Regulation of gene expression of ATP-binding cassette transporter (ABC)A1 and ABCG1 by liver X receptor/retinoid X receptor (LXR/RXR) ligands was investigated in the human intestinal cell line CaCo-2. Neither the RXR ligand, 9-cis retinoic acid, nor the natural LXR ligand 22-hydroxycholesterol alone altered ABCA1 mRNA levels. When added together, ABCA1 and ABCG1 mRNA levels were increased 3-and 7-fold, respectively. T0901317, a synthetic non-sterol LXR agonist, increased ABCA1 and ABCG1 gene expression 11-and 6-fold, respectively. ABCA1 mass was increased by LXR/RXR activation. T0901317 or 9-cis retinoic acid and 22-hydroxycholesterol increased cholesterol efflux from basolateral but not apical membranes.

Pneumonia remains the leading cause of infectious deaths and yet fundamentally new conceptual models underlying its pathogenesis have not emerged. Patients and mice with bacterial pneumonia have marked elevations of cardiolipin in lung fluid, a rare, mitochondrial-specific phospholipid that potently disrupts surfactant function. Intratracheal cardiolipin in mice recapitulates the clinical phenotype of pneumonia including impaired lung mechanics, modulation of cell survival and cytokine networks, and lobar consolidation. We have identified and characterized the activity of a novel cardiolipin transporter, ATP8b1, a mutant version of which is associated with severe pneumonia in humans and mice. ATP8b1 bound and internalized cardiolipin from extracellular fluid via a basic residue-enriched motif. Administration of cardiolipin binding motif peptide or ATP8b1 gene transfer in mice lessened lung injury and improved survival. The results unveil a new paradigm whereby ATP8b1 is a cardiolipin importer but its capacity to remove cardiolipin from lung fluid is exceeded during inflammation or ATP8b1 inefficiency. This discovery opens the door for new therapeutic strategies directed at modulating cardiolipin levels or its molecular interactions in pneumonia.

Abstract-The peroxisome proliferator activated receptor (PPAR␥) agonist rosiglitazone has been reported to yield cardiovascular benefits in patients by a mechanism that is not completely understood. We tested whether oral rosiglitazone (25 mg/kg per day, 21 days) treatment improves blood pressure and vascular function in a transgenic mouse expressing both human renin and human angiotensinogen transgenes (R ϩ A ϩ ). Rosiglitazone decreased systolic (138Ϯ5 versus 128Ϯ5 mm Hg) and mean blood pressure (145Ϯ5 versus 126Ϯ7 mm Hg) of R ϩ A ϩ mice as measured by tail-cuff and indwelling carotid catheters, respectively. Relaxation of carotid arteries to acetylcholine and authentic nitric oxide, but not papaverine, was impaired in R ϩ A ϩ mice when compared with littermate controls (RA Ϫ ). There were no effects of rosiglitazone on RA Ϫ mice; however, relaxation to acetylcholine (49Ϯ10 versus 82Ϯ9% at 100 mol/L) and nitric oxide (51Ϯ11 versus 72Ϯ6% at 10 mol/L) was significantly improved in treated R ϩ A ϩ mice. Rosiglitazone treatment of R ϩ A ϩ mice did not alter the expression of genes, including endothelial nitric oxide synthase (eNOS), angiotensin 1 receptors, and preproendothelin-1, nor did it alter the levels of eNOS or soluble guanylyl cyclase protein.In separate studies, carotid arteries from R ϩ A ϩ and RA Ϫ mice relaxed in a concentration-dependent manner to rosiglitazone, suggesting possible PPAR␥-independent effects in the vasculature. This response was not inhibited with the nitric oxide synthase inhibitor N -nitro-L-arginine methyl ester (200 mol/L) or the PPAR␥ antagonist bisphenol A diglycidyl ether; 4,4Ј-isopropylidenediphenol diglycidyl ether (100 mol/L). These data suggest that in addition to potential genomic regulation caused by PPAR␥ activation, the direct effect of rosiglitazone in blood vessels may contribute to the improved blood pressure and vessel function. Key Words: nitric oxide Ⅲ angiotensin Ⅲ endothelin Ⅲ carotid P eroxisome proliferator activated receptors (PPARs) are members of the nuclear hormone receptor superfamily and bind to DNA as a heterodimer with retinoid x receptor to regulate transcription. Three genes encode different PPARs (␣, ␤/␦, and ␥), and the gene products are differentially expressed in a variety of tissues. 1 PPARs have been most widely characterized with respect to their role in adipocyte growth and differentiation. 2 More recently, PPAR␥ has become the focus of attention for the treatment of noninsulin-dependent diabetes mellitus, due largely to successful treatment with the thiazolidinedione (TZD) class of drugs that act as specific PPAR␥ ligands. TZDs (ie, troglitazone, ciglitazone, pioglitazone, and rosiglitazone) activate PPAR␥, leading to improved insulin sensitivity and reduced blood pressure in both humans and animals through a mechanism that has not been completely elucidated. [3][4][5][6] These findings, coupled with the observation that PPAR␥ is expressed in both vascular muscle 7 and endothelium, 8 suggest that it may play an important role in the regulati...

The glia maturation factor (GMF), which was discovered in our laboratory, is a highly conserved protein predominantly localized in astrocytes. GMF is an intracellular regulator of stress-related signal transduction. We now report that the overexpression of GMF in astrocytes leads to the destruction of primary oligodendrocytes by interactions between highly purified cultures of astrocytes, microglia, and oligodendrocytes. We infected astrocytes with a replication-defective adenovirus carrying the GMF cDNA. The overexpression of GMF caused the activation of p38 MAP kinase and transcription factor NF-jB, as well as the induction of granulocytemacrophage colony-stimulating factor (GM-CSF) mRNA and protein in astrocytes. Small interfering RNA-mediated GMF knockdown completely blocked the GMF-dependent activation of p38 mitogen-activated protein kinase (MAPK), NF-jB, and enhanced expression of GM-CSF by astrocytes. Inhibition of p38 MAPK or NF-jB by specific inhibitors prevented GM-CSF production. The cell-free conditioned medium from overexpressing GMF astrocytes contained 320 ± 33 pg/mL of GM-CSF, which was responsible for enhanced production and secretion of TNF-a, IL-1b, IL-6, and IP-10 by microglia. Presence of these inflammatory cytokines in the conditioned medium from microglia efficiently destroyed oligodendrocytes in culture. These results suggest that GMF-induced production of GM-CSF in astrocytes is depending on p38 MAPK and NF-jB activation. The GM-CSF-dependent expression and secretion of inflammatory cytokine/chemokine, TNF-a, IL-1b, IL-6, and IP-10, is cytotoxic to oligodendrocytes, the myelinforming cells in the central nervous system, and as well as neurons. Our results suggest a novel pathway of GMF-initiated cytotoxicity of brain cells, and implicate its involvement in inflammatory diseases such as multiple sclerosis.

Abstract-Many of the actions of angiotensin II (Ang II) are mediated by angiotensin type 1 receptors (AT 1 ), of which there are 2 pharmacologically indistinguishable subtypes (AT 1A and AT 1B ). The purpose of this study was to evaluate the effect of an AT 1A homozygous deletion (AT 1A Ϫ/Ϫ ) on vascular reactivity. AT 1A Ϫ/Ϫ mice and control littermates (AT 1A Ϫ/Ϫ ) have reduced blood pressures and no pressor response to Ang II infusion. 6 These data implicate AT 1A as the primary subtype responsible for Ang II actions in mice. However, some reports suggest a potential role for AT 1B in the vasculature. 8 -11 For example, recent evidence implicates AT 1B as the predominant mediator of Ang II-induced contraction in the abdominal aorta and femoral arteries. 12 Although several investigators have addressed the differential role of AT 1A and AT 1B in Ang II-induced contraction, 8,11,13 there are no reports aimed at investigating the contribution of Ang II receptor subtypes to nitric oxide-mediated vessel relaxation, non-Ang II contractile responses, or the generation of vascular superoxide. Therefore, we tested whether a genetic deletion of the AT 1A receptor: (1) alters vascular responses to dilators and constrictors; (2) protects the vessels from Ang II-induced changes in reactivity; and (3) changes basal and Ang II-stimulated levels of vascular superoxide. Methods AnimalsMice heterozygous for the AT 1A receptor subtype (ϩ/Ϫ) were obtained from the Jackson Laboratory (Bar Harbor, Me). The colony was maintained on a mixed genetic background (Ϸ87% 129P3/J and Ϸ13% C57BL/6J), and littermates were used as controls. Offspring were born in ratios (ϩ/ϩ 25%, ϩ/Ϫ 62%, Ϫ/Ϫ 13%) similar to those reported by Oliverio et al. 14 Experiments were performed on male and female mice at an average age of 6.0Ϯ0.3 (AT 1A ϩ/ϩ ) and 5.8Ϯ0.4 (AT 1A Ϫ/Ϫ ) months. ReagentsAcetylcholine (ACh), sodium nitroprusside (SNP), papaverine (PAP), phenylephrine (PE), Ang II, and 5-hydroxytryptamine (5-HT) were purchased from Sigma Chemicals and dissolved in saline. Lucigenin (Sigma) was dissolved in phosphate-buffered saline.