Hem6: an ENU-induced recessive hypochromic microcytic anemia mutation in the mouse.
Ontology highlight
ABSTRACT:
SUBMITTER: Tian M
PROVIDER: S-EPMC2581980 | biostudies-literature |
REPOSITORIES: biostudies-literature
Similar Datasets
Project description:Mouse models of red blood cell abnormalities are important for understanding the underlying molecular mechanisms of human erythrocytic diseases. DBA.B6-Mha (Microcytic hypochromic anemia) congenic mice were generated from the cross between N-ethyl-N-nitrosourea (ENU)-mutagenized male C57BL/6J and female DBA/2J mice as part of the RIKEN large-scale ENU mutagenesis project. The mice were established by backcrossing with DBA/2J mice for more than 20 generations. These mice showed autosomal-dominant microcytic hypochromic anemia with decreased mean corpuscular volume (MCV) and mean corpuscular hemoglobin (MCH) levels and increased red blood cell distribution width (RDW) and plasma ferritin levels. Linkage analysis indicated that the Mha locus was located within an interval of approximately 1.95-Mb between D16Nut1 (58.35 Mb) and D16Mit185 (60.30 Mb) on mouse chromosome 16. Mutation analysis revealed that DBA.B6-Mha mice had a point mutation (c.921-2A>G) at the acceptor site of intron 4 in the coproporphyrinogen oxidase (Cpox) gene, a heme-synthesizing gene. RT-PCR revealed that the Cpox mRNA in DBA.B6-Mha mice caused splicing errors. Our results suggest that microcytic hypochromic anemia in DBA.B6-Mha mice is owing to impaired heme synthesis caused by splice mutations in Cpox. Therefore, the DBA.B6-Mha mice may be used to elucidate the molecular mechanisms underlying microcytic hypochromic anemia caused by mutations in Cpox. Although low MCV levels are known to confer malarial resistance to the host, there were no marked changes in the susceptibility of DBA.B6-Mha mice to rodent malarial (Plasmodium yoelii 17XL) infection.
| S-EPMC9671764 | biostudies-literature
Project description:Most common microcytic hypochromic anemias are iron deficiency anemia (IDA) and ?-thalassemia trait (BTT), in which oxidative stress (OxS) has an essential role. Catalase causes detoxification of H2O2 in cells, and it is an indispensable antioxidant enzyme. The study was designed to measure erythrocyte catalase activity (ECAT) in patients with IDA (10) or BTT (21), to relate it with thalassemia mutation type (? (0) or ? (+)) and to compare it with normal subjects (67). Ninety-eight individuals were analyzed since September 2013 to June 2014 in Tucumán, Argentina. Total blood count, hemoglobin electrophoresis at alkaline pH, HbA2, catalase, and iron status were performed. ?-thalassemic mutations were determined by real-time PCR. Normal range for ECAT was 70,0-130,0?MU/L. ECAT was increased in 14% (3/21) of BTT subjects and decreased in 40% (4/10) of those with IDA. No significant difference (p = 0,245) was shown between normal and BTT groups, while between IDA and normal groups the difference was proved to be significant (p = 0,000). In ? (0) and ? (+) groups, no significant difference (p = 0,359) was observed. An altered ECAT was detected in IDA and BTT. These results will help to clarify how the catalase activity works in these anemia types.
| S-EPMC4615862 | biostudies-literature
Project description:Krüppel-like factor 1 (KLF1) regulates erythroid lineage commitment, globin switching, and the terminal maturation of red blood cells. Variants in human KLF1 have been identified as an important causative factor in a wide spectrum of phenotypes. This study investigated two unrelated male children in China who had refractory anemia associated with poikilocythemia. These were accompanied by an upregulation of biochemical markers of hemolysis, along with abnormal hemoglobin (Hb) level and elevated reticulocyte counts. Next-generation sequencing revealed that the patients were compound heterozygotes for a KLF1 frameshift mutation c.525_526insCGGCGCC (p.(Gly176ArgfsTer179)) and one of two missense variants, c.892?G>C (p.(Ala298Pro)) and c.1012C>T (p.(Pro338Ser)). The subjects had microcytic hypochromic anemia, and their healthy parents had single mutation. The two missense mutations affected a highly conserved codon in the zinc finger DNA-binding domain of KLF1, but the protein stability was unaffected in K-562 cells. A KLF1-targeted promoter-reporter assay showed that the two mutations reduce the expression of the HBB, BCL11A, and CD44 genes involved in erythropoiesis, with consequent dyserythropoiesis and an ?/non-? chain imbalance. A systematic analysis was performed of the phenotypes associated with the KLF1 mutations in the two families, and the clinical characteristics and differential diagnoses of the disease are presented. This is the first report of an autosomal recessive anemia presenting with microcytic hypochromia, abnormal Hb profile, and other distinctive erythrocyte phenotypes, and provides insight into the multiple roles of KLF1 during erythropoiesis.
| S-EPMC4592085 | biostudies-literature
Project description:Divalent metal-iron transporter 1 (DMT1) is a mammalian iron transporter encoded by the SLC11A2 gene. DMT1 has a vital role in iron homeostasis by mediating iron uptake in the intestine and kidneys and by recovering iron from recycling endosomes after transferrin endocytosis. Mutations in SLC11A2 cause an ultra-rare hypochromic microcytic anemia with iron overload (AHMIO1), which has been described in eight patients so far. Here, we report two novel cases of this disease. The first proband is homozygous for a new SLC11A2 splicing variant (c.762 + 35A > G), becoming the first ever patient reported with a SLC11A2 splicing mutation in homozygosity. Splicing studies performed in this work confirm its pathogenicity. The second proband harbors the previously reported DMT1 G75R mutation in homozygosis. Functional studies with the G75R mutation in HuTu 80 cells demonstrate that this mutation results in improper DMT1 accumulation in lysosomes, which correlates with a significant decrease in DMT1 levels in patient-derived lymphoblast cell lines (LCLs). We also suggest that recombinant erythropoietin would be an adequate therapeutic approach for AHMIO1 patients as it improves their anemic state and may possibly contribute to mobilizing excessive hepatic iron.
| S-EPMC9024435 | biostudies-literature
Project description:Iron is essential for all cells but is toxic in excess, so iron absorption and distribution are tightly regulated. Serum iron is bound to transferrin and enters erythroid cells primarily via receptor-mediated endocytosis of the transferrin receptor (Tfr1). Tfr1 is essential for developing erythrocytes and reduced Tfr1 expression is associated with anemia. The transcription factors STAT5A/B are activated by many cytokines, including erythropoietin. Stat5a/b(-/-) mice are severely anemic and die perinatally, but no link has been made to iron homeostasis. To study the function of STAT5A/B in vivo, we deleted the floxed Stat5a/b locus in hematopoietic cells with a Tie2-Cre transgene. These mice exhibited microcytic, hypochromic anemia, as did lethally irradiated mice that received a transplant of Stat5a/b(-/-) fetal liver cells. Flow cytometry and RNA analyses of erythroid cells from mutant mice revealed a 50% reduction in Tfr1 mRNA and protein. We detected STAT5A/B binding sites in the first intron of the Tfr1 gene and found that expression of constitutively active STAT5A in an erythroid cell line increased Tfr1 levels. Chromatin immunoprecipitation experiments confirmed the binding of STAT5A/B to these sites. We conclude that STAT5A/B is an important regulator of iron update in erythroid progenitor cells via its control of Tfr1 transcription.
| S-EPMC2518907 | biostudies-literature
Project description:The aim of this study was to identify and characterize the causative mutation in the thrombocytopenic mouse strain HLB219 that was generated at the Jackson Laboratory as part of a large-scale N-ethyl-N-nitrosourea mutagenesis screen.The HLB219 mutation was identified by interval mapping of F2 mice generated from intercross breeding of HLB219 to both BALB/cByJ (BALB) and 129/SvImJ (129/Sv). Mpl was identified as a candidate gene and sequenced. The mutation was characterized in vivo in mouse hematopoietic stem/progenitor cell assays and in cell culture by expression in Ba/F3 cells.A novel mutation in the thrombopoietin (TPO) receptor Mpl in HLB219 mice caused a Cys-->Arg substitution at codon 40 in the extracellular region of the receptor. Mice homozygous for the Mpl(hlb219) mutation had an 80% decrease in the number of platelets in comparison to the wild-type C57BL/6J strain, low numbers of bone marrow megakaryocytes, high TPO levels, and decreased competitive repopulating ability, consistent with a loss-of-function mutation in the receptor. Mice heterozygous for Mpl(hlb219) however, showed an overdominance effect with a significant increase in platelet number. Functional analysis in vitro demonstrated that Ba/F3 cells expressing the mutant MPL(hlb219) protein failed to activate extracellular signal-regulated kinase and signal transducers and activators of transcription 5, but proliferated in the absence of TPO and required constitutive phosphorylation of RAC-alpha serine/threonine protein kinase (AKT) for cytokine-independent growth.Thrombocytopenia in HLB219 mice is caused by a recessive mutation in Mpl that abrogates mitogen-activated protein kinase-extracellular signal regulated kinase and janus kinase-signal transducers and activators of transcription signaling.
| S-EPMC2656350 | biostudies-literature
Project description:GU-AG consensus sequences are used for intron recognition in the majority of cases of pre-mRNA splicing in eukaryotes. Mutations at splice junctions often cause exon skipping, short deletions, or insertions in the mature mRNA, underlying one common molecular mechanism of genetic diseases. Using N-ethyl-N-nitrosourea, a novel recessive mutation named seal was produced, associated with fragile bones and susceptibility to fractures (spine and limbs). A single nucleotide transversion (T → A) at the second position of intron 36 of the Col1a1 gene, encoding the type I collagen, α1 chain, was responsible for the phenotype. Col1a1 seal mRNA expression occurred at greatly reduced levels compared to the wild-type transcript, resulting in reduced and aberrant collagen fibers in tibiae of seal homozygous mice. Unexpectedly, splicing of Col1a1 seal mRNA followed the normal pattern despite the presence of the donor splice site mutation, likely due to the action of a putative intronic splicing enhancer present in intron 25, which appeared to function redundantly with the splice donor site of intron 36. Seal mice represent a model of human osteogenesis imperfecta, and reveal a previously unknown mechanism for splicing "rescue."
| S-EPMC5600972 | biostudies-literature
Project description:We identified a novel fertile autosomal recessive mutation called peewee that results in dwarfing, in a region-specific ENU-induced mutagenesis. These mice at litter size were smaller those of other strains. Histological analysis revealed that the major organs appear normal, but abnormalities in cellular proliferation were observed in bone, liver, and testis. Haplotype analysis localized the peewee gene to a 3.3-Mb region between D5Mit83 and D5Mit356.3. There are 18 genes in this linkage area. We also performed in silico mapping using the PosMed(SM) program, which searches for connections among keywords and genes in an interval, but no similar phenotype descriptions were found for these genes. In the peewee mutant compared to the normal C57BL/6 J mouse, only Slc10a4 expression was lower. Our preliminary mutation analysis examining the nucleotide sequence of three exons, two introns, and an untranslated region of Slc10a4 did not find any sequence difference between the peewee mouse and the C57BL/6 J mouse. Detailed analysis of peewee mice might provide novel molecular insights into the complex mechanisms regulating body growth.
| S-EPMC2921851 | biostudies-literature
Project description:ContextGenetic lipodystrophies are rare disorders characterized by partial or complete loss of adipose tissue and predisposition to insulin resistance and its complications such as diabetes mellitus, hypertriglyceridemia, hepatic steatosis, acanthosis nigricans, and polycystic ovarian syndrome.ObjectiveThe objective of the study was to report a novel autosomal recessive lipodystrophy syndrome.ResultsWe report the detailed phenotype of two males and one female patient, 26-34 yr old, belonging to two pedigrees with an autosomal recessive syndrome presenting with childhood-onset lipodystrophy, muscle atrophy, severe joint contractures, erythematous skin lesions, and microcytic anemia. Other variable clinical features include hypergammaglobulinemia, hepatosplenomegaly, generalized seizures, and basal ganglia calcification. None of the patients had diabetes mellitus or acanthosis nigricans. Two had mild hypertriglyceridemia and all had low levels of high-density lipoprotein cholesterol. Skin biopsy of an erythematous nodular skin lesion from one of the patients revealed evidence of panniculitis. The lipodystrophy initially affected the upper body but later became generalized involving abdomen and lower extremities as well.ConclusionsWe conclude that these patients represent a novel autoinflammatory syndrome resulting in joint contractures, muscle atrophy, microcytic anemia, and panniculitis-induced lipodystrophy. The molecular genetic basis of this disorder remains to be elucidated.
| S-EPMC2936059 | biostudies-literature
Project description:Genetic ablation of the ferrireductase STEAP3, also known as TSAP6, leads to severe microcytic and hypochromic red cells with moderate anemia in the mouse. However, the mechanism leading to anemia is poorly understood. Previous results indicate that TSAP6/Steap3 is a regulator of exosome secretion. Using TSAP6/Steap3 knockout mice, we first undertook a comprehensive hematologic characterization of the red cell compartment, and confirmed a dramatic decrease in the volume and hemoglobin content of these erythrocytes. We observed marked anisocytosis as well as the presence of fragmenting erythrocytes. Consistent with these observations, we found by ektacytometry decreased membrane mechanical stability of knockout red cells. However, we were unable to document significant changes in the expression levels of the major skeletal and transmembrane proteins to account for this decrease in the membrane stability. Furthermore, there were no differences in red cell survival between wild type and knockout animals. However, when we monitored erythropoiesis, we found a decreased number of proerythroblasts in the bone marrow of TSAP6/Steap3(-/-) animals. In addition, progression from the proerythroblastic to the orthochromatic stage was affected, with accumulation of cells at the polychromatic stage. Altogether, our findings demonstrate that abnormal erythroid maturation is the main cause of anemia in these mice.
| S-EPMC4333063 | biostudies-literature