Genetic studies have revealed that Cbl-b plays a negative role in the antigen receptor-mediated proliferation of lymphocytes. However, we show that Cbl-b-deficient DT40 B cells display reduced phospholipase C (PLC)-gamma2 activation and Ca2+ mobilization upon B cell receptor (BCR) stimulation. In addition, the overexpression of Cbl-b in WEHI-231 mouse B cells resulted in the augmentation of BCR...

Activation of lymphocytes with 10 microM ionomycin leads to a rapid increase in the concentration of free cytoplasmic calcium ([Ca2+]i) and, at a slower rate, also to an increase in the cytoplasmic free magnesium concentration ([Mg2+]i). The ionomycin-induced Mg(2+)-mobilization response is dependent on the influx of extracellular Ca2+. After receptor-mediated lymphocyte activation, induced by ...

Generation of superoxide anion (O2-) and mobilization of intracellular Ca2+ in human neutrophils upon exposure to stimuli such as N-formylmethionylleucylphenylalanine (fMLP) were inhibited by the antibiotic cerulenin, which inhibits fatty acid and cholesterol biosynthesis. The inhibition of O2- generation and Ca2+-mobilization required certain periods of incubation with cerulenin and both abili...

We have explored the mechanisms involved in the induction of five stress-response genes (heme oxygenase [HO], c-fos, Egr-1, gadd153, and HSP70) in human diploid fibroblasts growth-arrested by treatment with the antiproliferative prostaglandin A2 (PGA2). The kinetics of c-fos and Egr-1 induction were found to be rapid with maximum expression occurring within 60 min of treatment, whereas maximum ...

Luminal Ca2+ has been proposed to regulate the sensitivity of intracellular Ca2+ stores to InsP3 and perhaps thereby to contribute to the mechanisms responsible for regenerative intracellular Ca2+ signals. Since Ca2+ release from intracellular stores is accompanied by K+ influx into the stores, InsP3-stimulated Ca2+ mobilization can be inhibited by substantially reducing the [K+] of incubation ...

The tumor-promoting phorbol diester 4 beta-phorbol 12-myristate 13-acetate (PMA) inhibited mobilization of intracellular Ca2+ in platelets by thrombin (also trypsin and 1-O-alkyl-2-acetyl-sn-glyceryl-3-phosphocholine). PMA was effective over the same concentration range that activates protein kinase C in intact platelets; IC50 vs. thrombin = 2 ng/ml, 3.4 nM: greater than 90% inhibition at 10-20...

In airway smooth muscle (ASM), full and partial muscarinic receptor agonists have been described to have large differences in their ability to induce signal transduction, including Ca2+-mobilization. Despite these differences, partial agonists are capable of inducing a submaximal to maximal ASM contraction. To further elucidate transductional differences between full and partial muscarinic rece...

This study provides new information about the relative importance of Ca2+ mobilization and entry in the renal vascular response to adrenoceptor activation. We measured renal blood flow (RBF) in Sprague-Dawley rats in vivo using electromagnetic flowmetry. We measured intracellular free Ca2+ concentration ([Ca2+]i) in isolated afferent arterioles utilizing ratiometric photometry of fura-2 fluores...

The effect of cyclosporine A to enhance vasoconstrictor-induced calcium (Ca2+) mobilization in vascular smooth muscle cells may contribute to important side effects in cyclosporine therapy such as hypertension and nephrotoxicity. On the other hand, atrial natriuretic peptide (ANP) is known to diminish vasoconstrictor-stimulated Ca2+ mobilization. The present study, therefore, examined the inter...

Using polymorphonuclear leucocyte-erythrocyte ghost hybrids entrapping the calcium-activated photoprotein obelin, we have demonstrated that sublytic amounts of the complement membrane attack complex induce a rapid but transient increase in intracellular free calcium ion concentration ([Ca2+]i). This increase in [Ca2+]i occurs prior to, and is required for, rapid removal of membrane attack compl...