Mutation of the surface-exposed amino acid Trp to Ala in the FVIII C2 domain results in defective secretion of the otherwise functional protein

The C2 domain of factor VIII (FVIII) is important for FVIII-phospholipid (PL) and FVIII-von Willebrand factor (VWF) interactions. A FVIII structural model, derived by electron crystallography, suggests four hydrophobic loops at the FVIII C2 domain-PL interface. Within loop four, the solvent-exposed amino acid, Trp(2313), is believed to contribute to FVIII-PL binding. To analyse this interaction, the amino-acid exchange Trp(2313) to Ala (W2313A) was introduced into the C2 domain of B-domain-deleted FVIII (dBFVIII). Both proteins, dBFVIII and W2313A, were expressed in a mammalian expression system. Labelling experiments showed that the mutation W2313A resulted in reduced secretion but did not affect intracellular synthesis of the protein. Specific activity, kinetic parameters, binding to VWF and haemostatic potential in a murine model of haemophilia A were found to be similar for both proteins. Binding studies to synthetic 4% phosphatidyl-l-serine vesicles showed, however, a 28-fold higher K(D) for W2313A, indicating the important role of Trp(2313) in the FVIII-PL interaction. In conclusion, the C2-domain-surface-exposed residue Trp(2313), is critical for secretion of the protein. The W2313A mutation weakens binding to phosphatidyl-l-serine vesicles but the mutant protein has the same effector function as dBFVIII in vitro and in vivo.     

Restriction in the repertoire of the immunoglobulin light chain subgroup in pathological cold agglutinins with anti-Pr specificity

BACKGROUND AND OBJECTIVES: In cold agglutinin disease, monoclonal red blood cell autoantibodies, termed cold agglutinins, induce haemolysis in patients exposed to the cold. Commonly, these autoantibodies are directed against the developmentally regulated I/i blood groups. A second blood group system, the Pr system (located on glycophorins), is involved less frequently. Anti-Pr cold agglutinins recognize either alpha 2,3- or alpha 2,6-linked N-acetylneuraminic acid as the immunodominant group. Cold agglutinins of anti-I/i specificity show a remarkable restriction in their genomic repertoire of the immunoglobulin heavy and light-chain immunoglobulin-variable domain (i.e. exclusive use of VH4-34 in heavy chains). For anti-Pr cold agglutinins, preliminary data on the repertoire of the light-chain variable domain indicate a preference for the subgroup Vkappa IV. To elucidate restrictions in the light-chain variable-domain subgroup repertoire of anti-Pr cold agglutinins systematically, and to discuss these results in the context of their anti-Pr(1-3) subclassification and immunodominant sialic acid, light chains in 13 anti-Pr cold agglutinins were investigated. MATERIALS AND METHODS: The anti-Pr light chains were isolated using temperature-dependent absorption/elution techniques. Subsequently, they were subjected to N-terminal Edman degradation, and the light chain Vkappa subgroup was affiliated using the Kabat database. RESULTS: Five of 13 (38%) light chains belonged to Vkappa IV, five of 13 (38%) to Vkappa I and three of 13 (23%) to Vkappa III. Anti-Pr with Vkappa IV subgroup light chains exclusively recognized alpha 2,3-linked N-acetylneuraminic acid. CONCLUSIONS: Including data from the literature, the repertoire of the light-chain variable domain in pathological anti-Pr cold agglutinins exhibits a clear bias towards the use of the single germline gene-derived subgroup, Vkappa IV (eight of 17 or 47%). The association of Vkappa IV subgroup light chain-containing anti-Pr cold agglutinins with binding to alpha 2,3-, but not alpha 2,6-linked N-acetyneuraminic acid raises speculations about a possible role of subgroup-derived determinants in anti-Pr binding.     

A PKR-like eukaryotic initiation factor 2alpha kinase from zebrafish contains Z-DNA binding domains instead of dsRNA binding domains

The double-stranded RNA (dsRNA)-dependent protein kinase (PKR) is induced as part of the IFN response in mammals and acts to shut down protein synthesis by the phosphorylation of eukaryotic initiation factor 2alpha (eIF2alpha). In fish, a PKR-like kinase activity has been detected, but the enzyme responsible has eluded characterization. Here, we describe a PKR-like kinase from zebrafish. Phylogenetic analysis shows that the C-terminal kinase domain is more closely related to the kinase domain of PKR than to any of the other three known eIF2alpha kinases. Surprisingly, instead of the two dsRNA binding domains found at the N terminus of PKR, there are two Zalpha domains. Zalpha domains specifically bind dsDNA and RNA in the left-handed Z conformation, often with high affinity. They have been found previously in two other IFN-inducible proteins, the dsRNA editing enzyme, ADAR1, and Z-DNA binding protein 1 (ZBP1), as well as in the poxvirus virulence factor, E3L. This previously undescribed kinase, designated PKZ (protein kinase containing Z-DNA binding domains), is transcribed constitutively at low levels and is highly induced after injection of poly(inosinic)-poly(cytidylic) acid, which simulates viral infection. Binding of Z-DNA by the Zalpha domain of PKZ was demonstrated by circular dichroism. PKZ inhibits translation in transfected cells; site-directed mutagenesis indicates that this inhibition depends on its catalytic activity. Identification of a gene combining Zalpha domains with a PKR-like kinase domain strengthens the hypothesis that the ability to bind left-handed nucleic acid plays a role in the host response to viruses.     

急性心肌缺血时高频心电图时域频域分析的实验研究

结扎家兔冠状动脉左室支的不同部位，用高频心电图时域频域法观察中高频成分、甚高频成分的变化。结果表明:缺血面积小于３５％时，中高频成分、甚高频成分随缺血范围的增大而增加；若缺血面积大于３５％时，中高频成分、甚高频成分减少。     

心肌细胞凋亡的信号传导机制研究

细胞凋亡在心血管疾病发病机制中扮演了重要角色 ,细胞凋亡信号的异常表达使心肌细胞数量不断减少 ,其中含有 BH3( Bcl-2 Homology3 )结构域的凋亡促进分子 (如 Bax,Bid,BNIP3等 )在凋亡信号传导途径中发挥了重要作用。     

过表达microRNA-144通过靶向调节泛素样PHD和环指结构域1基因诱导非小细胞肺癌凋亡

目的探讨microRNA-144 (miR-144)对非小细胞肺癌(Non-small-cell lung cancer,NSCLC)细胞增殖以及预后的影响。方法通过癌症基因组图谱(The cancer genome atlas,TCGA)检测NSCLC患者组织中miR-144以及泛素样PHD和环指结构域包含1(Ubiquitin like PHD and ring finger domain 1,UHRF1)的表达预后以及两者表达的相关性。采用CCK-8、AO/EB以及γH2A检测不同表达miR-144对NSCLC细胞活性、细胞凋亡、增殖以及DNA损伤的影响,Western blot检测PCNA、Bax、Bcl-2及UHRF1的表达。荧光素酶报告证明miR-144以及UHRF1的靶向关系。结果在NSCLC患者组织中,miR-144表达水平较低,低表达miR-144 NSCLC患者生存时间明显低于高表达miR-144者。UHRF1在NSCLC患者组织中明显升高,且在不同年龄、性别、TNM分期和种族有显著差异。低表达UHRF1非小细胞肺癌患者生存率明显高于高表达UHRF1的NSCLC患者。过表达miR-144能够明显降低A549细胞活性,诱导A549细胞凋亡,增加γH2ax表达;抑制PCNA以及Bax蛋白表达,上调Bcl-2表达。荧光素酶报告证明UHRF1是miR-144的靶基因。同时,低表达miR-144能够使UHRF1表达增加,过表达miR-144能够抑制UHRF1的表达。结论过表达miR-144通过靶向UHRF1诱导A549细胞凋亡以及DNA损伤,参与NSCLC的病理生理过程,进而影响预后。     

Two novel SASH1 mutations in Chinese families with dyschromatosis universalis hereditaria

BackgroundDyschromatosis universalis hereditaria (DUH) is a rare genodermatosis characterized by hyper‐ and hypo‐pigmented macules on the face, trunk, and extremities. The condition causes severe cosmetic problem which can lead to significant psychological distress to the patients and bear a negative impact on society. DUH is a condition with genetic heterogeneity. The SASH1 gene was recently identified as pathogenic genes in DUH patients.MethodsTwo families clinically diagnosed with dyschromatosis universalis hereditaria were enrolled. Whole‐exome sequencing combined with Sanger sequencing and bioinformatics analysis was performed in the probands. MutationTaster, CADD, SIFT, PolyPhen‐2, and LRT software, and The American College of Medical Genetics and Genomics Standards and Guidelines were employed to assess the pathogenicity of detected missense mutations. One hundred healthy unrelated Chinese individuals were used as controls. All participants signed an informed consent form.ResultsGenetic screening revealed a heterozygous SASH1 c.1547G>A (p.Ser516Asn) mutation for patients in family 1, and SASH1 c.1547G>T (p.Ser516Ile) for family 2. Both such de novo mutations are located in a highly conserved SLY domain in SASH1, have not been previously reported in any publication, and were not detected in any control databases.ConclusionsThe novel heterozygous mutations, SASH1 c.1547G>A and c.1547G>T, are likely responsible for the DUH phenotype in these two families. Our study expands the mutation spectrum of DUH. Whole‐exome sequencing showed its efficiency in the diagnostic of hereditary skin disorders.     

Central macular thickness in patients with sickle cell disease and no signs of retinopathy: a cross-sectional study of Jordanian patients

ObjectivesTo measure central macular thickness in Jordanian patients with sickle cell disease who did not have retinopathy and compare the findings with age- and sex-matched controls using spectral domain optical coherence tomography (SDOCT).MethodsIn this cross-sectional study, participants underwent visual acuity testing, slit-lamp bio-microscopy, dilated ophthalmoscopy, and SDOCT imaging to measure central macular thickness. Macular quadrant measurements and thickness difference indexes (TDIs) were compared between groups.ResultsTwenty eyes with sickle cell disease and 20 control eyes were enrolled. The median visual acuity in both groups was 20/20. The mean macular thickness was significantly lower in eyes with sickle cell disease than in matched controls (mean difference, 22.15 ± 6.44 µm). Peripheral quadrants were all significantly thinner in eyes with sickle cell disease, especially in superior and temporal quadrants. TDIs were lower in eyes with sickle cell disease than in control eyes.ConclusionsEyes with sickle cell disease that had no clinical evidence of retinopathy exhibited significantly lower central macular thickness in all quadrants, compared with eyes in age- and sex-matched controls. SDOCT is a non-invasive imaging modality that can detect preclinical changes in eyes with sickle cell disease and can be used to screen and monitor the disease process.