The Depletion of Nuclear Glutathione Impairs Cell Proliferation in 3t3 Fibroblasts

BACKGROUND:Glutathione is considered essential for survival in mammalian cells and yeast but not in prokaryotic cells. The presence of a nuclear pool of glutathione has been demonstrated but its role in cellular proliferation and differentiation is still a matter of debate. PRINCIPAL FINDINGS:We have studied proliferation of 3T3 fibroblasts for a period of 5 days. Cells were treated with two well known depleting agents, diethyl maleate (DEM) and buthionine sulfoximine (BSO), and the cellular and nuclear glutathione levels were assessed by analytical and confocal microscopic techniques, respectively. Both agents decreased total cellular glutathione although depletion by BSO was more sustained. However, the nuclear glutathione pool resisted depletion by BSO but not with DEM. Interestingly, cell proliferation was impaired by DEM, but not by BSO. Treating the cells simultaneously with DEM and with glutathione ethyl ester to restore intracellular GSH levels completely prevented the effects of DEM on cell proliferation. CONCLUSIONS:Our results demonstrate the importance of nuclear glutathione in the control of cell proliferation in 3T3 fibroblasts and suggest that a reduced nuclear environment is necessary for cells to progress in the cell cycle

Exploring capability maturity models and relevant practices as solutions addressing information technology service offshoring project issues

This research investigated Capability Maturity Models (CMM) / Capability Maturity Model Integration (CMMI) best practices and their effects on managing and mitigating critical issues associated with offshore development. Using a web-based survey, data was collected from 451 Information Technology and software development firms in the US. The results of the analysis show that IT companies applying CMM/CMMI models have fewer issues associated with IT offshoring. When US IT companies utilizing and incorporating different practices from TSP and People-CMM into CMMI-DEV/SVC and CMMI-ACQ, they have fewer offshoring issues related to language barriers and cultural differences

Exquisite sensitivity to subsecond, picomolar nitric oxide transients conferred on cells by guanylyl cyclase-coupled receptors

Nitric oxide (NO) functions as a diffusible transmitter in most tissues of the body and exerts its effects by binding to receptors harboring a guanylyl cyclase transduction domain, resulting in cGMP accumulation in target cells. Despite its widespread importance, very little is known about how this signaling pathway operates at physiological NO concentrations and in real time. To address these deficiencies, we have exploited the properties of a novel cGMP biosensor, named δ-FlincG, expressed in cells containing varying mixtures of NO-activated guanylyl cyclase and cGMP-hydrolyzing phosphodiesterase activity. Responsiveness to NO, signifying a physiologically relevant rise in cGMP to 30 nM or more, was seen at concentrations as low as 1 pM, making cells by far the most sensitive NO detectors yet encountered. Even cells coexpressing phosphodiesterase-5, a cGMP-activated isoform found in many NO target cells, responded to NO in concentrations as low as 10 pM. The dynamics of NO capture and signal transduction was revealed by administering timed puffs of NO from a local pipette. A puff lasting only 100 ms, giving a calculated peak intracellular NO concentration of 23 pM, was detectable. The results could be encapsulated in a quantitative model of cellular NO-cGMP signaling, which recapitulates the NO responsiveness reported previously from crude cGMP measurements on native cells, and which explains how NO is able to exert physiological effects at extremely low concentrations, when only a tiny proportion of its receptors would be occupied