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Martin Joyce-Brady

Publications and source records attributed to Martin Joyce-Brady.

8 recordsLinked to original sources
PubMed2006

Fibulin-5 gene expression in human lung fibroblasts is regulated by TGF-beta and phosphatidylinositol 3-kinase activity.

Fibulin-5 (FBLN5), an extracellular matrix glycoprotein required for normal elastogenesis, is coordinately expressed with elastin during lung injury and repair. We found that treatment with transforming growth factor-beta (TGF-beta) induced a rapid but transient increase in FBLN5 heterogeneous nuclear RNA (hnRNA) followed by a sustained increased in the steady-state level of FBLN5 mRNA. The transcription start site of the human FBLN5 gene was localized at 221 nucleotides upstream of the translation start site by using primer extension, Northern blots, and functional analysis of transcriptional activity in reporter plasmids containing 5'-flanking regions. TGF-beta markedly increased FBLN5 promoter activity in transient transfection assays. Two putative Smad-binding sites were identified within the proximal promoter and are required for this TGF-beta induction. Electrophoretic gel mobility shift assay revealed that TGF-beta strongly increased binding of Smad2 and Smad3 nuclear complexes to the proximal FBLN5 promoter and induced a Smad2/3-dependent binding of slow migrating nuclear protein complex. FBLN5 mRNA induction by TGF-beta was blocked by pretreatment with TGF-beta receptor inhibitor SB-431542, the phosphatidylinositol 3-kinase (PI3-kinase) inhibitor LY-294002, and actinomycin D. Basal and TGF-beta-induced FBLN5 hnRNA and mRNA were strongly and proportionally decreased by LY-294002, as was TGF-beta-induced phosphorylation of Akt, but not Smad3, as measured by Western blot analysis. In addition, LY-294002 markedly and proportionally decreased FBLN5 promoter activity in transient transfection analyses with TGF-beta-treated or untreated lung fibroblasts. These studies demonstrate that induction of FBLN5 gene expression in lung fibroblasts is mediated via canonical TGF-beta/Smad signaling and requires the PI3-kinase/Akt pathway.

Animals↗
PubMed2006

Hypoxia results in an HIF-1-dependent induction of brain-specific aldolase C in lung epithelial cells.

Aldolase C (EC 4.1.2.13) is a brain-specific aldolase isoform and a putative target of the transcription factor hypoxia-inducible factor (HIF)-1. We identified aldolase C as a candidate hypoxia-regulated gene in mouse lung epithelial (MLE) cells using differential display. We show that the message accumulates in a robust fashion when MLE cells are exposed to 1% oxygen and is inversely related to oxygen content. Induction in hypoxia is dependent on protein synthesis. We localized a hypoxia-responsive element (HRE) in the aldolase C promoter using a series of deletion and heterologous expression studies. The HRE overlaps with a region of the proximal aldolase C promoter that is also related to its brain-specific expression. The HRE contains an Arnt (HIF-1beta) and an HIF-1alpha site. We show that induction in hypoxia is dependent on the HIF-1 site and that HIF-1alpha protein is present, by gel-shift assay, within nuclear complexes of MLE cells in hypoxia. Aldolase C mRNA expression is developmentally regulated in the fetal lung, rapidly downregulated in the newborn lung at birth, and inducible in the adult lung when exposed to hypoxia. This pattern of regulation is not seen in the brain. This preservation of this HRE in the promoters of four other species suggests that aldolase C may function as a stress-response gene.

Animals↗
PubMed2003

Development and prospective validation of a model for predicting weaning in chronic ventilator dependent patients.

BACKGROUND: Approximately ten percent of patients placed on mechanical ventilation during acute illness will require long-term ventilator support. Unfortunately, despite rehabilitation, some will never be liberated from the ventilator. A method of predicting weaning outcomes for these patients could help conserve resources and minimize frustrating failed weaning attempts for this population. The objective of this investigation was to identify predictors of weaning outcome for patients admitted to a chronic ventilator unit (CVU). METHODS: This was a retrospective analysis with prospective validation. The study setting was a 25 bed CVU within a rehabilitation hospital. The training group consisted of 43 patients referred to our facility for weaning after > 3 weeks of mechanical ventilation. A multivariate model to predict weaning outcome was constructed in this group and applied to a prospective group of 31 patients followed during an 18-month period. RESULTS: A modified Glasgow Coma Scale (GCS) and the presence of sustained spontaneous respirations (SSR), defined as the presence of 2 breaths recorded above the ventilator settings on four occasions, were highly predictive of weaning success within six months of CVU admission. Patients with a modified GCS > or = 8 were 6.5 times more likely to wean than those with a modified GCS < 8 (95% confidence interval 1.6-26.3) and those with SSR were 25.5 times more likely to wean than those without SSR (95% confidence interval 4.3-51.9). CONCLUSIONS: In our population of CVU patients, simple parameters that were available on admission and did not directly reflect cardiopulmonary function were useful predictors of weaning outcome.

Journal Article↗
PubMed2003

Coordinate expression of fibulin-5/DANCE and elastin during lung injury repair.

Fibulin-5, previously known as DANCE and EVEC, is a secreted extracellular matrix protein that functions as a scaffold for elastin fiber assembly and as a ligand for integrins alphavbeta3, alphavbeta5, and alpha9beta1. Fibulin-5 is developmentally regulated in the lung, and lung air space enlargement develops in mice deficient in fibulin-5. Fibulin-5 is also induced in adult lung following lung injury by hyperoxia. To further examine the role of fibulin-5 during repair of lung injury, we assessed fibulin-5 expression during elastase-induced emphysema in C57/b mice. Mice were treated with either saline or elastase via the trachea, and the lung was examined 20 days after treatment. Fibulin-5 mRNA was induced almost fourfold, whereas elastin mRNA was minimally elevated. Immunohistochemistry studies showed that fibulin-5 was induced in cells within the alveolar wall following elastase treatment. Western analysis demonstrates that fibulin-5 was strongly expressed in isolated primary lung interstitial fibroblasts. Fibulin-5 protein was localized to the fibroblast cell layer in culture, and brief elastase treatment degraded the protein. Intact fibulin-5 did not accumulate in the culture media. Treatment of fibroblasts with the proinflammatory cytokine interleukin-1beta abolished fibulin-5 mRNA expression. Our results indicate that fibulin-5 is coordinately expressed and regulated with elastin in lung fibroblasts and may serve a key role during lung injury and repair.

Amino Acid Sequence↗
PubMed2002

Gamma-glutamyl transferase deficiency results in lung oxidant stress in normoxia.

gamma-Glutamyl transferase (GGT) is critical to glutathione homeostasis by providing substrates for glutathione synthesis. We hypothesized that loss of GGT would cause oxidant stress in the lung. We compared the lungs of GGT(enu1) mice, a genetic model of GGT deficiency, with normal mice in normoxia to study this hypothesis. We found GGT promoter 3 (P3) alone expressed in normal lung but GGT P3 plus P1, an oxidant-inducible GGT promoter, in GGT(enu1) lung. Glutathione content was barely decreased in GGT(enu1) lung homogenate and elevated nearly twofold in epithelial lining fluid, but the fraction of oxidized glutathione was increased three- and fourfold, respectively. Glutathione content in GGT(enu1) alveolar macrophages was decreased nearly sixfold, and the oxidized glutathione fraction was increased sevenfold. Immunohistochemical studies showed glutathione deficiency together with an intense signal for 3-nitrotyrosine in nonciliated bronchiolar epithelial (Clara) cells and expression of heme oxygenase-1 in the vasculature only in GGT(enu1) lung. When GGT(enu1) mice were exposed to hyperoxia, survival was decreased by 25% from control because of accelerated formation of vascular pulmonary edema, widespread oxidant stress in the epithelium, diffuse depletion of glutathione, and severe bronchiolar cellular injury. These data indicate a critical role for GGT in lung glutathione homeostasis and antioxidant defense in normoxia and hyperoxia.

Animals↗
PubMed2002

DANCE in developing and injured lung.

We identified rat developing arteries and neural crest derivatives with multiple epidermal growth factor-like domains (DANCE) as a developmentally regulated gene using suppression-subtractive hybridization. Northern analysis confirmed a fivefold induction of this mRNA transcript between fetal day 18 and 20 that persisted through postnatal day 17. The level was declining at postnatal day 21 and was similar in adult lung to that at fetal day 18. In adults DANCE mRNA abundance was highest in lung, kidney, and spleen, lower in heart, skeletal muscle, and brain, but absent from liver and thymus. It was abundant in pulmonary artery endothelium and a lung epithelial type 2 cell line, barely detectable in vascular smooth muscle, and absent in fibroblasts. In situ hybridization revealed a regulated pattern of expression in endothelial cells of fetal, postnatal, and adult lung. Because DANCE mRNA was inducible in systemic arteries during recovery from injury, we searched for induction in lung injured by hyperoxia. Mouse DANCE mRNA abundance was unchanged during an acute 3-day exposure period, induced threefold 5 days into the recovery phase, and returned to baseline at days 8, 11, and 14. In situ hybridization at day 5 suggested a diffuse pattern of induction. DANCE may play a role in lung endothelial cell biology during development repair after injury.

Aging↗