KLF1 null neonates display hydrops fetalis and a deranged erythroid transcriptome
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ABSTRACT: 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: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. Examination of mRNA expression in 3 Klf1-/- and 3 Klf1+/+ fetal livers This submission represents mRNA-Seq component of study.
Project description:Prolonged rupture of membranes (PROM) is thought to incur higher risk of neonatal infection, leading to expedited delivery and/or the use of empirical perinatal antibiotics. Here, we compared the transcriptional profile of neonatal cord blood between babies where rupture of membranes occurred greater than 24 hours before delivery (= PROM cases) and babies where rupture of membranes occurred less than 24 hours before delivery (= Control cases). On the basis that perinatal infection is more likely in births associated with PROM than those without, we tested the hypothesis that perinatal infection in a subset of births following PROM, exhibit immune responses evident in the neonatal cord blood transcriptome.
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:Infection with the human T lymphotropic virus type 1 (HTLV-1) remains asymptomatic in the majority of carriers; however, some 5% develop a chronic inflammation of the central nervous system termed HTLV-1-associated myelopathy (HAM). It is not well understood how the virus triggers the onset of HAM after many years of clinical latency and importantly, what distinguishes hosts who develop the disease from those who remain asymptomatic. In a previous study we identified a 80-gene transcriptional signature of HAM based in the hypothesis that patients with HAM can be distinguished from asymptomatic HTLV-1 carriers (ACs) and uninfected subjects by their whole blood transcriptional profiles. In this study we wished to validate the 80-gene signature on an independent cohort comprising 17 asymptomatic HTLV-1 carriers (ACs), 10 patients with HAM and 8 uninfected healthy control subjects. Patients attending the HTLV-1 clinic at St Mary’s hospital in London, UK were classified according to their clinical status as asymptomatic HTLV-1 carriers (ACs, n=17), patients with HTLV-1-associated meylopathy (HAM, n=10) or uninfected control subjects (n=8). Three ml of blood were drawn into a Tempus tube (Applied Biosystems, Foster City, CA, USA). Total RNA was extracted, globin mRNA depleted and following cRNA generation samples were analysed on HUmanWG6 v3 Illumina BeadChip arrays.
Project description:Infection with the human T lymphotropic virus type 1 (HTLV-1) remains asymptomatic in the majority of carriers; however, some 5% develop a chronic inflammation of the central nervous system termed HTLV-1-associated myelopathy (HAM). It is not well understood how the virus triggers the onset of HAM after many years of clinical latency and importantly, what distinguishes hosts who develop the disease from those who remain asymptomatic. In this study we tested the hypothesis that patients with HAM can be distinguished from asymptomatic HTLV-1 carriers (ACs) and uninfected subjects by their whole blood transcriptional profiles. Here, we compare unstimulated whole blood gene expression profiles of 20 asymptomatic HTLV-1 carriers (ACs), 10 patients with HAM and 9 uninfected healthy control subjects to (1) identify a transcriptional signature associated with presence of HAM and (2) identify cell types and pathways abnormally regulated in HAM by canonical and modular pathway analysis. Patients attending the HTLV-1 clinic at St Mary’s hospital in London, UK were classified according to their clinical status as asymptomatic HTLV-1 carriers (ACs, n=20), patients with HTLV-1-associated meylopathy (HAM, n=10) or uninfected control subjects (n=9). HTLV-1 proviral load (PVL) can differ among individuals by more than 10-fold and is typically higher in patients with HAM than in ACs, with a 1% PVL cut off generally separating disease from asymptomatic carriage. Thus, ACs were subdivided into AC low PVL (<1% infected PBMCs) and AC high PVL (>1% infected PBMCs). Three ml of blood were drawn into a Tempus tube (Applied Biosystems, Foster City, CA, USA). Total RNA was extracted, globin mRNA depleted and following cRNA generation samples were analysed on HUmanHT12 v3 Illumina BeadChip arrays.
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:EKLF/Klf1 is a Zinc-finger transcription activator essential for erythroid lineage commitment and terminal differentiation. Using ChIP-Seq, we investigate EKLF DNA binding and transcription activation mechanisms during mouse embryonic erythropoiesis. Our study focuses on global EKLF binding dynamics during embryonic erythropoiesis in primary WT and Nan/+ mouse fetal liver, and its correlation with chromatin accessibility, CBP occupancy, histone acetylation, and finally its effect on RNA Polymerase II pausing and elongation. Our goal is to elucidate the mechanisms of transcription activation by EKLF/Klf1 during embryonic erythropoiesis in vivo and in the context of RNA pol II pause-release control. Additionally, we aim to understand the unusually severe effects of conservative E to D change in Nan-EKLF and the molecular mechanisms leading to dominant anemia through global gene dysregulation.
Project description:The Krüppel-like factors, KLF1 and KLF2, positively regulate embryonic β-globin expression, and have additional overlapping roles in embryonic (primitive) erythropoiesis. KLF1-/-KLF2-/- double knockout mice are anemic at embryonic day 10.5 (E10.5) and die by E11.5, in contrast to single knockouts. To investigate the combined roles of KLF1 and KLF2 in primitive erythropoiesis, expression profiling of E9.5 erythroid cells was performed. A limited number of genes had a significantly decreasing trend of expression in wild-type, KLF1-/- and KLF1-/-KLF2-/-. Among these, c-myc emerged as a central node in the most significant gene network. c-myc expression is synergistically regulated by KLF1 and KLF2, and both factors bind the c-myc promoters. To characterize the role of c-myc in primitive erythropoiesis, ablation was performed specifically in mouse embryonic proerythroblast cells. After E9.5, these embryos exhibit an arrest in the normal expansion of circulating red cells and develop anemia analogous to KLF1-/-KLF2-/-. In the absence of c-myc, circulating erythroid cells do not show the normal increase in α- and β-like globin expression, but interestingly, have accelerated erythroid maturation, between E9.5 and E11.5. This study reveals a novel regulatory network by which KLF1 and KLF2 regulate c-myc, to control the primitive erythropoietic program. Timed-pregnant KLF1+/-, KLF1+/- KLF2+/- females were anesthetized and sacrificed. E9.5 yolk sacs were dissected from the embryo, cryoprotected in 20% sucrose in PBS and frozen in OCT media. A small portion of the embryo tail was used for PCR genotyping. Eight micron frozen yolk sac sections were obtained and laser capture microdissection (LCM) was used to isolate primitive erythroid precursors. For each biological replicate, 2 to 4 yolk sacs from 2 different litters were used. Total RNA was isolated from 8 different wild-type, 3 KLF1-/-, 3 KLF1-/- KLF2-/- erythroid samples and hybridized to Affymetrix 430 A 2.0 microarrays.