Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UMLS:C0038002 (splenomegaly)
 9,873 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Previous studies in transgenic mice and cultured cells have indicated that the major enhancer function for erythroid cell expression of the globin genes is provided by the heterodimeric basic-leucine zipper transcription factor NF-E2. Globin gene expression within cultured mouse erythroleukemia cells is highly dependent on NF-E2. To examine the requirement for this factor in vivo, we used homologous recombination in embryonic stem cells to generate mice lacking the hematopoietic-specific subunit, p45 NF-E2. The most dramatic aspect of the homozygous mutant mice was an absence of circulating platelets, which led to the death of most animals due to hemorrhage. In contrast, the effect of loss of NF-E2 on the erythroid lineage was surprisingly mild. Although neonates exhibited severe anemia and dysmorphic red-cell changes, probably compounded by concomitant bleeding, surviving adults exhibited only mild changes consistent with a small decrease in the hemoglobin content per cell. p45 NF-E2-null mice responded to anemia with compensatory reticulocytosis and splenomegaly. Globin chain synthesis was balanced, and switching from fetal to adult globins progressed normally. Although these findings are consistent with the substitution of NF-E2 function in vivo by one or more compensating proteins, gel shift assays using nuclear extracts from p45 NF-E2-null mice failed to reveal novel complexes formed on an NF-E2 binding site. Thus, regulation of globin gene transcription through NF-E2 binding sites in vivo is more complex than has been previously appreciated.
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PMID:Erythropoiesis and globin gene expression in mice lacking the transcription factor NF-E2. 756 98

Expression of the p45 subunit of transcription factor NF-E2 is restricted to selected blood cell lineages, including megakaryocytes and developing erythrocytes. Mice lacking p45 NF-E2 show profound thrombocytopenia, resulting from a late arrest in megakaryocyte differentiation, and a number of red blood cell defects, including anisocytosis and hypochromia. Here we report results of studies aimed to explore the pathophysiology of these abnormalities. Mice lacking NF-E2 produce very few platelet-like particles that display highly disorganized ultrastructure and respond poorly to platelet agonists, features consistent with the usually lethal hemorrhage in these animals. Thrombocytopenia was evident during fetal life and was not corrected by splenectomy in adults. Surprisingly, fetal NF-E2-deficient megakaryocyte progenitors showed reduced proliferation potential in vitro. Thus, NF-E2 is required for regulated megakaryocyte growth as well as for differentiation into platelets. All the erythroid abnormalities were reproduced in lethally irradiated wild-type recipients of hematopoietic cells derived from NF-E2-null fetuses. Whole blood from mice lacking p45 NF-E2 showed numerous small red blood cell fragments; however, survival of intact erythrocytes in vivo was indistinguishable from control mice. Considered together, these observations indicate a requirement for NF-E2 in generating normal erythrocytes. Despite impressive splenomegaly at baseline, mice lacking p45 NF-E2 survived splenectomy, which resulted in increased reticulocyte numbers. This reveals considerable erythroid reserve within extra-splenic sites of hematopoiesis and suggests a role for the spleen in clearing abnormal erythrocytes. Our findings address distinct aspects of the requirements for NF-E2 in blood cell homeostasis and establish its roles in proper differentiation of megakaryocytes and erythrocytes.
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PMID:Pathophysiology of thrombocytopenia and anemia in mice lacking transcription factor NF-E2. 1055 87