Publications (11) View all
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Article: TGFβ signaling induces expression of Gadd45b in retinal ganglion cells.
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ABSTRACT: Purpose. Growth arrest and DNA damage protein 45b (Gadd45b) functions as an intrinsic neuroprotective molecule protecting retinal ganglion cells (RGCs) from injury. This study was performed to elucidate further the induction pathway of Gadd45b expression in RGCs. Methods. The induction of Gadd45b expression in response to TGFβ/NFκB signaling was investigated in RGC5 cultures in vitro and murine retina in vivo. Gadd45b mRNA and protein expression were detected by quantitative real-time RT-PCR, immunoblot assay, immunohistochemistry, and immunocytochemistry. Activation of NFκB and TGFβ/Gadd45b signaling were assessed by measuring phosphorylation of NFκB and using specific inhibitors. Gadd45b siRNA was transfected into RGC5 to silence Gadd45b mRNA expression. Results. Expression of TGFβ receptors I and II was detected in RGC5 in vitro and RGCs in vivo. TGFβ induced abundant Gadd45b mRNA and protein expression, exhibiting a dose-dependent response in vitro. Exogenous TGFβ1 induced up-regulation of Gadd45b expression in RGCs in murine retina in vivo. TGFβ1 stimulated phosphorylation of NFκB, and inhibition of NFκB phosphorylation blocked induction of Gadd45b by TGFβ1 in RGC5. Induction of Gadd45b by TGFβ1 increased the resistance of RGC5 against TNFβ cytotoxicity and paraquat oxidative stress. Conclusions. TGFβ signaling induced Gadd45b expression in RGCs. Modulation of the TGFβ/NFκB/Gadd45b signaling pathway may provide a means to enhance the neuroprotective effect of Gadd45b in RGCs.Investigative ophthalmology & visual science 01/2013; · 3.43 Impact Factor -
Article: Sphingosine-1-Phosphate Receptor 3 is a Novel Biomarker in Acute Lung Injury.
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ABSTRACT: Rationale: The inflamed lung exhibits oxidative and nitrative modifications of multiple target proteins potentially reflecting disease severity and progression. We identified the sphingosine 1-phosphate receptor 3 (S1PR3), a critical signaling molecule mediating cell proliferation and vascular permeability, as a nitrated plasma protein in mice with acute lung injury (ALI). We explored S1PR3 as a potential biomarker in murine and human ALI. Methods: In vivo nitrated and total S1PR3 levels were determined by immunoprecipitation and microarray studies in mice and by ELISA in human plasma. In vitro nitrated S1PR3 levels were evaluated in human lung vascular endothelial cells (EC) or within microparticles shed from EC following exposure to barrier-disrupting agonists (LPS, LMW-HA, thrombin). S1PR3-containing microparticle effects on EC barrier function were assessed by transendothelial electrical resistance (TER). Results: Nitrated S1PR3 was identified in the plasma of murine ALI model and in humans with severe sepsis induced-ALI. Elevated total S1PR3 plasma levels (> 251 pg/ml) were linked to sepsis and ALI mortality. In vitro EC exposure to barrier-disrupting agents induced S1PR3 nitration and shedding of S1PR3-containing microparticles that significantly reduced TER consistent with increased permeability. These changes were attenuated by reduced S1PR3 expression (siRNAs). Conclusions: These results suggest that microparticles containing nitrated S1PR3 shed into the circulation during inflammatory lung states represents a novel ALI biomarker linked to disease severity and outcome.American Journal of Respiratory Cell and Molecular Biology 07/2012; · 5.13 Impact Factor -
Article: Role of sphingolipids in murine radiation-induced lung injury: protection by sphingosine 1-phosphate analogs.
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ABSTRACT: Clinically significant radiation-induced lung injury (RILI) is a common toxicity in patients administered thoracic radiotherapy. Although the molecular etiology is poorly understood, we previously characterized a murine model of RILI in which alterations in lung barrier integrity surfaced as a potentially important pathobiological event and genome-wide lung gene mRNA levels identified dysregulation of sphingolipid metabolic pathway genes. We hypothesized that sphingolipid signaling components serve as modulators and novel therapeutic targets of RILI. Sphingolipid involvement in murine RILI was confirmed by radiation-induced increases in lung expression of sphingosine kinase (SphK) isoforms 1 and 2 and increases in the ratio of ceramide to sphingosine 1-phosphate (S1P) and dihydro-S1P (DHS1P) levels in plasma, bronchoalveolar lavage fluid, and lung tissue. Mice with a targeted deletion of SphK1 (SphK1(-/-)) or with reduced expression of S1P receptors (S1PR1(+/-), S1PR2(-/-), and S1PR3(-/-)) exhibited marked RILI susceptibility. Finally, studies of 3 potent vascular barrier-protective S1P analogs, FTY720, (S)-FTY720-phosphonate (fTyS), and SEW-2871, identified significant RILI attenuation and radiation-induced gene dysregulation by the phosphonate analog, fTyS (0.1 and 1 mg/kg i.p., 2×/wk) and to a lesser degree by SEW-2871 (1 mg/kg i.p., 2×/wk), compared with those in controls. These results support the targeting of S1P signaling as a novel therapeutic strategy in RILI.The FASEB Journal 06/2011; 25(10):3388-400. · 5.71 Impact Factor -
Article: Interleukin-1 receptor-associated kinase 3 gene associates with susceptibility to acute lung injury.
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ABSTRACT: Sepsis is the most common cause of acute lung injury (ALI), leading to organ dysfunction and death in critically ill patients. Previous studies associated variants of interleukin-1 receptor-associated kinase genes (IRAKs) with differential immune responses to pathogens and with outcomes during sepsis, and revealed that increased expression levels of the IRAK3 gene were correlated with poor outcomes during sepsis. Here we explored whether common variants of the IRAK3 gene were associated with susceptibility to, and outcomes of, severe sepsis. After our discovery of polymorphism, we genotyped a subset of seven single-nucleotide polymorphisms (SNPs) in 336 population-based control subjects and 214 patients with severe sepsis, collected as part of a prospective study of adults from a Spanish network of intensive care units. Whereas IRAK3 SNPs were not associated with susceptibility to severe sepsis, rs10506481 showed a significant association with the development of ALI among patients with sepsis (P = 0.007). The association remained significant after adjusting for multiple comparisons, population stratification, and clinical variables (odds ratio, 2.50; 95% confidence interval, 1.15-5.47; P = 0.021). By imputation, we revealed three additional SNPs independently associated with ALI (P < 0.01). One of these (rs1732887) predicted the disruption of a putative human-mouse conserved transcription factor binding site, and demonstrated functional effects in vitro (P = 0.017). Despite the need for replication in independent studies, our data suggest that common SNPs in the IRAK3 gene may be determinants of sepsis-induced ALI.American Journal of Respiratory Cell and Molecular Biology 02/2011; 45(4):740-5. · 5.13 Impact Factor -
Article: Functional variants of the sphingosine-1-phosphate receptor 1 gene associate with asthma susceptibility.
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ABSTRACT: The genetic mechanisms underlying asthma remain unclear. Increased permeability of the microvasculature is a feature of asthma, and the sphingosine-1-phosphate receptor (S1PR1) is an essential participant regulating lung vascular integrity and responses to lung inflammation. We explored the contribution of polymorphisms in the S1PR1 gene to asthma susceptibility. A combination of gene resequencing for single nucleotide polymorphism (SNP) discovery, case-control association, functional evaluation of associated SNPs, and protein immunochemistry studies was used. Immunohistochemistry studies demonstrated significantly decreased S1PR1 protein expression in pulmonary vessels in lungs of asthmatic patients compared with those of nonasthmatic subjects (P < .05). Direct DNA sequencing of 27 multiethnic samples identified 39 S1PR1 variants (18 novel SNPs). Association studies were performed based on genotyping results from cosmopolitan tagging SNPs in 3 case-control cohorts from Chicago and New York totaling 1,061 subjects (502 cases and 559 control subjects). The promoter SNP rs2038366 (-1557G/T) was found to be associated with asthma (P = .03) in European Americans. In African Americans an association was found for both asthma and severe asthma for intronic SNP rs3753194 (c.-164+170A/G; P = .006 and P = .040, respectively) and for promoter SNP rs59317557 (-532C/G) with severe asthma (P = .028). Consistent with predicted in silico functionality, alleles of the promoter SNPs rs2038366 (-1557G/T) and rs59317557 (-532C/G) influenced the activity of a luciferase S1PR1 reporter vector in transfected endothelial cells exposed to growth factors (epidermal growth factor, platelet-derived growth factor, and vascular endothelial growth factor) known to be increased in asthmatic airways. These data provide strong support for a role for S1PR1 gene variants in asthma susceptibility and severity.The Journal of allergy and clinical immunology 08/2010; 126(2):241-9, 249.e1-3. · 9.17 Impact Factor
