A Step-by-Step Guide for the Production of Recombinant Fluorescent TAT-HA-Tagged Proteins and their Transduction into Mammalian Cells

Investigating the function of target proteins for functional prospection or therapeutic applications typically requires the production and purification of recombinant proteins. The fusion of these proteins with tag peptides and fluorescently derived proteins allows the monitoring of candidate proteins using SDS-PAGE coupled with western blotting and fluorescent microscopy, respectively. However, protein engineering poses a significant challenge for many researchers. In this protocol, we describe step-by-step the engineering of a recombinant protein with various tags: TAT-HA (trans-activator of transduction-hemagglutinin), 6×His and EGFP (enhanced green fluorescent protein) or mCherry. Fusion proteins are produced in E. coli BL21(DE3) cells and purified by immobilized metal affinity chromatography (IMAC) using a Ni-nitrilotriacetic acid (NTA) column. Then, tagged recombinant proteins are introduced into cultured animal cells by using the penetrating peptide TAT-HA. Here, we present a thorough protocol providing a detailed guide encompassing every critical step from plasmid DNA molecular assembly to protein expression and subsequent purification and outlines the conditions necessary for protein transduction technology into animal cells in a comprehensive manner. We believe that this protocol will be a valuable resource for researchers seeking an exhaustive, step-by-step guide for the successful production and purification of recombinant proteins and their entry by transduction within living cells. © 2024 The Authors. Current Protocols published by Wiley Periodicals LLC. Basic Protocol 1: DNA cloning, molecular assembly strategies, and protein production Basic Protocol 2: Protein purification Basic Protocol 3: Protein transduction in mammalian cells.

Follicular cells protect Xenopus oocyte from abnormal maturation via integrin signaling downregulation and O-GlcNAcylation control

Xenopus oocytes are encompassed by a layer of follicular cells that contribute to oocyte growth and meiosis in relation to oocyte maturation. However, the effects of the interaction between follicular cells and the oocyte surface on meiotic processes are unclear. Here, we investigated Xenopus follicular cell function using oocyte signaling and heterologous-expressing capabilities. We found that oocytes deprotected from their surrounding layer of follicular cells and expressing the epidermal growth factor (EGF) receptor (EGFR) and the Grb7 adaptor undergo accelerated prophase I to metaphase II meiosis progression upon stimulation by EGF. This unusual maturation unravels atypical spindle formation but is rescued by inhibiting integrin β1 or Grb7 binding to the EGFR. In addition, we determined that oocytes surrounded by their follicular cells expressing EGFR-Grb7 exhibit normal meiotic resumption. These oocytes are protected from abnormal meiotic spindle formation through the recruitment of O-GlcNAcylated Grb7, and OGT (O-GlcNAc transferase), the enzyme responsible for O-GlcNAcylation processes, in the integrin β1-EGFR complex. Folliculated oocytes can be forced to adopt an abnormal phenotype and exclusive Grb7 Y338 and Y188 phosphorylation instead of O-GlcNAcylation under integrin activation. Furthermore, an O-GlcNAcylation increase (by inhibition of O-GlcNAcase), the glycosidase that removes O-GlcNAc moieties, or decrease (by inhibition of OGT) amplifies oocyte spindle defects when follicular cells are absent highlighting a control of the meiotic spindle by the OGT-O-GlcNAcase duo. In summary, our study provides further insight into the role of the follicular cell layer in oocyte meiosis progression.

O-GlcNAc Dynamics: The Sweet Side of Protein Trafficking Regulation in Mammalian Cells

The transport of proteins between the different cellular compartments and the cell surface is governed by the secretory pathway. Alternatively, unconventional secretion pathways have been described in mammalian cells, especially through multivesicular bodies and exosomes. These highly sophisticated biological processes rely on a wide variety of signaling and regulatory proteins that act sequentially and in a well-orchestrated manner to ensure the proper delivery of cargoes to their final destination. By modifying numerous proteins involved in the regulation of vesicular trafficking, post-translational modifications (PTMs) participate in the tight regulation of cargo transport in response to extracellular stimuli such as nutrient availability and stress. Among the PTMs, O-GlcNAcylation is the reversible addition of a single N-acetylglucosamine monosaccharide (GlcNAc) on serine or threonine residues of cytosolic, nuclear, and mitochondrial proteins. O-GlcNAc cycling is mediated by a single couple of enzymes: the O-GlcNAc transferase (OGT) which catalyzes the addition of O-GlcNAc onto proteins, and the O-GlcNAcase (OGA) which hydrolyses it. Here, we review the current knowledge on the emerging role of O-GlcNAc modification in the regulation of protein trafficking in mammalian cells, in classical and unconventional secretory pathways.

Involvement of the pro-oncogenic enzyme fatty acid synthase in the hallmarks of cancer: a promising target in anti-cancer therapies

An accelerated de novo lipogenesis (DNL) flux is a common characteristic of cancer cells required to sustain a high proliferation rate. The DNL enzyme fatty acid synthase (FASN) is overexpressed in many cancers and is pivotal for the increased production of fatty acids. There is increasing evidences of the involvement of FASN in several hallmarks of cancer linked to its ability to promote cell proliferation via membranes biosynthesis. In this review we discuss about the implication of FASN in the resistance to cell death and in the deregulation of cellular energetics by increasing nucleic acids, protein and lipid synthesis. FASN also promotes cell proliferation, cell invasion, metastasis and angiogenesis by enabling the building of lipid rafts and consequently to the localization of oncogenic receptors such as HER2 and c-Met in membrane microdomains. Finally, FASN is involved in immune escape by repressing the activation of pro-inflammatory cells and promoting the recruitment of M2 macrophages and T regulatory cells in the tumor microenvironment. Here, we provide an overview of the involvement of the pro-oncogenic enzyme in the hallmarks of cancer making FASN a promising target in anti-cancer therapy to circumvent resistance to chemotherapies.

Serum persistent organic pollutants and diminished ovarian reserve: a single-exposure and mixture exposure approach from a French case-control study

STUDY QUESTION

Are persistent organic pollutants (POPs) associated with a diminished ovarian reserve (DOR) in women of reproductive age?

SUMMARY ANSWER

Amongst 17 POPs detected in over 20% of serum samples, only p,p'-DDE was significantly associated with an increased risk of DOR, and β-hexachlorocyclohexane (β-HCH) was significantly associated with a decreased risk of DOR whilst mixture analyses yielded non-significant associations and did not detect any interactions between POPs.

WHAT IS KNOWN ALREADY

Animal studies have shown that several POPs can alter folliculogenesis and increase follicle depletion. However, only a few studies have been conducted in humans, with small sample sizes and inconsistent results.

STUDY DESIGN, SIZE, DURATION

Our study included 138 cases and 151 controls from the AROPE case-control study. Study participants were women between 18 and 40 years of age recruited amongst couples consulting for infertility in four fertility centres in western France between 2016 and 2020.

PARTICIPANTS/MATERIALS, SETTING, METHODS

Cases of DOR were defined as women with anti-Müllerian hormone (AMH) levels ≤1.1 ng/ml and/or antral follicle count (AFC) <7, and controls were women with AMH levels between 1.1 and 5 ng/ml and AFC ≥ 7, without genital malformations and with a menstrual cycle length between 26 and 35 days. A total of 43 POPs (including 15 organochlorine pesticides, 17 polychlorinated biphenyls, and 9 polybromodiphenylethers) were measured in the serum at inclusion into the study. We conducted logistic regression adjusted for potential confounders using a directed acyclic graph to study the effect of each POP on DOR as single exposures, and used Bayesian kernel machine regression (BKMR) to measure the mixture effect of POPs on DOR.

MAIN RESULTS AND THE ROLE OF CHANCE

Of the 43 POPs, 17 were detected in over 20% of the serum samples. In the single-exposure multivariate logistic regressions, p,p'-DDE (median 165.0 IQR 161.0 ng/l in controls) as a continuous exposure was significantly associated with an increased risk of DOR (odds ratio (OR) 1.39, 95% CI 1.10-1.77) and non-significantly associated with an increased risk of DOR for the second and third terciles (OR 1.46, 95% CI 0.74-2.87, and OR 1.72, 95% CI 0.88-3.37, respectively). β-HCH (median 24.2 IQR 21.5 ng/l in controls) was significantly associated with a decreased risk of DOR when β-HCH was treated as a continuous exposure (OR 0.63, 95% CI 0.44-0.89) and for the third tercile of exposure (OR 0.43, 95% CI 0.21-0.84) and non-significantly associated with a decreased risk of DOR for the second tercile (OR 0.77, 95% CI 0.42-1.42). All sensitivity analyses confirmed our results. BKMR showed similar associations for single exposures but found no significant associations for the total mixture effect. In addition, the BKMR results did not suggest any interactions between POPs.

LIMITATIONS, REASONS FOR CAUTION

Controls were recruited amongst infertile couples and thus may not be representative of all women of reproductive age. However, their POP concentrations were in the same range as in the general French population.

WIDER IMPLICATIONS OF THE FINDINGS

This study is the first to examine the associations between serum POPs and DOR. The well-recognized anti-androgenic properties of p,p'-DDE and estrogenic properties of β-HCH could explain these associations of opposite direction. If these results are replicated elsewhere, this could have an impact on fertility prevention messages and help in understanding the impact of POPs on the female reproductive system.

STUDY FUNDING/COMPETING INTEREST(S)

This study was funded by the Fondation de France (grant numbers 2014-50537 and 00110196) and the French Biomedicine Agency (2016). None of the authors have any conflicts of interest to declare.

TRIAL REGISTRATION NUMBER

N/A.

P-553 Response to controlled ovarian stimulation and preimplantation genetic testing for molecular disease (PGT-M) outcomes for Myotonic dystrophy type I (DM1) : A French multicentric study

Study question

Does ovarian response to controlled ovarian hyperstimulation (COH) is altered in female affected by DM1 ?

Summary answer

Ovarian response to COH is not altered in female affected by DM1 as compared to partners of affected males

What is known already

Myotonic dystrophy type 1 is the most common adult muscular dystrophy caused by a CTG trinucleotide repeat expansion which may expand across generation. As this pathology presents an autosomal dominant inheritance, PGT may be an option to achieve a pregnancy with healthy baby. There are conflicting reports about response to COH for affected female. Moreover, few data are available concerning the chance to have a healthy baby after PGT for couple with one member affected by DM1

Study design, size, duration

The present study is a retrospective observational study carried out from January 2006 through January 2020. This multicentric study was conducted in all the five centers performing PGT-M in France.

Participants/materials, setting, methods

A total of 229 couples started at least one COH cycle for the PGT procedure. The patient carrying the mutation was the female for 178 couples and the male for the 51 others. Overall, 648 COH cycles started and 560 oocytes retrieval for subsequent PGT were performed (430 for affected female and 130 for affected male). Parameters of ovarian response and PGT outcomes were compared according to the member affected by DM1.

Main results and the role of chance

Age and BMI at the first COH cycle were not significantly different between both group but female carried mutation presented lower AMH level than partner of affected male. The starting and total doses of gonadotrophin were significantly higher for mutated females. The number of retrieved and mature oocytes per cycle were not statistically different (12 [8–16] versus 11 [8–16] retrieved oocytes, p = 0.63 and 9 [6–13] versus 9 [6-13] mature oocytes, p = 0.73, respectively). In both group, more than 70% of oocyte retrieval led to embryo biopsy.

The proportion of started cycle allowing the obtention of at least one healthy embryo was significantly lower when the female was affected with DM1 (58.6% vs 70.4%, p = 0.012). In the female affected group, 49.7% of the cycles with oocytes retrieval lead to a fresh embryo transfer and a subsequent live birth rate per transfer of 21.4%. These results were not statistically different from the couple with affected male (58.5% of cycles with fresh embryo transfer (p = 0.08) and 23.6% live birth rate per transfer).

Overall, after fresh or frozen embryo transfer, 30.8% of females with DM1and 41.2% of parter of affected males had at least one live birth from PGT.

Limitations, reasons for caution

This a retrospective study included patients who were selected ovarian reserve parameters before PGT process. Moreover, the large time of inclusion may influence our conclusion.

Wider implications of the findings

Information provided herein extends knowledge about the current state of COH for DM1 affected female. Moreover, PGT results presented here allow to provide patients with proposer counseling before starting PGT process.

Trial registration number

CEROG-2020-GYN-0603

[Fatty acid synthase, a "multi-FASet" enzyme]

In mammals, fatty acids are supplied by diet or synthesized de novo by fatty acid synthase (FASN). Beyond its key role in energy storage, FASN is involved in many biological processes. It actively participates in the synthesis of membrane components necessary for cell division, protein modification, cell signaling and cell proliferation. In this review, we discuss the various physiological functions of FASN as well as its involvement in cancer, the expression of the lipogenic enzyme being particularly high in this disease.

Evaluation of the expression of fatty acid synthase and O‑GlcNAc transferase in patients with liver cancer by exploration of transcriptome databases and experimental approaches

Tumor occurrence and development are closely related to metabolism abnormalities. One of the metabolic networks that is dysregulated during carcinogenesis is the fatty acid synthesis pathway, which is mainly controlled by fatty acid synthase (FASN). We previously demonstrated in proliferating HepG2 liver cancer cells that FASN expression depends on the catalytic activity of O-GlcNAc transferase (OGT) and the activation of the mechanistic/mammalian target of rapamycin (mTOR) pathway. The aim of the present study was to go further in these investigations by analyzing datasets and tissues of patients with liver cancer. To that purpose, transcriptome databases were explored, and reverse transcription-quantitative PCR, western blotting and immunohistochemistry were used. Database analyses revealed that FASN and OGT gene expression was higher in certain cancer tissues, including liver hepatocellular carcinoma, compared with that in non-cancerous tissues. At the protein level, FASN expression was higher in the liver cancer-derived cell lines HepG2 and Hep3B compared with the immortalized human hepatocytes IHH cell line. However, neither the expression of OGT nor of its product O-GlcNAcylation showed any significant difference among the three hepatic cell lines. Subsequently, the expression of FASN and OGT at the protein and mRNA levels was evaluated in human liver cancer and non-tumoral tissues from the same patients with different liver lesions. The results from western blotting demonstrated a significant increase in OGT ands O-GlcNAcylation expression in liver cancer tissues independently of the type of lesion characterizing the non-tumoral counterpart. As previously reported for HepG2 proliferating cells, the protein level of FASN was positively correlated with the activation of mTOR and, although a rather upward trend, a high variability in its expression was monitored between patients. However, the results from immunohistochemistry showed no particular modification for OGT and O-GlcNAcylation expression and a significant increase in FASN expression in cancer tissues compared with that in adjacent non-tumoral tissues. Non-significant changes were observed for FASN and OGT mRNA levels between tumoral and non-tumoral samples, with a high variability between patients. Taken together, these results demonstrated that FASN expression was higher in hepatic cancer tissues in comparison with non-tumoral tissues. Furthermore, OGT expression and activity were shown to vary greatly between cell or cancer type, making any generalization difficult.

P–665 Influence of premature progesterone elevation on embryo development

Study question

Does a serum progesterone level higher than 1.3 ng/mL on the day of ovulation trigger have an impact on blastocyst development?

Summary answer

Elevated progesterone level has no significant impact on top blastocyst rate, usable blastocyst rate and on morphokinetics.

What is known already

Premature elevation of progesterone level on the day of ovulation trigger prior to IVF is common and causes a decrease in endometrial receptivity. A freeze all strategy is then recommended. However, cumulative live birth rates have also been described as lower in cases of high progesterone levels.

Study design, size, duration

This was a retrospective bicentric cohort follow-up study, including 1150 IVF/ICSI cycles performed between 2016 and 2018 with at least 1 day–5 blastocyst available for transfer or freezing. Among these cycles, 524 were performed with use of a time-lapse system (Embryoscope). Serum Progesterone level was measured on the day of ovulation trigger, and a value &gt;1.3 ng/ml was used to identify premature progesterone elevation.

Participants/materials, setting, methods

The cycles were divided into 2 groups according to serum progesterone level: 1335 cycles were allocated in the normal progesterone group (P &lt; 1,3) and 215 in the progesterone premature elevation group (P &gt; 1.3). Patient’s characteristics, ovarian stimulation characteristics, IVF cycles characteristics and embryology parameters were anonymously recorded and compared between the 2 groups.

Main results and the role of chance

Female age, smoking status, AFC and AMH levels were comparable between the 2 groups. Female BMI was significantly higher in the P &lt; 1,3 than in the P &gt; 1.3 group (26.1 versus 24.7 kg/m² respectively). Total FSH dose, estradiol level, number of follicles &gt;11mm and number of retrieved oocytes were significantly higher in the P &gt; 1.3 group than in P &lt; 1.3 group No difference was observed between the 2 groups in terms of top blastocyst rate per mature oocyte and usable blastocyst rate per mature oocyte. When morphokinetic analysis was available, time to blastulation was the only significantly different parameter between the 2 groups (110.4 hours in P &lt; 1.3 versus 107.9 hours in P &gt; 1.3, p = 0.04). Cumulative live birth rate per cycle was not statistically different between the two groups (23.1% for P &lt; 1.3 versus 28.7% for P &gt; 1.3) (p &gt; 0.05).

Limitations, reasons for caution

The retrospective design of the study should lead to careful analysis of the results. The progesterone threshold refers to a specific assay, and should not be generalized to other assays.

Wider implications of the findings: Premature elevation of serum progesterone level on the day of ovulation trigger does not seem to affect embryo developmental competence. This further supports the relevance of freeze all strategy in this situation.

Trial registration number

Not applicable

P–696 The duration of estrogen treatment prior to frozen-blastocyst transfer does not impact live birth rate

Study question

Does the prolonged duration of oestrogen treatment prior to frozen-blastocyst transfer (FET) affect live birth rate?

Summary answer

Variation in the duration of estrogen treatment prior to frozen-blastocyst transfer does not impact live birth rate.

What is known already

With improvements in cryopreservation techniques and fertility preservation, single embryo transfer policy and the increase in freeze-all cycles, frozen blastocyst transfer (FET) has strongly risen over the last years. Artificial endometrial preparation (AEP) is often used prior to FET. The endometrium is prepared by a sequentially treatment of estrogen and progesterone in order to synchronize endometrium and the embryo development. Whether the duration of progesterone administration before FET is well established, the optimal estrogen treatment duration remains controversial.

Study design, size, duration

All consecutive frozen thawed autologous blastocyst transfer cycles conducted between January 1, 2012 and July 1, 2019 in our University IVF center were included in this retrospective cohort study. We included 2235 single blastocyst FET cycles prepared with hormonal replacement therapy using oral E2 and vaginal progesterone administration in 1376 patients aged from 18 to 43 years.

Participants/materials, setting, methods

Patient’s characteristics, stimulation characteristics, FET cycles characteristics and cycles outcomes were anonymously recorded and analyzed. Univariate and multivariate analysis were performed. At first, each FET cycle was analyzed individually and secondly taking into account that some of the patients had undergone several FET, the model considered the number of implanting attempts for each woman.

Main results and the role of chance

We found no significant difference in the mean duration of estradiol administration before frozen embryo transfer between the group live birth versus non-live birth (27.0 ± 5.4 days versus 26.6 ± 5.0 days ; p=0.11). Endometrial thickness was not significantly different between the 2 groups (8.3 ± 1.7 mm versus 8,2 ± 1,7 mm ; p = 0.21). When the duration of estradiol exposure was analyzed in weeks, we observed no difference for the £ 21 days group (OR = 0.97 ; IC 0.64–1.47 ; p = 0.88), 29–35 days group (OR = 0.89 ; IC 0.68–1.16 ; p = 0.37) and &gt; 35 days group (OR = 0.75 ; IC 0.50–1.15 ; p = 0.10) compared to the reference group (22–28 days). After multivariate analysis, the duration of estradiol treatment before frozen embryo transfer did not affect live birth.

Limitations, reasons for caution

The relatively limited numbers of cycles with more than 35 days or less than 21 days as well as the retrospective design of the study are significant limitations.

Wider implications of the findings: Variation in the duration of estradiol supplementation before progesterone initiation does not impact FET outcomes. We therefore can be reassuring with our patients when E2 treatments need to be extended, allowing flexibility in scheduling the day of transfer.

Trial registration number

Not applicable

O-GlcNAcylation Prediction: An Unattained Objective

BACKGROUND

O-GlcNAcylation is an essential post-translational modification (PTM) in mammalian cells. It consists in the addition of a N-acetylglucosamine (GlcNAc) residue onto serines or threonines by an O-GlcNAc transferase (OGT). Inhibition of OGT is lethal, and misregulation of this PTM can lead to diverse pathologies including diabetes, Alzheimer's disease and cancers. Knowing the location of O-GlcNAcylation sites and the ability to accurately predict them is therefore of prime importance to a better understanding of this process and its related pathologies.

PURPOSE

Here, we present an evaluation of the current predictors of O-GlcNAcylation sites based on a newly built dataset and an investigation to improve predictions.

METHODS

Several datasets of experimentally proven O-GlcNAcylated sites were combined, and the resulting meta-dataset was used to evaluate three prediction tools. We further defined a set of new features following the analysis of the primary to tertiary structures of experimentally proven O-GlcNAcylated sites in order to improve predictions by the use of different types of machine learning techniques.

RESULTS

Our results show the failure of currently available algorithms to predict O-GlcNAcylated sites with a precision exceeding 9%. Our efforts to improve the precision with new features using machine learning techniques do succeed for equal proportions of O-GlcNAcylated and non-O-GlcNAcylated sites but fail like the other tools for real-life proportions where ~1.4% of S/T are O-GlcNAcylated.

CONCLUSION

Present-day algorithms for O-GlcNAcylation prediction narrowly outperform random prediction. The inclusion of additional features, in combination with machine learning algorithms, does not enhance these predictions, emphasizing a pressing need for further development. We hypothesize that the improvement of prediction algorithms requires characterization of OGT's partners.

Dual regulation of fatty acid synthase (FASN) expression by O-GlcNAc transferase (OGT) and mTOR pathway in proliferating liver cancer cells

Fatty acid synthase (FASN) participates in many fundamental biological processes, including energy storage and signal transduction, and is overexpressed in many cancer cells. We previously showed in a context of lipogenesis that FASN is protected from degradation by its interaction with O-GlcNAc transferase (OGT) in a nutrient-dependent manner. We and others also reported that OGT and O-GlcNAcylation up-regulate the PI3K/AKT/mTOR pathway that senses mitogenic signals and nutrient availability to drive cell cycle. Using biochemical and microscopy approaches, we show here that FASN co-localizes with OGT in the cytoplasm and, to a lesser extent, in the membrane fraction. This interaction occurs in a cell cycle-dependent manner, following the pattern of FASN expression. Moreover, we show that FASN expression depends on OGT upon serum stimulation. The level of FASN also correlates with the activation of the PI3K/AKT/mTOR pathway in hepatic cell lines, and in livers of obese mice and in a chronically activated insulin and mTOR signaling mouse model (PTEN-null mice). These results indicate that FASN is under a dual control of O-GlcNAcylation and mTOR pathways. In turn, blocking FASN with the small-molecule inhibitor C75 reduces both OGT and O-GlcNAcylation levels, and mTOR activation, highlighting a novel reciprocal regulation between these actors. In addition to the role of O-GlcNAcylation in tumorigenesis, our findings shed new light on how aberrant activity of FASN and mTOR signaling may promote the emergence of hepatic tumors.

Female obesity does not impact live birth rate after frozen-thawed blastocyst transfer

STUDY QUESTION

Does female obesity affect live birth rate after frozen-thawed blastocyst transfer?

SUMMARY ANSWER

Live birth rate was not statistically different between obese and normal weight patients after frozen-thawed blastocyst transfer (FBT).

WHAT IS KNOWN ALREADY

Obesity is a major health problem across the world, especially in women of reproductive age. It impacts both spontaneous fertility and clinical outcomes after assisted reproductive technology. However, the respective impact of female obesity on oocyte quality and endometrial receptivity remains unclear. While several studies showed that live birth rate was decreased in obese women after fresh embryo transfer in IVF cycle, only two studies have evaluated the effects of female body mass index (BMI) on pregnancy outcomes after frozen-thawed blastocyst transfer (FBT), reporting conflicting data.

STUDY DESIGN, SIZE, DURATION

This retrospective case control study was conducted in all consecutive frozen-thawed autologous blastocyst transfer (FBT) cycles conducted between 2012 and 2017 in a single university-based centre. A total of 1415 FBT cycles performed in normal weight women (BMI = 18.5-24.9 kg/m2) and 252 FBT cycles performed in obese women (BMI ≥ 30 kg/m2) were included in the analysis.

PARTICIPANTS/MATERIALS, SETTING, METHODS

Endometrial preparation was standard and based on hormonal replacement therapy. One or two blastocysts were transferred according to couple's history and embryo quality.

MAIN RESULTS AND THE ROLE OF CHANCE

Female and male age, smoking status, basal AMH level and type of infertility were comparable in obese and normal weight groups. Concerning FBT cycles, the duration of hormonal treatment, the stage and number of embryos (84% single blastocyst transfer and 16% double blastocysts transfer) used for transfer were comparable between both groups. Mean endometrium thickness was significantly higher in obese than in normal weight group (8.7 ± 1.8 vs 8.1 ± 1.6 mm, P < 0.0001). Concerning FBT cycle outcomes, implantation rate, clinical pregnancy rate and live birth rate were comparable in obese and in normal weight groups. Odds ratio (OR) demonstrated no association between live birth rate after FBT and female BMI (OR = 0.92, CI 0.61-1.38, P = 0.68).

LIMITATIONS, REASONS FOR CAUTION

Anthropometric parameters such as hip to waist ratio were not used. Polycystic ovarian syndrome status was not included in the analysis.

WIDER IMPLICATIONS OF THE FINDINGS

Our study showed that live birth rate after frozen-thawed blastocyst transfer was not statistically different in obese and in normal-weight women. Although this needs confirmation, this suggests that the impairment of uterine receptivity observed in obese women after fresh embryo transfer might be associated with ovarian stimulation and its hormonal perturbations rather than with oocyte/embryo quality.

STUDY FUNDING/COMPETING INTEREST(S)

No external funding was received. There are no competing interests.

TRIAL REGISTRATION NUMBER

N/A.

Follow-up of guidelines and impact on the management of suspected deep vein thrombosis in emergency departments

AIMS

To evaluate the implementation of the European Society of Cardiology (ESC) guidelines concerning the diagnostic management of deep vein thrombosis (DVT) in emergency departments (ED); and to estimate the additional financial cost and the increase in the time spent in the ED if the guidelines are not followed.

PATIENTS AND METHODS

Retrospective, bi-centric study including all patients directly admitted or referred to the ED for a suspected isolated DVT, between April 1, 2019, and July 30, 2019. The diagnostic management was compared to the 2017 ESC's guidelines.

RESULTS

107 patients were included, 13 had DVT (12%) and three had superficial venous thrombosis (3%). A total of 26 patients (24%) had a diagnostic management according to guidelines. In 72 patients (67%), no assessment of clinical probability score was found. Among the 35 patients in whom a clinical probability score was calculated, 5 patients had an unnecessary D-dimer assay and 2 patients had unjustified imaging. The median time spent in the ED was 185minutes when the recommendations were followed, and 250minutes when they were not (P=0.317). The total estimated additional cost was €232.20.

CONCLUSION

The rate of adherence to the guidelines is low, mainly due to the absence of calculation of a clinical probability. This leads, in addition to the risk of diagnostic error, to an increase in the time spent in the EDs and inappropriate use of the technical platform, resulting in additional costs of care.

[Pre-implantation genetic testing: Comparison between cleavage stage and blastocyst biopsy]

OBJECTIVES

Preimplantation genetic testing (PGT) refers to the set of techniques for testing whether embryos obtained through in vitro fertilization have genetic defect. There is a lack of global standardization regarding practices between countries or even from one center to another. In ours, biopsies are preferably performed on day 3 embryos, but also at the blastocyst stage on day 5. The blastocyst biopsy often requires systematic freezing of the embryos before obtaining the genetic results, whereas day 3 biopsy allows fresh embryo transfer of the healthy or balanced embryo after getting the genetic results. We wanted to compare the chances of success for couples performing PGT in our center according to the day of the biopsy.

METHODS

For this, we carried out a retrospective monocentric study including all PGT cycles performed between 2016 and 2019 divided into two groups: day 3 or day 5 biopsy.

RESULTS

There was no significant difference in terms of live birth rate (P=0.7375) after fresh embryo transfers, as well for pregnancy rates, clinical pregnancy rates, implantation rates and miscarriage rates. On the other hand, we observed higher live birth rates after frozen-thawed embryo transfer when the biopsy was performed on day 5 rather on day 3 (P=0.0001). We also wanted to assess what was the most efficient biopsy strategy in our laboratory. Our rates of useful embryos were similar regardless of the day of the biopsy (34% in D3 and 37.7% in D5, P=0.244). No statistical difference was found in the number of unnecessarily biopsied embryos in the two groups. But still, the percentage of embryos biopsied on D5 and immediately frozen was 42.8% (118 blastocysts), while no embryo biopsied on D3 led to this case.

CONCLUSION

Therefore, our results are in favor of generalization of the D5 biopsy as the international standard. However, the organizational, financial and logistical implications that this technic would impose make it unsystematic in our center.

Exploring the Potential of β-Catenin O-GlcNAcylation by Using Fluorescence-Based Engineering and Imaging

Monitoring glycosylation changes within cells upon response to stimuli remains challenging because of the complexity of this large family of post-translational modifications (PTMs). We developed an original tool, enabling labeling and visualization of the cell cycle key-regulator β-catenin in its O-GlcNAcylated form, based on intramolecular Förster resonance energy transfer (FRET) technology in cells. We opted for a bioorthogonal chemical reporter strategy based on the dual-labeling of β-catenin with a green fluorescent protein (GFP) for protein sequence combined with a chemically-clicked imaging probe for PTM, resulting in a fast and easy to monitor qualitative FRET assay. We validated this technology by imaging the O-GlcNAcylation status of β-catenin in HeLa cells. The changes in O-GlcNAcylation of β-catenin were varied by perturbing global cellular O-GlcNAc levels with the inhibitors of O-GlcNAc transferase (OGT) and O-GlcNAcase (OGA). Finally, we provided a flowchart demonstrating how this technology is transposable to any kind of glycosylation.

Evolution of serum Anti-Müllerian Hormone (AMH) level in young women treated with chemotherapy for breast cancer according to basal AMH level

OBJECTIVE

Serum AMH level has been shown to decrease in women treated for breast cancer in several studies. However, whether basal AMH status affects AMH dynamics during chemotherapy remains to be clarified. The objective of this study was to compare serum AMH dynamics in young women with either low, normal or high basal serum AMH level at diagnosis, during and after treatment with chemotherapy for breast cancer.

STUDY DESIGN

In this secondary analysis of a prospective cohort study, serum AMH was measured during and after chemotherapy in 239 women of reproductive age diagnosed with breast cancer and treated with chemotherapy. The association between AMH dynamics throughout chemotherapy and during follow-up and basal AMH status, i.e. low AMH (<1 μg/l, <7 pmol/l), normal AMH (1-4.9 μg/l, 7-36 pmol/l) and high AMH (≥5 μg/l, >36 pmol/l), was evaluated. Menses occurrence was also recorded.

RESULTS

A total of 21 women had low, 154 had normal and 64 had high basal AMH level. Serum AMH rapidly decreased during chemotherapy in all groups, and its variation during chemotherapy and follow-up was not significantly different between the 3 groups.

CONCLUSION

No association was found between AMH variation during chemotherapy and follow-up, and basal AMH level at diagnosis. However, women with high basal AMH levels have significantly higher AMH levels throughout chemotherapy and follow-up than women with normal or low basal AMH levels at diagnosis.

[Mental health care in French correctional facilities during the Covid-19 pandemic]

OBJECTIVE

The impact of the Covid-19 pandemic on the 11 million people currently incarcerated worldwide is the subject of many concerns. Prisons and jails are filled with people suffering from many preexisting medical conditions increasing the risk of complications. Detainees' access to medical services is already limited and overcrowding poses a threat of massive contagion. Beyond the health impact of the crisis, the tightening of prison conditions worries. On March 16, 2020, in France, the lockdown measures have been accompanied by specific provisions for prisons: all facilities have suspended visitations, group activities and external interventions. Over 10,000 prisoners have been released to reduce the prison population and the risk of virus propagation. These adjustments had major consequences on the healthcare system in French prisons. The objectives of this article are to describe the reorganization of the three levels of psychiatric care for inmates in France in the context of Covid-19 pandemic and to have a look at the impact of lockdown measures and early releases on mental health of prisoners.

METHODS

This work is based on a survey conducted in April 2020 in France among psychiatric healthcare providers working in 42 ambulatory units for inmates and in the 9 full-time inpatient psychiatric wards exclusively for inmates called "UHSAs" (which stands for "unités hospitalières spécialement aménagées", and can be translated as "specially equipped hospital units"). A review of the international literature on mental healthcare system for inmates during the Covid-19 epidemic has also been performed.

RESULTS

The Covid-19 epidemic has been rather contained during the period of confinement in French prisons but the impact of confinement measures on the prison population is significant. The three levels of psychiatric care for inmates have implemented specific measures to ensure continuity of care, to support detainees during Coronavirus lockdown and to prevent an infection's spread. Among the most important are: limitation of medical consultations to serious and urgent cases, creation of "Covid units", cancellation of voluntary psychiatric hospitalizations, reinforcement of preventive hygiene measures and reshuffling of medical staff. Prolonged confinement has consequences on mental health of detainees. Currently, mental health workers are facing multiple clinical situations such as forced drug and substance withdrawal (linked to difficulties in supplying psychoactive substances), symptoms of anxiety (due to concerns for their own and their relatives' well-being) and decompensation among patients with severe psychiatric conditions. Early releases from prison may also raise some issues. People recently released from prison are identified as at high risk of death by suicide and drug overdose. The lack of time to provide the necessary link between health services within prisons and health structures outside could have serious consequences, emphasizing the well-known "revolving prison doors" effect.

DISCUSSION

The current lockdown measures applied in French jails and prisons point out the disparities between psychiatric care for inmates and psychiatric care for general population. Giving the high vulnerability of prison population, public health authorities should pay more attention to health care in prisons.

Identification of lipid raft glycoproteins obtained from boar spermatozoa

The surface of the spermatozoa is coated with glycoproteins the redistribution of which during in vitro capacitation plays a key role in the subsequent fertilization process. Lipid rafts are membrane microdomains involved in signal transduction through receptors and include or recruit specific types of proteins and glycoproteins. Few studies have focused on identifying glycoproteins resident in the lipid rafts of spermatozoa. Proteins associated with lipid rafts modify their localization during capacitation. The objective of the study was to identify the glycoproteins associated with lipid rafts of capacitated boar spermatozoa through a lectin-binding assay coupled to mass spectrometry approach. From the proteomic profiles generated by the raft proteins extractions, we observed that after capacitation the intensity of some bands increased while that of others decreased. To determine whether the proteins obtained from lipid rafts are glycosylated, lectin blot assays were performed. Protein bands with a good resolution and showing significant glycosylation modifications after capacitation were analyzed by mass spectrometry. The bands of interest had an apparent molecular weight of 64, 45, 36, 34, 24, 18 and 15 kDa. We sequenced the 7 bands and 20 known or potential glycoproteins were identified. According to us, for ten of them this is the first time that their association with sperm lipid rafts is described (ADAM5, SPMI, SPACA1, Seminal plasma protein pB1, PSP-I, MFGE8, tACE, PGK2, SUCLA2, MDH1). Moreover, LYDP4, SPAM-1, HSP60, ZPBP1, AK1 were previously reported in lipid rafts of mouse and human spermatozoa but not in boar spermatozoa. We also found and confirmed the presence of ACR, ACRBP, AWN, AQN3 and PRDX5 in lipid rafts of boar spermatozoa. This paper provides an overview of the glycosylation pattern in lipid rafts of boar spermatozoa before and after capacitation. Further glycomic analysis is needed to determine the type and the variation of glycan chains of the lipid rafts glycoproteins on the surface of spermatozoa during capacitation and acrosome reaction.

Analyse des courriers de plainte adressés au service d’urgence d’un centre hospitalier général

Objectif : L’objectif principal de notre travail était d’analyser les courriers de plainte (CP) adressés à un service d’urgence (SU). L’objectif secondaire était de déterminer s’il existait une corrélation entre CP et temporalité de passage au SU.

Matériel et méthodes : Étude rétrospective monocentrique sur six ans portant sur les CP concernant les prises en charge en SU.

Résultats : Quatre-vingt-un CP ont été analysés, la moyenne annuelle et l’incidence étaient de 13,5 CP/an et de 5,5 CP/ 10 000 passages. L’incidence était de 3,5 CP/10 000 passages pour les enfants vs 6,1 CP/10 000 passages pour les adultes (p = 0,11). Le plaignant était la famille dans 44 CP (55 %) et le patient dans 34 CP (42 %). Il n’y avait pas de différence significative entre le jour et la nuit (5,7 CP/10 000 vs 4,8 CP/ 10 000 passages ; p = 0,57) ni entre horaires de garde et horaires hors garde (5,6 CP/10 000 vs 5,2 CP/10 000 passages ; p = 0,78). Nous avons dénombré 133 doléances, avec une cause médicale dans 64 CP (48 %), une cause organisationnelle dans 44 CP (33 %), une cause relationnelle dans 25 CP (19 %). Une indemnisation financière a été demandée dans 13 CP (16 %) et a été accordée pour deux dossiers (2 %). Aucun CP n’a entraîné de poursuite en justice.

Conclusion : L’incidence des CP de notre SU reste dans la moyenne basse des données retrouvées au niveau national et sans relation avec la temporalité du passage. L’analyse des CP permet d’améliorer la qualité de la prise en charge et de proposer des mesures correctives en relation avec la commission des usagers.

OGT Controls the Expression and the Glycosylation of E-cadherin, and Affects Glycosphingolipid Structures in Human Colon Cell Lines

Colorectal cancer (CRC) affects both women and men living in societies with a high sedentary lifestyle. Amongst the phenotypic changes exhibited by tumor cells, a wide range of glycosylation has been reported for colon cancer-derived cell lines and CRC tissues. These aberrant modifications affect different aspects of glycosylation, including an increase in core fucosylation and GlcNAc branching on N-glycans, alteration of O-glycans, upregulated sialylation, and O-GlcNAcylation. Although O-GlcNAcylation and complex glycosylations differ in many aspects, sparse evidences report on the interference of O-GlcNAcylation with complex glycosylation. Nevertheless, this relationship is still a matter of debate. Combining different approaches on three human colon cell lines (HT29, HCT116 and CCD841CoN), it is herein reported that silencing O-GlcNAc transferase (OGT, the sole enzyme driving O-GlcNAcylation), only slightly affects overall N- and O-glycosylation patterns. Interestingly, silencing of OGT in HT29 cells upregulates E-cadherin (a major actor of epithelial-to-mesenchymal transition) and changes its glycosylation. On the other hand, OGT silencing perturbs biosynthesis of glycosphingolipids resulting in a decrease in gangliosides and an increase in globosides. Together, these results provide novel insights regarding the selective regulation of complex glycosylations by O-GlcNAcylation in colon cancer cells.

O-GlcNAcylation Is Involved in the Regulation of Stem Cell Markers Expression in Colon Cancer Cells

The dynamic O-linked-N-acetylglucosamine posttranslational modification of nucleocytoplasmic proteins has emerged as a key regulator of diverse cellular processes including several hallmarks of cancer. However, the role played by this modification in the establishment of CSC phenotype has been poorly studied so far and remains unclear. In this study we confirmed the previous reports showing that colon cancer cells exhibit higher O-GlcNAc basal levels than non-malignant cells, and investigated the role played by O-GlcNAcylation in the regulation of CSC phenotype. We found that the modification of O-GlcNAcylation levels by pharmacological inhibition of the O-GlcNAc-transferase enzyme that adds O-GlcNAc (OGT), but not of the enzyme that removes it (OGA), increased the expression of all stem cell markers tested in our colon malignant cell lines, and induced the appearance of a double positive (CD44+/CD133+) small stem cell-like subpopulation (which corresponded to 1-10%) that displayed very aggressive malignant phenotype such as increased clonogenicity and spheroid formation abilities in 3D culture. We reasoned that OGT inhibition would mimic in the tumor the presence of severe nutritional stress, and indeed, we demonstrated that nutritional stress reproduced in colon cancer cells the effects obtained with OGT inhibition. Thus, our data strongly suggests that stemness is regulated by HBP/O-GlcNAcylation nutrient sensing pathway, and that O-GlcNAc nutrient sensor represents an important survival mechanism in cancer cells under nutritional stressful conditions.

Identification of O-Glcnacylated Proteins in Trypanosoma cruzi

Originally an anthropozoonosis in the Americas, Chagas disease has spread from its previous borders through migration. It is caused by the protozoan Trypanosoma cruzi. Differences in disease severity have been attributed to a natural pleomorphism in T. cruzi. Several post-translational modifications (PTMs) have been studied in T. cruzi, but to date no work has focused on O-GlcNAcylation, a highly conserved monosaccharide-PTM of serine and threonine residues mainly found in nucleus, cytoplasm, and mitochondrion proteins. O-GlcNAcylation is thought to regulate protein function analogously to protein phosphorylation; indeed, crosstalk between both PTMs allows the cell to regulate its functions in response to nutrient levels and stress. Herein, we demonstrate O-GlcNAcylation in T. cruzi epimastigotes by three methods: by using specific antibodies against the modification in lysates and whole parasites, by click chemistry labeling, and by proteomics. In total, 1,271 putative O-GlcNAcylated proteins and six modification sequences were identified by mass spectrometry (data available via ProteomeXchange, ID PXD010285). Most of these proteins have structural and metabolic functions that are essential for parasite survival and evolution. Furthermore, O-GlcNAcylation pattern variations were observed by antibody detection under glucose deprivation and heat stress conditions, supporting their possible role in the adaptive response. Given the numerous biological processes in which O-GlcNAcylated proteins participate, its identification in T. cruzi proteins opens a new research field in the biology of Trypanosomatids, improve our understanding of infection processes and may allow us to identify new therapeutic targets.

Pratique de l’échographie clinique au sein d’un réseau territorial d’urgence

Objectif : L’échographie clinique en médecine d’urgence (ECMU) est un outil essentiel de notre pratique. L’objectif principal de notre étude était d’évaluer les caractéristiques des médecins pratiquant l’ECMU au sein de notre territoire. L’objectif secondaire était d’analyser les facteurs influençant une pratique régulière.

Matériel et méthodes : Étude descriptive multicentrique et déclarative, réalisée auprès de médecins urgentistes travaillant au sein d’un réseau territorial de médecine d’urgence à l’aide d’un questionnaire en ligne.

Résultats : Cent onze questionnaires sur 120 envoyés ont été renseignés (92 %). Onze services (92 %) étaient dotés en échographe dont neuf (82 %) en dotation propre. Soixantesix médecins (59 %) déclaraient pratiquer l’échographie régulièrement. La FAST (focused assessment with sonography for traumas) était la plus pratiquée (80 médecins, 72 %), suivie de l’exploration hémodynamique (50 médecins, 45 %) et pleurale (44 médecins, 40 %). Dans le groupe des médecins ne pratiquant pas l’ECMU, 17 médecins sur 22 (77 %) l’expliquaient par un manque de formation. Dans le même temps, l’intérêt porté à l’ECMU par les urgentistes était coté à 7 ± 2 sur une échelle de 0 à 9. Les facteurs associés à la fréquence de la pratique de l’ECMU étaient le sexe (p < 0,001), le type d’activité (p = 0,005), le type de formation à l’échographie (p < 0,001) et l’ancienneté d’équipement de son service en échographe (p < 0,001).

Conclusion : Cette enquête a montré que la pratique régulière était majoritaire avec un intérêt porté par les praticiens à l’ECMU élevé. Cependant, le frein principal à son développement était un niveau de formation jugé insuffisant par certains praticiens.

Cyclin D1 Stability Is Partly Controlled by O-GlcNAcylation

Cyclin D1 is the regulatory partner of the cyclin-dependent kinases (CDKs) CDK4 or CDK6. Once associated and activated, the cyclin D1/CDK complexes drive the cell cycle entry and G1 phase progression in response to extracellular signals. To ensure their timely and accurate activation during cell cycle progression, cyclin D1 turnover is finely controlled by phosphorylation and ubiquitination. Here we show that the dynamic and reversible O-linked β-N-Acetyl-glucosaminylation (O-GlcNAcylation) regulates also cyclin D1 half-life. High O-GlcNAc levels increase the stability of cyclin D1, while reduction of O-GlcNAcylation strongly decreases it. Moreover, elevation of O-GlcNAc levels through O-GlcNAcase (OGA) inhibition significantly slows down the ubiquitination of cyclin D1. Finally, biochemical and cell imaging experiments in human cancer cells reveal that the O-GlcNAc transferase (OGT) binds to and glycosylates cyclin D1. We conclude that O-GlcNAcylation promotes the stability of cyclin D1 through modulating its ubiquitination.

Combinatorial regulation of hepatic cytoplasmic signaling and nuclear transcriptional events by the OGT/REV-ERBα complex

The nuclear receptor REV-ERBα integrates the circadian clock with hepatic glucose and lipid metabolism by nucleating transcriptional comodulators at genomic regulatory regions. An interactomic approach identified O-GlcNAc transferase (OGT) as a REV-ERBα-interacting protein. By shielding cytoplasmic OGT from proteasomal degradation and favoring OGT activity in the nucleus, REV-ERBα cyclically increased O-GlcNAcylation of multiple cytoplasmic and nuclear proteins as a function of its rhythmically regulated expression, while REV-ERBα ligands mostly affected cytoplasmic OGT activity. We illustrate this finding by showing that REV-ERBα controls OGT-dependent activities of the cytoplasmic protein kinase AKT, an essential relay in insulin signaling, and of ten-of-eleven translocation (TET) enzymes in the nucleus. AKT phosphorylation was inversely correlated to REV-ERBα expression. REV-ERBα enhanced TET activity and DNA hydroxymethylated cytosine (5hmC) levels in the vicinity of REV-ERBα genomic binding sites. As an example, we show that the REV-ERBα/OGT complex modulates SREBP-1c gene expression throughout the fasting/feeding periods by first repressing AKT phosphorylation and by epigenomically priming the Srebf1 promoter for a further rapid response to insulin. Conclusion: REV-ERBα regulates cytoplasmic and nuclear OGT-controlled processes that integrate at the hepatic SREBF1 locus to control basal and insulin-induced expression of the temporally and nutritionally regulated lipogenic SREBP-1c transcript.

The Many Ways by Which O-GlcNAcylation May Orchestrate the Diversity of Complex Glycosylations

Unlike complex glycosylations, O-GlcNAcylation consists of the addition of a single N-acetylglucosamine unit to serine and threonine residues of target proteins, and is confined within the nucleocytoplasmic and mitochondrial compartments. Nevertheless, a number of clues tend to show that O-GlcNAcylation is a pivotal regulatory element of its complex counterparts. In this perspective, we gather the evidence reported to date regarding this connection. We propose different levels of regulation that encompass the competition for the nucleotide sugar UDP-GlcNAc, and that control the wide class of glycosylation enzymes via their expression, catalytic activity, and trafficking. We sought to better envision that nutrient fluxes control the elaboration of glycans, not only at the level of their structure composition, but also through sweet regulating actors.

O-GlcNAc transferase associates with the MCM2-7 complex and its silencing destabilizes MCM-MCM interactions

O-GlcNAcylation of proteins is governed by O-GlcNAc transferase (OGT) and O-GlcNAcase (OGA). The homeostasis of O-GlcNAc cycling is regulated during cell cycle progression and is essential for proper cellular division. We previously reported the O-GlcNAcylation of the minichromosome maintenance proteins MCM2, MCM3, MCM6 and MCM7. These proteins belong to the MCM2–7 complex which is crucial for the initiation of DNA replication through its DNA helicase activity. Here we show that the six subunits of MCM2–7 are O-GlcNAcylated and that O-GlcNAcylation of MCM proteins mainly occurs in the chromatin-bound fraction of synchronized human cells. Moreover, we identify stable interaction between OGT and several MCM subunits. We also show that down-regulation of OGT decreases the chromatin binding of MCM2, MCM6 and MCM7 without affecting their steady-state level. Finally, OGT silencing or OGA inhibition destabilizes MCM2/6 and MCM4/7 interactions in the chromatin-enriched fraction. In conclusion, OGT is a new partner of the MCM2–7 complex and O-GlcNAcylation homeostasis might regulate MCM2–7 complex by regulating the chromatin loading of MCM6 and MCM7 and stabilizing MCM/MCM interactions.

Recurrent attacks of acute hepatic porphyria: major role of the chronic inflammatory response in the liver

BACKGROUND

Acute intermittent porphyria (AIP) is an inherited disorder of haem metabolism characterized by life-threatening acute neurovisceral attacks due to the induction of hepatic δ-aminolevulinic acid synthase 1 (ALAS1) associated with hydroxymethylbilane synthase (HMBS) deficiency. So far, the treatment of choice is hemin which represses ALAS1. The main issue in the medical care of AIP patients is the occurrence of debilitating recurrent attacks.

OBJECTIVE

The aim of this study was to determine whether chronic hemin administration contributes to the recurrence of acute attacks.

METHODS

A follow-up study was conducted between 1974 and 2015 and included 602 French AIP patients, of whom 46 had recurrent AIP. Moreover, we studied the hepatic transcriptome, serum proteome, liver macrophage polarization and oxidative and inflammatory profiles of Hmbs^-/- mice chronically treated by hemin and extended the investigations to five explanted livers from recurrent AIP patients.

RESULTS

The introduction of hemin into the pharmacopeia has coincided with a 4.4-fold increase in the prevalence of chronic patients. Moreover, we showed that both in animal model and in human liver, frequent hemin infusions generate a chronic inflammatory hepatic disease which induces HO1 remotely to hemin treatment and maintains a high ALAS1 level responsible for recurrence.

CONCLUSION

Altogether, this study has important impacts on AIP care underlying that hemin needs to be restricted to severe neurovisceral crisis and suggests that alternative treatment targeting the liver such as ALAS1 and HO1 inhibitors, and anti-inflammatory therapies should be considered in patients with recurrent AIP.

Drug resistance related to aberrant glycosylation in colorectal cancer

Colorectal cancer (CRC) is the fourth leading cause of cancer-related deaths in the world. Drug resistance of tumour cells remains the main challenge toward curative treatments efficiency. Several epidemiologic studies link emergence and recurrence of this cancer to metabolic disorders. Glycosylation that modifies more than 80% of human proteins is one of the most widepread nutrient-sensitive post-translational modifications. Aberrant glycosylation participates in the development and progression of cancer. Thus, some of these glycan changes like carbohydrate antigen CA 19-9 (sialyl Lewis a, sLea) or those found on carcinoembryonic antigen (CEA) are already used as clinical biomarkers to detect and monitor CRC. The current review highlights emerging evidences accumulated mainly during the last decade that establish the role played by altered glycosylations in CRC drug resistance mechanisms that induce resistance to apoptosis and activation of signaling pathways, alter drug absorption and metabolism, and led to stemness acquisition. Knowledge in this field of investigation could aid to the development of better therapeutic approaches with new predictive biomarkers and targets tied in with adapted diet.

Apart From Rhoptries, Identification of Toxoplasma gondii's O-GlcNAcylated Proteins Reinforces the Universality of the O-GlcNAcome

O-linked β-N-acetylglucosaminylation or O-GlcNAcylation is a widespread post-translational modification that belongs to the large and heterogeneous group of glycosylations. The functions managed by O-GlcNAcylation are diverse and include regulation of transcription, replication, protein's fate, trafficking, and signaling. More and more evidences tend to show that deregulations in the homeostasis of O-GlcNAcylation are involved in the etiology of metabolic diseases, cancers and neuropathologies. O-GlcNAc transferase or OGT is the enzyme that transfers the N-acetylglucosamine residue onto target proteins confined within the cytosolic and nuclear compartments. A form of OGT was predicted for Toxoplasma and recently we were the first to show evidence of O-GlcNAcylation in the apicomplexans Toxoplasma gondii and Plasmodium falciparum. Numerous studies have explored the O-GlcNAcome in a wide variety of biological models but very few focus on protists. In the present work, we used enrichment on sWGA-beads and immunopurification to identify putative O-GlcNAcylated proteins in Toxoplasma gondii. Many of the proteins found to be O-GlcNAcylated were originally described in higher eukaryotes and participate in cell shape organization, response to stress, protein synthesis and metabolism. In a more original way, our proteomic analyses, confirmed by sWGA-enrichment and click-chemistry, revealed that rhoptries, proteins necessary for invasion, are glycosylated. Together, these data show that regardless of proteins strictly specific to organisms, O-GlcNAcylated proteins are rather similar among living beings.

Cross-Dysregulation of O-GlcNAcylation and PI3K/AKT/mTOR Axis in Human Chronic Diseases

The hexosamine biosynthetic pathway (HBP) and the phosphatidylinositol 3-kinase (PI3K)/AKT/mammalian target of rapamycin (mTOR) signaling pathway are considered as nutrient sensors that regulate several essential biological processes. The hexosamine biosynthetic pathway produces uridine diphosphate N-acetylglucosamine (UDP-GlcNAc), the substrate for O-GlcNAc transferase (OGT), the enzyme that O-GlcNAcylates proteins on serine (Ser) and threonine (Thr) residues. O-linked β-N-acetylglucosaminylation (O-GlcNAcylation) and phosphorylation are highly dynamic post-translational modifications occurring at the same or adjacent sites that regulate folding, stability, subcellular localization, partner interaction, or activity of target proteins. Here we review recent evidence of a cross-regulation of PI3K/AKT/mTOR signaling pathway and protein O-GlcNAcylation. Furthermore, we discuss their co-dysregulation in pathological conditions, e.g., cancer, type-2 diabetes (T2D), and cardiovascular, and neurodegenerative diseases.

Identification of O-GlcNAcylated proteins in Plasmodium falciparum

BACKGROUND

Post-translational modifications (PTMs) constitute a huge group of chemical modifications increasing the complexity of the proteomes of living beings. PTMs have been discussed as potential anti-malarial drug targets due to their involvement in many cell processes. O-GlcNAcylation is a widespread PTM found in different organisms including Plasmodium falciparum. The aim of this study was to identify O-GlcNAcylated proteins of P. falciparum, to learn more about the modification process and to understand its eventual functions in the Apicomplexans.

METHODS

The P. falciparum strain 3D7 was amplified in erythrocytes and purified. The proteome was checked for O-GlcNAcylation using different methods. The level of UDP-GlcNAc, the donor of the sugar moiety for O-GlcNAcylation processes, was measured using high-pH anion exchange chromatography. O-GlcNAcylated proteins were enriched and purified utilizing either click chemistry labelling or adsorption on succinyl-wheat germ agglutinin beads. Proteins were then identified by mass-spectrometry (nano-LC MS/MS).

RESULTS

While low when compared to MRC5 control cells, P. falciparum disposes of its own pool of UDP-GlcNAc. By using proteomics methods, 13 O-GlcNAcylated proteins were unambiguously identified (11 by click-chemistry and 6 by sWGA-beads enrichment; 4 being identified by the 2 approaches) in late trophozoites. These proteins are all part of pathways, functions and structures important for the parasite survival. By probing clicked-proteins with specific antibodies, Hsp70 and α-tubulin were identified as P. falciparum O-GlcNAc-bearing proteins.

CONCLUSIONS

This study is the first report on the identity of P. falciparum O-GlcNAcylated proteins. While the parasite O-GlcNAcome seems close to those of other species, the structural differences exhibited by the proteomes provides a glimpse of innovative therapeutic paths to fight malaria. Blocking biosynthesis of UDP-GlcNAc in the parasites is another promising option to reduce Plasmodium life cycle.

The RBM14/CoAA-interacting, long intergenic non-coding RNA Paral1 regulates adipogenesis and coactivates the nuclear receptor PPARγ

Adipocyte differentiation and function relies on a network of transcription factors, which is disrupted in obesity-associated low grade, chronic inflammation leading to adipose tissue dysfunction. In this context, there is a need for a thorough understanding of the transcriptional regulatory network involved in adipose tissue pathophysiology. Recent advances in the functional annotation of the genome has highlighted the role of non-coding RNAs in cellular differentiation processes in coordination with transcription factors. Using an unbiased genome-wide approach, we identified and characterized a novel long intergenic non-coding RNA (lincRNA) strongly induced during adipocyte differentiation. This lincRNA favors adipocyte differentiation and coactivates the master adipogenic regulator peroxisome proliferator-activated receptor gamma (PPARγ) through interaction with the paraspeckle component and hnRNP-like RNA binding protein 14 (RBM14/NCoAA), and was therefore called PPARγ-activator RBM14-associated lncRNA (Paral1). Paral1 expression is restricted to adipocytes and decreased in humans with increasing body mass index. A decreased expression was also observed in diet-induced or genetic mouse models of obesity and this down-regulation was mimicked in vitro by TNF treatment. In conclusion, we have identified a novel component of the adipogenic transcriptional regulatory network defining the lincRNA Paral1 as an obesity-sensitive regulator of adipocyte differentiation and function.

Effect of amyloid-Β (25-35) in hyperglycemic and hyperinsulinemic rats, effects on phosphorylation and O-GlcNAcylation of tau protein

Aggregation of the amyloid beta (Aβ) peptide and hyperphosphorylation of tau protein, which are markers of Alzheimer's disease (AD), have been reported also in diabetes mellitus (DM). One regulator of tau phosphorylation is O-GlcNAcylation, whereas for hyperphosphorylation it could be GSK3beta, which is activated in hyperglycemic conditions. With this in mind, both O-GlcNAcylation and phosphorylation of tau protein were evaluated in the brain of rats with streptozotocin (STZ)-induced hyperglycemia and hyperinsulinemia and treated with the Aß25-35 peptide in the hippocampal region CA1. Weight, glycated hemoglobin, glucose, and insulin were determined. Male Wistar rats were divided in groups (N=20): a) control, b) treated only with the Aβ25-35 peptide, c) treated with Aβ25-35 and STZ, and d) treated only with STZ. Results showed statistically significant differences in the mean weight, glucose levels, insulin concentration, and HbA1c percentage, between C- and D-treated groups and not STZ-treated A and B (P<0.05). Interestingly, our results showed diminution of O-GlcNAcylation and increase in P-tau-Ser-396 in the hippocampal area of the Aβ25-35- and STZ-treated groups; moreover, enhanced expression of GSK3beta was observed in this last group. Our results suggest that hyperinsulinemia-Aβ25-35-hyperglycemia is relevant for the down regulation of O-GlcNAcylation and up-regulation of the glycogen synthase kinase-3 beta (GSK3beta), favoring Aβ25-35-induced neurotoxicity in the brain of rats.

Glucokinase expression is regulated by glucose through O-GlcNAc glycosylation

Blood glucose fluctuates with the fasting-feeding cycle. One of the liver's functions is to maintain blood glucose concentrations within a physiological range. Glucokinase (GCK) or hexokinase IV, is the main enzyme that regulates the flux and the use of glucose in the liver leading to a compensation of hyperglycemia. In hepatocytes, GCK catalyzes the phosphorylation of glucose into glucose-6-phosphate. This critical enzymatic reaction is determinant for the metabolism of glucose in the liver which includes glycogen synthesis, glycolysis, lipogenesis and gluconeogenesis. In liver, simultaneous increase of glucose and insulin enhances GCK activity and gene expression, changes its subcellular location and interaction with regulatory proteins. The post-translational O-linked β-N-acetylglucosaminylation (O-GlcNAcylation) acts as a glucose-sensitive modification and is believed to take part in hepatic glucose sensing by modifying key regulatory proteins. Therefore, we aimed to determine whether GCK is modified by O-GlcNAcylation in the liver of mice and investigated the role that this modification plays in regulating GCK protein expression. We demonstrated that endogenous GCK expression correlated with O-GlcNAc levels in the pathophysiological model ob/ob mice. More specifically, in response to the pharmacological inhibition of O-GlcNAcase (OGA) contents of GCK increased. Using the GlcNAc specific lectin succinylated-WGA and click chemistry labeling approaches, we demonstrated that GCK is modified by O-GlcNAcylation. Further, we demonstrated that siRNA-mediated Ogt knock-down not only decreases O-GlcNAc content but also GCK protein level. Altogether, our in vivo and in vitro results demonstrate that GCK expression is regulated by nutrient-sensing O-GlcNAc cycling in liver.

Bayesian Hybrid Model-State Estimation Applied to Simultaneous Contact Formation Recognition and Geometrical Parameter Estimation

In this paper we describe a Bayesian approach to model selection and state estimation for sensor-based robot tasks. The approach is illustrated with a hybrid model-state estimation example from force-controlled autonomous compliant motion: simultaneous (discrete) contact formation recognition and estimation of (continuous) geometrical parameters. Previous research in this area mostly tries to solve one of the two subproblems, or treats the contact formation recognition problem separately, avoiding integration between the solutions to the contact formation recognition and the geometrical parameter estimation problems. A more powerful hybrid model, explicitly modeling contact formation transitions, is developed to deal with larger uncertainties. This paper demonstrates that Kalman filter variants have limits: iterated extended Kalman filters can only handle small uncertainties on the geometrical parameters, while the non-minimal state Kalman filter cannot deal with model selection. Particle filters can handle the increased level of model complexity. Explicit measurement equations for the particle filter are derived from the implicit kinematic and energetic constraints. The experiments prove that the particle filter approach successfully estimates the hybrid joint posterior density of the discrete contact formation variable and the 12-dimensional, continuous geometrical parameter vector during the execution of an assembly task. The problem shows similarities with the well-known problems of data association in simultaneous localization and map-building (SLAM) and model selection in global localization.

O-GlcNAcylation and the Metabolic Shift in High-Proliferating Cells: All the Evidence Suggests that Sugars Dictate the Flux of Lipid Biogenesis in Tumor Processes

Cancer cells are characterized by their high capability to proliferate. This imposes an accelerated biosynthesis of membrane compounds to respond to the need for increasing the membrane surface of dividing cells and remodeling the structure of lipid microdomains. Recently, attention has been paid to the upregulation of O-GlcNAcylation processes observed in cancer cells. Although O-GlcNAcylation of lipogenic transcriptional regulators is described in the literature (e.g., FXR, LXR, ChREBP), little is known about the regulation of the enzymes that drive lipogenesis: acetyl co-enzyme A carboxylase and fatty acid synthase (FAS). The expression and catalytic activity of both FAS and O-GlcNAc transferase (OGT) are high in cancer cells but the reciprocal regulation of the two enzymes remains unexplored. In this perspective, we collected data linking FAS and OGT and, in so doing, pave the way for the exploration of the intricate functions of these two actors that play a central role in tumor growth.

Silencing the Nucleocytoplasmic O-GlcNAc Transferase Reduces Proliferation, Adhesion, and Migration of Cancer and Fetal Human Colon Cell Lines

The post-translational modification of proteins by O-linked β-N-acetylglucosamine (O-GlcNAc) is regulated by a unique couple of enzymes. O-GlcNAc transferase (OGT) transfers the GlcNAc residue from UDP-GlcNAc, the final product of the hexosamine biosynthetic pathway (HBP), whereas O-GlcNAcase (OGA) removes it. This study and others show that OGT and O-GlcNAcylation levels are increased in cancer cell lines. In that context, we studied the effect of OGT silencing in the colon cancer cell lines HT29 and HCT116 and the primary colon cell line CCD841CoN. Herein, we report that OGT silencing diminished proliferation, in vitro cell survival and adhesion of primary and cancer cell lines. SiOGT dramatically decreased HT29 and CCD841CoN migration, CCD841CoN harboring high capabilities of migration in Boyden chamber system when compared to HT29 and HCT116. The expression levels of actin and tubulin were unaffected by OGT knockdown but siOGT seemed to disorganize microfilament, microtubule, and vinculin networks in CCD841CoN. While cancer cell lines harbor higher levels of OGT and O-GlcNAcylation to fulfill their proliferative and migratory properties, in agreement with their higher consumption of HBP main substrates glucose and glutamine, our data demonstrate that OGT expression is not only necessary for the biological properties of cancer cell lines but also for normal cells.