Recent studies have indicated a role of complement in regulating T-cell immunity but the mechanism of action of complement in this process remains to be clarified. Here we studied mice deficient in decay-accelerating factor (DAF), a key membrane complement regulator whose deficiency led to increased complement-dependent T-cell immune responses in vivo. By crossing OT-II and OT-I T-cell receptor...

Expression of decay-accelerating factor (DAF or CD55) and of CD59 during hematopoietic cell development in normal bone marrow and on peripheral blood leukocytes were characterized by three-color immunofluorescence experiments. With this technique cell subsets were identified by forward light scatter, orthogonal light scatter, and two cell-surface antigens. For each cell lineage, specific combin...

AIMS To investigate the deposition of complement components, C3d and C5b-9, and the expression of complement regulating factors (S protein, membrane cofactor protein (MCP; CD46), protectin (CD59), decay accelerating factor (DAF; CD55), and type 1 complement receptor (CR1; CD35)) in gastric cancers. METHODS Specimens of gastric cancer were examined by immunohistochemistry and immunoelectron mi...

How are the rates of aging of different tissues coordinated? In Caenorhabditis elegans, decreasing insulin/IGF-1 signaling extends lifespan by activating the transcription factor DAF-16/FOXO. If DAF-16 levels are experimentally increased in one tissue, such as the intestine, DAF-16 activity in other tissues rises. Here we test the hypothesis that this "FOXO-to-FOXO" signaling occurs via feedbac...

Decay accelerating factor (DAF) is a glycophospholipid-anchored membrane glycoprotein that protects mammalian host cells from inadvertant complement lysis. The effects of inhibiting mucin-type O-glycosylation on the cell surface expression of DAF were studied by introducing an expression vector for human DAF into wild-type Chinese hamster ovary and ldlD cells. The ldlD cells express reversible ...

In Caenorhabditis elegans, an insulin-like signaling pathway, which includes the daf-2 and age-1 genes, controls longevity and stress resistance. Downregulation of this pathway activates the forkhead transcription factor DAF-16, whose transcriptional targets are suggested to play an essential role in controlling the phenotypes governed by this pathway. We have surveyed the genes that have the D...

The glycosylphosphatidylinositol (GPI)-anchored complement regulatory protein decay-accelerating factor (DAF) is used by a number of enteroviruses as a receptor during infection. DAF and other GPI-anchored proteins can be found in cholesterol-rich ordered domains within the plasma membrane that are known as "lipid rafts." We have shown, by using drugs to specifically inhibit various endocytosis...

Insulin regulates development, metabolism, and lifespan via a conserved PI3K/Akt pathway that promotes cytoplasmic sequestration of FoxO transcription factors. The regulation of nuclear FoxO is poorly understood. In the nematode Caenorhabditis elegans, insulin-like signaling functions in larvae to inhibit dauer arrest and acts during adulthood to regulate lifespan. In a screen for genes that mo...

Activation of the innate immune system results in a rapid microbicidal response against microorganisms, which needs to be fine-tuned because uncontrolled immune responses can lead to infection and cancer, as well as conditions such as Crohn disease, atherosclerosis, and Alzheimer disease. Here we report that excessive activity of the conserved FOXO transcription factor DAF-16 enhances susceptib...

Vulval development in Caenorhabditis elegans serves as an excellent model to examine the crosstalk between different conserved signaling pathways that are deregulated in human cancer. The concerted action of the RAS/MAPK, NOTCH, and WNT pathways determines an invariant pattern of cell fates in three vulval precursor cells. We have discovered a novel form of crosstalk between components of the I...