Mutations of the SLX4 gene in Fanconi anemia

Fanconi anemia is a rare recessive disorder characterized by genome instability, congenital malformations, progressive bone marrow failure and predisposition to hematologic malignancies and solid tumors. At the cellular level, hypersensitivity to DNA interstrand crosslinks is the defining feature in Fanconi anemia. Mutations in thirteen distinct Fanconi anemia genes have been shown to interfere with the DNA-replication-dependent repair of lesions involving crosslinked DNA at stalled replication forks. Depletion of SLX4, which interacts with multiple nucleases and has been recently identified as a Holliday junction resolvase, results in increased sensitivity of the cells to DNA crosslinking agents. Here we report the identification of biallelic SLX4 mutations in two individuals with typical clinical features of Fanconi anemia and show that the cellular defects in these individuals' cells are complemented by wildtype SLX4, demonstrating that biallelic mutations in SLX4 (renamed here as FANCP) cause a new subtype of Fanconi anemia, Fanconi anemia-P.     

A germline variant in the TP53 polyadenylation signal confers cancer susceptibility

To identify new risk variants for cutaneous basal cell carcinoma, we performed a genome-wide association study of 16 million SNPs identified through whole-genome sequencing of 457 Icelanders. We imputed genotypes for 41,675 Illumina SNP chip-typed Icelanders and their relatives. In the discovery phase, the strongest signal came from rs78378222[C] (odds ratio (OR) = 2.36, P = 5.2 × 10(-17)), which has a frequency of 0.0192 in the Icelandic population. We then confirmed this association in non-Icelandic samples (OR = 1.75, P = 0.0060; overall OR = 2.16, P = 2.2 × 10(-20)). rs78378222 is in the 3' untranslated region of TP53 and changes the AATAAA polyadenylation signal to AATACA, resulting in impaired 3'-end processing of TP53 mRNA. Investigation of other tumor types identified associations of this SNP with prostate cancer (OR = 1.44, P = 2.4 × 10(-6)), glioma (OR = 2.35, P = 1.0 × 10(-5)) and colorectal adenoma (OR = 1.39, P = 1.6 × 10(-4)). However, we observed no effect for breast cancer, a common Li-Fraumeni syndrome tumor (OR = 1.06, P = 0.57, 95% confidence interval 0.88-1.27).     

eIF2A,an initiator tRNA carrier refractory to eIF2α kinases,functions synergistically with eIF5B

The initiator tRNA (Met-tRNA _i ^Met ) at the P site of the small ribosomal subunit plays an important role in the recognition of an mRNA start codon. In bacteria, the initiator tRNA carrier, IF2, facilitates the positioning of Met-tRNA _i ^Met on the small ribosomal subunit. Eukarya contain the Met-tRNA _i ^Met carrier, eIF2 (unrelated to IF2), whose carrier activity is inhibited under stress conditions by the phosphorylation of its α-subunit by stress-activated eIF2α kinases. The stress-resistant initiator tRNA carrier, eIF2A, was recently uncovered and shown to load Met-tRNA _i ^Met on the 40S ribosomal subunit associated with a stress-resistant mRNA under stress conditions. Here, we report that eIF2A interacts and functionally cooperates with eIF5B (a homolog of IF2), and we describe the functional domains of eIF2A that are required for its binding of Met-tRNA _i ^Met , eIF5B, and a stress-resistant mRNA. The results indicate that the eukaryotic eIF5B–eIF2A complex functionally mimics the bacterial IF2 containing ribosome-, GTP-, and initiator tRNA-binding domains in a single polypeptide.     

Mutations in the cyclin family member FAM58A cause an X-linked dominant disorder characterized by syndactyly, telecanthus and anogenital and renal malformations

We identified four girls with a consistent constellation of facial dysmorphism and malformations previously reported in a single mother-daughter pair. Toe syndactyly, telecanthus and anogenital and renal malformations were present in all affected individuals; thus, we propose the name 'STAR syndrome' for this disorder. Using array CGH, qPCR and sequence analysis, we found causative mutations in FAM58A on Xq28 in all affected individuals, suggesting an X-linked dominant inheritance pattern for this recognizable syndrome.     

猪毛蒿对其他植物生长的他感作用

为测定猪毛蒿二次代谢物对其他植物产生的他感作用,利用气相色谱、质谱分析鉴定了猪毛蒿水溶性及挥发性二次代谢物,结果表明。猪毛蒿含有较多的水溶性及挥发性二次代谢物。这些物质对与其共生及与其非共生植物的种子发芽、幼苗生长具有较强的他感作用,这种作用随二次代谢物浓度的增高而增大,对非共生植物的作用远大于共生的植物。     

Absence of expression of OKT8 antigen on cultured human, calf and rat oligodendrocytes

Monoclonal antibodies which recognize human suppressor T cells (OKT8) have been reported by Oger and co-workers to bind to cultured sheep oligodendrocytes. These authors speculated that an immune response directed at determinants shared by suppressor lymphocytes and oligodendrocytes could explain the decrease in both circulating blood suppressor T cells and oligodendrocytes in patients with multiple sclerosis. In view of the vital issue of potential cross-reactivity between oligodendrocytes and lymphocytes, we studied the binding of viable cultured calf, rat and human oligodendrocytes using monoclonal antibodies to human T cells and monocytes. We report here that we were unable to confirm the presence of shared determinants among oligodendrocytes and any leukocytes, including human T cells or monocytes. As the reported observations of lymphocyte-oligodendrocyte shared determinants could not be identified in three other species, including man, we found no evidence to support the hypothesis that such shared determinants are of importance in the pathogenesis of multiple sclerosis.     

Morphogenesis of human colon cancer cells with fetal rat mesenchymes in organ culture

The morphogenesis and cytodifferentiation of human colon cancer cells (LS174T and HT29) were examined by combining cancer cells with fetal rat digestive-tract mesenchyme in organ culture. LS174T cells migrated into the mesenchyme to form glandular structures composed of single columnar cells with their nuclei oriented basally, while HT29 cells formed cell masses with little lumen formation. Immunohistochemical studies with antibodies against carcinoembryonic antigen and secretory components showed that the composition of cell surface glycoproteins was not necessarily reversed to the normal type, even when neoplastic cells exhibited normal glandular structures.     

Rapid neutrophil adhesion to activated endothelium mediated by GMP-140.

Granule membrane protein-140 (GMP-140), a membrane glycoprotein of platelet and endothelial cell secretory granules, is rapidly redistributed to the plasma membrane during cellular activation and degranulation. Also known as PADGEM protein, GMP-140 is structurally related to two molecules involved in leukocyte adhesion to vascular endothelium: ELAM-1, a cytokine-inducible endothelial cell receptor for neutrophils, and the MEL-14 lymphocyte homing receptor. These three proteins define a new gene family, termed selectins, each of which contains an N-terminal lectin domain, followed by an epidermal growth factor-like module, a variable number of repeating units related to those in complement-binding proteins, a transmembrane domain, and a short cytoplasmic tail. Here we demonstrate that GMP-140 can mediate leukocyte adhesion, thus establishing a functional similarity with the other selectins. Human neutrophils and promyelocytic HL-60 cells bind specifically to COS cells transfected with GMP-140 complementary DNA and to microtitre wells coated with purified GMP-140. Cell binding does not require active neutrophil metabolism but is dependent on extracellular Ca2+. Within minutes after stimulation with phorbol esters or histamine, human endothelial cells become adhesive for neutrophils; this interaction is inhibited by antibodies to GMP-140. Thus, GMP-140 expressed by activated endothelium might promote rapid neutrophil targeting to sites of acute inflammation.     

Neuronal types in long-term culture of avian retina

Zusammenfassung Morphologische Befunde an Nervenzellen der Retina von Hühnerembryonen werden mitgeteilt. Mit der Bodian-Silberimprägnation in Langzeit-Gewebekulturen konnten multipolare Ganglienzellen, bipolare und Horizontalzellen, Amakrine und Synapsen identifiziert werden.

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This work was supported by the Medical Research Council of Canada.