The adaptor protein FADD and the initiator caspase-8 mediate activation of NF-κB by TRAIL

Besides inducing apoptosis, tumor necrosis factor-related apoptosis-inducing ligand (TRAIL) activates NF-κB. The apoptosis signaling pathway of TRAIL is well characterized involving TRAIL receptors, Fas-associated protein with death domain (FADD) and caspase-8. In contrast, the molecular mechanism of TRAIL signaling to NF-κB remains controversial. Here, we characterized the receptor–proximal mediators of NF-κB activation by TRAIL. Deletion of the DD of TRAIL receptors 1 and 2 revealed that it is essential in NF-κB signaling. Because FADD interacts with the TRAIL receptor DD, FADD was tested. RNAi-mediated knockdown of FADD or FADD deficiency in JURKAT T-cell leukemia cells decreased or disabled NF-κB signaling by TRAIL. In contrast, TRAIL-induced activation of NF-κB was maintained upon loss of receptor interacting protein 1 (RIP1) or knockdown of FLICE-like inhibitory protein (FLIP). Exogenous expression of FADD rescued TRAIL-induced NF-κB signaling. Loss-of-function mutations of FADD within the RHDLL motif of the death effector domain, which is required for TRAIL-induced apoptosis, abrogated FADD's ability to recruit caspase-8 and mediate NF-κB activation. Accordingly, deficiency of caspase-8 inhibited TRAIL-induced activation of NF-κB, which was rescued by wild-type caspase-8, but not by a catalytically inactive caspase-8 mutant. These data establish the mechanism of TRAIL-induced NF-κB activation involving the TRAIL receptor DD, FADD and caspase-8, but not RIP1 or FLIP. Our results show that signaling of TRAIL-induced apoptosis and NF-κB bifurcates downstream of caspase-8.

[Peripheral suprathreshold stimulation in preperimetric glaucoma]

BACKGROUND AND PURPOSE

Early glaucomatous visual field defects can occur outside the central 30 degrees , which is usually examined in perimetric tests used for glaucoma diagnosis and screening. This study aimed to evaluate the diagnostic value of peripheral suprathreshold stimulation in open angle glaucoma before the development of reproducible visual field damage in standard 30 degrees automatic white-on-white perimetry.

METHODS

A total of 352 eyes of 352 patients (ages 35-69 years; visual acuity 0.8 or better) from the Erlanger Glaucoma Registry were included in this study. They were divided into two groups: normal eyes and preperimetric glaucoma. All patients underwent a standardized glaucoma examination including Octopus 500EZ static perimetry (G1 program, all three phases); 95 eyes of 95 patients also received a 135-point suprathreshold test pattern of the Humphrey Field Analyzer (model 750i) for detecting peripheral visual field defects. Sensitivity and specificity were calculated for any single test point in phase 3 of the G1 test pattern and the Humphrey 135-point pattern. A score was calculated, and cluster analysis was performed.

RESULTS

In 33 of 176 (18.8%) eyes with preperimetric glaucoma, the score was 3 or higher in phase 3 of the G1 program (normal eyes: 19 of 196; 9.7%). For both examination modalities, the highest sensitivity was found in test locations in the superior nasal midperiphery, corresponding to neuroretinal rim loss predominantly in the inferotemporal sector in early glaucomatous optic disc atrophy.

CONCLUSION

Positive test results using suprathreshold stimulation in the midperiphery can be found in patients with preperimetric glaucoma at a significantly higher frequency than in normal subjects. Longitudinal studies will show whether such tests can be useful for predicting perimetric manifestation of the disease.

Therapierefraktäre Bindehautchemosis

We saw a 62-year-old male with a conjunctival chemosis, which was resistant to local therapy. Excisional biopsy and histological work-up of the tissue were performed. Additional immunohistochemical staining using the Lyve-1 antibody (specific for lymphatic vascular endothelium) allowed the diagnosis of a lymphangioma of the conjunctiva to be made.

Toxicogenomics, drug discovery, and the pathologist

The field of toxicogenomics, which currently focuses on the application of large-scale differential gene expression (DGE) data to toxicology, is starting to influence drug discovery and development in the pharmaceutical industry. Toxicological pathologists, who play key roles in the development of therapeutic agents, have much to contribute to DGE studies, especially in the experimental design and interpretation phases. The intelligent application of DGE to drug discovery can reveal the potential for both desired (therapeutic) and undesired (toxic) responses. The pathologist's understanding of anatomic, physiologic, biochemical, immune, and other underlying factors that drive mechanisms of tissue responses to noxious agents turns a bewildering array of gene expression data into focused research programs. The latter process is critical for the successful application of DGE to toxicology. Pattern recognition is a useful first step, but mechanistically based DGE interpretation is where the long-term future of these new technologies lies. Pathologists trained to carry out such interpretations will become important members of the research teams needed to successfully apply these technologies to drug discovery and safety assessment. As a pathologist using DGE, you will need to learn to read DGE data in the same way you learned to read glass slides, patiently and with a desire to learn and, later, to teach. In return, you will gain a greater depth of understanding of cell and tissue function, both in health and disease.

31P-CP-MAS NMR studies on TPP+ bound to the ion-coupled multidrug transport protein EmrE

The binding of tetraphenylphosphonium (TPP+) to EmrE, a membrane-bound, 110 residue Escherichia coli multidrug transport protein, has been observed by 31P cross-polarisation-magic-angle spinning nuclear magnetic resonance spectroscopy (CP-MAS NMR). EmrE has been reconstituted into dimyristoyl phosphatidylcholine bilayers. CP-MAS could selectively distinguish binding of TPP+ to EmrE in the fluid membrane. A population of bound ligand appears shifted 4 ppm to lower frequency compared to free ligand in solution, which suggests a rather direct and specific type of interaction of the ligand with the protein. This is also supported by the observed restricted motion of the bound ligand. The observation of another weakly bound substrate population arises from ligand binding to negatively charged residues in the protein loop regions.

Genomewide search for type 2 diabetes susceptibility genes in four American populations

Type 2 diabetes is a serious, genetically influenced disease for which no fully effective treatments are available. Identification of biochemical or regulatory pathways involved in the disease syndrome could lead to innovative therapeutic interventions. One way to identify such pathways is the genetic analysis of families with multiple affected members where disease predisposing genes are likely to be segregating. We undertook a genomewide screen (389-395 microsatellite markers) in samples of 835 white, 591 Mexican American, 229 black, and 128 Japanese American individuals collected as part of the American Diabetes Association's GENNID study. Multipoint nonparametric linkage analyses were performed with diabetes, and diabetes or impaired glucose homeostasis (IH). Linkage to diabetes or IH was detected near markers D5S1404 (map position 77 cM, LOD = 2.80), D12S853 (map position 82 cM, LOD = 2.81) and GATA172D05 (X-chromosome map position 130 cM, LOD = 2.99) in whites, near marker D3S2432 (map position 51 cM, LOD = 3.91) in Mexican Americans, and near marker D10S1412 (map position 14 cM, LOD = 2.39) in African Americans mainly collected in phase 1 of the study. Further analyses showed evidence for interactions between the chromosome 5 locus and region on chromosome 12 containing the MODY 3 gene (map position 132 cM) and between the X-chromosome locus and region near D12S853 (map position 82 cM) in whites. Although these results were not replicated in samples collected in phase 2 of the GENNID study, the region on chromosome 12 was replicated in samples from whites described by Bektas et al. (1999).

The political economy of health care: colonial Namibia 1915-1961

The political economy of health care services in colonial Namibia during 1915-1961 closely reflected the extreme racial and class imbalance of power in a conquest state. The colonial power allocated to the indigent nine-tenths, the poorest nine-tenths of the people, an average 43% of the health care budget between 1922 and 1954. The League of Nations mandate proved toothless in pressuring the Mandatory power to rectify this or other inequalities.

Influence of intercellular agents on proliferation and gene activity of cultured human skin epithelium cells (NCTC 2544)

"Human skin epithelium cells" (NCTC strain 2544; HSEpicell) are established cells and grow to a monolayer the same way as epithelial cells. Addition of proliferating or antiproliferating substances results in a typical dose-dependent influence on the cell growth: steroids inhibit mitosis, polyamines stimulate proliferation, while prostaglandin E2, theophylline and papaverine reduce cell growth. Since the pattern of chromosomal nonhistone proteins indicates alterations of gene activity, DNA-binding proteins of HSE picells are analysed. Compared to native human skin fibroblasts (La Col 1115) there are only slight differences, in contrast to cancer cells. Therefore HSE picells may represent undifferentiated non-cancer cells. Hydrocortisone and theophylline inhibit cell proliferation by different mechanisms. As indicated by the pattern of DNA-binding proteins, both substances also act on HSEpicells in two different ways. As HSEpicells can be used for studying cell regulation, water-soluble extract and DNA-binding proteins of psoriatic scales as well as sera of psoriasis patients are tested in respect to any proliferating component. However, no influence on cell proliferation could be found.

Long-term tissue culture of epithelial-like cells from human skin (NCTC strain 2544). II. Viscosity changes after enzyme treatment

Human skin epithelial-like cells (NCTC strain 2544) were grown in NCTC 135 medium. Neuraminidase and hyaluronidase were added to the growth medium. Cells were incubated 96 h at 36 degrees C. Growth rate and viscosity of cell suspensions were measured after forming single cells mechanically (mopping). With addition of neuraminidase and hyaluronidase, respectively, the growth rate remains unchanged. With neuraminidase a distinct raise in viscosity was achieved, whereas with hyaluronidase only a small effect was seen. The characteristic structure viscosity is maintained in all forms of the viscosity curves at different shear-rates.

Separation, isolation, and amino acid composition of the albumin-like fraction from psoriatic scales

The albumin-like fraction of psoriatic scales was isolated either directly by slab gel electroporesis or after previous treatment with polyethylene glycol6000. After both isolation procedures the amino acid composition was determined. Both proteins were rich of glutamic acid, glycine, and alanine. On the other hand both contained very small amounts of cysteine and tyrosine. Only after the direct isolation procedure the amino-sugar galactosamine could be detected.