Validation of a commercially available anti-REDD1 antibody using RNA interference and REDD1-/- mouse embryonic fibroblasts

REDD1 is a transcriptional target gene of p53 and HIF-1, and an inhibitor of mTOR (mechanistic target of rapamycin) complex 1 (mTORC1)-signaling through PP2A-dependent interaction, making it an important convergence point of both tumor suppression and cell growth pathways. In accordance with this positioning, REDD1 levels are transcriptionally upregulated in response to a variety of cellular stress factors such as nutrient deprivation, hypoxia and DNA damage. In the absence of such conditions, and in particular where growth factor signaling is activated, REDD1 expression is typically negligible; therefore, it is necessary to induce REDD1 prior to experimentation or detection in model systems. Here, we evaluated the performance of a commercially available polyclonal antibody recognizing REDD1 by Western blotting in the presence of thapsigargin, a pharmacological inducer of ER stress well known to upregulate REDD1 protein expression. Further, REDD1 antibody specificity was challenged in HEK-293 cells in the presence of RNA interference and with a REDD1 ^-/- mouse embryonic fibroblast knockout cell line. Results showed reproducibility and specificity of the antibody, which was upheld in the presence of thapsigargin treatment. We conclude that this antibody can be used to reliably detect REDD1 endogenous expression in samples of both human and mouse origin.

Cleaning up Western blot signals from immunoprecipitated samples using alternative detection methods

High background signal is a common problem experienced when detecting proteins isolated through immunoprecipitation (IP) by Western blotting (WB). The most frequent cause of high background is signal interference from the heavy and light chain fragments of the denatured immunoprecipitating (or capture) antibody ' by-products of IP labeled by species-specific secondary antibodies at the WB stage. Here we comment on alternative methods for the detection of immunoprecipitated proteins by WB that avoid labeling of the heavy and light chain to varying extents. Certain methods have been described elsewhere (1), however, their use remains less widespread than traditional detection methods despite offering the researcher considerable advantages.

Involvement of phosphatidylinositol 5-phosphate in insulin-stimulated glucose uptake in the L6 myotube model of skeletal muscle

The phosphoinositide phospholipid PtdIns5P has previously been implicated in insulin-stimulated translocation of the glucose transporter GLUT4 into the plasma membrane of adipocytes, but its potential role in glucose transport in muscle has not been explored. The involvement of PtdIns5P in insulin-stimulated glucose uptake was therefore investigated in myotubes of the skeletal muscle cell line L6. Stimulation with insulin produced a transient increase in PtdIns5P, which was abolished by the over-expression of the highly active PtdIns5P 4-kinase PIP4Kα. PIP4Kα over-expression also abolished both the enhanced glucose uptake and the robust peak of PtdIns(3,4,5)P (3) production stimulated by insulin in myotubes. Delivery of exogenous PtdIns5P into unstimulated myotubes increased Akt phosphorylation, promoted GLUT4 relocalisation from internal membrane to plasma membrane fractions and its association with plasma membrane lawns and also stimulated glucose uptake in a tyrosine kinase and phosphoinositide 3-kinase (PI 3-kinase)-dependent fashion. Our results are consistent with a role for insulin-stimulated PtdIns5P production in regulating glucose transport by promoting PI 3-kinase signalling.

Annual health outcomes and treatment costs for schizophrenia populations

This article describes a model that estimates annual patient health and cost outcomes for schizophrenia under alternative treatment scenarios. We estimate these outcomes for typical antipsychotics and show how treatment with atypical antipsychotics could have an impact on these outcomes. Patients are divided into 5 subcategories--newly diagnosed, no episode, acute episode(s), extended care, and institutionalized--and patient health and cost outcomes are estimated for each category. The proportion of people in each category is estimated for U.S. general, state mental hospital, and community mental health populations. Outcomes include extrapyramidal and moderate/severe schizophrenia symptom days, employed days, suicides, hospital days, and health costs. For patients treated with typical antipsychotics, annual per-patient symptom days ranged from 55 to 365 and costs ranged from $16,000 to $57,000, depending on disease severity. Atypical antipsychotics may reduce symptoms and costs through better efficacy for negative symptoms and better compliance.