Project description:The SP/KLF family of transcription factors harbour three C-terminal C2H2 zinc fingers interspersed by two linkers which confers DNA-binding to a 9-10bp motif. Mutations in KLF1, the founding member of the family, are common. Missense mutations in linker two result in a mild phenotypes. However, when co-inherited with loss-of-function mutations, they result in severe non-spherocytic hemolytic anemia. We generated a mouse model of this disease by crossing Klf1+/- mice with Klf1H350R/+ mice that harbour a missense mutation in linker-2. Klf1H350R/- mice exhibit severe hemolysis without thalassemia. RNA-seq demonstrated loss of expression of genes encoding transmembrane and cytoskeletal proteins, but not globins. ChIP-seq showed no change in DNA-binding specificity, but a global reduction in affinity, which was confirmed using recombinant proteins and in vitro binding assays. This study provides new insights into how linker mutations in zinc finger transcription factors result in different phenotypes to those caused by loss-of-function mutations.
Project description:The SP/KLF family of transcription factors harbour three C-terminal C2H2 zinc fingers interspersed by two linkers which confers DNA-binding to a 9-10bp motif. Mutations in KLF1, the founding member of the family, are common. Missense mutations in linker two result in a mild phenotypes. However, when co-inherited with loss-of-function mutations, they result in severe non-spherocytic hemolytic anemia. We generated a mouse model of this disease by crossing Klf1+/- mice with Klf1H350R/+ mice that harbour a missense mutation in linker-2. Klf1H350R/- mice exhibit severe hemolysis without thalassemia. RNA-seq demonstrated loss of expression of genes encoding transmembrane and cytoskeletal proteins, but not globins. ChIP-seq showed no change in DNA-binding specificity, but a global reduction in affinity, which was confirmed using recombinant proteins and in vitro binding assays. This study provides new insights into how linker mutations in zinc finger transcription factors result in different phenotypes to those caused by loss-of-function mutations.
Project description:We describe a case of severe neonatal anemia with kernicterus due to compound heterozygosity for null mutations in KLF1, each inherited from asymptomatic parents. One of the mutations is novel. This is the first described case of a KLF1 null human. The phenotype of severe DAT-negative non-spherocytic hemolytic anaemia (NSHA), jaundice, hepato-splenomegaly, and marked erythroblastosis is more severe than that present in CDA type IV due to dominant mutations in the second zinc-finger of KLF1. There was a very high level of HbF expression into childhood (>70%), consistent with a key role for KLF1 in human hemoglobin switching. We performed RNA-seq on circulating erythroblasts and found human KLF1 acts like mouse Klf1 to coordinate expression of many genes required to build a red cell including those encoding globins, cytoskeletal components, AHSP, heme synthesis enzymes, cell cycle regulators, and blood group antigens. We identify novel KLF1 target genes including KIF23 and KIF11 which are required for proper cytokinesis. We also identify new roles for KLF1 in autophagy, global transcriptional control and RNA splicing. We suggest loss of KLF1 should be considered in otherwise unexplained cases of severe neonatal NSHA or hydrops fetalis. mRNA sequencing on peripheral blood from a family trio (mother, father and proband) where parents were asymptomatic and proband had severe neonatal anemia.
Project description:Klf1 (formerly known as Eklf) regulates the development of erythroid cells from bi-potent progenitor cells via the transcriptional activation of a diverse set of genes. Mice lacking Klf1 die in utero prior to E15 from severe anemia due to the inadequate expression of genes controlling hemoglobin production, cell membrane and cytoskeletal integrity, and the cell cycle and proliferation. We have recently described the full repertoire of Klf1 binding sites in vivo by performing Klf1 ChIP-seq in primary erythroid tissue (E14.5 fetal liver). Here we describe the Klf1-dependent erythroid transcriptome by comparing mRNA-seq from Klf1+/+ and Klf1-/- erythroid tissue. This has revealed novel target genes not previously obtainable by traditional microarray technology and provided novel insights into the function of Klf1 as a transcriptional activator such as interactions with Gata1, Scl/Tal1 and p300. We also describe a set of erythroid specific promoters not previously identified that drive high level expression of otherwise ubiquitously expressed genes in erythroid cells. Additionally, our study has identified for the first time two novel lnc-RNAs that are dynamically expressed during erythroid differentiation as well as a role for Klf1 in directing apoptotic gene expression to drive the terminal stages of erythroid maturation. Examination of mRNA expression in 3 Klf1-/- and 3 Klf1+/+ fetal livers This submission represents mRNA-Seq component of study.
Project description:We describe a case of severe neonatal anemia with kernicterus due to compound heterozygosity for null mutations in KLF1, each inherited from asymptomatic parents. One of the mutations is novel. This is the first described case of a KLF1 null human. The phenotype of severe DAT-negative non-spherocytic hemolytic anaemia (NSHA), jaundice, hepato-splenomegaly, and marked erythroblastosis is more severe than that present in CDA type IV due to dominant mutations in the second zinc-finger of KLF1. There was a very high level of HbF expression into childhood (>70%), consistent with a key role for KLF1 in human hemoglobin switching. We performed RNA-seq on circulating erythroblasts and found human KLF1 acts like mouse Klf1 to coordinate expression of many genes required to build a red cell including those encoding globins, cytoskeletal components, AHSP, heme synthesis enzymes, cell cycle regulators, and blood group antigens. We identify novel KLF1 target genes including KIF23 and KIF11 which are required for proper cytokinesis. We also identify new roles for KLF1 in autophagy, global transcriptional control and RNA splicing. We suggest loss of KLF1 should be considered in otherwise unexplained cases of severe neonatal NSHA or hydrops fetalis.
Project description:Klf1 (formerly known as Eklf) regulates the development of erythroid cells from bi-potent progenitor cells via the transcriptional activation of a diverse set of genes. Mice lacking Klf1 die in utero prior to E15 from severe anemia due to the inadequate expression of genes controlling hemoglobin production, cell membrane and cytoskeletal integrity, and the cell cycle and proliferation. We have recently described the full repertoire of Klf1 binding sites in vivo by performing Klf1 ChIP-seq in primary erythroid tissue (E14.5 fetal liver). Here we describe the Klf1-dependent erythroid transcriptome by comparing mRNA-seq from Klf1+/+ and Klf1-/- erythroid tissue. This has revealed novel target genes not previously obtainable by traditional microarray technology and provided novel insights into the function of Klf1 as a transcriptional activator such as interactions with Gata1, Scl/Tal1 and p300. We also describe a set of erythroid specific promoters not previously identified that drive high level expression of otherwise ubiquitously expressed genes in erythroid cells. Additionally, our study has identified for the first time two novel lnc-RNAs that are dynamically expressed during erythroid differentiation as well as a role for Klf1 in directing apoptotic gene expression to drive the terminal stages of erythroid maturation.
Project description:The p21 RAS subfamily of small GTPases, including KRAS, HRAS, and NRAS, regulates cell proliferation, cytoskeletal organization and other signaling networks, and is the most frequent target of activating mutations in cancer. Activating germline mutations of KRAS and HRAS cause severe developmental abnormalities leading to Noonan, cardio-facial-cutaneous and Costello syndrome, but activating germline mutations of NRAS have not been reported. Autoimmune lymphoproliferative syndrome (ALPS) is the most common genetic disease of lymphocyte apoptosis and causes autoimmunity as well as excessive lymphocyte accumulation, particularly of CD4-, CD8- ab T cells. Mutations in ALPS typically affect CD95 (Fas/APO-1)-mediated apoptosis, one of the extrinsic death pathways involving tumor necrosis factor receptor (TNFR) superfamily proteins, but certain ALPS individuals have no such mutations. We show here that the salient features of ALPS as well as a predisposition to hematological malignancies can be caused by a heterozygous germline Gly13Asp activating mutation of the NRAS oncogene that does not impair CD95-mediated apoptosis. The increase in active, GTP-bound NRAS augments RAF/MEK/ERK signaling which markedly decreases the pro-apoptotic protein BIM and attenuates intrinsic, nonreceptor-mediated mitochondrial apoptosis. Thus, germline activating mutations in NRAS differ from other p21 Ras oncoproteins by causing selective immune abnormalities without general developmental defects. Our observations on the effects of NRAS activation indicate that RAS-inactivating drugs, such as farnesyl-transferase inhibitors (FTIs) should be examined in human autoimmune and lymphocyte homeostasis disorders. Experiment Overall Design: Describes the discovery of a new gene underlying a novel type of autoimmune lymphoproliferative syndrome, and characterizes the mechanisms involved in the pathogenesis of the disease.
Project description:In this study we investigated how changes in pH and ocean chemistry consistent with the scenarios of the Intergovernmental Panel on Climate Change (IPCC) drive major changes in gene expression, respiration, photosynthesis and symbiosis of the coral, Acropora millepora, long before they affect biomineralization. Changes in gene expression were consistent with metabolic suppression, an increase in oxidative stress, apoptosis and symbiont loss. Other expression patterns demonstrated up-regulation of membrane transporters, as well as the regulation of genes involved in membrane cytoskeletal interactions and cytoskeletal remodeling. These widespread changes in gene expression emphasize the need to expand future studies of ocean acidification to include a wider spectrum of cellular processes, many of which may occur well before impacts on calcification.
Project description:KLF1 (EKLF) regulates a diverse suite of genes to direct erythroid cell differentiation from bi-potent progenitors. To determine the local cis-regulatory contexts and transcription factor networks in which KLF1 operates, we performed KLF1 ChIP-seq in the mouse. We found at least 945 sites in the genome of E14.5 fetal liver erythroid cells which are occupied by endogenous KLF1. Many of these recovered sites reside in erythroid gene promoters such as β-globin, but the majority are distant to any known gene. Our data suggests KLF1 directly regulates most aspects of terminal erythroid differentiation including production of α and β-globin protein chains, heme biosynthesis, co-ordination of proliferation and anti-apoptotic pathways, and construction of the red cell membrane and cytoskeleton by functioning primarily as a transcriptional activator. Additionally, we suggest new mechanisms for KLF1 co-operation with other transcription factors, in particular the erythroid transcription factor GATA1, to maintain homeostasis in the erythroid compartment. Examination of KLF1 occupancy in primary erythroid cells. KLF1-ChIP and input samples were run on AB SOLiD Systems 2.0 and 3.0. The genomic alignment files (*sorted.txt) and peak file (*bed) contain the combined System 2.0 and 3.0 data.