A novel function for the sperm adhesion protein IZUMO1 in cell-cell fusion.

Mammalian sperm-egg adhesion depends on the trans-interaction between the sperm-specific type I glycoprotein IZUMO1 and its oocyte-specific GPI-anchored receptor JUNO. However, the mechanisms and proteins (fusogens) that mediate the following step of gamete fusion remain unknown. Using live imaging and content mixing assays in a heterologous system and structure-guided mutagenesis, we unveil an unexpected function for IZUMO1 in cell-to-cell fusion.

Malaria parasites utilize two essential plasma membrane fusogens for gamete fertilization.

Cell fusion of female and male gametes is the climax of sexual reproduction. In many organisms, the Hapless 2 (HAP2) family of proteins play a critical role in gamete fusion. We find that Plasmodium falciparum, the causative agent of human malaria, expresses two HAP2 proteins: PfHAP2 and PfHAP2p.

Live imaging-based assay for visualising species-specific interactions in gamete adhesion molecules.

Successful gamete fusion requires species-specific membrane adhesion. However, the interaction of adhesion molecules in gametes is difficult to study in real time through low-throughput microscopic observation. Therefore, we developed a live imaging-based adhesion molecule (LIAM) assay to study gamete adhesion molecule interactions in cultured cells.

HAP2/GCS1 is a gamete fusion protein homologous to somatic and viral fusogens.

Cell-cell fusion is inherent to sexual reproduction. Loss of HAPLESS 2/GENERATIVE CELL SPECIFIC 1 (HAP2/GCS1) proteins results in gamete fusion failure in diverse organisms, but their exact role is unclear. In this study, we show that HAP2/GCS1 is sufficient to promote mammalian cell-cell fusion.

Structural basis of eukaryotic cell-cell fusion.

Cell-cell fusion proteins are essential in development. Here we show that the C. elegans cell-cell fusion protein EFF-1 is structurally homologous to viral class II fusion proteins.

Conserved eukaryotic fusogens can fuse viral envelopes to cells.

Caenorhabditis elegans proteins AFF-1 and EFF-1 [C. elegans fusion family (CeFF) proteins] are essential for developmental cell-to-cell fusion and can merge insect cells. To study the structure and function of AFF-1, we constructed vesicular stomatitis virus (VSV) displaying AFF-1 on the viral envelope, substituting the native fusogen VSV glycoprotein.

AFF-1, a FOS-1-regulated fusogen, mediates fusion of the anchor cell in C. elegans.

Cell fusion is fundamental for reproduction and organ formation. Fusion between most C. elegans epithelial cells is mediated by the EFF-1 fusogen.

Genetic control of fusion pore expansion in the epidermis of Caenorhabditis elegans.

Developmental cell fusion is found in germlines, muscles, bones, placentae, and stem cells. In Caenorhabditis elegans 300 somatic cells fuse during development. Although there is extensive information on the early intermediates of viral-induced and intracellular membrane fusion, little is known about late stages in membrane fusion.

The C. elegans developmental fusogen EFF-1 mediates homotypic fusion in heterologous cells and in vivo.

During cell-cell fusion, two cells' plasma membranes merge, allowing the cytoplasms to mix and form a syncytium. Little is known about the mechanisms of cell fusion. Here, we asked whether eff-1, shown previously to be essential for fusion in Caenorhabditis elegans, acts directly in the fusion machinery.

The type I membrane protein EFF-1 is essential for developmental cell fusion.

Multinucleate cells are widespread in nature, yet the mechanism by which cells fuse their plasma membranes is poorly understood. To identify animal fusogens, we performed new screens for mutations that abolish cell fusion within tissues of C. elegans throughout development.

Haptoglobin-related protein as a serum marker in malignant lymphoma.

A novel serum 21 kDa haptoglobin-related protein (Hpr) was investigated in patients with malignant lymphoma, to evaluate its correlation with clinical and histologic features at presentation and its possible role as a tumor marker for patient outcome. One hundred fifty eight serum samples were taken from 88 patients with non-Hodgkin's lymphoma (n=58) and Hodgkin's disease (n=30) at presentation and in the course of follow-up. Sera from 61 healthy volunteers served as normal controls.

Cell cycle inhibition in human BE-13 T cell leukemia cells by haptoglobin-related (HPR) antisense cDNA.

We have recently cloned and sequenced a human haptoglobin-related cDNA. Hpr expression was found in various tumor cell lines. To determine whether the haptoglobin related protein (hpr) affects the growth of an established T-cell leukemia cell line, an Hpr antisense expression vector that specifically reduces hpr production was constructed.

Transcriptionally active haptoglobin-related (Hpr) gene in hepatoma G2 and leukemia molt-4 cells.

The aim of the present study was to answer the question: Is the haptoglobin-related (Hpr) gene expressed in tumor cells? Our strategy of cloning the cDNA was to screen a human hepatoma G2 cDNA expression library in lambda gt11 using three different probes complementary to the coding strands of regions of the Hpr gene that contain codon changes permitting a discrimination from haptoglobin gene Hp1F. Among 8 x 10(5) recombinant phages screened, 2 hybridized to all three probes under stringent conditions. A 1.

Increased levels of a 21-kDa protein in the circulation of tumor-bearing patients.

A novel non-ras 21-kDa protein (p21) was detected in sera of cancer patients by enzyme-linked immunosorbent assay (ELISA), using polyclonal anti-p21 antibodies. While only 4.6% of the healthy donors (n = 43) showed p21 serum levels higher than the mean +/- 2 SD of the normal group, 33 to 80% of the cancer patients (n = 94) with various tumors were positive in the ELISA test.

Characterization of DNA binding properties of Yp20: an abundant nuclear protein isolated from Saccharomyces cerevisiae.

The aim of this study was to elucidate the function of Yp20 (yeast 20 kDa protein) which is an abundant basic DNA-binding protein copurified with yeast chromatin. The work presented here shows that Yp20 is a sequence specific DNA binding protein. DNA binding activity was extremely thermostable.

Enzyme-linked-immunosorbent-assay for the detection of a novel 21-kda protein associated with the clinical course of patients with urogenital tumors.

A novel 21 kDa protein (p21) was detected in sera of patients with urogenital tumors by ELISA, using rabbit polyclonal antibodies generated against the p21 polypeptide. Eight out of 11 patients (72%) exhibited a 2-5 fold increase in pre-treatment p21 serum levels as compared with 20 healthy individuals. A decrease of p21 levels was observed in 6 out of 8 patients in which a regression of the disease was shown post-treatment.

A novel 21-kDa protein as a serum marker for benign and malignant urogenital tumors: preliminary communication.

A novel 21-kDa protein (p21) was isolated from auto-immune complexes, found in sera of 14 patients with malignant urogenital tumors and isolated on Protein A-Sepharose. Isolated complexes were analyzed in 15% polyacrylamide-SDS minigels. After staining with Coomassie blue R, the bands were scanned with a clinical densitometer.

DNA binding properties of Saccharomyces cerevisiae chromatin associated ras-related protein Yp20.

Yp20 is an abundant 20 kDa chromatin associated protein which has been shown to be related antigenically to genuine Hras products. Using Southwestern blots we have demonstrated that Yp20 is a DNA binding protein. It is also shown that protein Yp20 like protein HM (an abundant thermostable 20 kDa DNA binding protein isolated from mitochondria) and like the 21 kDa autonomously replicating sequence binding factor II (ABFII) is able to introduce superhelical turns into circular relaxed DNA in the presence of DNA topoisomerase I activity.

Saccharomyces cerevisiae chromatin associated protein Yp20 is a guanine nucleotide binding protein.

Yp20 is a 20kD protein whose role is still obscure which copurifies with yeast histones. Yeast histones were separated by sodium dodecyl sulfate polyacrylamide gel electrophoresis and transferred to nitrocellulose. Incubation of the nitrocellulose blots with [gamma-35S] GTP gamma S demonstrated that Yp20 is a GTP binding protein.