Insights into the Mycobacterial Response to Nitrogen Limitation; Characterisation of the GlnR Regulon

The ability to sense and initiate a response to situations of nitrogen-limitation is essential for bacterial survival. In extensively investigated organisms, the nitrogen-stress response consists of changes in intracellular metabolite levels, post-translational modification of proteins (such as metabolic enzymes) and a transcriptomic response mediated by a global response regulator. However, in mycobacteria the nitrogen stress response has not been comprehensively investigated. In this study mycobacterial nitrogen limiting conditions were optimised and the mechanism of GlnR activation investigated; M. smegmatis GlnR requires a highly conserved aspartate residue (D48), corresponding to a putative phosphorylation site, for function. In addition, a ChIP-seq approach combined with global expression analyses, permitted characterisation of the GlnR mediated global transcriptomic response stimulated during nitrogen. In M. smegmatis, 52 GlnR binding sites were identified, controlling the expression of at least 103 genes in response to nitrogen limitation. The majority of GlnR regulated genes were involved in nitrogen uptake and nitrogen scavenging. A consensus GlnR DNA binding motif was identified and AC-n9-AC DNA residues shown to be essential for GlnR:DNA binding. In M. tuberculosis 36 GlnR binding sites were identified in nitrogen limitation, however no consensus GlnR:DNA binding motif could be determined. Initial analysis suggests GlnR may be involved in a general stress response in M. tuberculosis, rather than mediating a nitrogen scavenging response as observed in M. smegmatis. This study provides the first global analysis of nitrogen limitation in mycobacteria and identifies GlnR as the main nitrogen response regulator. From this analysis it appears that the role of GlnR is different in M. tuberculosis compared to M. smegmatis, which may provide key insights into how pathogenic and non-pathogenic species survive nutrient limiting conditions.Open Acces

Review of Rereading Victorian Fiction; Rethinking Victorian Culture

These two fine volumes have their roots in a Victorian literature conference at the University of Liverpool in 1996, which I had the good fortune to attend. At the time, I remember being struck in particular by the erudition of a number of the papers presented and by the impressive range of material covered in eclectic ways. It is extremely pleasing to see many of the best papers from the conference expanded in these two volumes, pleasing not least because these two collections offer an extremely good snapshot representing the diverse richness and buoyant state of Victorian Studies at the turn of our century. One of the things that emerges in several essays, explicitly or implicitly, is the generally troubling nature of the word ‘Victorian’ for scholars today. Unlike, say, a generation or so ago, the umbrella the, ‘Victorian’ no longer seems useful, apart from demarcating the years of the monarch’s reign. Any students of the period know that there are more social and political differences between 1837 and 1901 than there are similarities, and the literature across the period is no different. While the titles of these two volumes both employ ‘Victorian’ descriptively, the essay inside demonstrate over and over again the literary and cultural diversity and complexity across the nineteenth century, rather than the uniformity that ‘Victorian’ might suggest. As John Lucas puts it: There is a strong case for arguing that, except in the most rigorously controlled of contexts, “Victorian” and “Victorianism” are terms we could well do without. They are all too frequently employed in ways that are chronologically indefensible, historically dubious, intellectually confusing and ideologically unacceptable- at least, if you’re a socialist. “Victorian” in particular is used to imply a cultural and political homogeneity which, the evidence suggests, never existed

Equipping the Saints: Best Practices in Contextual Theological Education (Cleveland, OH: Pilgrim Press, 2010)

Reviewed by R. Leon Carroll, Jr

Reconceptualizing Women\u27s Work: A Focus on the Domestic and Eligibility Work of Women on Welfare

The types of work performed by women receiving public assistance are examined. Research on women\u27s work often neglects the labor of poor women, reinforcing the view that women receiving welfare do not work. This perspective is challenged with focus group and interview data from welfare recipients in New Orleans, Louisiana. We conclude that within the restrictions of public assistance, poor women are engaging in three types of work: domestic work for their families, economic work for cash-both legal and illegal work, and eligibility work. Eligibility work is defined as the labor necessary to obtain and maintain public assistance

Suberanilohydroxamic acid prevents TGF-β1-induced COX-2 repression in human lung fibroblasts post-transcriptionally by TIA-1 downregulation

Cyclooxygenase-2 (COX-2), with its main antifibrotic metabolite PGE, is regarded as an antifibrotic gene. Repressed COX-2 expression and deficient PGE have been shown to contribute to the activation of lung fibroblasts and excessive deposition of collagen in pulmonary fibrosis. We have previously demonstrated that COX-2 expression in lung fibroblasts from patients with idiopathic pulmonary fibrosis (IPF) is epigenetically silenced and can be restored by epigenetic inhibitors. This study aimed to investigate whether COX-2 downregulation induced by the profibrotic cytokine transforming growth factor-β1 (TGF-β1) in normal lung fibroblasts could be prevented by epigenetic inhibitors. We found that COX-2 protein expression and PGE production were markedly reduced by TGF-β1 and this was prevented by the pan-histone deacetylase inhibitor suberanilohydroxamic acid (SAHA) and to a lesser extent by the DNA demethylating agent Decitabine (DAC), but not by the G9a histone methyltransferase (HMT) inhibitor BIX01294 or the EZH2 HMT inhibitor 3-deazaneplanocin A (DZNep). However, chromatin immunoprecipitation assay revealed that the effect of SAHA was unlikely mediated by histone modifications. Instead 3'-untranslated region (3'-UTR) luciferase reporter assay indicated the involvement of post-transcriptional mechanisms. This was supported by the downregulation by SAHA of the 3'-UTR mRNA binding protein TIA-1 (T-cell intracellular antigen-1), a negative regulator of COX-2 translation. Furthermore, TIA-1 knockdown by siRNA mimicked the effect of SAHA on COX-2 expression. These findings suggest SAHA can prevent TGF-β1-induced COX-2 repression in lung fibroblasts post-transcriptionally through a novel TIA-1-dependent mechanism and provide new insights into the mechanisms underlying its potential antifibrotic activity

Effect of epigenetic inhibitors on lung fibroblast phenotype change in idiopathic pulmonary fibrosis

Introduction and objectives: Idiopathic Pulmonary Fibrosis (IFP) is a fatal interstitial lung disease with unknown aetiology. Lung myofibroblasts (activated fibrobalsts) are the major effector cells in the pathogenesis of IPF. Transforming growth factor-β (TGF-β1) is a potent activator of fibroblasts. Lack of effective treatment options necessitates novel therapeutic approaches. Epigenetic drugs, by inhibiting chromatin modifying enzymes involved in gene expression control, represent promising agents capable of modulating the cellular phenotype. We previously demonstrated that the cyclooxygenase-2 (COX-2) gene is epigenetically silenced in lung fibroblasts from IPF patients (F-IPF)[1] and epigenetic inhibitors and restore COX-2 expression. However, whether epigenetic inhibitors can alter fibroblast phenotype remains unknown. This study aimed to investigate the effect of four different epigenetic enzyme inhibitors on fibroblast phenotype change in IPF. Methods: F-IPF and fibroblasts from non-fibrotic lung (F-NL) treated with TGF-β1 were cultured to test the effects of the epigenetic inhibitors BIX01294 (BIX, G9a histone methyltransferase inhibitor), 3- deazaneplanocin A (DZNep, EZH2 histone methyltransferase inhibitor), SAHA (histone deacetylases inhibitor) and Decitabine (DAC, DNA demethylating agent), in comparison with the COX-2 products prostaglandin E2 (PGE2). The expression of COX-2 and myofibroblast markers collagen 1 (COL1) and α- smooth muscle actin (α-SMA) was assessed. The COX-2 DNA promoter methylation level was analysed by bisulfite sequencing. Results: TGF-β1 induced a myofibroblast phenotype in F-NL characterised by COL1 and α-SMA upregulation and COX-2 downregulation, similar to F-IPF. PGE2 and SAHA were able to maintain/restore COX-2 expression in TGF-β1-induced myofibroblasts and F-IPF. DAC demonstrated similar effect in TGF-β1 treated F-NL only. SAHA also reduced COL1 and α-SMA expression. But DZNep and BIX showed no effect. No differences in the COX-2 promoter methylation was detected between F-NL and F-IPF. Conclusions: Among the epigenetic inhibitors tested, SAHA shows a promising antifibrotic effect by inhibiting fibroblast activation and the underlying molecular mechanisms are currently under investigation

Patterns of Vertebrate Diversity and Protection in Brazil

Most conservation decisions take place at national or finer spatial scales. Providing useful information at such decision-making scales is essential for guiding the practice of conservation. Brazil is one of the world’s megadiverse countries, and consequently decisions about conservation in the country have a disproportionate impact on the survival of global biodiversity. For three groups of terrestrial vertebrates (birds, mammals, and amphibians), we examined geographic patterns of diversity and protection in Brazil, including that of endemic, small-ranged, and threatened species. To understand potential limitations of the data, we also explored how spatial bias in collection localities may influence the perceived patterns of diversity. The highest overall species richness is in the Amazon and Atlantic Forests, while the Atlantic Forest dominates in terms of country endemics and small-ranged species. Globally threatened species do not present a consistent pattern. Patterns for birds were similar to overall species richness, with higher concentrations of threatened species in the Atlantic Forest, while mammals show a more generalized pattern across the country and a high concentration in the Amazon. Few amphibians are listed as threatened, mostly in the Atlantic Forest. Data deficient mammals occur across the country, concentrating in the Amazon and southeast Atlantic Forest, and there are no data deficient birds in Brazil. In contrast, nearly a third of amphibians are data deficient, widespread across the country, but with a high concentration in the far southeast. Spatial biases in species locality data, however, possibly influence the perceived patterns of biodiversity. Regions with low sampling density need more biological studies, as do the many data deficient species. All biomes except the Amazon have less than 3% of their area under full protection. Reassuringly though, rates of protection do correlate with higher biodiversity, including higher levels of threatened and small-ranged species. Our results indicate a need for expanded formal protection in Brazil, especially in the Atlantic forest, and with an emphasis on fully protected areas

S52 Suberanilohydroxamic acid (SAHA) inhibits collagen deposition in a transforming growth factor β1-driven precision cut lung slice (PCLS) model of pulmonary fibrosis

Introduction and objectives Idiopathic Pulmonary Fibrosis (IPF) is a chronic, progressive interstitial lung disease that is refractory to current treatment options. Transforming growth factor (TGF)-β1 is a key pro-fibrotic cytokine that plays a crucial role in IPF pathogenesis. Our group previously demonstrated distinct epigenetic modifications involved in repression of the antifibrotic gene cyclooxygenase-2 (COX-2) in fibroblasts from IPF (F-IPF) lungs compared with fibroblasts from non-fibrotic lungs (F-NL). Epigenetic drugs capable of inhibiting DNA and histone modifications may, therefore, represent a putative novel therapy. The aim of this study was to investigate the ability of 4 epigenetic inhibitors to regulate TGF-β-driven fibrosis in ex vivo mouse lung. Methods A precision-cut lung slice (PCLS) model of fibrosis was established using the previously described1 CC10-tTS-rtTA-TGFβ1 transgenic (tgTGF-β1) mouse. The model was first assessed by investigating PCLS overexpression of TGF-β1 in response to stimulation of the transgene by doxycycline treatment. Gene expression of COX-2 and fibrotic markers including collagen were assessed after 4 days of treatment. The anti-fibrotic potential of 4 epigenetic inhibitors; BIX01294 (BIX, inhibitor of G9a histone methyltransferase), 3-deazaneplanocin A (DZNep, inhibitor of EZH2 histone methyltransferase), SAHA (inhibitor of histone deacetylases, HDACs) and Decitabine (DAC, DNA demethylating agent) was investigated. Viability of PCLS was assessed by MTT and Prestoblue® assay. Results Treatment of PCLS from tgTGF-β1 mice with doxycycline induced a concentration-dependent increase in global TGF-β1, pro-fibrotic markers including collagen and pro-inflammatory COX-2, which was comparable to recombinant TGF-β1 treatment. Treatment with three of the epigenetic inhibitors BIX01294, DZNep and DAC did not reduce the pro-fibrotic response following doxycycline treatment. However SAHA demonstrated a significant suppressive effect on COX-2 and collagen expression, while not directly affecting TGF-β1 transgene expression. Conclusions The data suggests that SAHA has the potential to reduce fibrosis in a TGF-β1 driven model of pulmonary fibrosis. Further work is currently underway to assess the anti-fibrotic potential of this drug in tgTGF-β1 animals

Suberanilohydroxamic acid (SAHA) inhibits collagen deposition in a transforming growth factor β1-driven precision cut lung slice (PCLS) model of pulmonary fibrosis

Introduction and Objectives: Idiopathic Pulmonary Fibrosis (IPF) is a chronic, progressive interstitial lung disease that is refractory to current treatment options. Transforming growth factor (TGF)-β1 is a key pro-fibrotic cytokine that plays a crucial role in IPF pathogenesis. Our group previously demonstrated distinct epigenetic modifications involved in repression of the antifibrotic gene cyclooxygenase-2 (COX-2) in fibroblasts from IPF (F-IPF) lungs compared with fibroblasts from non-fibrotic lungs (F-NL). Epigenetic drugs capable of inhibiting DNA and histone modifications may, therefore, represent a putative novel therapy. The aim of this study was to investigate the ability of 4 epigenetic inhibitors to regulate TGF-β-driven fibrosis in ex vivo mouse lung. Methods: A precision-cut lung slice (PCLS) model of fibrosis was established using the previously described [1] CC10-tTS-rtTA-TGFβ1 transgenic (tgTGF-β1) mouse. The model was first assessed by investigating PCLS overexpression of TGF-β1 in response to stimulation of the transgene by doxycycline treatment. Gene expression of COX-2 and fibrotic markers including collagen were assessed after 4 days of treatment. The anti-fibrotic potential of 4 epigenetic inhibitors; BIX01294 (BIX, inhibitor of G9a histone methyltransferase), 3-deazaneplanocin A (DZNep, inhibitor of EZH2 histone methyltransferase), SAHA (inhibitor of histone deacetylases, HDACs) and Decitabine (DAC, DNA demethylating agent) was investigated. Viability of PCLS was assessed by MTT and Prestoblue® viability assay. Results: Treatment of PCLS from tgTGF-β1 mice with doxycycline induced a concentration-dependent increase in global TGF-β1, pro-fibrotic markers including collagen and pro-inflammatory COX-2, which was comparable to recombinant TGF-β1 treatment. Treatment with three of the epigenetic inhibitors BIX01294, DZNep and DAC did not reduce the pro-fibrotic response following doxycycline treatment. However SAHA demonstrated a significant suppressive effect on COX-2 and collagen expression, while not directly affecting TGF-β1 transgene expression. Conclusions: The data suggests that SAHA has the potential to reduce fibrosis in a TGF-β1 driven model of pulmonary fibrosis. Further work is currently underway to assess the anti-fibrotic potential of this drug in tgTGF-β1 animals