Production of galactosylated complex-type N-glycans in glycoengineered Saccharomyces cerevisiae.

N-glycosylation is an important posttranslational modification affecting the properties and quality of therapeutic proteins. Glycoengineering in yeast aims to produce proteins carrying human-compatible glycosylation, enabling the production of therapeutic proteins in yeasts. In this work, we demonstrate further development and characterization of a glycoengineering strategy in a Saccharomyces cerevisiae Δalg3 Δalg11 strain where a truncated Man3GlcNAc2 glycan precursor is formed due to a disrupted lipid-linked oligosaccharide synthesis pathway. We produced galactosylated complex-type and hybrid-like N-glycans by expressing a human galactosyltransferase fusion protein both with and without a UDP-glucose 4-epimerase domain from Schizosaccharomyces pombe. Our results showed that the presence of the UDP-glucose 4-epimerase domain was beneficial for the production of digalactosylated complex-type glycans also when extracellular galactose was supplied, suggesting that the positive impact of the UDP-glucose 4-epimerase domain on the galactosylation process can be linked to other processes than its catalytic activity. Moreover, optimization of the expression of human GlcNAc transferases I and II and supplementation of glucosamine in the growth medium increased the formation of galactosylated complex-type glycans. Additionally, we provide further characterization of the interfering mannosylation taking place in the glycoengineered yeast strain. KEY POINTS: • Glycoengineered Saccharomyces cerevisiae can form galactosylated N-glycans. • Genetic constructs impact the activities of the expressed glycosyltransferases. • Growth medium supplementation increases formation of target N-glycan structure.

Production and characterization of Aspergillus niger GH29 family α-fucosidase and production of a novel non-reducing 1-fucosyllactose.

Fucosylated oligosaccharides are interesting molecules due to their bioactive properties. In particular, their application as active ingredient in milk powders is attractive for dairy industries. The objective of this study was to characterize the glycosyl hydrolase family 29 α-fucosidase produced by Aspergillus niger and test its ability to transfucosylate lactose with a view towards potential industrial applications such as the valorization of the lactose side stream produced by dairy industry. In order to reduce costs and toxicity the use of free fucose instead of environmentally questionable fucose derivatives was studied. In contrast to earlier studies, a recombinantly produced A. niger α-fucosidase was utilized. Using pNP-fucose as substrate, the optimal pH for hydrolytic activity was determined to be 3.8. The optimal temperature for a 30-min reaction was 60 °C, and considering temperature stability, the optimal temperature for a 24-h reaction was defined as 45 °C For the same hydrolysis reaction, the kinetic values were calculated to be 0.385 mM for the KM and 2.8 mmol/(mg*h) for the Vmax. Transfucosylation of lactose occurred at high substrate concentrations when reaction time was elongated to several days. The structure of the product trisaccharide was defined as 1-fucosyllactose, where fucose is α-linked to the anomeric carbon of the ß-glucose moiety of lactose. Furthermore, the enzyme was able to hydrolyze its own transfucosylation product and 2'-fucosyllactose but only poorly 3-fucosyllactose. As a conclusion, α-fucosidase from A. niger can transfucosylate lactose using free fucose as substrate producing a novel non-reducing 1-fucosyllactose.

Predictive role of free prostate-specific antigen in a prospective active surveillance program (PRIAS).

PURPOSE: To evaluate the utility of percentage of free serum PSA (%fPSA) as a predictor of adverse rebiopsy findings, treatment change and radical prostatectomy (RP) findings in a prospective active surveillance (AS) trial. METHODS: Patients enrolled in the global PRIAS study with baseline %fPSA available were included. Putative baseline predictors (e.g. PSA, %fPSA) of adverse rebiopsy findings were explored using logistic regression analysis. Association of variables with treatment change and RP findings over time were evaluated with Cox regression analysis. Active treatment-free survival was assessed with a Kaplan-Meier method. RESULTS: Of 3701 patients recruited to PRIAS, 939 had %fPSA measured at study entry. Four hundred and thirty-eight of them had %fPSA available after 1 year. Median follow-up was 17.2 months. First rebiopsy results were available for 595 patients and of those, 144 (24.2 %) had adverse findings. A total of 283 (30.1 %) patients discontinued surveillance, of those 181 (64.0 %) due to protocol-based reasons. Although median %fPSA values were significantly lower in patients who changed treatment, according to the multivariate regression analysis, initial %fPSA value was not predictive for treatment change or adverse rebiopsy findings. However, the probability of discontinuing AS was significantly lower in patients with "favourable" initial %fPSA characteristics and %fPSA during follow-up (initial %fPSA ≥15 and positive %fPSA velocity) compared to those with "adverse" %fPSA characteristics (initial %fPSA <15 and negative %fPSA velocity). CONCLUSIONS: Diagnostic %fPSA provides no additional prognostic value when compared to other predictors already in use in AS protocols. However, %fPSA velocity during surveillance may aid in predicting the probability for future treatment change.

Outcome and prognostic features in adult pineoblastomas: analysis of cases from the SEER database.

BACKGROUND: Adult pineoblastomas (PBL) are rare central nervous system tumors. Patient and treatment factors associated with outcome are poorly defined and limited to small retrospective case series and single case reports. Using the Surveillance, Epidemiology, and End Results (SEER) cancer registry, we investigated clinicopathological factors associated with outcome in adult PBL. METHODS: Adult patients (≥16 years old) with PBL diagnosed between 1990 and 2007 were identified from the SEER database. Kaplan-Meier survival analysis and Cox models were used to examine the effect of variables on overall survival. The variables analyzed included patient's age at diagnosis, gender, race, tumor location, uni-focal or multi-focal tumor, tumor size, surgical resection, and the use of adjuvant radiotherapy. RESULTS: Ninety-five patients were identified, with a median age at diagnosis of 39.2 years. Sixty-one patients (64 %) underwent surgery and 44 patients (47.4 %) received adjuvant radiotherapy. Forty-two patients (44 %) had both surgery and radiotherapy. The median overall survival was 176 months. Univariate analysis identified younger age at diagnosis, uni-focal and localized disease as important predictors of overall survival. On multivariate analysis, only age at diagnosis and localized disease emerged as important prognostic factors. CONCLUSIONS: Despite the numerous limitations of the SEER database, this study represents the largest analysis of adult PBL to date. Clinically relevant prognostic factors were younger age of diagnosis and localized disease. The role of surgery and adjuvant radiotherapy remains to be defined. Our data suggest these treatment modalities may not influence overall survival.

Gastrostomy insertion in the 21st century: PEG or laparoscopic? Report from a large single-centre series.

PURPOSE: To determine whether laparoscopic-assisted gastrostomy (LAG) has superseded percutaneous endoscopic gastrostomy (PEG) based on the clinical outcomes. METHODS: A retrospective study was undertaken for the period January 06-December 09. Demographic and clinical outcomes were recorded and the two groups were compared. RESULTS: 164 patients were studied (PEG, n = 107; LAG, n = 57). 93.5 % of PEG patients required two general anaesthetics compared with 8 % of LAG patients. Median time to using the gastrostomy was 24 (range 0-168) h in PEG and 0 (0-96) h in LAG patients (p < 0.001). Major complications occurred in 15/107 (14 %) of PEG and 2/57 (3.5 %) of LAG patients (p = 0.05). Re-operation rate following complications was 18/107 (16.8 %) for PEG and 3/57 (5.2 %) for LAG (p = 0.05). Minor complications arose in 41/107 (38 %) of PEG and 32/57 (56 %) of LAG (p = 0.05). Post-operative hospital stay was 2 (1-40) days for PEG and 2 (0-20) days for LAG (p = 0.01). The day-case rate was 0/107 for PEG and 5/57 (9 %) for LAG. There was no gastrostomy-related mortality in the series. CONCLUSION: LAG requires fewer anaesthetics, is associated with shorter time to feeding, shortened hospital stay and has a reduced risk of major complications. LAG is a very good alternative to the PEG in children.

Outcome and prognostic features in anaplastic ganglioglioma: analysis of cases from the SEER database.

Anaplastic ganglioglioma (AGG) are rare central nervous system tumours. Patient and treatment factors associated with outcome are poorly defined and limited to small retrospective case series and single case reports. Using the Surveillance, Epidemiology, and End Results (SEER) cancer registry, we investigated potential clinicopathological factors that can affect outcome in patients with anaplastic ganglioglioma. Patients with anaplastic ganglioglioma diagnosed between 1973 and 2007 were identified from the SEER database. Kaplan-Meier survival analysis and Cox models were used to examine the effect of variables on overall survival. The variables analysed included patient age at diagnosis, gender, race, tumour location, uni-focal or multi-focal tumour, surgical resection and the use of adjuvant radiotherapy. Fifty-eight patients were identified, with a median age at diagnosis of 25.5 years. Ninety-three percent of patients underwent surgery and 36% received adjuvant radiotherapy. The median overall survival was 28.5 months. The most common tumour site was the temporal lobe (27%). Univariate and multivariate analysis identified surgery and uni-focal disease as important predictors of overall survival. Adjuvant radiotherapy did not influence overall survival. This study represents the largest analysis of anaplastic ganglioglioma to date. Furthermore it also emphasises the role of national tumour databases for furthering our understanding of rare brain tumours and determining management options.

Mining Data From Plasma Cell Differentiation Identified Novel Genes for Engineering of a Yeast Antibody Factory.

Saccharomyces cerevisiae is a common platform for production of therapeutic proteins, but it is not intrinsically suited for the manufacturing of antibodies. Antibodies are naturally produced by plasma cells (PCs) and studies conducted on PC differentiation provide a comprehensive blueprint for the cellular transformations needed to create an antibody factory. In this study we mined transcriptomics data from PC differentiation to improve antibody secretion by S. cerevisiae. Through data exploration, we identified several new target genes. We tested the effects of 14 genetic modifications belonging to different cellular processes on protein production. Four of the tested genes resulted in improved antibody expression. The ER stress sensor IRE1 increased the final titer by 1.8-fold and smaller effects were observed with PSA1, GOT1, and HUT1 increasing antibody titers by 1. 6-, 1. 4-, and 1.4-fold. When testing combinations of these genes, the highest increases were observed when co-expressing IRE1 with PSA1, or IRE1 with PSA1 and HUT1, resulting in 3.8- and 3.1-fold higher antibody titers. In contrast, strains expressing IRE1 alone or in combination with the other genes produced similar or lower levels of recombinantly expressed endogenous yeast acid phosphatase compared to the controls. Using a genetic UPR responsive GFP reporter construct, we show that IRE1 acts through constitutive activation of the unfolded protein response. Moreover, the positive effect of IRE1 expression was transferable to other antibody molecules. We demonstrate how data exploration from an evolutionary distant, but highly specialized cell type can pinpoint new genetic targets and provide a novel concept for rationalized cell engineering.

Tailoring N-Glycan Biosynthesis for Production of Therapeutic Proteins in Saccharomyces cerevisiae.

The ability to control and adjust the N-glycosylation pathway of Saccharomyces cerevisiae is a key step toward production of therapeutic glycoproteins such as antibodies or erythropoietin. The focus of this chapter is to describe the road from yeast-type N-glycosylation to human-type complex N-glycosylation. The chapter describes the cell engineering and provides the detailed analytical procedures required to perform glycan analysis using MALDI-TOF mass spectrometry.

The effects of long-term exposure to disease-modifying drugs during pregnancy in multiple sclerosis.

BACKGROUND AND OBJECTIVE: Women with multiple sclerosis (MS) who intend to get pregnant are often advised to discontinue disease modifying therapy (DMT) prior to conception. This recommendation is not based on medical evidence and may interfere with disease control by immunomodulatory drugs. The present study was designed to help discuss the effect of DMT for MS on pregnancy and on disease course. PATIENTS AND METHODS: Retrospective data from 152 pregnancies of 132 women with MS were collected by the physician in charge of the case. All data were entered into a specific file for qualitative and quantitative statistical analysis. RESULTS: From the total group of patients, 89 pregnancies occurred without any exposure to MS drugs, while 61 pregnancies occurred with at least eight weeks of exposure to MS immunomodulatory drugs. The rate of obstetric and neonatal complications was similar in both groups, except for the newborn weight and height which was smaller for mothers receiving medications. Mothers' post-delivery relapse rate and EDSS scores in the follow-up period were significantly higher in the absence of treatment. CONCLUSION: It is possible that, with further such supportive data, international guidelines on MS treatment in young women who intend to get pregnant may need to be revised.

Glatiramer acetate exposure in pregnancy: preliminary safety and birth outcomes.

With the increasing incidence of multiple sclerosis (MS) in women and the earlier use of disease modifying therapy (DMT), issues surrounding DMT and pregnancy are a regular subject of discussion with regards to optimal management. Current recommendations are to withdraw DMT prior to conception, leaving patients exposed to an uncertain period of untreated disease. The objective of this study is to report preliminary experience on glatiramer acetate (GA) exposure through conception, pregnancy and the post-partum period in a series of 13 patients with previously highly active relapsing-remitting MS. This is a prospective observational case series. Fourteen pregnancies of 13 women resulted in 13 live births (one twin pregnancy), nine exposed to GA throughout pregnancy. There were no birth defects and treatment was well tolerated. No relapses occurred during pregnancy in those continuing on treatment. In conclusion, our early experience suggests that when considering the risks and benefits of treatment withdrawal prior to pregnancy, it may be reasonable to continue GA in those patients with previously highly active disease. Consideration should also be given to the initiation of a birth register, similar to such initiatives in epilepsy, to generate more robust safety data in this controversial area.

Purification and cDNA cloning of UDP-GlcNAc:GlcNAcbeta1-3Galbeta1-4Glc(NAc)-R [GlcNAc to Gal]beta1,6N-acetylglucosaminyltransferase from rat small intestine: a major carrier of dIGnT activity in rat small intestine.

A rat intestinal beta1,6N-acetylglucosaminyltransferase (beta1-6GnT) responsible for the formation of the beta1,6-branched poly-N-acetyllactosamine structure has been purified to apparent homogeneity by successive column chromatographic procedures using an assay wherein pyridylaminated lacto- N-triose II (GlcNAcbeta1-3Galbeta1-4Glc-PA) was used as an acceptor substrate and the reaction product was GlcNAcbeta1-3(GlcNAcbeta1-6)Galbeta1-4Glc-PA. The purified enzyme catalyzed the conversion of the polylactosamine acceptor GlcNAcbeta1-3'LacNAc into GlcNAcbeta1-3'(GlcNAcbeta1-6') LacNAc (dIGnT activity), but it could not transfer GlcNAc to LacNAcbeta1-3'LacNAc (cIGnT activity). This enzyme could also convert mucin core 1 and core 3 analogs, Galbeta1-3GalNAcalpha1-O-paranitrophenyl (pNP) and GlcNAcbeta1-3GalNAcalpha1-O-pNP, into Galbeta1-3(GlcNAcbeta1-6) GalNAcalpha1-O-pNP (C2GnT activity) and GlcNAcbeta1-3(GlcNAcbeta1-6)GalNAcalpha1-O-pNP (C4GnT activity), respectively. Based on the partial amino acid sequences of the purified protein, the cDNA encoding this enzyme was cloned. The COS-1 cells transiently transfected with this cDNA had high dI/C2/C4GnT activities in a ratio of 0.34:1.00:0.90, compared with non- or mock-transfected cells. The primary structure shows a significant homology with human and viral mucin-type core 2 beta1-6GnTs (C2GnT-Ms), indicating that this enzyme is the rat ortholog of human and viral C2GnT-Ms. This is the first identification and purification of this enzyme as a major carrier of dIGnT activity in the small intestine. This rat ortholog should mostly be responsible for making distal I-branch structures on poly-N-acetyllactosamine sequences in this tissue, as well as making mucin core 2 and core 4 structures, given that it also has high C2/C4GnT activities.

Several polylactosamine-modifying glycosyltransferases also use internal GalNAcbeta1-4GlcNAc units of synthetic saccharides as acceptors.

The GalNAcbeta1-4GlcNAc determinant (LdN) occurs in some human and bovine glycoconjugates and also in lower vertebrates and invertebrates. It has been found in unsubstituted as well as terminally substituted forms at the distal end of conjugated glycans, but it has not been reported previously at truly internal positions of polylactosamine chains. Here, we describe enzyme-assisted conversion of LdNbeta1-OR oligosaccharides into GlcNAcbeta1-3GalNAcbeta1-4GlcNAcbeta1-OR. The extension reactions, catalyzed by human serum, were modeled after analogous beta3-GlcNAc transfer processes that generate GlcNAcbeta1-3Galbeta1-4GlcNAcbeta1-OR. The newly synthesized GlcNAcbeta1-3GalNAc linkages were unambiguously identified by nuclear magnetic resonance data, including the appropriate long-range correlations in heteronuclear multiple bond correlation spectra. The novel GlcNAcbeta1-3'LdN determinant proved to be a functional acceptor for several mammalian glycosyltransferases, suggesting that human polylactosamines may contain internal LdN units in many distinct forms. The GlcNAcbeta1-3'LdN determinant was unusually resistant toward jackbean beta-N-acetylhexosaminidase; the slow degradation should lead to a convenient method for the search of putative internal LdN determinants in natural polylactosamine chains.