To characterize the contribution of glycogen synthase kinase 3␤ (GSK3␤) inactivation to insulin-stimulated glucose metabolism, wild-type (WT-GSK), catalytically inactive (KM-GSK), and uninhibitable (S9A-GSK) forms of GSK3␤ were expressed in insulin-responsive 3T3-L1 adipocytes using adenovirus technology. WT-GSK, but not KM-GSK, reduced basal and insulin-stimulated glycogen synthase activity without affecting the -fold stimulation of the enzyme by insulin. S9A-GSK similarly decreased cellular glycogen synthase activity, but also partially blocked insulin stimulation of the enzyme. S9A-GSK expression also markedly inhibited insulin stimulation of IRS-1-associated phosphatidylinositol 3-kinase activity, but only weakly inhibited insulinstimulated Akt/PKB phosphorylation and glucose uptake, with no effect on GLUT4 translocation. To further evaluate the role of GSK3␤ in insulin signaling, the GSK3␤ inhibitor lithium was used to mimic the consequences of insulin-stimulated GSK3␤ inactivation. Although lithium stimulated the incorporation of glucose into glycogen and glycogen synthase enzyme activity, the inhibitor was without effect on GLUT4 translocation and pp70 S6 kinase. Lithium stimulation of glycogen synthesis was insensitive to wortmannin, which is consistent with its acting directly on GSK3␤ downstream of phosphatidylinositol 3-kinase. These data support the hypothesis that GSK3␤ contributes to insulin regulation of glycogen synthesis, but is not responsible for the increase in glucose transport.The peptide hormone insulin elicits a broad array of metabolic responses. In muscle and adipose tissue, insulin promotes the storage of sugar by coordinately accelerating both the rate of glucose entry into the cell and glycogen synthase activity. The former is mediated by the insulin-dependent redistribution of glucose transport proteins (GLUT4) from intracellular compartments to the plasma membrane (1), and the latter by multisite dephosphorylation of the enzyme coupled with activation by the soluble metabolite glucose 6-phosphate (2). Although much progress has been made characterizing the molecular signaling events emanating from the insulin receptor and progressing to these targets, the complete pathway has not yet been elucidated. The general purpose of this study was to evaluate the relative contribution of the serine/threonine kinase GSK3␤1 to insulin regulation of these molecular events. GSK3␤ was originally identified based on its kinase activity toward an in vitro substrate, glycogen synthase (3). Subsequent studies have described roles for the enzyme in many different cellular processes. For example, the potent GSK3␤ inhibitor lithium was used to identify roles for the enzyme in spore and stalk development in Dictyostelium (4, 5) and in expansion of dorsal mesoderm in Xenopus (4, 5). A critical role for GSK3␤ in pattern formation has been confirmed through investigation of the Drosophila ortholog shaggy/zeste-white 3 (6). Moreover, overexpression of GSK3␤ in cultured cells led to the proposal of a role for...

The prevalence of asthma has increased dramatically over the last 25 years in the United States and in other nations as a result of ill-defined changes in living conditions in modern society. On 18 and 19 October 2004 the U.S. Environmental Protection Agency and the National Institute of Environmental Health Sciences sponsored the workshop “Environmental Influences on the Induction and Incidence of Asthma” to review current scientific evidence with respect to factors that may contribute to the induction of asthma. Participants addressed two broad questions: a) What does the science suggest that regulatory and public health agencies could do now to reduce the incidence of asthma? and b) What research is needed to improve our understanding of the factors that contribute to the induction of asthma and our ability to manage this problem? In this article (one of four articles resulting from the workshop), we briefly characterize asthma and its public health and economic impacts, and intervention strategies that have been successfully used to prevent induction of asthma in the workplace. We conclude with the findings of seven working groups that focus on ambient air, indoor pollutants (biologics), occupational exposures, early life stages, older adults, intrinsic susceptibility, and lifestyle. These groups found strong scientific support for public health efforts to limit in utero and postnatal exposure to cigarette smoke. However, with respect to other potential types of interventions, participants noted many scientific questions, which are summarized in this article. Research to address these questions could have a significant public health and economic impact that would be well worth the investment.

BackgroundThe mechanisms underlying ozone (O3)-induced pulmonary inflammation remain unclear. Interleukin-10 (IL-10) is an anti-inflammatory cytokine that is known to inhibit inflammatory mediators.ObjectivesWe investigated the molecular mechanisms underlying interleuken-10 (IL-10)–mediated attenuation of O3-induced pulmonary inflammation in mice.MethodsIl10-deficient (Il10−/−) and wild-type (Il10+/+) mice were exposed to 0.3 ppm O3 or filtered air for 24, 48, or 72 hr. Immediately after exposure, differential cell counts and total protein (a marker of lung permeability) were assessed from bronchoalveolar lavage fluid (BALF). mRNA and protein levels of cellular mediators were determined from lung homogenates. We also used global mRNA expression analyses of lung tissue with Ingenuity Pathway Analysis to identify patterns of gene expression through which IL-10 modifies O3-induced inflammation.ResultsMean numbers of BALF polymorphonuclear leukocytes (PMNs) were significantly greater in Il10−/− mice than in Il10+/+ mice after exposure to O3 at all time points tested. O3-enhanced nuclear NF-κB translocation was elevated in the lungs of Il10−/− compared with Il10+/+ mice. Gene expression analyses revealed several IL-10–dependent and O3-dependent mediators, including macrophage inflammatory protein 2, cathepsin E, and serum amyloid A3.ConclusionsResults indicate that IL-10 protects against O3-induced pulmonary neutrophilic inflammation and cell proliferation. Moreover, gene expression analyses identified three response pathways and several genetic targets through which IL-10 may modulate the innate and adaptive immune response. These novel mechanisms of protection against the pathogenesis of O3-induced pulmonary inflammation may also provide potential therapeutic targets to protect susceptible individuals.