasts measured on the microarray. Analysis of the murine erythroid lncRNA transcriptome indicates that ~75% arise from promoters and 25% from enhancers, many of which are regulated by the key erythroid transcription factors GATA1 and SCL/TAL1. Erythroid lncRNA expression is largely conserved among 8 different mouse strains, yet only 15% of mouse lncRNAs are expressed in humans and vice versa, reflecting dramatically greater species-specificity than coding genes. We investigated potential functions of 21 relatively abundant erythroid-specific murine lncRNAs (both conserved and non-conserved) by RNA interference in primary mouse erythroid precursors, and identified 7 whose knockdown inhibited features of terminal erythroid maturation including cell size reduction and enucleation. Strikingly, at least 6 of the 7 lncRNAs have no detectable expression in human erythroblasts, demonstrating that lack of conservation between mammalian species does not predict lack of function. These results reflect marked evolutionary differences between protein-coding genes and lncRNAs and indicate that the latter exert tissue- and species-specific roles in development. For data usage terms and conditions, please refer to http://www.genome.gov/27528022 and http://www.genome.gov/Pages/Research/ENCODE/ENCODEDataReleasePolicyFinal2008.pdf

Project description:Mammals express thousands of long noncoding (lnc) RNAs, a few of which are shown to function in tissue development. However, the entire repertoire of lncRNAs and the extent to which they regulate biological processes in different tissues and species are not defined. Indeed, most lncRNAs are not conserved between species, raising questions about function. We used RNA-Seq to identify lncRNAs in primary murine fetal liver erythroblasts expressing the lineage marker TER119, megakaryocytes (CD41+) cultured from embryonic day (E) 14.5 murine fetal liver and megakaryocyte erythroid progenitors (MEPs) isolated from mouse bone marrow. We identified 683 and 594 polyadenylated lncRNAs expressed in red blood cell (erythroid) precursors of mice and humans, respectively. More than one half of erythroid lncRNAs are un-annotated, emphasizing the opportunity for new discovery through studies of specialized cell types. We analyzed the expression of these identified lncRNAs in several hematopoietic compartments using a custom microarray to identify erythroid-specific lncRNAs that were robustly expressed in both fetal liver and adult erythroid cells as targets for knockdown. Over 90% of fetal liver erythroid lncRNAs detected using RNA-seq were expressed in adult erythroblasts measured on the microarray. Analysis of the murine erythroid lncRNA transcriptome indicates that ~75% arise from promoters and 25% from enhancers, many of which are regulated by the key erythroid transcription factors GATA1 and SCL/TAL1. Erythroid lncRNA expression is largely conserved among 8 different mouse strains, yet only 15% of mouse lncRNAs are expressed in humans and vice versa, reflecting dramatically greater species-specificity than coding genes. We investigated potential functions of 21 relatively abundant erythroid-specific murine lncRNAs (both conserved and non-conserved) by RNA interference in primary mouse erythroid precursors, and identified 7 whose knockdown inhibited features of terminal erythroid maturation including cell size reduction and enucleation. Strikingly, at least 6 of the 7 lncRNAs have no detectable expression in human erythroblasts, demonstrating that lack of conservation between mammalian species does not predict lack of function. These results reflect marked evolutionary differences between protein-coding genes and lncRNAs and indicate that the latter exert tissue- and species-specific roles in development. For data usage terms and conditions, please refer to http://www.genome.gov/27528022 and http://www.genome.gov/Pages/Research/ENCODE/ENCODEDataReleasePolicyFinal2008.pdf A custom Agilent microarray was designed to interrogate expression levels of long noncoding RNAs identified using RNA-seq in several different hematopoietic progenitor and differentiated cell populations. LncRNA gene definitions and RNA-seq data used to identify long noncoding RNAs are deposited in GEO with the accession numbers GSE51667 and GSE40522 respectively. The Agilent eArray platform was used to customize the SurePrint G3 Mouse GE 8x60K microarray to add 3 custom-designed probes (60nt length) each against several categories of genes, namely pseudogene, genes with small RNA overlap, low stringency lncRNAs and high stringency lncRNAs . We interrogated 7 types of hematopoietic cells, HSC, CMP, MEP, GMP, early and late erythroblasts and granulocytes. Expression measurements were determined at least in duplicate for all samples and in triplicate for most samples.

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Mus musculus

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