Altered sterol metabolism in budding yeast affects mitochondrial iron-sulfur (Fe-S) cluster synthesis.

Ergosterol synthesis is essential for cellular growth and viability of the budding yeast Saccharomyces cerevisiae, and intracellular sterol distribution and homeostasis are therefore highly regulated in this species. Erg25 is an iron-containing C4-methyl sterol oxidase that contributes to the conversion of 4,4-dimethylzymosterol to zymosterol, a precursor of ergosterol. The ERG29 gene encodes an endoplasmic reticulum (ER)-associated protein, and here we identified a role for Erg29 in the methyl sterol oxidase step of ergosterol synthesis. ERG29 deletion resulted in lethality in respiring cells, but respiration-incompetent (Rho- or Rho0) cells survived, suggesting that Erg29 loss leads to accumulation of oxidized sterol metabolites that affect cell viability. Down-regulation of ERG29 expression in Δerg29 cells indeed led to accumulation of methyl sterol metabolites, resulting in increased mitochondrial oxidants and a decreased ability of mitochondria to synthesize iron-sulfur (Fe-S) clusters due to reduced levels of Yfh1, the mammalian frataxin homolog, which is involved in mitochondrial iron metabolism. Using a high-copy genomic library, we identified suppressor genes that permitted growth of Δerg29 cells on respiratory substrates, and these included genes encoding the mitochondrial proteins Yfh1, Mmt1, Mmt2, and Pet20, which reversed all phenotypes associated with loss of ERG29 Of note, loss of Erg25 also resulted in accumulation of methyl sterol metabolites and also increased mitochondrial oxidants and degradation of Yfh1. We propose that accumulation of toxic intermediates of the methyl sterol oxidase reaction increases mitochondrial oxidants, which affect Yfh1 protein stability. These results indicate an interaction between sterols generated by ER proteins and mitochondrial iron metabolism.

The mannoprotein TIR3 (CAGL0C03872g) is required for sterol uptake in Candida glabrata.

Sterol uptake in the pathogenic fungus, Candida glabrata, occurs via the sterol transporter, CgAus1p. Azole inhibition of sterol biosynthesis can under certain circumstances be reversed by adding exogenously sterol. Here we demonstrate that the CgTIR3 (CAGL0C03872g) gene product is also required for sterol uptake, since Cgtir3Δ strains fail to take up sterol both aerobically and under hypoxic conditions. Western analysis using an HA-tagged TIR3 strain showed that CgTir3p localizes to the cell wall, and its expression is induced by serum. Semi-quantitative reverse transcriptase-PCR also showed that two transcription regulatory genes, CgUPC2A and CgUPC2B, control CgTIR3 as well as CgAUS1 gene expression. Interestingly, complementation studies using Cgtir3Δ showed that ScDAN1, a mannoprotein required for sterol uptake in Saccharomyces cerevisiae, could not complement the C. glabrata TIR3 function. Furthermore, sterol analyses, in which both the CgAUS1 and CgTIR3 genes were constitutively expressed, resulted in aerobic sterol uptake although the amount of uptake was considerably less than that of cells cultured aerobically with serum. These results suggest that additional factors other than CgAUS1 and CgTIR3 are required for sterol uptake in C. glabrata.

Genome-wide survey of transcriptional initiation in the pathogenic fungus, Candida glabrata.

DNA sequencing of the 5'-flanking region of the transcriptome effectively identifies transcription initiation sites and also aids in identifying unknown genes. This study describes a comprehensive polling of transcription start sites and an analysis of full-length complementary DNAs derived from the genome of the pathogenic fungus Candida glabrata. A comparison of the sequence reads derived from a cDNA library prepared from cells grown under different culture conditions against the reference genomic sequence of the Candida Genome Database (CGD: http://www.candidagenome.org/) revealed the expression of 4316 genes and their acknowledged transcription start sites (TSSs). In addition this analysis also predicted 59 new genes including 22 that showed no homology to the genome of Saccharomyces cerevisiae, a genetically close relative of C. glabrata. Furthermore, comparison of the 5'-untranslated regions (5'-UTRs) and core promoters of C. glabrata to those of S. cerevisiae showed various global similarities and differences among orthologous genes. Thus, the C. glabrata transcriptome can complement the annotation of the genome database and should provide new insights into the organization, regulation, and function of genes of this important human pathogen.

Characterization of a mutation that results in independence of oxidosqualene cyclase (Erg7) activity from the downstream 3-ketoreductase (Erg27) in the yeast ergosterol biosynthetic pathway.

In yeast, deletion of ERG27, which encodes the sterol biosynthetic enzyme, 3-keto-reductase, results in a concomitant loss of the upstream enzyme, Erg7p, an oxidosqualene cyclase (OSC). However, this phenomenon occurs only in fungi, as mammalian Erg27p orthologues are unable to rescue yeast Erg7p activity. In this study, an erg27 mutant containing the mouse ERG27 orthologue was isolated that was capable of growing without sterol supplementation (FGerg27). GC/MS analysis of this strain showed an accumulation of squalene epoxides, 3-ketosterones, and ergosterol. This strain which was crossed to a wildtype and daughter segregants showed an accumulation of squalene epoxides as well as ergosterol indicating that the mutation entailed a leaky block at ERG7. Upon sequencing the yeast ERG7 gene an A598S alteration was found in a conserved alpha helical region. We theorize that this mutation stabilizes Erg7p in a conformation that mimics Erg27p binding. This mutation, while decreasing OSC activity still retains sufficient residual OSC activity such that the strain in the presence of the mammalian 3-keto reductase enzyme functions and no longer requires the yeast Erg27p. Because sterol biosynthesis occurs in the ER, a fusion protein was synthesized combining Erg7p and Erg28p, a resident ER protein and scaffold of the C-4 demethyation complex. Both FGerg27 and erg27 strains containing this fusion plasmid and the mouse ERG27 orthologue showed restoration of ergosterol biosynthesis with minimal accumulation of squalene epoxides. These results indicate retention of Erg7p in the ER increases its activity and suggest a novel method of regulation of ergosterol biosynthesis.

Identification of new surfaces of cofilin that link mitochondrial function to the control of multi-drug resistance.

ADF/cofilin family proteins are essential regulators of actin cytoskeletal dynamics. Recent evidence also implicates cofilin in the regulation of mitochondrial function. Here, we identify new functional surfaces of cofilin that are linked with mitochondrial function and stress responses in the budding yeast Saccharomyces cerevisiae. Our data link surfaces of cofilin that are involved in separable activities of actin filament disassembly or stabilisation, to the regulation of mitochondrial morphology and the activation status of Ras, respectively. Importantly, charge alterations to conserved surfaces of cofilin that do not interfere with its actin regulatory activity lead to a dramatic increase in respiratory function that triggers a retrograde signal to upregulate a battery of ABC transporters and concurrent metabolic changes that support multi-drug resistance. We hypothesise that cofilin functions within a bio-sensing system that connects the cytoskeleton and mitochondrial function to environmental challenge.

Dap1/PGRMC1 binds and regulates cytochrome P450 enzymes.

Cytochrome P450 enzymes are heme-dependent monoxygenases that play a central role in human physiology. Despite the numerous physiological processes that P450 enzymes impact, the electron donors P450 oxidoreductase and cytochrome b5 are the only proteins known to interact with and modulate the activity of ER microsomal P450s. Here, we report that Dap1/PGRMC1 is required for ER P450 function in yeast and humans. We show that S. pombe Dap1 is a hemoprotein that binds and positively regulates Cyp51A1 and Cyp61A1, two P450s required for sterol biosynthesis. Similarly, loss of human PGRMC1 reduces activity of Cyp51A1, blocking cholesterol synthesis and increasing production of toxic sterol intermediates. PGRMC1 stably binds Cyp51A1 and human P450s from three additional families including Cyp3A4, which metabolizes pharmaceutical compounds. These findings demonstrate that PGRMC1 is required for P450 activity and suggest that interindividual variation in PGRMC1 function may impact multiple biochemical pathways and drug metabolism.

An "exacerbate-reverse" strategy in yeast identifies histone deacetylase inhibition as a correction for cholesterol and sphingolipid transport defects in human Niemann-Pick type C disease.

Niemann-Pick type C (NP-C) disease is a fatal lysosomal lipid storage disorder for which no effective therapy exists. A genome-wide, conditional synthetic lethality screen was performed using the yeast model of NP-C disease during anaerobiosis, an auxotrophic condition that requires yeast to utilize exogenous sterol. We identified 12 pathways and 13 genes as modifiers of the absence of the yeast NPC1 ortholog (NCR1) and quantified the impact of loss of these genes on sterol metabolism in ncr1Δ strains grown under viable aerobic conditions. Deletion of components of the yeast NuA4 histone acetyltransferase complex in ncr1Δ strains conferred anaerobic inviability and accumulation of multiple sterol intermediates. Thus, we hypothesize an imbalance in histone acetylation in human NP-C disease. Accordingly, we show that the majority of the 11 histone deacetylase (HDAC) genes are transcriptionally up-regulated in three genetically distinct fibroblast lines derived from patients with NP-C disease. A clinically approved HDAC inhibitor (suberoylanilide hydroxamic acid) reverses the dysregulation of the majority of the HDAC genes. Consequently, three key cellular diagnostic criteria of NP-C disease are dramatically ameliorated as follows: lysosomal accumulation of both cholesterol and sphingolipids and defective esterification of LDL-derived cholesterol. These data suggest HDAC inhibition as a candidate therapy for NP-C disease. We conclude that pathways that exacerbate lethality in a model organism can be reversed in human cells as a novel therapeutic strategy. This "exacerbate-reverse" approach can potentially be utilized in any model organism for any disease.

Germline polymorphisms in patients with advanced nonsmall cell lung cancer receiving first-line platinum-gemcitabine chemotherapy: a prospective clinical study.

BACKGROUND: The authors assessed the impact of germline polymorphisms on clinical outcome in patients with advanced nonsmall cell lung cancer (NSCLC) who received platinum-gemcitabine (PG) chemotherapy. METHODS: In total, 137 patients with stage IIIB/IV NSCLC were included who received first-line PG chemotherapy (74% of patients received cisplatin, and 26% received carboplatin). Twenty-three germline polymorphisms that were identified in peripheral blood samples were analyzed for progression-free survival (PFS), treatment response, overall survival (OS), and toxicity. RESULTS: The median PFS was 5.8 months, the median OS was 10.2 months, and 44 patients (32%) had a partial treatment response. Carriers of the excision repair cross-complementation group 1 (ERCC1) mutant thymine (T) allele had a lower treatment response rate (29% vs 52%; P = .02), shorter PFS (adjusted hazard ratio [HR], 1.60; P = .04), and shorter OS (adjusted HR, 1.54; P = .05) compared with carriers of the wild-type cytosine/cytosine (CC) genotype. The xeroderma pigmentosum group A member 10 (XPD10) mutant adenine (A) allele (adjusted HR, 0.64; P = .04) and the x-ray cross-complementing group 1 (XRCC1) mutant guanine (G) allele (adjusted HR, 0.51; P = .02) also were independent predictors of OS. Carriers of the mutant adenosine triphosphate-dependent DNA helicase Q1 (RECQ1) C allele or the mutant cytidine deaminase (CDA) C allele were more likely to experience severe leukocytopenia (26% vs 10% [P = .03] and 28% vs 11% [P = .02], respectively) compared with wild-type genotype carriers. Patients who carried the homozygous mutant glutathione S-transferase π 1(GSTP1) GG genotype were at considerable risk for severe platinum-associated polyneuropathy (18% vs 3% in wild-type vs heterozygous mutant patients, respectively; P = .01). CONCLUSIONS: To the authors' knowledge, this is the first prospective study to date in patients with advanced NSCLC describing predictive germline polymorphisms not only for the clinical activity of PG chemotherapy (ERCC1, XPD10) but also for its toxicity (GSTP1, RECQ1, CDA). Nonplatinum-containing chemotherapy in carriers of the ERCC1 T allele or the XPD10 G allele should be studied prospectively.

Transcription factors CgUPC2A and CgUPC2B regulate ergosterol biosynthetic genes in Candida glabrata.

Zn[2]-Cys[6] binuclear transcription factors Upc2p and Ecm22p regulate the expression of genes involved in ergosterol biosynthesis and exogenous sterol uptake in Saccharomyces cerevisiae. We identified two UPC2/ECM22 homologues in the pathogenic fungus Candida glabrata which we designated CgUPC2A and CgUPC2B. The contribution of these two genes to sterol homeostasis was investigated. Cells that lack CgUPC2A (upc2AΔ) exhibited enhanced susceptibility to the sterol biosynthesis inhibitors, fluconazole and lovastatin, whereas upc2BΔ-mutant cells were as susceptible to the drugs as wild-type cells. The growth of upc2AΔ cells was also severely attenuated under anaerobic conditions. Lovastatin treatment enhanced the expression of ergosterol biosynthetic genes, ERG2 and ERG3 in wild-type and upc2BΔ but not in upc2AΔ cells. Similarly, serum-induced expression of ERG2 and ERG3 was completely impaired in upc2AΔ cells but was unaffected in upc2BΔ cells, whereas serum-induced expression of the sterol transporter gene CgAUS1 was impaired in both upc2AΔ and upc2BΔ cells. These results suggest that in C. glabrata CgUPC2A but not in CgUPC2B is the main transcriptional regulator of the genes responsible for maintaining sterol homeostasis as well as susceptibility to sterol inhibitors.

Metabolic response to iron deficiency in Saccharomyces cerevisiae.

Iron is an essential cofactor for enzymes involved in numerous cellular processes, yet little is known about the impact of iron deficiency on cellular metabolism or iron proteins. Previous studies have focused on changes in transcript and proteins levels in iron-deficient cells, yet these changes may not reflect changes in transport activity or flux through a metabolic pathway. We analyzed the metabolomes and transcriptomes of yeast grown in iron-rich and iron-poor media to determine which biosynthetic processes are altered when iron availability falls. Iron deficiency led to changes in glucose metabolism, amino acid biosynthesis, and lipid biosynthesis that were due to deficiencies in specific iron-dependent enzymes. Iron-sulfur proteins exhibited loss of iron cofactors, yet amino acid synthesis was maintained. Ergosterol and sphingolipid biosynthetic pathways had blocks at points where heme and diiron enzymes function, whereas Ole1, the essential fatty acid desaturase, was resistant to iron depletion. Iron-deficient cells exhibited depletion of most iron enzyme activities, but loss of activity during iron deficiency did not consistently disrupt metabolism. Amino acid homeostasis was robust, but iron deficiency impaired lipid synthesis, altering the properties and functions of cellular membranes.

Divergent interactions involving the oxidosqualene cyclase and the steroid-3-ketoreductase in the sterol biosynthetic pathway of mammals and yeasts.

In mammals and yeasts, oxidosqualene cyclase (OSC) catalyzes the formation of lanosterol, the first cyclic intermediate in sterol biosynthesis. We used a murine myeloma cell line (NS0), deficient in the 17ß-hydroxysteroid dehydrogenase type 7 (HSD17B7), as a model to study the potential interaction of the HSD17B7 with the OSC in mammals. HSD17B7 is the orthologue of the yeast steroid-3-ketoreductase (ERG27), an enzyme of ergosterol biosynthesis that plays a protective role towards OSC. Tracer experiments with NS0 cells showed that OSC is fully active in these mammalian cells, suggesting that in mammals the ketosteroid reductase is not required for OSC activity. Mouse and human HSD17B7 were overexpressed in ERG27-deletant yeast cells, and recombinant strains were tested for (i) the ability to grow on different media, (ii) steroid-3-ketoreductase activity, and (iii) OSC activity. Recombinant strains grew more slowly than the control yeast ERG27-overexpressing strain on sterol-deficient media, whereas the growth rate was normal on media supplemented with a 3-ketoreductase substrate. The full enzymatic functionality of mammalian steroid-3-ketoreductase expressed in yeast along with the lack of (yeast) OSC activity point to an inability of the mammalian reductase to assist yeast OSC. Results demonstrate that in mammals, unlike in yeast, OSC and steroid-3-ketoreductase are non-interacting proteins.

A sterol-regulatory element binding protein is required for cell polarity, hypoxia adaptation, azole drug resistance, and virulence in Aspergillus fumigatus.

At the site of microbial infections, the significant influx of immune effector cells and the necrosis of tissue by the invading pathogen generate hypoxic microenvironments in which both the pathogen and host cells must survive. Currently, whether hypoxia adaptation is an important virulence attribute of opportunistic pathogenic molds is unknown. Here we report the characterization of a sterol-regulatory element binding protein, SrbA, in the opportunistic pathogenic mold, Aspergillus fumigatus. Loss of SrbA results in a mutant strain of the fungus that is incapable of growth in a hypoxic environment and consequently incapable of causing disease in two distinct murine models of invasive pulmonary aspergillosis (IPA). Transcriptional profiling revealed 87 genes that are affected by loss of SrbA function. Annotation of these genes implicated SrbA in maintaining sterol biosynthesis and hyphal morphology. Further examination of the SrbA null mutant consequently revealed that SrbA plays a critical role in ergosterol biosynthesis, resistance to the azole class of antifungal drugs, and in maintenance of cell polarity in A. fumigatus. Significantly, the SrbA null mutant was highly susceptible to fluconazole and voriconazole. Thus, these findings present a new function of SREBP proteins in filamentous fungi, and demonstrate for the first time that hypoxia adaptation is likely an important virulence attribute of pathogenic molds.

Dap1p, a heme-binding protein that regulates the cytochrome P450 protein Erg11p/Cyp51p in Saccharomyces cerevisiae.

Alkylating agents chemically modify DNA and cause mutations that lead to cancer. In the budding yeast Saccharomyces cerevisiae, resistance to the alkylating agent methyl methanesulfonate (MMS) is mediated in part by Dap1p (damage resistance protein 1). Dap1p is related to cytochrome b5, which activates cytochrome P450 proteins, elevating the metabolism of lipids and xenobiotic compounds. We have found that Dap1p, like cytochrome b5, binds to heme and that Dap1p targets the cytochrome P450 protein Erg11p/Cyp51p. Genetic analysis indicates that Erg11p acts downstream of Dap1p. Furthermore, Dap1p regulates the stability of Erg11p, and Erg11p is stabilized in dap1Delta cells by the addition of heme. Thus, Dap1p utilizes heme to stabilize Erg11p, which in turn regulates ergosterol synthesis and MMS resistance. Dap1p homologues have been identified in numerous eukaryotes, including mammals, suggesting that the Dap1p-cytochrome P450 protein pathway is broadly conserved in eukaryotic species.

Cumulative mutations affecting sterol biosynthesis in the yeast Saccharomyces cerevisiae result in synthetic lethality that is suppressed by alterations in sphingolipid profiles.

UPC2 and ECM22 belong to a Zn(2)-Cys(6) family of fungal transcription factors and have been implicated in the regulation of sterol synthesis in Saccharomyces cerevisiae and Candida albicans. Previous reports suggest that double deletion of these genes in S. cerevisiae is lethal depending on the genetic background of the strain. In this investigation we demonstrate that lethality of upc2Delta ecm22Delta in the S288c genetic background is attributable to a mutation in the HAP1 transcription factor. In addition we demonstrate that strains containing upc2Delta ecm22Delta are also inviable when carrying deletions of ERG6 and ERG28 but not when carrying deletions of ERG3, ERG4, or ERG5. It has previously been demonstrated that UPC2 and ECM22 regulate S. cerevisiae ERG2 and ERG3 and that the erg2Delta upc2Delta ecm22Delta triple mutant is also synthetically lethal. We used transposon mutagenesis to isolate viable suppressors of hap1Delta, erg2Delta, erg6Delta, and erg28Delta in the upc2Delta ecm22Delta genetic background. Mutations in two genes (YND1 and GDA1) encoding apyrases were found to suppress the synthetic lethality of three of these triple mutants but not erg2Delta upc2Delta ecm22Delta. We show that deletion of YND1, like deletion of GDA1, alters the sphingolipid profiles, suggesting that changes in sphingolipids compensate for lethality produced by changes in sterol composition and abundance.

Synthetically lethal interactions involving loss of the yeast ERG24: the sterol C-14 reductase gene.

ERG2 and ERG24 are yeast sterol biosynthetic genes which are targets of morpholine antifungal compounds. ERG2 and ERG24 encode the C-8 sterol isomerase and the C-14 reductase, respectively. ERG2 is regarded as a non-essential gene but the viability of ERG24 depends on genetic background, type of medium, and CaCl(2) concentration. We demonstrate that erg2 and erg24 mutants are viable in the deletion consortium background but are lethal when combined in the same haploid strain. The erg2erg24 double mutant can be suppressed by mutations in the sphingolipid gene ELO3 but not ELO2. Suppression occurs on rich medium but not on synthetic complete medium. We also demonstrate that the suppressed elo3erg2erg24 does not have a sterol composition markedly different from that of erg24. Further genetic analysis indicates that erg24 combined with mutations in erg6 or erg28 is synthetically lethal but when combined with mutations in erg3 is weakly viable. These results suggest that novel sterol intermediates probably contribute to the synthetic lethality observed in this investigation.

A systematic study of yeast sterol biosynthetic protein-protein interactions using the split-ubiquitin system.

Sterol biosynthesis occurs in the ER and most sterol biosynthetic enzymes have transmembrane domains. However, due to difficulties in characterizing membrane protein-protein interactions, the nature of the sterol biosynthetic complex as well as in vivo interactions between various enzymes have not been described. We employed a split-ubiquitin membrane protein yeast two-hybrid system to characterize interactions between sterol biosynthetic proteins. Fourteen bait constructs were co-transformed into a reporter yeast strain with 14 prey constructs representing all sterol enzymatic reactions beginning with the synthesis of squalene. Our results not only confirmed several previous interactions, but also allowed us to identify novel interactions. Based on these results, ergosterol biosynthetic enzymes display specific protein-protein interactions forming a functional complex we designate, the ergosome. In this complex, Erg11p, Erg25p, Erg27p, and Erg28p appear to form a core center that can interact with other enzymes in the pathway. Also Erg24p and Erg2p, two enzymes that are sensitive to morpholine antifungals, appear to interact with one another; however, the profile of protein interaction partners appears to be unique. Erg2p and Erg3p, two enzymes catalyzing sequential reactions also appear to have different interaction partners. Our results provide a working model as to how sterol biosynthetic enzymes are topologically organized not only in yeast but in plant and animal systems that share many of these biosynthetic reactions.

Optical spectroscopy for the classification of malignant lesions of the bronchial tree.

Optical spectroscopy may be used for in vivo, noninvasive distinction of malignant from normal tissue. The aim of our study was to analyze the accuracy of various optical spectroscopic techniques for the classification of cancerous lesions of the bronchial tree. We developed a fiberoptic instrument allowing the measurement of autofluorescence spectroscopy (AFS), diffuse reflectance spectroscopy (DRS), and differential path length spectroscopy (DPS) during bronchoscopy. Spectroscopic measurements were obtained from 191 different endobronchial lesions (63 malignant and 128 nonmalignant) in 107 patients. AFS, DRS, and DPS sensitivity/specificity for the distinction between malignant and nonmalignant bronchial lesions were 73%/82%, 86%/81%, and 81%/88%, respectively. All three optical spectroscopic modalities facilitate an increase of the positive predictive value of autofluorescence bronchoscopy for the detection of endobronchial tumors. Even better results were obtained when the three spectroscopic techniques were combined.

Prognostic value of pre-operative glucose-corrected maximum standardized uptake value in patients with non-small cell lung cancer after complete surgical resection and 5-year follow-up.

INTRODUCTION: In this study we evaluated the value of pre-operative glucose corrected maximum standard uptake value (GC-SUVmax) as prognostic factor in patients with early stage non-small cell lung cancer (NSCLC) after complete surgical resection. METHODS: This study was designed as a retrospectively evaluated single center study with prospective data registry. Inclusion criteria were: histologically proven stage I NSCLC, 18F-FDG-PET/CT scan prior to surgery, complete resection (R0) and follow up in our outpatient department. Exclusion criteria were: history of malignancy other than NSCLC, diabetes and (neo) adjuvant therapy. Follow up period was 5 years. RESULTS: Between 2006 and 2008 a total of 33 patients (16 males, 17 females) met the inclusion criteria. SUVmax and GC-SUVmax were strongly correlated (Spearman's ρ = 0.97). Five-year overall survival (OS) rate was 70 % (95 % CI = 56-87 %). Patients who died within 5 years of follow up had significantly higher pre-operative GC-SUVmax (median = 10.6, IQR = 8.3-14.4) than patients who were alive at 5-year follow up (median = 6.4, IQR = 3.0-9.8), p = 0.04. SUVmax showed similar differences: 10.4 (8-12.9) vs. 6.6 (3.0-8.8), p = 0.047. The area under the receiver-operating characteristic (ROC) curve at 5 years was 0.70 (95 % CI = 0.50-0.90) for GC-SUVmax and 0.71 (95 % CI = 0.51-0.91) for SUVmax (p = 0.75). CONCLUSION: Pre-operative FDG tumor uptake in patients with NSCLC is predictive for survival after complete surgical resection. GC-SUVmax, as an additional value to SUVmax, may better approach competitive inhibition of FDG and glucose in tumors, however, in this study this potential advantage, if any, was very small.

The ERG28-encoded protein, Erg28p, interacts with both the sterol C-4 demethylation enzyme complex as well as the late biosynthetic protein, the C-24 sterol methyltransferase (Erg6p).

In Saccharomyces cerevisiae, the C-24 sterol methyltransferase (Erg6p) converts zymosterol to fecosterol, an enzymatic step following C-4 demethylation of 4,4-dimethylzymosterol. Our previous study showed that an endoplasmic reticulum (ER) transmembrane protein, Erg28p, functions as a scaffold to tether the C-4 demethylation enzymatic complex (Erg25p-Erg26p-Erg27p) to the ER. To determine whether Erg28p also interacts with other ergosterol biosynthetic proteins, we compared protein levels of Erg3p, Erg6p, Erg7p, Erg11p and Erg25p in three pairs of erg28 and ERG28 strains. In erg28 strains, the Erg6p level in the ER fraction was decreased by about 50% relative to the wild-type strain, while ER protein levels of the four other ergosterol proteins showed no significant differences. Co-immunoprecipitation experiments, using an erg28 strain transformed with the epitope-tagged plasmid pERG28-HA and proteins detected with anti-HA and anti-Erg6p antibodies, indicated that Erg6p and Erg28p reciprocally co-immunoprecipitate. Further, the split ubiquitin yeast membrane two-hybrid system designed to detect protein interactions between membrane bound proteins also indicated an Erg28p-Erg6p interaction when pERG6-Cub was used as the bait and pERG28-NubG was used as the prey. We conclude that Erg28p may not only anchor the C-4 demethylation enzyme complex to the ER but also acts as a protein bridge to the Erg6p enzyme required for the next ergosterol biosynthetic step.

Improving the specificity of fluorescence bronchoscopy for the analysis of neoplastic lesions of the bronchial tree by combination with optical spectroscopy: preliminary communication.

Detection of malignancies of the bronchial tree in an early stage, such as carcinoma in situ (CIS), augments the cure rate considerably. It has been shown that the sensitivity of autofluorescence bronchoscopy is better than white light bronchoscopy for the detection of CIS and dysplastic lesions. Autofluorescence bronchoscopy is, however, characterized by a low specificity with a high rate of false positive findings. In the present paper we propose to combine autofluorescence bronchoscopy with optical spectroscopy to improve the specificity of autofluorescence imaging, while maintaining the high sensitivity. Standard autofluorescence bronchoscopy was used to find suspect lesions in the upper bronchial tree, and these lesions were subsequently characterized spectroscopically using a custom made fiberoptic probe. Autofluorescence spectra of the lesions as well as reflectance spectra were measured. We will show in this preliminary report that the addition of either of these spectroscopic techniques decreases the rate of false positives findings, with the best results obtained when both spectroscopic modalities are combined.