As compared with interferon alfa, temsirolimus improved overall survival among patients with metastatic renal-cell carcinoma and a poor prognosis. The addition of temsirolimus to interferon did not improve survival. (ClinicalTrials.gov number, NCT00065468 [ClinicalTrials.gov].).

Abstract. We analyzed the binding of fibronectin to integrin a5/31 in various cells; in some cells fibronectin bound with low affinity (e.g., K562 cells) whereas in others (e.g., CHO), it bound with high affinity (Kd ,~ 100 nM) in an energy-dependent manner. We constructed chimeras of the extracellular and transmembrane domains of c~3 joined to the cytoplasmic domains of otsBl. The affinity state of these chimeras was assessed by binding of fibrinogen or the monoclonal antibody, PACl. The cytoplasmic domains of 0~5/~ conferred an energy-dependent high affinity state on otnbB3 in CliO but not K562 cells. Three additional tx cytoplasmic domains (ix2, otv~, ot~B) conferred PAC1 binding in CHO cells, while three others (otM, OiL, av) did not. In the high affinity ot chimeras, cotransfection with a truncated (~3A724) or mutated (~3(S752"-~P)) 83 subunit abolished high affinity binding. Thus, both cytoplasmic domains are required for energy-dependent, cell type-specific affinity modulation. In addition, mutations that disrupted a highly conserved o~ subunit GFFICR motif, resulted in high affinity binding of ligands to Otnb/~3. In contrast to the chimeras, the high affinity state of these mutants was independent of cellular metabolism, cell type, and the bulk of the ~ subunit cytoplasmic domain. Thus, integrin cytoplasmic domains mediate inside-out signaling. Furthermore, ' the highly conserved GFFKR motif of the c~ Subunit cytoplasmic domain maintains the default low affinity state.

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Fibronectin (Fn) matrices are vital to vertebrate development and wound healing and modulate tumorigenesis. We used a recombinant Fn-binding integrin alpha IIb beta3, to define rules for integrin-initiated Fn matrix formation. We report the following. First, multiple Fn-binding integrins can support matrix assembly; their activation state controls fibrillogenesis. Second, Fn binding to cells expressing an activated integrin is necessary but not sufficient for matrix assembly. Additional "postoccupancy" events involving the integrin beta, but not the alpha subunit, cytoplasmic domain are needed. Third, these postoccupancy events require an intact actin cytoskeleton. We propose a model for integrin involvement in Fn fibrillogenesis that reconciles previous paradoxes and suggests novel approaches to the therapeutic control of Fn matrix assembly.

The ligand-binding function of integrin adhesion receptors depends on divalent cations. A mutant alpha IIb beta 3 integrin (platelet gpIIb/IIIa) that lacks ligand recognition shows immunologic evidence of a perturbed interaction with divalent cations. This was found to be caused by a G----T mutation that resulted in an Asp119----Tyr119 substitution in the beta 3 subunit. This residue is proximal to bound ligand and is in a conserved region among integrins that are enriched in oxygenated residues. The spacing of these residues aligns with the calcium-binding residues in EF hand proteins, suggesting interaction with receptor-bound divalent cation as a mechanism of ligand binding common to all integrins.

Rationale Epidemiologic evidence indicates that exposures to fine particulate matter air pollution (PM2.5) contribute to global burden of disease, primarily as a result of increased risk of cardiovascular morbidity and mortality. However, mechanisms by which PM2.5 exposure induces cardiovascular injury remain unclear. PM2.5-induced endothelial dysfunction and systemic inflammation have been implicated, but direct evidence is lacking. Objective To examine whether acute exposure to PM2.5 is associated with endothelial injury and systemic inflammation. Methods and Results Blood was collected from healthy, non-smoking, young adults over three study periods that included episodes of elevated PM2.5 levels. Microparticles and immune cells in blood were measured by flow cytometry, and plasma cytokine/growth factors were measured using multiplexing laser beads. PM2.5 exposure was associated with elevated levels of endothelial microparticles (annexin V+/CD41−/CD31+) including subtypes expressing arterial-, venous-, and lung-specific markers, but not microparticles expressing CD62+. These changes were accompanied by suppressed circulating levels of pro-angiogenic growth factors (EGF, sCD40L, PDGF, RANTES, GROα, and VEGF), and an increase in the levels of anti-angiogenic (TNFα, IP-10) and proinflammatory cytokines (MCP-1, MIP-1α/β, IL-6, and IL-1β), and markers of endothelial adhesion (sICAM-1 and sVCAM-1). PM2.5 exposure also was associated with an inflammatory response characterized by elevated levels of circulating CD14+, CD16+, CD4+, and CD8+, but not CD19+ cells. Conclusions Episodic PM2.5 exposures are associated with increased endothelial cell apoptosis, an anti-angiogenic plasma profile, and elevated levels of circulating monocytes, and T, but not B, lymphocytes. These changes could contribute to the pathogenic sequelae of atherogenesis and acute coronary events.

Intracellular signaling alters integrin adhesive functions in inflammation, immune responses, hemostasis, thrombosis, and retinal development. By truncating the cytoplasmic domain of alpha IIb, the affinity of integrin alpha IIb beta 3 for ligand was increased. Reconstitution with the cytoplasmic domain from integrin alpha 5 did not reverse the increased affinity. Thus, the cytoplasmic domain of the alpha subunit of GPIIb-IIIa controls ligand binding affinity, which suggests mechanisms for inside-out transmembrane signaling through integrins. These findings imply the existence of hitherto unappreciated hereditary and acquired thrombotic disorders in humans.