Genome-wide studies have recently revealed the unexpected complexity of the genetic response to apparently simple physiological changes. Here, we show that when yeast cells are exposed to Cd(2+), most of the sulfur assimilated by the cells is converted into glutathione, a thiol-metabolite essential for detoxification. Cells adapt to this vital metabolite requirement by modifying globally their proteome to reduce the production of abundant sulfur-rich proteins. In particular, some abundant glycolytic enzymes are replaced by sulfur-depleted isozymes. This global change in protein expression allows an overall sulfur amino acid saving of 30%. This proteomic adaptation is essentially regulated at the mRNA level. The main transcriptional activator of the sulfate assimilation pathway, Met4p, plays an essential role in this sulfur-sparing response.

The Arg-Gly-Asp sequence resides in the cell attachment region offibronectin. Arg-Gly-Asp-containing peptides support fibroblast attachment, inhibit fibroblast adhesion to fibronectin, and inhibit fibronectin binding to thrombinstimulated platelets. In view of the similarities between the binding of fibronectin, fibrinogen, and von Willebrand factor to stimulated platelets, we have examined the effects of ArgGly-Asp-containing peptides on the interaction of these latter two adhesive proteins with platelets. Gly-Arg-Gly-Asp-Ser-Pro was used as a prototype peptide, and this hexapeptide inhibited fibrinogen binding to ADP and thrombin-stimulated platelets in the 10-200 jaM range. The inhibition exceeded 90% at high concentrations of peptide and was observed in the presence of either calcium or magnesium. Platelet aggregation was also inhibited by the peptide in this dose range. The hexapeptide inhibited fibrinogen binding to platelets with receptors fixed in an exposed state, indicating direct interference with the ligand-platelet interaction. The peptide was 1/2 to 1/3rd as potent in inhibiting fibrinogen as fibronectin binding to platelets, but fibrinogen and von Willebrand factor binding were inhibited to an identical extent. Conservative amino acid substitutions for the arginine, glycine, or aspartic acid markedly reduced inhibitory activity and the Asp-Gly-Arg sequence was inactive. These results indicate that Arg-Gly-Asp-containing peptides can inhibit the binding of the three adhesive proteins to stimulated platelets, establishing a basic common feature between the interaction of these molecules with platelets.Platelet attachment, spreading, and aggregation on extracellular matrices are central events in thrombus formation. These events can be regulated by a family ofplatelet adhesive glycoproteins-fibrinogen, fibronectin, and von Willebrand factor (vWF). Fibrinogen is a cofactor for platelet aggregation (1-3), fibronectin supports platelet attachment and spreading reactions (4-7), and vWF is important in platelet attachment to and spreading on subendothelial matrices (7-9). At a mechanistic level, the role of these adhesive proteins in platelet functions can be attributed to their interaction with specific binding sites on the cell surface. Although binding of these proteins to resting platelets is not detected, saturable interactions can be demonstrated with platelets stimulated by agonists such as thrombin (10-15). The binding of all three proteins to thrombin-stimulated platelets is divalent ion dependent (11,14,16,17), and platelets from patients with Glanzmann thrombasthenia exhibit decreased capacity to bind all three proteins (11,18,19). Synthetic peptides corresponding in sequence to the carboxyl-terminal region of the y chain of fibrinogen inhibit the binding of all three molecules to platelets (20), suggesting that common mechanisms may be involved in these interactions.Recent studies have demonstrated that the Arg-Gly-Asp sequence within fibronectin is involved in the cell attachment func...

Erythroid-specific genes contain binding sites for NF-E1 (also called GF-1 and Eryf-1; refs 1-3 respectively), the principal DNA-binding protein of the erythrocytic lineage. NF-E1 expression seems to be restricted to the erythrocytic lineage. A closely related (if not identical) protein is found in both a human megakaryocytic cell line and purified human megakaryocytes; it binds to promoter regions of two megakaryocytic-specific genes. The binding sites and partial proteolysis profile of this protein are indistinguishable from those of the erythroid protein; also, NF-E1 messenger RNA is the same size in both the megakaryocytic and erythroid cell lines. Furthermore, point mutations that abolish binding of NF-E1 result in a 70% decrease in the transcriptional activity of a megakaryocytic-specific promoter. We also find that NF-E2, another trans-acting factor of the erythrocytic lineage, is present in megakaryocytes. Transcriptional effects in both lineages might then be mediated in part by the same specific trans-acting factors. Our data strengthen the idea of a close association between the erythrocytic and the megakaryocytic lineages and could also explain the expression of markers specific to the erythrocytic and megakaryocytic lineages in most erythroblastic and megakaryoblastic permanent cell lines.

Background-Weight loss in obese insulin-resistant but not in insulin-sensitive persons reduces coronary heart disease risk. To what extent changes in gene expression are related to atherosclerosis and cardiovascular function is unknown. Methods and Results-We studied the effect of diet restriction-induced weight loss on gene expression in the adipose tissue, the heart, and the aortic arch and on atherosclerosis and cardiovascular function in mice with combined leptin and LDL-receptor deficiency. Obesity, hypertriglyceridemia, and insulin resistance are associated with hypertension, impaired left ventricular function, and accelerated atherosclerosis in those mice. Compared with lean mice, peroxisome proliferator-activated receptors (PPAR)-␣ and PPAR-␥ expression was downregulated in obese double-knockout mice. Diet restriction caused a 45% weight loss, an upregulation of PPAR-␣ and PPAR-␥, and a change in the expression of genes regulating glucose transport and insulin sensitivity, lipid metabolism, oxidative stress, and inflammation, most of which are under the transcriptional control of these PPARs. Changes in gene expression were associated with increased insulin sensitivity, decreased hypertriglyceridemia, reduced mean 24-hour blood pressure and heart rate, restored circadian variations of blood pressure and heart rate, increased ejection fraction, and reduced atherosclerosis. PPAR-␣ and PPAR-␥ expression was inversely related to plaque volume and to oxidized LDL content in the plaques. Conclusions-Induction of PPAR-␣ and PPAR-␥ in adipose tissue, heart, and aortic arch is a key mechanism for reducing atherosclerosis and improving cardiovascular function resulting from weight loss. Improved lipid metabolism and insulin signaling is associated with decreased tissue deposition of oxidized LDL that increases cardiovascular risk in persons with the metabolic syndrome. Key Words: atherosclerosis Ⅲ circadian rhythm Ⅲ genes Ⅲ lipoproteins Ⅲ obesity I nsulin resistance is now receiving increasing attention not only as a precursor to type 2 diabetes but also as a predictor of increased risk of cardiovascular disease. 1 Fat distributed in the abdominal region is a risk factor for type 2 diabetes and cardiovascular disease and is associated closely with insulin resistance. 2 Weight loss in insulin-resistant but not in insulinsensitive obese persons reduces their risk of coronary heart disease (CHD). 3 It is not known, however, to what extent changes in the intra-abdominal adipose gene expression profile are important for the reduction of the risk. 4 Several adipokines, and more specifically peroxisome proliferator-activated receptors (PPARs), regulate a number of the processes that contribute to the development of atherosclerosis, including dyslipidemia, arterial hypertension, endothelial dysfunction, insulin resistance, and vascular remodeling. Adipokines are preferentially expressed in intraabdominal adipose tissue, and the secretion of proinflammatory adipokines is elevated with increasing adiposity. Approaches to re...