Genome-Wide Characterization of the Phosphate Starvation Response in Schizosaccharomyces pombe

Background: Inorganic phosphate is an essential nutrient required by organisms for growth. During phosphate starvation, Saccharomyces cerevisiae activates the phosphate signal transduction (PHO) pathway, leading to expression of the secreted acid phosphatase, PHO5. The fission yeast, Schizosaccharomyces pombe, regulates expression of the ScPHO5 homolog (pho1+) via a non-orthologous PHO pathway involving genetically identified positive (pho7+) and negative (csk1+) regulators. The genes induced by phosphate limitation and the molecular mechanism by which pho7+ and csk1+ function are unknown. Here we use a combination of molecular biology, expression microarrays, and chromatin immunoprecipitation coupled with high-throughput sequencing (ChIP-Seq) to characterize the role of pho7+ and csk1+ in the PHO response. Results: We define the set of genes that comprise the initial response to phosphate starvation in S. pombe. We identify a conserved PHO response that contains the ScPHO5 (pho1+), ScPHO84 (SPBC8E4.01c), and ScGIT1 (SPBC1271.09) orthologs. We identify members of the Pho7 regulon and characterize Pho7 binding in response to phosphate-limitation and Csk1 activity. We demonstrate that activation of pho1+ requires Pho7 binding to a UAS in the pho1+ promoter and that Csk1 repression does not regulate Pho7 enrichment. Further, we find that Pho7-dependent activation is not limited to phosphate-starvation, as additional environmental stress response pathways require pho7+ for maximal induction. Conclusions: We provide a global analysis of the transcriptional response to phosphate limitation in S. pombe. Our results elucidate the conserved core regulon induced in response to phosphate starvation in this ascomycete distantly related to S. cerevisiae and provide a better understanding of flexibility in environmental stress response networks.Chemistry and Chemical BiologyMolecular and Cellular Biolog

Champion Teams: An Implementation Strategy to Drive Practice Improvement

Developing collaborative practice is an ongoing process requiring frequent upgrades as team members and processes are added. Recently, faculty in ETSU’s Department of Family Medicine have been experimenting with a mechanism for iterative upgrades to team care practice known as Champion Teams. Champion Teams are based on the Institute of Medicine’s learning health care system approach in which practitioners develop an internal strategy for implementing new evidence based practices on an ongoing basis. In this presentation, our interprofessional team will describe team-based education and practice at ETSU as it relates to the Champion Team concept including its origins, evidence-base, and the logistics of how it functions. We will provide examples of four Champion Team projects including: 1) integrating behavioral health, 2) increasing attendance at medical visits, 3) increasing vaccination rates, and 4) a transition to a new pharmacological regimen for congestive heart failure patients. The exemplars will demonstrate how quality improvement data informed progressive changes and confirmed implementation outcomes. During discussion, we will encourage participants to identify their own targets for champion teams

Carbonic anhydrase IX promotes tumor growth and necrosis in vivo and inhibition enhances anti-VEGF therapy.

PURPOSE: Bevacizumab, an anti-VEGFA antibody, inhibits the developing vasculature of tumors, but resistance is common. Antiangiogenic therapy induces hypoxia and we observed increased expression of hypoxia-regulated genes, including carbonic anhydrase IX (CAIX), in response to bevacizumab treatment in xenografts. CAIX expression correlates with poor prognosis in most tumor types and with worse outcome in bevacizumab-treated patients with metastatic colorectal cancer, malignant astrocytoma, and recurrent malignant glioma. EXPERIMENTAL DESIGN: We knocked down CAIX expression by short hairpin RNA in a colon cancer (HT29) and a glioblastoma (U87) cell line which have high hypoxic induction of CAIX and overexpressed CAIX in HCT116 cells which has low CAIX. We investigated the effect on growth rate in three-dimensional (3D) culture and in vivo, and examined the effect of CAIX knockdown in combination with bevacizumab. RESULTS: CAIX expression was associated with increased growth rate in spheroids and in vivo. Surprisingly, CAIX expression was associated with increased necrosis and apoptosis in vivo and in vitro. We found that acidity inhibits CAIX activity over the pH range found in tumors (pK = 6.84), and this may be the mechanism whereby excess acid self-limits the build-up of extracellular acid. Expression of another hypoxia inducible CA isoform, CAXII, was upregulated in 3D but not two-dimensional culture in response to CAIX knockdown. CAIX knockdown enhanced the effect of bevacizumab treatment, reducing tumor growth rate in vivo. CONCLUSION: This work provides evidence that inhibition of the hypoxic adaptation to antiangiogenic therapy enhances bevacizumab treatment and highlights the value of developing small molecules or antibodies which inhibit CAIX for combination therapy

The hypoxia-inducible genes VEGF and CA9 are differentially regulated in superficial vs invasive bladder cancer

Regulation by hypoxia may underlie the expression of vascular endothelial growth factor in bladder cancer. We have compared the distribution of vascular endothelial growth factor mRNA with a hypoxia marker, carbonic anhydrase 9 (CA IX). vascular endothelial growth factor mRNA was analysed by in situ hybridisation and CA IX by immunochemistry in 22 cases of bladder cancer. The relationship of microvessels to the distribution of CA IX was determined. In a separate series of 49 superficial tumours, CA IX immunostaining was compared with clinico-pathological outcome. In superficial and invasive disease there was overlap in the expression of vascular endothelial growth factor and CA IX, CA IX being more widespread. Both were expressed predominantly on the luminal surface, and surrounding areas of necrosis (invasive tumours). Expression of both factors was greater in superficial disease. Expression was absent within ∼80 μm of microvessels. Unlike vascular endothelial growth factor, CA IX did not predict outcome in superficial disease. Differential responses to reoxygenation provide one explanation: vascular endothelial growth factor mRNA declined rapidly, while CA IX expression was sustained for >72 h. Expression of vascular endothelial growth factor mRNA in bladder tumours is consistent with hypoxic regulation and suggests differential regulation in superficial vs invasive disease. The expression of CA IX on the luminal surface justifies investigation of its utility as a therapeutic target/prognostic indicator

Carbonic anhydrase XII is a marker of good prognosis in invasive breast carcinoma

Hypoxia and pH influence gene expression in tumours, and it is becoming increasingly clear that the pattern of genes expressed by a tumour determines its growth and survival characteristics. Hypoxia-inducible factor-1 (HIF-1) is a key mediator of the cellular response to hypoxia and high HIF-1 expression has been identified as a poor prognostic factor in tumours. Recently, we identified the tumour-associated carbonic anhydrases (CA), CA9 and CA12 as hypoxia-inducible in tumour cell lines. Furthermore, we identified CA IX to be a poor prognostic factor in breast cancer. The aim of this study was to assess the prognostic significance of CA XII. CA XII expression was studied by immunohistochemistry in a series of 103 cases of invasive breast cancer and any association with recognised prognostic factors or relation with the outcome was examined. CA XII expression was present in 77 out of 103 (75%) cases and was associated with lower grade (P=0.001), positive estrogen receptor status (P<0.001), and negative epidermal growth factor receptor status (P<0.001). Furthermore, although CA XII expression was associated with an absence of necrosis (P<0.001), expression of CA XII in some high-grade tumours was induced in regions directly adjacent to morphological necrosis. Additionally, using univariate analysis, CA XII positive tumours were associated with a lower relapse rate (P=0.04) and a better overall survival (P=0.01). In conclusion, CA XII expression is influenced both by factors related to differentiation and hypoxia in breast cancer in vivo and CA XII expression is associated with a better prognosis in an unselected series of invasive breast carcinoma patients

Natural History of Geographic Atrophy Secondary to Age-Related Macular Degeneration: Results from the Prospective Proxima A and B Clinical Trials.

Abstract Purpose To better characterize visual function decline and geographic atrophy (GA) progression secondary to age-related macular degeneration (AMD). Design Proxima A (NCT02479386) and Proxima B (NCT02399072) were global, prospective, non-interventional, observational clinical trials. Participants Eligible patients were aged ≥50 years. Patients in Proxima A had bilateral GA without choroidal neovascularization (CNV) in either eye (N=295). Patients in Proxima B had GA with no CNV in the study eye and CNV±GA in the fellow eye (fellow eye CNV cohort, n=168); or GA with no CNV in the study eye, without CNV/GA in the fellow eye (fellow eye intermediate AMD cohort, n=32). Methods Changes in visual function and imaging/anatomic parameters were evaluated over time using a Mixed Model for Repeated Measurement (MMRM) accounting for key baseline characteristics. Main Outcome Measures Pre-specified endpoints included change in GA area from baseline, best corrected visual acuity (BCVA) score assessed by ETDRS, and BCVA under low-luminance conditions (LLVA). Results At 24 months, the adjusted mean (standard error; SE) change in GA lesion area from baseline was 3.87 (0.15) mm2 in participants with bilateral GA (Proxima A), 3.55 (0.16) mm2 in the fellow eye CNV cohort (Proxima B), and 2.96 (0.25) mm2 in the fellow eye intermediate AMD cohort (Proxima B). GA progression was greater in patients with baseline non-subfoveal (vs. subfoveal) GA lesions, and tended to increase as baseline low-luminance deficit increased (Proxima A; Proxima B, all patients). Conversion to GA or CNV in the fellow eye occurred in 30% and 6.7% of participants, respectively, in the Proxima B intermediate AMD cohort at month 12. Adjusted mean (SE) changes in BCVA and LLVA (ETDRS letters) in the study eye from baseline to 24 months: −13.88 (1.40) and −7.64 (1.20) in Proxima A, −9.49 (1.29) and −7.57 (1.26) in the Proxima B fellow eye CNV cohort, −11.48 (3.39) and −8.37 (3.02) in the Proxima B fellow eye intermediate AMD cohort, respectively. Conclusions The prospective Proxima A and B studies highlight the severe functional impact of GA and the rapid rate of GA lesion progression over a 2-year period, including in patients with unilateral GA at baseline

Construction, Verification and Experimental Use of Two Epitope-Tagged Collections of Budding Yeast Strains

A major challenge in the post-genomic era is the development of experimental approaches to monitor the properties of proteins on a proteome-wide level. It would be particularly useful to systematically assay protein subcellular localization, post-translational modifications and protein–protein interactions, both at steady state and in response to environmental stimuli. Development of new reagents and methods will enhance our ability to do so efficiently and systematically. Here we describe the construction of two collections of budding yeast strains that facilitate proteome-wide measurements of protein properties. These collections consist of strains with an epitope tag integrated at the C-terminus of essentially every open reading frame (ORF), one with the tandem affinity purification (TAP) tag, and one with the green fluorescent protein (GFP) tag. We show that in both of these collections we have accurately tagged a high proportion of all ORFs (approximately 75% of the proteome) by confirming expression of the fusion proteins. Furthermore, we demonstrate the use of the TAP collection in performing high-throughput immunoprecipitation experiments. Building on these collections and the methods described in this paper, we hope that the yeast community will expand both the quantity and type of proteome level data available

Reciprocal relationship between expression of hypoxia inducible factor 1α (HIF-1α) and the pro-apoptotic protein Bid in ex vivo colorectal cancer

Hypoxia inducible factor 1 (HIF-1) represses the transcription of pro-apoptotic bid in colorectal cancer cells in vitro. To assess the clinical relevance of this observation, HIF-1α and Bid were assessed in serial sections of 39 human colorectal adenocarcinomas by immunohistochemistry. In high HIF-1α nuclear-positive cell subpopulations, there was a significant reduction in Bid expression (ANOVA, P=0.04). Given the role of Bid in drug-induced apoptosis, these data add impetus to strategies targeting HIF-1 for therapeutic gain