Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UMLS:C0002871 (anemia)
 52,094 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Here, we show that the human homologue of the Caenorhabditis elegans biological clock protein CLK-2 (HCLK2) associates with the S-phase checkpoint components ATR, ATRIP, claspin and Chk1. Consistent with a critical role in the S-phase checkpoint, HCLK2-depleted cells accumulate spontaneous DNA damage in S-phase, exhibit radio-resistant DNA synthesis, are impaired for damage-induced monoubiquitination of FANCD2 and fail to recruit FANCD2 and Rad51 (critical components of the Fanconi anaemia and homologous recombination pathways, respectively) to sites of replication stress. Although Thr 68 phosphorylation of the checkpoint effector kinase Chk2 remains intact in the absence of HCLK2, claspin phosphorylation and degradation of the checkpoint phosphatase Cdc25A are compromised following replication stress as a result of accelerated Chk1 degradation. ATR phosphorylation is known to both activate Chk1 and target it for proteolytic degradation, and depleting ATR or mutation of Chk1 at Ser 345 restored Chk1 protein levels in HCLK2-depleted cells. We conclude that HCLK2 promotes activation of the S-phase checkpoint and downstream repair responses by preventing unscheduled Chk1 degradation by the proteasome.
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PMID:HCLK2 is essential for the mammalian S-phase checkpoint and impacts on Chk1 stability. 1738 38

Dominantly inherited beta-thalassemia (thal) or "inclusion body beta-thalassemias" are heterogeneous at the molecular level and are due to mutations at or near the beta-globin gene locus. Many of these involve mutations of exon 3 of the beta-globin gene. They include frameshifts, premature chain termination (nonsense) mutations, and complex rearrangements that lead to the synthesis of truncated or elongated and highly unstable beta-globin gene products. The resulting beta chain variants are very unstable, and in many cases, the products of the dominantly inherited beta-thal are not detectable. Hematological and clinical observations made in several families with comparable forms of beta-thal and with certain highly unstable hemoglobin (Hb) variants, have indicated a striking overlap; many subjects with detectable unstable Hb variants and with a dominant type of beta-thal without a detectable abnormal Hb, have similar phenotypes. Here, a review of dominantly inherited beta-thal is given, and new examples of hyperunstable Hbs (Hb Stara Zagora and Hb Jambol) are presented. The first example is a hyperunstable variant named Hb Stara Zagora that was found in a 2-year-old Bulgarian boy. The abnormal Hb is associated with severe hemolytic anemia as a consequence of its hyper instability. The anemia was noticed at the age of 2 months and since then he has been on a regular monthly blood transfusion regimen. Hemoglobin analysis revealed no abnormalities, except the presence of inclusion bodies. Sequencing of the beta-globin gene revealed a heterozygosity for a 6 bp deletion (-TGGCTA) at codons 137 (the second and third bp), 138 and 139 (the first bp), thus forming a new codon at position 139 (GAT). This event eliminates three amino acids (Val-Ala-Asn) and introduces a new residue (Asp). It creates a new restriction site for HphI. The parents and his twin brother had no history of hemolysis. The paternity of the child was confirmed by DNA analysis. The second example is a new hyperunstable variant named Hb Jambol, found as a de novo mutation in a 2-year-old Bulgarian girl with severe hemolytic anemia. The mutation was detected through RNA/DNA analysis. It represents a complex genomic rearrangement involving an insertion of 23 nucleotides (nts) after IVS-II-535, a deletion of 310 nts extending from IVS-II-550 to the first nt of codon 108, and an insertion of 28 nts at the deletion junctions (derived from inverted sequence between nts +3707 and +3734 3' to the beta-globin gene termination codon). At the protein level, this mutation leads to a deletion of four amino acid residues (Leu-Leu-Glu-Asn) at positions 105, 106, 107 and 108, and an insertion of nine residues (Val-Pro-Ser-Val-Thr-Leu-Phe-Phe-Asp) at the same location, creating an abnormal elongated beta chain of 151 amino acid residues. The parents had no history of hemolysis. The paternity of the child was confirmed by DNA analysis.
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PMID:Dominantly Inherited beta-Thalassemia. 1748 3

A group comprising 27 young children (1-4 y of age) suffering from uncomplicated falciparum malaria were studied to characterize the isolates and to measure humoral immune responses during acute infection and after recovery. Finger prick blood from each individual was collected on d 1. After treatment with chloroquine, a further blood sample was collected from each child on d 7, 30, 90 and 180 for assay of antibody responses to P. falciparum antigens. Isolates from individual patients were incubated in vitro for demonstration of rosette formation, assay of plasmodial growth rate and analysis of Pfcrt gene polymorphism. Out of 27 isolates of P. falciparum, 20 showed formation of rosettes in vitro. The growth rate at 96 h varied widely among the isolates. In Pfcrt gene analysis at 76-codon site, 14 showed wild-type Lys 76, 7 showed mutant type Thr 76 and 6 had mixed type. 14 children, all with anaemia on d 7, showed a positive direct antiglobulin test (DAT). Sera positive by ELISA IgG on d 90 also showed parasite growth inhibitory activity in vitro. Significant levels of IgG, IgG1 and IgG3 subclass antibodies against MSP1 were detected in 14 sera collected on d 90. On d 180, there was a decline in IgG and its subtypes. These findings suggest that a variability in isolates may occur in one and the same seasonal area, making children prone to infection. As a consequence, they develop antibodies during recovery phase from an acute attack, which remain in circulation for a period of 4-5 months. After that, a decline in antibody level may again make them susceptible to the disease. Prevalence of different serotypes in a small area may suggest the complexity of malaria transmission.
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PMID:A longitudinal investigation of Plasmodium falciparum malaria in children in northern India. 1785 23

Infection of domestic cats with feline immunodeficiency virus (FIV) is an important model system for studying human immunodeficiency virus type 1 (HIV-1) infection due to numerous similarities in pathogenesis induced by these two lentiviruses. However, many molecular aspects of FIV replication remain poorly understood. It is well established that retroviruses use short peptide motifs in Gag, known as late domains, to usurp cellular endosomal sorting machinery and promote virus release from infected cells. For example, the Pro-Thr/Ser-Ala-Pro [P(T/S)AP] motif of HIV-1 Gag interacts directly with Tsg101, a component of the endosomal sorting complex required for transport I (ESCRT-I). A Tyr-Pro-Asp-Leu (YPDL) motif in equine infectious anemia virus (EIAV), and a related sequence in HIV-1, bind the endosomal sorting factor Alix. In this study we sought to identify and characterize FIV late domain(s) and elucidate cellular machinery involved in FIV release. We determined that mutagenesis of a PSAP motif in FIV Gag, small interfering RNA-mediated knockdown of Tsg101 expression, and overexpression of a P(T/S)AP-binding fragment of Tsg101 (TSG-5') each inhibited FIV release. We also observed direct binding of FIV Gag peptides to Tsg101. In contrast, mutagenesis of a potential Alix-binding motif in FIV Gag did not affect FIV release. Similarly, expression of the HIV-1/EIAV Gag-binding domain of Alix (Alix-V) did not disrupt FIV budding, and FIV Gag peptides showed no affinity for Alix-V. Our data demonstrate that FIV relies predominantly on a Tsg101-binding PSAP motif in the C terminus of Gag to promote virus release in HeLa cells, and this budding mechanism is highly conserved in feline cells.
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PMID:Molecular characterization of feline immunodeficiency virus budding. 1809 66

Apoptin, a protein of the chicken anemia virus (CAV), consists of 121 amino acids (aa) and represents a novel, potentially tumor-specific therapeutic and diagnostic agent. The C-terminal part of Apoptin (aa 81-121) is believed to contain a bipartite nuclear localization signal (NLS) (NLS1: aa 82-88 and NLS2: aa 111-121), which is only active in tumor cells after phosphorylation of threonine(108) by tumor-specific cytoplasmic phosphokinases. Furthermore, a nuclear export signal (NES) (aa 97-105) seems to enable nuclear export of Apoptin only in healthy cells. The specificity for tumor cell nuclei also applies to the truncated C-terminal part of Apoptin (aa 81-121), which therefore represents a highly attractive peptide sequence for peptide synthesis. Here we describe for the first time the synthesis of fluorescein isothiocyanate (FITC)- and Dansyl-labelled conjugates containing this C-terminal part of Apoptin, with either phosphorylated or nonphosphorylated threonine(108). The phosphorylated conjugates were synthesized in an attempt to achieve nuclear accumulation in healthy cells, which lack cytoplasmic tumor-specific phosphokinases. Surprisingly, all the conjugates accumulated rapidly within the cell nuclei of both tumor and non-tumor cells from the bladder, brain and prostate and led to cell death. By coupling Apoptin(81-121) to FITC and DOTA (1,4,7,10-tetraazacyclododecane-1,4,7,10-tetraacetic acid) at either the C- or N-terminus we could exlude that the coupling site is decisive for tumor cell-specific nuclear localization. The labels FITC, DOTA and Dansyl were not responsible for cell death in healthy cells because cell death was not prevented by using an unlabelled Apoptin(81-121) peptide. Cellular and nuclear uptake of the FITC-labelled Apoptin(81-121) peptide was almost completely abolished after altering the NLS2 (replacement of five arginines with serines).
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PMID:Value of apoptin's 40-amino-acid C-terminal fragment for the differentiation between human tumor and non-tumor cells. 1831 87

Phosphorylations within N- and C-terminal degrons independently control the binding of cyclin E to the SCF(Fbw7) and thus its ubiquitination and proteasomal degradation. We have now determined the physiologic significance of cyclin E degradation by this pathway. We describe the construction of a knockin mouse in which both degrons were mutated by threonine to alanine substitutions (cyclin E(T74A T393A)) and report that ablation of both degrons abolished regulation of cyclin E by Fbw7. The cyclin E(T74A T393A) mutation disrupted cyclin E periodicity and caused cyclin E to continuously accumulate as cells reentered the cell cycle from quiescence. In vivo, the cyclin E(T74A T393A) mutation greatly increased cyclin E activity and caused proliferative anomalies. Cyclin E(T74A T393A) mice exhibited abnormal erythropoiesis characterized by a large expansion of abnormally proliferating progenitors, impaired differentiation, dysplasia, and anemia. This syndrome recapitulates many features of early stage human refractory anemia/myelodysplastic syndrome, including ineffective erythropoiesis. Epithelial cells also proliferated abnormally in cyclin E knockin mice, and the cyclin E(T74A T393A) mutation delayed mammary gland involution, implicating cyclin E degradation in this anti-mitogenic response. Hyperproliferative mammary epithelia contained increased apoptotic cells, suggesting that apoptosis contributes to tissue homeostasis in the setting of cyclin E deregulation. Overall these data show the critical role of both degrons in regulating cyclin E activity and reveal that complete loss of Fbw7-mediated cyclin E degradation causes spontaneous and cell type-specific proliferative anomalies.
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PMID:Cyclin E phosphorylation regulates cell proliferation in hematopoietic and epithelial lineages in vivo. 1855 82

In response to DNA damage or replication fork stress, the Fanconi anemia pathway is activated, leading to monoubiquitination of FANCD2 and FANCI and their colocalization in foci. Here we show that, in the chicken DT40 cell system, multiple alanine-substitution mutations in six conserved and clustered Ser/Thr-Gln motifs of FANCI largely abrogate monoubiquitination and focus formation of both FANCI and FANCD2, resulting in loss of DNA repair function. Conversely, FANCI carrying phosphomimic mutations on the same six residues induces constitutive monoubiquitination and focus formation of FANCI and FANCD2, and protects against cell killing and chromosome breakage by DNA interstrand cross-linking agents. We propose that the multiple phosphorylation of FANCI serves as a molecular switch in activation of the Fanconi anemia pathway. Mutational analysis of putative phosphorylation sites in human FANCI indicates that this switch is evolutionarily conserved.
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PMID:FANCI phosphorylation functions as a molecular switch to turn on the Fanconi anemia pathway. 1898 65

alphaIIbbeta3 interaction with fibrinogen promotes Src-dependent platelet spreading in vitro. To determine the consequences of this outside-in signaling pathway in vivo, a "beta3(Delta760-762)" knockin mouse was generated that lacked the 3 C-terminal beta3 residues (arginine-glycine-threonine [RGT]) necessary for alphaIIbbeta3 interaction with c-Src, but retained beta3 residues necessary for talin-dependent fibrinogen binding. beta3(Delta760-762) mice were compared with wild-type beta3(+/+) littermates, beta3(+/-) heterozygotes, and knockin mice where beta3 RGT was replaced by beta1 C-terminal cysteine-glycine-lysine (EGK) to potentially enable signaling by Src kinases other than c-Src. Whereas beta3(+/+), beta3(+/-) and beta3/beta1(EGK) platelets spread and underwent tyrosine phosphorylation normally on fibrinogen, beta3(Delta760-762) platelets spread poorly and exhibited reduced tyrosine phosphorylation of c-Src substrates, including beta3 (Tyr(747)). Unlike control mice, beta3(Delta760-762) mice were protected from carotid artery thrombosis after vessel injury with FeCl(3). Some beta3(Delta760-762) mice exhibited prolonged tail bleeding times; however, none demonstrated spontaneous bleeding, excess bleeding after surgery, fecal blood loss, or anemia. Fibrinogen binding to beta3(Delta760-762) platelets was normal in response to saturating concentrations of protease-activated receptor 4 or glycoprotein VI agonists, but responses to adenosine diphosphate were impaired. Thus, deletion of beta3 RGT disrupts c-Src-mediated alphaIIbbeta3 signaling and confers protection from arterial thrombosis. Consequently, targeting alphaIIbbeta3 signaling may represent a feasible antithrombotic strategy.
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PMID:Antithrombotic effects of targeting alphaIIbbeta3 signaling in platelets. 1935 14

Dematin is an actin-binding protein originally identified in the junctional complex of the erythrocyte plasma membrane, and is present in many nonerythroid cells. Dematin headpiece knockout mice display a spherical red cell phenotype and develop a compensated anemia. Dematin has two domains: a 315-residue, proline-rich "core" domain and a 68-residue carboxyl-terminal villin-type "headpiece" domain. Expression of full-length dematin in E. coli as a GST recombinant protein results in truncation within a proline, glutamic acid, serine, threonine rich region (PEST). Therefore, we designed a mutant construct that replaces the PEST sequence. The modified dematin has high actin binding activity as determined by actin sedimentation assays. Negative stain electron microscopy demonstrates that the modified dematin also exhibits actin bundling activity like that of native dematin. Circular dichroism (CD) and NMR spectral analysis, however, show little secondary structure in the modified dematin. The lack of secondary structure is also observed in native dematin purified from human red blood cells. (15)N-HSQC NMR spectra of modified dematin indicate that the headpiece domain is fully folded whereas the core region is primarily unfolded. Our finding suggests that the core is natively unfolded and may serve as a scaffold to organize the components of the junctional complex.
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PMID:Dematin exhibits a natively unfolded core domain and an independently folded headpiece domain. 1924 72

Alpha-thalassaemia is a very rare disease in Northern Europe in contrast to hereditary spherocytosis that is associated with red blood cell membrane defects. We report here alpha-thalassaemia case who was also found to bear the erythrocyte membrane protein 4.2 gene mutations. mRNA relative quantification of red cell membrane protein genes in a Polish patient with alpha-thalassaemia trait indicated EPB42 as the gene that could also be involved in anaemia pathogenesis. Sequencing revealed the presence of two novel mutations in the protein 4.2 gene: a G1701A genetic change that predicts an alanine to threonine at position 567 of the protein (A567T) and a T-->A substitution that is located at position +6 of the donor splice site of intron 2 (IVS2nt+6T>A). This is the sixth variant of the erythrocyte membrane protein 4.2 gene mutations identified outside the Japanese population.
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PMID:The use of real-time PCR technique in the detection of novel protein 4.2 gene mutations that coexist with thalassaemia alpha in a single patient. 1950 87


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