Hypoxia research, where to now?

Investigating how cells and organisms sense and respond to O2 levels is essential to our understanding of physiology and pathology. This field has advanced considerably since the discovery of the major transcription factor family, hypoxia-inducible factor (HIF), and the enzymes that control its levels: prolyl hydroxylases (PHDs). However, with its expansion, new complexities have emerged. Herein we highlight three main areas where, in our opinion, the research community could direct some of their attention. These include non-transcriptional roles of HIFs, specificity and O2 sensitivity of 2-oxoglutarate-dependent dioxygenases (2-OGDDs), and new tools and methods to detect O2 concentrations in cells and organs. A greater understanding of these areas would answer big questions and help drive our knowledge of cellular responses to hypoxia forward.

Global acetylome profiling indicates EPA impedes but OA promotes prostate cancer motility through altered acetylation of PFN1 and FLNA

Prostate cancer (PCa) is one of the leading causes of cancer morbidity and mortality in men. Metastasis is the main cause of PCa-associated death. Recent evidence indicated a significant reduction in PCa mortality associated with higher ω-3 polyunsaturated fatty acids (PUFAs) consumption. However, the underlying mechanisms remained elusive. In this study, we applied global acetylome profiling to study the effect of fatty acids treatment. Results indicated that oleic acid (OA, monounsaturated fatty acid, MUFA, 100 µM) elevates while EPA (eicosapentaenoic acid, 100 µM) reduces the acetyl-CoA level, which alters the global acetylome. After treatment, two crucial cell motility regulators, PFN1 and FLNA, were found with altered acetylation levels. OA increased the acetylation of PFN1 and FLNA, whereas EPA decreased PFN1 acetylation level. Furthermore, OA promotes while EPA inhibits PCa migration and invasion. Immunofluorescence assay indicated that EPA impedes the formation of lamellipodia or filopodia through reduced localization of PFN1 and FLNA to the leading edge of cells. Therefore, perturbed acetylome may be one critical step in fatty acid-affected cancer cell motility. This study provides some new insights into the response of ω-3 PUFAs treatment and a better understanding of cancer cell migration and invasion modulation.

Enhancing radiotherapy outcomes in rectal cancer: A systematic review of targeting hypoxia-induced radioresistance

Introduction

Neoadjuvant radiotherapy is successfully used in rectal cancer to improve overall survival. However, treatment response is both unpredictable and variable. There is strong evidence to show that the phenomenon of tumour hypoxia is associated with radioresistance, however the mechanism(s) behind this are poorly understood. Consequently, there have only been a small number of studies evaluating methods targeting hypoxia-induced radioresistance. The purpose of this systematic review is to evaluate the potential effectiveness of targeting hypoxia-induced radioresistance in rectal cancer and provide recommendations for future research in this area.

Methods

A comprehensive literature search was performed following the PRISMA guidelines. This study was registered on the Prospero database (CRD42023441983).

Results

Eight articles met the inclusion criteria. All studies identified were in vitro or in vivo studies, there were no clinical trials. Of the 8 studies identified, 5 assessed the efficacy of drugs which directly or indirectly targeted hypoxia and three that identified potential targets. There was conflicting in vivo evidence for the use of metformin to overcome hypoxia induced radioresistance. Vorinostat, atovaquone, and evofosfamide showed promising preclinical evidence that they can overcome hypoxia-induced radioresistance.

Discussion

The importance of investigating hypoxia-induced radioresistance in rectal cancer is crucial. However, to date, only a small number of preclinical studies exist evaluating this phenomenon. This systematic review highlights the importance of further research to fully understand the mechanism behind this radioresistance. There are promising targets identified in this systematic review however, substantially more pre-clinical and clinical research as a priority for future research is needed.

Oxygen-regulated post-translation modifications as master signalling pathway in cells

Oxygen is essential for viability in mammalian organisms. However, cells are often exposed to changes in oxygen availability, due to either increased demand or reduced oxygen supply, herein called hypoxia. To be able to survive and/or adapt to hypoxia, cells activate a variety of signalling cascades resulting in changes to chromatin, gene expression, metabolism and viability. Cellular signalling is often mediated via post-translational modifications (PTMs), and this is no different in response to hypoxia. Many enzymes require oxygen for their activity and oxygen can directly influence several PTMS. Here, we review the direct impact of changes in oxygen availability on PTMs such as proline, asparagine, histidine and lysine hydroxylation, lysine and arginine methylation and cysteine dioxygenation, with a focus on mammalian systems. In addition, indirect hypoxia-dependent effects on phosphorylation, ubiquitination and sumoylation will also be discussed. Direct and indirect oxygen-regulated changes to PTMs are coordinated to achieve the cell's ultimate response to hypoxia. However, specific oxygen sensitivity and the functional relevance of some of the identified PTMs still require significant research.

The role of autophagy in hypoxia-induced radioresistance

Radiotherapy is a widely used treatment modality against cancer, and although survival rates are increasing, radioresistant properties of tumours remain a significant barrier for curative treatment. Tumour hypoxia is one of the main contributors to radioresistance and is common in most solid tumours. Hypoxia is responsible for many molecular changes within the cell which helps tumours to survive under such challenging conditions. These hypoxia-induced molecular changes are predominantly coordinated by the hypoxia inducible factor (HIF) and have been linked with the ability to confer resistance to radiation-induced cell death. To overcome this obstacle research has been directed towards autophagy, a cellular process involved in self degradation and recycling of macromolecules, as HIF plays a large role in its coordination under hypoxic conditions. The role that autophagy has following radiotherapy treatment is conflicted with evidence of both cytoprotective and cytotoxic effects. This literature review aims to explore the intricate relationship between radiotherapy, hypoxia, and autophagy in the context of cancer treatment. It provides valuable insights into the potential of targeting autophagy as a therapeutic strategy to improve the response of hypoxic tumours to radiotherapy.

Comprehensive analysis of the lysine succinylome in fish oil-treated prostate cancer cells

Prostate cancer (PCa) poses a significant health threat to males, and research has shown that fish oil (FO) can impede PCa progression by activating multiple mitochondria-related pathways. Our research is focused on investigating the impact of FO on succinylation, a posttranslational modification that is closely associated with mitochondria in PCa cells. This study employed a mass spectrometry-based approach to investigate succinylation in PCa cells. Bioinformatics analysis of these succinylated proteins identified glutamic-oxaloacetic transaminase 2 (GOT2) protein as a key player in PCa cell proliferation. Immunoprecipitation and RNA interference technologies validated the functional data. Further analyses revealed the significance of GOT2 protein in regulating nucleotide synthesis by providing aspartate, which is critical for the survival and proliferation of PCa cells. Our findings suggest that FO-dependent GOT2 succinylation status has the potential to inhibit building block generation. This study lays a solid foundation for future research into the role of succinylation in various biological processes. This study highlights the potential use of FO as a nutrition supplement for managing and slowing down PCa progression.

Targeting SOD1 via RNAi with PEGylated graphene oxide nanoparticles in platinum-resistant ovarian cancer

Acquired platinum resistance poses a significant therapeutic impediment to ovarian cancer patient care, accounting for more than 200,000 deaths annually worldwide. We previously identified that overexpression of the antioxidant superoxide dismutase 1 (SOD1) in ovarian cancer is associated with a platinum-resistant phenotype via conferring oxidative stress resistance against platinum compounds. We further demonstrated that enzymatic inhibition using small-molecule inhibitors or silencing of SOD1 via RNA interference (RNAi) increased cisplatin sensitivity and potency in vitro. We launched this study to explore the potential therapeutic applications of SOD1 silencing in vivo in order to reverse cisplatin resistance using a graphene-based siRNA delivery platform. PEGylated graphene oxide (GO) polyethyleneimine (GOPEI-mPEG) nanoparticle was complexed with SOD1 siRNA. GOPEI-mPEG-siSOD1 exhibited high biocompatibility, siRNA loading capacity, and serum stability, and showed potent downregulation of SOD1 mRNA and protein levels. We further observed that cisplatin and PEI elicited mitochondrial dysfunction and transcriptionally activated the mitochondrial unfolded protein response (UPRmt) used as a reporter for their respective cytotoxicities. SOD1 silencing was found to augment cisplatin-induced cytotoxicity resulting in considerable tumour growth inhibition in cisplatin-sensitive A2780 and cisplatin-resistant A2780DDP subcutaneous mouse xenografts. Our study highlights the potential therapeutic applicability of RNAi-mediated targeting of SOD1 as a chemosensitizer for platinum-resistant ovarian cancers.

Functional crosstalk between chromatin and hypoxia signalling

Eukaryotic genomes are organised in a structure called chromatin, comprising of DNA and histone proteins. Chromatin is thus a fundamental regulator of gene expression, as it offers storage and protection but also controls accessibility to DNA. Sensing and responding to reductions in oxygen availability (hypoxia) have recognised importance in both physiological and pathological processes in multicellular organisms. One of the main mechanisms controlling these responses is control of gene expression. Recent findings in the field of hypoxia have highlighted how oxygen and chromatin are intricately linked. This review will focus on mechanisms controlling chromatin in hypoxia, including chromatin regulators such as histone modifications and chromatin remodellers. It will also highlight how these are integrated with hypoxia inducible factors and the knowledge gaps that persist.

Endotyping COPD: hypoxia-inducible factor-2 as a molecular "switch" between the vascular and airway phenotypes?

COPD is a heterogeneous disease with multiple clinical phenotypes. COPD endotypes can be determined by different expressions of hypoxia-inducible factors (HIFs), which, in combination with individual susceptibility and environmental factors, may cause predominant airway or vascular changes in the lung. The pulmonary vascular phenotype is relatively rare among COPD patients and characterised by out-of-proportion pulmonary hypertension (PH) and low diffusing capacity of the lung for carbon monoxide, but only mild-to-moderate airway obstruction. Its histologic feature, severe remodelling of the small pulmonary arteries, can be mediated by HIF-2 overexpression in experimental PH models. HIF-2 is not only involved in the vascular remodelling but also in the parenchyma destruction. Endothelial cells from human emphysema lungs express reduced HIF-2α levels, and the deletion of pulmonary endothelial Hif-2α leads to emphysema in mice. This means that both upregulation and downregulation of HIF-2 have adverse effects and that HIF-2 may represent a molecular "switch" between the development of the vascular and airway phenotypes in COPD. The mechanisms of HIF-2 dysregulation in the lung are only partly understood. HIF-2 levels may be controlled by NAD(P)H oxidases via iron- and redox-dependent mechanisms. A better understanding of these mechanisms may lead to the development of new therapeutic targets.

Fixed Cell Immunofluorescence for Quantification of Hypoxia-Induced Changes in Histone Methylation

Hypoxia and its signalling pathway play a key role in human physiology and a variety of diseases. Alterations in histone methylation coordinate transcriptional responses to hypoxia. Here, we detail a fixed cell immunofluorescence method for quantifying hypoxia-induced changes in histone methylation, exemplified by the measurement of H3K27me3.

Overcoming the Impact of Hypoxia in Driving Radiotherapy Resistance in Head and Neck Squamous Cell Carcinoma

Hypoxia is very common in most solid tumours and is a driving force for malignant progression as well as radiotherapy and chemotherapy resistance. Incidences of head and neck squamous cell carcinoma (HNSCC) have increased in the last decade and radiotherapy is a major therapeutic technique utilised in the treatment of the tumours. However, effectiveness of radiotherapy is hindered by resistance mechanisms and most notably by hypoxia, leading to poor patient prognosis of HNSCC patients. The phenomenon of hypoxia-induced radioresistance was identified nearly half a century ago, yet despite this, little progress has been made in overcoming the physical lack of oxygen. Therefore, a more detailed understanding of the molecular mechanisms of hypoxia and the underpinning radiobiological response of tumours to this phenotype is much needed. In this review, we will provide an up-to-date overview of how hypoxia alters molecular and cellular processes contributing to radioresistance, particularly in the context of HNSCC, and what strategies have and could be explored to overcome hypoxia-induced radioresistance.

Systems approaches to understand oxygen sensing: how multi-omics has driven advances in understanding oxygen-based signalling

Hypoxia is a common denominator in the pathophysiology of a variety of human disease states. Insight into how cells detect, and respond to low oxygen is crucial to understanding the role of hypoxia in disease. Central to the hypoxic response is rapid changes in the expression of genes essential to carry out a wide range of functions to adapt the cell/tissue to decreased oxygen availability. These changes in gene expression are co-ordinated by specialised transcription factors, changes to chromatin architecture and intricate balances between protein synthesis and destruction that together establish changes to the cellular proteome. In this article, we will discuss the advances of our understanding of the cellular oxygen sensing machinery achieved through the application of 'omics-based experimental approaches.

Von Hippel-Lindau (VHL) small-molecule inhibitor binding increases stability and intracellular levels of VHL protein

Von Hippel-Lindau (VHL) disease is characterized by frequent mutation of VHL protein, a tumor suppressor that functions as the substrate recognition subunit of a Cullin2 RING E3 ligase complex (CRL2VHL). CRL2VHL plays important roles in oxygen sensing by targeting hypoxia-inducible factor-alpha (HIF-α) subunits for ubiquitination and degradation. VHL is also commonly hijacked by bifunctional molecules such as proteolysis-targeting chimeras to induce degradation of target molecules. We previously reported the design and characterization of VHL inhibitors VH032 and VH298 that block the VHL:HIF-α interaction, activate the HIF transcription factor, and induce a hypoxic response, which can be beneficial to treat anemia and mitochondrial diseases. How these compounds affect the global cellular proteome remains unknown. Here, we use unbiased quantitative MS to identify the proteomic changes elicited by the VHL inhibitor compared with hypoxia or the broad-spectrum prolyl-hydroxylase domain enzyme inhibitor IOX2. Our results demonstrate that VHL inhibitors selectively activate the HIF response similar to the changes induced in hypoxia and IOX2 treatment. Interestingly, VHL inhibitors were found to specifically upregulate VHL itself. Our analysis revealed that this occurs via protein stabilization of VHL isoforms and not via changes in transcript levels. Increased VHL levels upon VH298 treatment resulted in turn in reduced levels of HIF-1α protein. This work demonstrates the specificity of VHL inhibitors and reveals different antagonistic effects upon their acute versus prolonged treatment in cells. These findings suggest that therapeutic use of VHL inhibitors may not produce overt side effects from HIF stabilization as previously thought.

Oxygen-dependent changes in binding partners and post-translational modifications regulate the abundance and activity of HIF-1α/2α

Cellular adaptation to low-oxygen environments is mediated in part by the hypoxia-inducible factors (HIFs). Like other transcription factors, the stability and transcriptional activity of HIFs-and consequently, the hypoxic response-are regulated by post-translational modifications (PTMs) and changes in protein-protein interactions. Our current understanding of PTM-mediated regulation of HIFs is primarily based on in vitro protein fragment-based studies typically validated in fragment-expressing cells treated with hypoxia-mimicking compounds. Here, we used immunoprecipitation-based mass spectrometry to characterize the PTMs and binding partners for full-length HIF-1α and HIF-2α under normoxic (21% oxygen) and hypoxic (1% oxygen) conditions. Hypoxia substantially altered the complexity and composition of the HIFα protein interaction networks, particularly for HIF-2α, with the hypoxic networks of both isoforms being enriched for mitochondrial proteins. Moreover, both HIFα isoforms were heavily covalently modified. We identified ~40 PTM sites composed of 13 different types of modification on both HIFα isoforms, including multiple cysteine modifications and an unusual phosphocysteine. More than 80% of the PTMs identified were not previously known and about half exhibited oxygen dependency. We further characterized an evolutionarily conserved phosphorylation of Ser31 in HIF-1α as a regulator of its transcriptional function, and we propose functional roles for Thr406, Thr528, and Ser581 in HIF-2α. These data will help to delineate the different physiological roles of these closely related isoforms in fine-tuning the hypoxic response.

Syncope: call for the missed diagnosis

Funding Acknowledgements

Type of funding sources: None.

Background

Syncope is a common reason for emergency department attendance. This entity may be associated with significant morbidity and mortality and its differential diagnosis is not straightforward. Arrhythmic causes include tachycardia and bradycardia; the later may require pacemaker implantation. Many hospitals lack a dedicated syncope unit to approach these patients. So, patients’ triage may fall into medical or surgical (trauma) areas.

Purpose

To describe the population of patients that required permanent pacemaker implantation in the year of 2019, particularly those who had a previous visit to the emergency department with syncope or presyncope.

Methods

Single-center descriptive analysis of patients that implanted a permanent pacemaker in 2019 (inclusion criteria). Additional information was collected in patients with emergency department visits in the 365 days that preceded the device implantation.

Results

In 2019, a total of 398 patients were admitted for pacemaker implantation in 2019, 55% male (n = 218), 45% female (n = 180), with mean age of 79 years. Regarding indications for pacing, 41% (n= 156) had complete atrioventricular (AV) block, 26% (n = 105) had a second degree AV block, 16% (n = 64) had sinus node dysfunction, 13.5% (n = 53) had atrial fibrillation with slow ventricular conduction, and 3.5% (n = 14) had other indications.

Twenty-two percent (n = 88) of patients had a previous visit to the emergency department (other than the ones that triggered the pacemaker implantation) with complaints of syncope (60%) or presyncope (40%). Of these, 73% (n = 64) were referred to a medical area and 27% (n = 24) were referred to a surgical area; 40 patients presented with traumatic lesions (68% cranioencephalic trauma and 32% other traumas). Of the 88 patients, only 67% (n = 59) performed an ECG and only 23% (n = 20) were referred for observation by a cardiologist in the emergency department.

Comparing medical and surgical triage, we observe that patients referred to the surgical area were less likely to perform an ECG and to be observed by a cardiologist (with statistical significance).

Conclusions

Our work describes a common problem in hospitals without dedicated syncope evaluation units. As all the patients ended up implanting a pacemaker, it is interesting to observe that 22%of these had a "warning" visit to the emergency and 33% of the last did not get and ECG. Also, trauma-oriented approaches result in a lower likelihood of performing a complete evaluation of the cause of the syncopal event. This analysis highlights the need for a comprehensive and multidisciplinary approach of patients presenting with syncope and presyncope to promote early identification and treatment of arrhythmic causes, reducing patient morbidity and healthcare costs.

Role of Hypoxia in the Control of the Cell Cycle

The cell cycle is an important cellular process whereby the cell attempts to replicate its genome in an error-free manner. As such, mechanisms must exist for the cell cycle to respond to stress signals such as those elicited by hypoxia or reduced oxygen availability. This review focuses on the role of transcriptional and post-transcriptional mechanisms initiated in hypoxia that interface with cell cycle control. In addition, we discuss how the cell cycle can alter the hypoxia response. Overall, the cellular response to hypoxia and the cell cycle are linked through a variety of mechanisms, allowing cells to respond to hypoxia in a manner that ensures survival and minimal errors throughout cell division.

Abstract IA-017: Chromatin and gene transcription in hypoxia

Oxygen is essential for the life of most multicellular organism and changes in oxygen availability have implications in physiological and pathophysiological conditions. In response to hypoxia (low oxygen availability) transcriptional changes are induced. The transcriptional response to hypoxia is mediated primarily by the Hypoxia Inducible Factor (HIF) family of transcription factors. HIFs are activated in hypoxia via inhibition of prolyl hydroxylases (PHDs), a group of molecular dioxygenases, which require oxygen for their activity. Whilst the role of HIFs in the transcriptional response to hypoxia is well characterized, little is known with regards to chromatin structure in low oxygen stress and how this coordinates the transcriptional response. It was recently shown that chromatin is sensitive to oxygen levels, with hypoxia altering histone methylation at hypoxia responsive genes via inhibition of specific JmjC histone demethylases. To further investigate chromatin structure and its role in hypoxia induced gene transcription, we have performed ATAC-seq and RNA-seq in human cancer cell lines in acute and prolonged hypoxia. We find that acute hypoxia leads to increased promoter accessibility at a subset of hypoxia inducible genes, and this mostly precedes changes in mRNA expression, with further changes in chromatin structure after prolonged hypoxia. In addition, ChIP-seq data on histone methylation marks (H3K4me and H3K36me3), revealed similar earlier patterns of genomic distribution. Furthermore, we dissected the impact of HIF in the observed changes using a chemical probe and specific HIF1beta depletion analysis of ATAC-seq. This work gives insights into the role of chromatin dynamics in regulating the transcriptional response to hypoxia and elucidating the mechanisms behind these changes may lead to targeted therapies for hypoxia driven diseases.

Citation Format: Michael Batie, Julianty Frost, Sonia Rocha. Chromatin and gene transcription in hypoxia [abstract]. In: Proceedings of the AACR Virtual Special Conference on Radiation Science and Medicine; 2021 Mar 2-3. Philadelphia (PA): AACR; Clin Cancer Res 2021;27(8_Suppl):Abstract nr IA-017.

The identification of the Rosa S-locus and implications on the evolution of the Rosaceae gametophytic self-incompatibility systems

In Rosaceae species, two gametophytic self-incompatibility (GSI) mechanisms are described, the Prunus self-recognition system and the Maleae (Malus/Pyrus/Sorbus) non-self- recognition system. In both systems the pistil component is a S-RNase gene, but from two distinct phylogenetic lineages. The pollen component, always a F-box gene(s), in the case of Prunus is a single gene, and in Maleae there are multiple genes. Previously, the Rosa S-locus was mapped on chromosome 3, and three putative S-RNase genes were identified in the R. chinensis ‘Old Blush’ genome. Here, we show that these genes do not belong to the S-locus region. Using R. chinensis and R. multiflora genomes and a phylogenetic approach, we identified the S-RNase gene, that belongs to the Prunus S-lineage. Expression patterns support this gene as being the S-pistil. This gene is here also identified in R. moschata, R. arvensis, and R. minutifolia low coverage genomes, allowing the identification of positively selected amino acid sites, and thus, further supporting this gene as the S-RNase. Furthermore, genotype–phenotype association experiments also support this gene as the S-RNase. For the S-pollen GSI component we find evidence for multiple F-box genes, that show the expected expression pattern, and evidence for diversifying selection at the F-box genes within an S-haplotype. Thus, Rosa has a non-self-recognition system, like in Maleae species, despite the S-pistil gene belonging to the Prunus S-RNase lineage. These findings are discussed in the context of the Rosaceae GSI evolution. Knowledge on the Rosa S-locus has practical implications since genes controlling floral and other ornamental traits are in linkage disequilibrium with the S-locus.

Use of ChIP-qPCR to Study the Crosstalk Between HIF and NF-κB Signaling in Hypoxia and Normoxia

Hypoxia and inflammation are intensely connected in a functional crosstalk. Within this crosstalk, two major transcription factors take center stage: HIF and NF-κB. To investigate transcription factor function, an important aspect is its ability to bind DNA. The most appropriate method to study this property in cells is the use of chromatin immunoprecipitation followed by qPCR and/or next generation sequencing. This allows identification of potentially directly regulated genes as well as enhancer regions. Here we describe the ChIP-qPCR method in detail, including key aspects important for the success of the technique.

A Systematic Review on Anti-diabetic Properties of Chalcones

The use of anti-diabetic drugs has been increasing worldwide and the evolution of therapeutics has been enormous. Still, the currently available anti-diabetic drugs do not present the desired efficacy and are generally associated with serious adverse effects. Thus, entirely new interventions, addressing the underlying etiopathogenesis of type 2 diabetes mellitus, are required. Chalcones, secondary metabolites of terrestrial plants and precursors of the flavonoids biosynthesis, have been used for a long time in traditional medicine due to their wide-range of biological activities, from which the anti-diabetic activity stands out. This review systematizes the information found in literature about the anti-diabetic properties of chalcones, in vitro and in vivo. Chalcones are able to exert these properties by acting in different therapeutic targets: Dipeptidyl Peptidase 4 (DPP-4); Glucose Transporter Type 4 (GLUT4), Sodium Glucose Cotransporter 2 (SGLT2), α-amylase, α-glucosidase, Aldose Reductase (ALR), Protein Tyrosine Phosphatase 1B (PTP1B), Peroxisome Proliferator-activated Receptor-gamma (PPARγ) and Adenosine Monophosphate (AMP)-activated Protein Kinase (AMPK). Chalcones are, undoubtedly, promising anti-diabetic agents, and some crucial structural features have already been established. From the Structure-Activity Relationships analysis, it can generally be stated that the presence of hydroxyl, prenyl and geranyl groups in their skeleton improves their activity for the evaluated anti-diabetic targets.

Oxygen-sensing mechanisms in cells

The importance of oxygen for the survival of multicellular and aerobic organisms is well established and documented. Over the years, increased knowledge of its use for bioenergetics has placed oxygen at the centre of research on mitochondria and ATP-generating processes. Understanding the molecular mechanisms governing cellular oxygen sensing and response has allowed for the discovery of novel pathways oxygen is involved in, culminating with the award of the Nobel Prize for Medicine and Physiology in 2019 to the pioneers of this field, Greg Semenza, Peter Ratcliffe and William Kaelin. However, it is now beginning to be appreciated that oxygen can be a signalling molecule involved in a vast array of molecular processes, most of which impinge on gene expression control. This review will focus on the knowns and unknowns of oxygen as a signalling molecule, highlighting the role of 2-oxoglutarate-dependent dioxygenases as central players in the cellular response to deviations in oxygen tension.

0187 The Effects of Nocturnal Aircraft Noise on Self-Reported Sleep

Introduction

Nocturnal traffic noise can fragment sleep through cortical arousals and induce self-reported sleep disturbance. Here we present data gathered around Atlanta International Airport in a pilot field study on the effects of aircraft noise on sleep.

Methods

N=34 subjects participated in a five night in-home study. Every night, subjects recorded noise inside their bedroom, and completed questionnaires the following morning containing items on sleep latency; number of awakenings; sleepiness (Stanford Sleepiness Scale); 11-point scales on sleep quality, tiredness, ease of falling asleep and calmness or restlessness of sleep; and a 5-point scale on sleep disturbance by noise. We analyzed the effect of both the average (LAEq,sleep) and maximum (LAS,max,sleep) aircraft noise level during a subject’s sleep period for each questionnaire outcome in repeated measures multiple regression adjusted for the number of aircraft noise events during sleep, sex, age, and if the window was open or closed.

Results

A total of 165 sleep questionnaires (97.1% of expected) were completed. Self-reported awakenings increased by n=0.051 per decibel (dB) LAS,max,sleep (p<0.001). An increase in LAS,max,sleep was associated with a significant increase in tiredness (0.118/dB, p=0.005). There was a significant effect of sex on tiredness in the LAEq,sleep model, whereby men were less tired than women. There were no significant effects of LAEq,sleep on any questionnaire outcomes.

Conclusion

There was some evidence for adverse effects of aircraft noise on self-reported sleep outcomes. Effects were predominantly found for maximum rather than average noise exposure during the sleep period, stressing the importance of individual noise events for sleep. A larger-scale, adequately powered National Sleep Study will be conducted to better understand the observed effects.

Support

This research was funded by the U.S. Federal Aviation Administration Office of Environment and Energy through ASCENT, the FAA Center of Excellence for Alternative Jet Fuels and the Environment, project 017 through FAA Award Number 13-C-AJE-UPENN-011 under the supervision of Natalia Sizov. Any opinions, findings, conclusions or recommendations expressed in this material are those of the authors and do not necessarily reflect the views of the FAA.

Risk and limits in dental practice: a Portuguese approach to medical-legal evaluation and professional liability

Patient safety and quality of healthcare delivery systems are an objective of WHO. This study aims to present and analyse Portuguese clinical data on risk and malpractice in dental practice. Data from the Forensic Dentistry Laboratory (Faculty of Medicine, University of Coimbra) was analysed, between the years of 2013 to 2018. One hundred and seven technical reports were selected, and seventy nine files were included in the iatrogenic sequelae group. Data included the analysis of the performance of dental professionals. Sequelae were divided in descending order of occurrence:1) mandibular dysfunction (53,2%)[(42)79]; 2) neurological deficit (39,2%)[(31)79]; 3) tooth loss (6,3%)[(5)79]; and 4) opening deficit (1,3%)[(1)79].Three major areas with significant expression in the field of expert evaluations were analysed: 1) orthodontic treatment (51,9%), implant rehabilitation (29,1%), and oral surgery. Given the prevalence of malpractice, the need to assess its causes and recognise standards for its prevention is necessary.

HIF-1β Positively Regulates NF-κB Activity via Direct Control of TRAF6

NF-κB signalling is crucial for cellular responses to inflammation but is also associated with the hypoxia response. NF-κB and hypoxia inducible factor (HIF) transcription factors possess an intense molecular crosstalk. Although it is known that HIF-1α modulates NF-κB transcriptional response, very little is understood regarding how HIF-1β contributes to NF-κB signalling. Here, we demonstrate that HIF-1β is required for full NF-κB activation in cells following canonical and non-canonical stimuli. We found that HIF-1β specifically controls TRAF6 expression in human cells but also in Drosophila melanogaster. HIF-1β binds to the TRAF6 gene and controls its expression independently of HIF-1α. Furthermore, exogenous TRAF6 expression is able to rescue all of the cellular phenotypes observed in the absence of HIF-1β. These results indicate that HIF-1β is an important regulator of NF-κB with consequences for homeostasis and human disease.

Characterisation of sphaeractinomyxon types (Cnidaria: Myxozoa) from marine and freshwater oligochaetes in a Portuguese estuary, with the demise of the endocapsa collective group

Six types of sphaeractinomyxon are reported from the coelomic cavity of oligochaetes collected from the Minho River estuary in northern Portugal. Four new types are morphologically and molecularly described from freshwater species belonging to the genera Psammoryctides Hrabě and Potamothrix Vejdovský et Mrázek in the upper estuary, thus significantly increasing the number of known freshwater sphaeractinomyxon. In the lower estuary, sphaeractinomyxon types 8 and 10 of Rangel et al. (2016) are recorded infecting the marine oligochaete Tubificoides pseudogaster (Dahl). A single specimen of T. pseudogaster further displayed infection by one of the four new types found in the upper estuary, suggesting the involvement of sphaeractinomyxon in the life cycles of myxosporean species that infect migratory fish hosts. The acquisition of these second hosts is proposed to have allowed the myxosporean counterparts of sphaeractinomyxon to cross environmental barriers and conquer new habitats. Phylogenetic analyses of the SSU rRNA gene reveal the four new types clustering within the monophyletic clade of mugiliform-infecting myxobolids, strengthening the previously proposed involvement of the sphaeractinomyxon collective group in the life cycles of this specific group of myxosporeans. Endocapsa types also cluster within the latter clade, having actinospores that differ from those of sphaeractinomyxon only in the presence of valvular swellings that do not change when in contact with water. In this study, however, one type was found displaying actinospores with and without valvular swellings in the same oligochaete specimen. This overlap in actinospore morphology is given as grounds for the demise of the endocapsa collective group.

Shifted phenology in the pine processionary moth affects the outcome of tree-insect interaction

In the Mediterranean and temperate regions, an increase in the frequency and intensity of drought events has been recorded, probably due to climate change. In consequence, trees will more frequently experience hydric stress, a condition that can be expected to affect insect-tree interactions, while adaptation mechanisms may be further in course. The effect of tree water stress on the performance of two allochronic populations of Thaumetopoea pityocampa was here studied. Namely, we compared a unique population of this insect, in which the larvae develop in the summer (SP), with the typical population having winter larval development (WP), to test the adaptation hypothesis to host plant status. Larvae of each population were fed on needles of young potted Pinus pinaster plants under two water supply regimes: (i) well-watered (control) and (ii) subjected to 3 months of drought stress. Compared to control, stressed plants had higher amounts of soluble sugars, phenols, and higher C/N ratio, whereas water content and chlorophylls concentrations were lower. In general, T. pityocampa larvae had lower performances on water-stressed plants, as shown by lower survival rates, lower needle consumption, and longer development times. Yet, the detrimental effects of tree stress were only significant for the WP larvae, while SP larvae were able to overcome such conditions. Results demonstrate that tree water stress can negatively affect T. pityocampa populations. Furthermore, the evidence is also provided that responses to the physiological condition of the host trees may occur at the population level, as a result of adaptation mechanisms driven by climate change.

P644 A not so innocent athlete"s heart

We report the case of a 17 years old athlete who resorted to the emergency service for palpitations and dizziness during exercising. He mentioned two episodes of syncope associated with exercise in the last 6 months. He was tachycardic (200 bpm) and hypotensive (85/56 mmHg). The electrocardiogram showed regular wide complex tachycardia with left bundle branch block morphology with superior axis restored to sinus rhythm after electrical cardioversion. In sinus rhythm, it showed T-wave inversion in V1-V5. Patient was admitted for study. Transthoracic echocardiography demonstrated mild enlargement and dysfunction of the right ventricle (RV) with global hypocontractility (FAC of 29%). The cardiac magnetic resonance (CMR revealed a RV end-diastolic volume indexed to surface body area of 180 mL/m2, global hypocinesia and RV dyssynchrony, subepicardial late enhancement in the distal septum and in the middle segment of the infero-septal wall. The patient underwent genetic study which showed a mutation in the gene that encodes the desmocolin-2 protein (DSC-2) involved in the pathogenesis of arrhythmogenic right ventricular cardiomyopathy (ARVC). According to the 2010 modified Task Force criteria for this diagnosis, the patient presented 4 major criteria for ARVC (characteristic ventricular tachycardia, repolarization and morphofunctional changes and the presence of pathogenic mutation) and the diagnosis was made. Thus, given the clinical presentation, it was implanted a subcutaneous cardioverter and patient is currently in follow-up at the Cardiology service.

ARVC is present in 1 to 1000-5000 people and is responsible for 20% of all sudden cardiac deaths, especially in athletes. Diagnosis is based on structural, functional, electrophysiological and genetic criteria reflecting underlying histological changes. This case shows and reviews the essential characteristics to the disease recognition and, therefore, to the prevention of its most feared complication: sudden cardiac death.

An insight into the sialome, mialome and virome of the horn fly, Haematobia irritans

BACKGROUND

The horn fly (Haematobia irritans) is an obligate blood feeder that causes considerable economic losses in livestock industries worldwide. The control of this cattle pest is mainly based on insecticides; unfortunately, in many regions, horn flies have developed resistance. Vaccines or biological control have been proposed as alternative control methods, but the available information about the biology or physiology of this parasite is rather scarce.

RESULTS

We present a comprehensive description of the salivary and midgut transcriptomes of the horn fly (Haematobia irritans), using deep sequencing achieved by the Illumina protocol, as well as exploring the virome of this fly. Comparison of the two transcriptomes allow for identification of uniquely salivary or uniquely midgut transcripts, as identified by statistically differential transcript expression at a level of 16 x or more. In addition, we provide genomic highlights and phylogenetic insights of Haematobia irritans Nora virus and present evidence of a novel densovirus, both associated to midgut libraries of H. irritans.

CONCLUSIONS

We provide a catalog of protein sequences associated with the salivary glands and midgut of the horn fly that will be useful for vaccine design. Additionally, we discover two midgut-associated viruses that infect these flies in nature. Future studies should address the prevalence, biological effects and life cycles of these viruses, which could eventually lead to translational work oriented to the control of this economically important cattle pest.

JmjC histone demethylases act as chromatin oxygen sensors

Oxygen sensing is important in physiology but also in disease. We find that hypoxia (oxygen deficiency) triggers rapid and hypoxia-inducible factor (HIF)-independent histone methylation changes which are reversible upon reoxygenation. Hypoxia-induced histone methylation genomic distribution precedes transcriptional changes and is mimicked by specific Jumonji-C (JmjC) histone demethylase depletion. Oxygen sensing by JmjC histone demethylases is required for the cellular response to hypoxia.

Hypoxia induces rapid changes to histone methylation and reprograms chromatin

Oxygen is essential for the life of most multicellular organisms. Cells possess enzymes called molecular dioxygenases that depend on oxygen for activity. A subclass of molecular dioxygenases is the histone demethylase enzymes, which are characterized by the presence of a Jumanji-C (JmjC) domain. Hypoxia can alter chromatin, but whether this is a direct effect on JmjC-histone demethylases or due to other mechanisms is unknown. Here, we report that hypoxia induces a rapid and hypoxia-inducible factor–independent induction of histone methylation in a range of human cultured cells. Genomic locations of histone-3 lysine-4 trimethylation (H3K4me3) and H3K36me3 after a brief exposure of cultured cells to hypoxia predict the cell’s transcriptional response several hours later. We show that inactivation of one of the JmjC-containing enzymes, lysine demethylase 5A (KDM5A), mimics hypoxia-induced cellular responses. These results demonstrate that oxygen sensing by chromatin occurs via JmjC-histone demethylase inhibition.

RNA-seq analysis of PHD and VHL inhibitors reveals differences and similarities to the hypoxia response

Background: Hypoxia-inducible factor (HIF) transcription factors are well known to control the transcriptional response to hypoxia. Given the importance of cellular response to hypoxia, a number of pharmacological agents to interfere with this pathway have been developed and entered pre-clinical or clinical trial phases. However, how similar or divergent the transcriptional response elicited by different points of interference in cells is currently unknown. Methods: We performed RNA-sequencing to analyse the similarities and differences of transcriptional response in HeLa cells treated with hypoxia or chemical agents that stabilise HIF by inhibiting components of the hypoxia signalling pathway - prolyl hydroxylase (PHD) inhibitor or von Hippel-Lindau (VHL) inhibitor. Results: This analysis revealed that hypoxia produces the highest changes in gene transcription, with activation and repression of genes being in large numbers. Treatment with the PHD inhibitor IOX2 or the VHL inhibitor VH032 led mostly to gene activation, majorly via a HIF-dependent manner. These results were also confirmed by qRT-PCR using more specific and/or efficient inhibitors, FG-4592 (PHDs) and VH298 (VHL). Conclusion: PHD inhibition and VHL inhibition mimic gene activation promoted by hypoxia via a HIF-dependent manner. However, gene repression is mostly associated with the hypoxia response and not common to the response elicited by inhibitors of the pathway.

[The processes of α-synuclein amyloid protein complexes involved in the pathogenesis of Parkinson's disease]

AIM

To analyze interactions between α-synuclein (αS) protein and lipids using biophysical methods.

MATERIAL AND METHODS

Recombinant α-synuclein synthesized in prokaryotic cells was used. To characterize the interaction of αS with negatively charged vesicles of DOPS (1,2-dioleoyl-sn-glycero-3-phospho-L-serine, sodium salt) and DOPG (1,2-dioleoyl-sn-glycero-3-phospho-(1'-rac-glycerol), sodium salt) and the consequences of such interactions on αS amyloid formation, combined circular dichroism, fluorescence and imaging methods in vitro were applied.

RESULTS AND CONCLUSION

Lipid head-group chemistry modulates αS interactions and also affects amyloid fiber formation. Pre-formed αS oligomers, typically present in a small amount in the αS starting material, acted as templates for linear growth of anomalous amyloid fibers in the presence of vesicles. At the same time, the remaining αS monomers were restricted from vesicle-mediated nucleation of amyloid fibers. Although not a dominant process in bulk experiments, this hidden αS aggregation pathway may be of importance in vivo.

TNFSF14/LIGHT, a Non-Canonical NF-κB Stimulus, Induces the HIF Pathway

Non-canonical NF-κB signalling plays important roles in the development and function of the immune system but it also is deregulated in a number of inflammatory diseases. Although, NF-κB and HIF crosstalk has been documented, this has only been described following canonical NF-κB stimulation, involving RelA/p50 and the HIF-1 dimer. Here, we report that the non-canonical inducer TNFSF14/LIGHT leads to HIF induction and activation in cancer cells. We demonstrate that only HIF-2α is induced at the transcriptional level following non-canonical NF-κB activation, via a mechanism that is dependent on the p52 subunit. Furthermore, we demonstrate that p52 can bind to the HIF-2α promoter in cells. These results indicate that non-canonical NF-κB can lead to HIF signalling implicating HIF-2α as one of the downstream effectors of this pathway in cells.

SINHCAF/FAM60A and SIN3A specifically repress HIF-2α expression

The SIN3A-HDAC (histone deacetylase) complex is a master transcriptional repressor, required for development but often deregulated in disease. Here, we report that the recently identified new component of this complex, SINHCAF (SIN3A and HDAC-associated factor)/FAM60A (family of homology 60A), links the SIN3A-HDAC co-repressor complex function to the hypoxia response. We show that SINHCAF specifically represses HIF-2α mRNA and protein expression, via its interaction with the transcription factor SP1 (specificity protein 1) and recruitment of HDAC1 to the HIF-2α promoter. SINHCAF control over HIF-2α results in functional cellular changes in in vitro angiogenesis and viability. Our analysis reveals an unexpected link between SINHCAF and the regulation of the hypoxia response.

Hypoxia and Chromatin: A Focus on Transcriptional Repression Mechanisms

Hypoxia or reduced oxygen availability has been studied extensively for its ability to activate specific genes. Hypoxia-induced gene expression is mediated by the HIF transcription factors, but not exclusively so. Despite the extensive knowledge about how hypoxia activates genes, much less is known about how hypoxia promotes gene repression. In this review, we discuss the potential mechanisms underlying hypoxia-induced transcriptional repression responses. We highlight HIF-dependent and independent mechanisms as well as the potential roles of dioxygenases with functions at the nucleosome and DNA level. Lastly, we discuss recent evidence regarding the involvement of transcriptional repressor complexes in hypoxia.

Cross-Talk between Inflammation, Coagulation/Fibrinolysis and Vascular access in Hemodialysis Patients

This work aimed to study the association between fibrinolytic/endothelial cell function and inflammatory markers in chronic kidney disease (CKD) patients undergoing hemodialysis (HD) and recombinant human erythropoietin (rhEPO) therapies, and its relationship with the type of vascular access (VA) used for the HD procedure. As fibrinolytic/endothelial cell function markers we evaluated plasminogen activator inhibitor type-1 (PAI-1), tissue plasminogen activator (tPA) and D-dimers, and as inflammatory markers; C-reactive protein (CRP), soluble interleukin (IL)-2 receptor (s-IL2R), IL-6 and serum albumin levels. The study was performed in 50 CKD patients undergoing regular HD, 11 with a central venous dialysis catheter (CVC) and 39 with an arteriovenous fistula (AVF), and in 25 healthy controls. Compared to controls, CKD patients presented with significantly higher levels of CRP, s-IL2R, IL-6 and D-dimers, and significantly lower levels of PAI-1. The tPA/PAI-1 ratio was significantly higher in CKD patients. We also found statistical significant correlations in CKD patients between D-dimers levels and inflammatory markers: CRP, albumin, s-IL2R and IL-6. When comparing the two groups of CKD patients, we found that those with a CVC presented statistically significant lower levels of hemoglobin concentration and albumin, and higher levels of CRP, IL-6, D-dimers and tPA. Our results showed an association between fibrinolytic/endothelial cell function and increased inflammatory markers in CKD patients. The increased levels of D-dimer, tPA and inflammatory markers in CKD patients using a CVC, led us to propose a relationship between the type of VA chosen for HD, and the risk of thrombogenesis.

Draft genome and reference transcriptomic resources for the urticating pine defoliator Thaumetopoea pityocampa (Lepidoptera: Notodontidae)

The pine processionary moth Thaumetopoea pityocampa (Lepidoptera: Notodontidae) is the main pine defoliator in the Mediterranean region. Its urticating larvae cause severe human and animal health concerns in the invaded areas. This species shows a high phenotypic variability for various traits, such as phenology, fecundity and tolerance to extreme temperatures. This study presents the construction and analysis of extensive genomic and transcriptomic resources, which are an obligate prerequisite to understand their underlying genetic architecture. Using a well-studied population from Portugal with peculiar phenological characteristics, the karyotype was first determined and a first draft genome of 537 Mb total length was assembled into 68,292 scaffolds (N50 = 164 kb). From this genome assembly, 29,415 coding genes were predicted. To circumvent some limitations for fine-scale physical mapping of genomic regions of interest, a 3X coverage BAC library was also developed. In particular, 11 BACs from this library were individually sequenced to assess the assembly quality. Additionally, de novo transcriptomic resources were generated from various developmental stages sequenced with HiSeq and MiSeq Illumina technologies. The reads were de novo assembled into 62,376 and 63,175 transcripts, respectively. Then, a robust subset of the genome-predicted coding genes, the de novo transcriptome assemblies and previously published 454/Sanger data were clustered to obtain a high-quality and comprehensive reference transcriptome consisting of 29,701 bona fide unigenes. These sequences covered 99% of the cegma and 88% of the busco highly conserved eukaryotic genes and 84% of the busco arthropod gene set. Moreover, 90% of these transcripts could be localized on the draft genome. The described information is available via a genome annotation portal (http://bipaa.genouest.org/sp/thaumetopoea_pityocampa/).

Dietary management of maternal phenylketonuria with glycomacropeptide and amino acids supplements: A case report

BACKGROUND

In maternal PKU, protein substitute (PS) is provided by phenylalanine (PHE)-free l-amino acids (AA), but glycomacropeptide-based protein substitute (GMP) is an alternative consideration.

OBJECTIVE

To describe the first Portuguese Maternal Phenylketonuria (MPKU) partially managed with GMP.

CASE REPORT

A 31 year old MPKU female with classical PKU (mutations P281L/P281L), diagnosed by newborn screening, had a lifelong history of poor metabolic control. She has a history of partial bicornuate uterus and had a previous miscarriage in the first trimester. Pre-conception, her median blood PHE was 462 μmol/L but throughout pregnancy the median reduced to 258 μmol/L. GMP provided 30 g/day protein equivalent (46 mg/day PHE). Total protein equivalent from PS increased from 58 to 86 g/day during pregnancy but AA provided all additional protein equivalent intake. Both GMP and AA were well tolerated with no morning sickness. Normal morphologic evaluation and adequate fetal growth with cephalic biometry near the 5th percentile was determined. The infant was born at 39.3 weeks: weight 2570 g (3rd percentile), length 47.5 cm (10th percentile) and head circumference (HC) of 31.5 cm (1st percentile). In the neonatal period, the infant had craniofacial dimorphism with metopic suture prominence. Father also had bitemporal narrowing. By 12 months of age, the infant's weight (15th percentile), length (50th percentile) and HC (10th-50th percentile) were normal although bitemporal narrowing persisted.

CONCLUSIONS

This is the first case reporting the use of GMP in MPKU. Its PHE content did not adversely affect metabolic control although it only provided part of the PS intake. Some intrauterine development delay occurred in the last trimester, although we consider that this is unlikely to be associated with MPKU syndrome or the use of GMP. More published data is essential to examine the impact of using GMP in MPKU on morning sickness severity and aversion, maternal weight gain, blood amino acid concentrations and variability of blood PHE concentrations.

Homo-PROTACs: bivalent small-molecule dimerizers of the VHL E3 ubiquitin ligase to induce self-degradation

E3 ubiquitin ligases are key enzymes within the ubiquitin proteasome system which catalyze the ubiquitination of proteins, targeting them for proteasomal degradation. E3 ligases are gaining importance as targets to small molecules, both for direct inhibition and to be hijacked to induce the degradation of non-native neo-substrates using bivalent compounds known as PROTACs (for ‘proteolysis-targeting chimeras’). We describe Homo-PROTACs as an approach to dimerize an E3 ligase to trigger its suicide-type chemical knockdown inside cells. We provide proof-of-concept of Homo-PROTACs using diverse molecules composed of two instances of a ligand for the von Hippel-Lindau (VHL) E3 ligase. The most active compound, CM11, dimerizes VHL with high avidity in vitro and induces potent, rapid and proteasome-dependent self-degradation of VHL in different cell lines, in a highly isoform-selective fashion and without triggering a hypoxic response. This approach offers a novel chemical probe for selective VHL knockdown, and demonstrates the potential for a new modality of chemical intervention on E3 ligases.

Targeting the ubiquitin proteasome system to modulate protein homeostasis using small molecules has promising therapeutic potential. Here the authors describe Homo-PROTACS: small molecules that can induce the homo-dimerization of E3 ubiquitin ligases and cause their proteasome-dependent degradation.

Effect of heat waves on embryo mortality in the pine processionary moth

Extreme climate events such as heat waves are predicted to become more frequent with climate change, representing a challenge for many organisms. The pine processionary moth Thaumetopoea pityocampa is a Mediterranean pine defoliator, which typically lays eggs during the summer. We evaluated the effects of heat waves on egg mortality of three populations with different phenologies: a Portuguese population with a classical life cycle (eggs laid in summer), an allochronic Portuguese population reproducing in spring, and a Tunisian population from the extreme southern limit of T. pityocampa distribution range, in which eggs are laid in fall. We tested the influence of three consecutive hot days on egg survival and development time, using either constant (CT) or daily cycling temperatures (DT) with equivalent mean temperatures. Maximum temperatures (T max) used in the experiment ranged from 36 to 48°C for DT and from 30 to 42°C for CT. Heat waves had a severe negative effect on egg survival when T max reached 42°C for all populations. No embryo survived above this threshold. At high mean temperatures (40°C), significant differences were observed between populations and between DT and CT regimes. Heat waves further increased embryo development time. The knowledge we gained about the upper lethal temperature to embryos of this species will permit better prediction of the potential expansion of this insect under different climate warming scenarios.

Group-Based Optimization of Potent and Cell-Active Inhibitors of the von Hippel-Lindau (VHL) E3 Ubiquitin Ligase: Structure-Activity Relationships Leading to the Chemical Probe (2S,4R)-1-((S)-2-(1-Cyanocyclopropanecarboxamido)-3,3-dimethylbutanoyl)-4-hydroxy-N-(4-(4-methylthiazol-5-yl)benzyl)pyrrolidine-2-carboxamide (VH298)

The von Hippel–Lindau tumor suppressor protein is the substrate binding subunit of the VHL E3 ubiquitin ligase, which targets hydroxylated α subunit of hypoxia inducible factors (HIFs) for ubiquitination and subsequent proteasomal degradation. VHL is a potential target for treating anemia and ischemic diseases, motivating the development of inhibitors of the VHL:HIF-α protein–protein interaction. Additionally, bifunctional proteolysis targeting chimeras (PROTACs) containing a VHL ligand can hijack the E3 ligase activity to induce degradation of target proteins. We report the structure-guided design and group-based optimization of a series of VHL inhibitors with low nanomolar potencies and improved cellular permeability. Structure–activity relationships led to the discovery of potent inhibitors 10 and chemical probe VH298, with dissociation constants <100 nM, which induced marked HIF-1α intracellular stabilization. Our study provides new chemical tools to probe the VHL-HIF pathways and new VHL ligands for next-generation PROTACs.

Evaluation of Hematobin as a Vaccine Candidate to Control Haematobia irritans (Diptera: Muscidae) Loads in Cattle

The horn fly, Haematobia irritans (L.), is a blood-sucking livestock ectoparasite responsible for substantial livestock losses. In the present work, the potential use of recombinant hematobin (HTB), a horn fly salivary protein, as an antigen for cattle vaccination was investigated. In this trial, horn fly loads and H. irritans's blood intake were assessed in vaccinated (n = 4) and control (n = 4) crossbred dark-coated steers, which were naturally infected. The vaccinated group received a 1 ml subcutaneous injection of 100 µg of HTB protein emulsified in 500 µl of Incomplete Freund Adjuvant (AIF) on days 0 and 30. The control group received on the same days 1 ml of distilled water emulsified in 500 µl of AIF. The vaccinated group had significantly more HTB-specific IgG antibodies after the HTB booster and had a lower fly load than the control group (206 ± 23 vs. 285 ± 23 flies per animal, respectively). Blood intake by H. irritans did not differ between groups. In summary, these results suggest that vaccinating cattle with HTB could reduce cattle H. irritans load.

Hypoxia and Inflammation in Cancer, Focus on HIF and NF-κB

Cancer is often characterised by the presence of hypoxia and inflammation. Paramount to the mechanisms controlling cellular responses under such stress stimuli, are the transcription factor families of Hypoxia Inducible Factor (HIF) and Nuclear Factor of κ-light-chain-enhancer of activated B cells (NF-κB). Although, a detailed understating of how these transcription factors respond to their cognate stimulus is well established, it is now appreciated that HIF and NF-κB undergo extensive crosstalk, in particular in pathological situations such as cancer. Here, we focus on the current knowledge on how HIF is activated by inflammation and how NF-κB is modulated by hypoxia. We summarise the evidence for the possible mechanism behind this activation and how HIF and NF-κB function impacts cancer, focusing on colorectal, breast and lung cancer. We discuss possible new points of therapeutic intervention aiming to harness the current understanding of the HIF-NF-κB crosstalk.

KDM2 Family Members are Regulated by HIF-1 in Hypoxia

Hypoxia is not only a developmental cue but also a stress and pathological stimulus in many human diseases. The response to hypoxia at the cellular level relies on the activity of the transcription factor family, hypoxia inducible factor (HIF). HIF-1 is responsible for the acute response and transactivates a variety of genes involved in cellular metabolism, cell death, and cell growth. Here, we show that hypoxia results in increased mRNA levels for human lysine (K)-specific demethylase 2 (KDM2) family members, KDM2A and KDM2B, and also for Drosophila melanogaster KDM2, a histone and protein demethylase. In human cells, KDM2 family member's mRNA levels are regulated by HIF-1 but not HIF-2 in hypoxia. Interestingly, only KDM2A protein levels are significantly induced in a HIF-1-dependent manner, while KDM2B protein changes in a cell type-dependent manner. Importantly, we demonstrate that in human cells, KDM2A regulation by hypoxia and HIF-1 occurs at the level of promoter, with HIF-1 binding to the KDM2A promoter being required for RNA polymerase II recruitment. Taken together, these results demonstrate that KDM2 is a novel HIF target that can help coordinate the cellular response to hypoxia. In addition, these results might explain why KDM2 levels are often deregulated in human cancers.

Life cycle inference and phylogeny of Ortholinea labracis n. sp. (Myxosporea: Ortholineidae), a parasite of the European seabass Dicentrarchus labrax (Teleostei: Moronidae), in a Portuguese fish farm

Ortholinea labracis n. sp. is described and its life cycle is inferred from a Southern Portuguese fish farm, with basis on microscopic and molecular procedures. This myxosporean parasite infects the urinary bladder of the European seabass Dicentrarchus labrax and the intestinal epithelium of a marine oligochaete of the genus Tectidrilus. Myxospores subspherical in valvular view and ellipsoidal in sutural view measuring 7.6 ± 0.3 (6.8-8.7) μm in length, 7.2 ± 0.2 (6.7-7.7) μm in width and 6.5 ± 0.4 (5.8-7.7) μm in thickness. Two polar capsules, 3.0 ± 0.2 (2.6-3.4) μm long and 2.4 ± 0.1 (2.0-2.9) μm wide, located at the same level, but with divergent orientation and opening to opposite sides of the suture line. Sequencing of the SSU rRNA gene revealed a similarity of 100% between the analysed myxospores and triactinomyxon actinospores. The phylogenetic setting of O. labracis n. sp. shows subgrouping in correlation with tissue tropism, but identifies this parasite as another exception to the main division of Myxosporea into the main freshwater and marine lineages.