New self-sexing Aedes aegypti strain eliminates barriers to scalable and sustainable vector control for governments and communities in dengue-prone environments

For more than 60 years, efforts to develop mating-based mosquito control technologies have largely failed to produce solutions that are both effective and scalable, keeping them out of reach of most governments and communities in disease-impacted regions globally. High pest suppression levels in trials have yet to fully translate into broad and effective Aedes aegypti control solutions. Two primary challenges to date-the need for complex sex-sorting to prevent female releases, and cumbersome processes for rearing and releasing male adult mosquitoes-present significant barriers for existing methods. As the host range of Aedes aegypti continues to advance into new geographies due to increasing globalisation and climate change, traditional chemical-based approaches are under mounting pressure from both more stringent regulatory processes and the ongoing development of insecticide resistance. It is no exaggeration to state that new tools, which are equal parts effective and scalable, are needed now more than ever. This paper describes the development and field evaluation of a new self-sexing strain of Aedes aegypti that has been designed to combine targeted vector suppression, operational simplicity, and cost-effectiveness for use in disease-prone regions. This conditional, self-limiting trait uses the sex-determination gene doublesex linked to the tetracycline-off genetic switch to cause complete female lethality in early larval development. With no female progeny survival, sex sorting is no longer required, eliminating the need for large-scale mosquito production facilities or physical sex-separation. In deployment operations, this translates to the ability to generate multiple generations of suppression for each mosquito released, while being entirely self-limiting. To evaluate these potential benefits, a field trial was carried out in densely-populated urban, dengue-prone neighbourhoods in Brazil, wherein the strain was able to suppress wild mosquito populations by up to 96%, demonstrating the utility of this self-sexing approach for biological vector control. In doing so, it has shown that such strains offer the critical components necessary to make these tools highly accessible, and thus they harbour the potential to transition mating-based approaches to effective and sustainable vector control tools that are within reach of governments and at-risk communities who may have only limited resources.

Self-limiting fall armyworm: a new approach in development for sustainable crop protection and resistance management

BACKGROUND

The fall armyworm, Spodoptera frugiperda, is a significant and widespread pest of maize, sorghum, rice, and other economically important crops. Successful management of this caterpillar pest has historically relied upon application of synthetic insecticides and through cultivation of genetically engineered crops expressing insecticidal proteins (Bt crops). Fall armyworm has, however, developed resistance to both synthetic insecticides and Bt crops, which risks undermining the benefits delivered by these important crop protection tools. Previous modelling and empirical studies have demonstrated that releases of insecticide- or Bt-susceptible insects genetically modified to express conditional female mortality can both dilute insecticide resistance and suppress pest populations.

RESULTS

Here, we describe the first germline transformation of the fall armyworm and the development of a genetically engineered male-selecting self-limiting strain, OX5382G, which exhibits complete female mortality in the absence of an additive in the larval diet. Laboratory experiments showed that males of this strain are competitive against wild-type males for copulations with wild-type females, and that the OX5382G self-limiting transgene declines rapidly to extinction in closed populations following the cessation of OX5382G male releases. Population models simulating the release of OX5382G males in tandem with Bt crops and non-Bt 'refuge' crops show that OX5382G releases can suppress fall armyworm populations and delay the spread of resistance to insecticidal proteins.

CONCLUSIONS

This article describes the development of self-limiting fall armyworm designed to control this pest by suppressing pest populations, and population models that demonstrate its potential as a highly effective method of managing resistance to Bt crops in pest fall armyworm populations. Our results provide early promise for a potentially valuable future addition to integrated pest management strategies for fall armyworm and other pests for which resistance to existing crop protection measures results in damage to crops and impedes sustainable agriculture.

Effect of COVID-19 outbreak on emergency department attendances in an Italian academic hospital

Background

Coronavirus disease 2019 (COVID-19) is a viral infection caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). The disease was discovered during the 2019 outbreak in Mainland China and the first cases were reported in Italy on February 21, 2020. This study evaluates the emergency department (ED) attendances of an academic hospital in northern Italy before and after media reported the news of the first infected patients in Italy.

Methods

Adult attendances in ED in February 2020 were analysed dividing the period into 4 weeks (days 1-7, 8-14, 15-21, 22-28) compared with the same periods in 2019. The visits were analysed separately according to the Italian colour code of triage: white (non-critical), green (low-critical), yellow (medium critical), red (life-threatening). The mean weekly number of attendances was compared with t-test.

Results

February 2020 total ED attendances compared with February 2019 were 4865 vs 5029 (-3.3%), of which white codes were 834 vs 762 (+9.4%), green 2450 vs 2580 (-5.0%), yellow 1427 vs 1536 (-7.1%), red 154 vs 151 (+2.0%). February 2020 weekly mean ED attendances compared with February 2019 had statistically significant difference only in the fourth week (days 22-28) for green codes (75 vs 92, p = 0.007) and yellow codes (41 vs 52, p = 0.047), not for white (27 vs 26, p = 0.760) and red codes (5 vs 5, p = 0.817). The first three weeks of February 2020 compared with 2019 showed no statistically significant difference in weekly mean ED attendances.

Conclusions

There was a significant reduction of green and yellow codes attendances at ED in the fourth week of February 2020, corresponding to the initial phase of Italian COVID-19 outbreak. The fear of contracting SARS-CoV-2 by attending the ED probably acted as a significant deterrent in visits, especially for low and medium critical patients. Additional data are required to better understand the phenomenon, including the behaviour of non-critical attendances.

Key messages

A reduction of green and yellow codes attendances was reported during initial phase of COVID-19 outbreak in an Italian academic hospital.

Fear of contracting COVID-19 infection in a hospital setting could impact on emergency department attendances.

Medical records completeness: can Link Professionals improve quality in a Rehabilitation Hospital?

Background

The completeness of Medical Record (MR) is an indicator of the quality of care provided. IMFR (Medical and Physical Rehabilitation Institute), a hospital part of the Udine Healthcare Trust with 400 discharges yearly, launched at the end of 2017 a MR-quality program based on the involvement of Link Professionals (LP): doctors, nurses and therapists specifically trained. The main aim of this study is to determine if involving LP would improve MR completeness and would keep it over time. The second aim is to describe the 1-year experience of MR completeness and professional attitude toward recording medical information in it.

Methods

In December 2017 a new MR was introduced at the IMFR and its completeness was evaluated in January 2018. From January to April 2018, 17 LP educated all colleagues on the recording behavior through periodic meetings and focus groups. Then, LP peer-reviewed 20 inpatients paper-based MRs, assessing completeness, in April 2018 and then quarterly until January 2019. The evaluation was performed with a tool including a total of 73 items, divided in pertinence to the three professional figures involved. Feedbacks on MR completeness were given to professionals by LP in two-weeks. External data validation was performed to ensure data consistency. Significance (p < 0.01) was assessed by Cochran-Armitage test for trends.

Results

The overall completeness of MR improved significantly from 59.6% (552 items out of 926; Jan-18) to 77.0% (738/959; Apr-18), settling to 78.3% (696/889) in January-19, with an overall trend of + 18.7%. Items pertaining to doctors improved significantly from 56.4% (217/385) to 81.4% (1173/1441), nurses’ from 60.7% (165/272) to 78.6% (740/941), therapists’ from 79.0% (79/100) to 91.7% (277/302). External validation results in 75% of agreement.

Conclusions

The involvement of LP proved effectiveness in encouraging professionals behavior, supporting the MR completeness improvement and keep it over one year time.

Key messages

Professionals involvement and short-term feedbacks contribute to the healthcare quality improvement. Peer-reviewing medical records improves professionals attitude in recording behavior.

Complexity in managing the blood transfusion process: experience of an Italian Academic Hospital

Issue

Blood components transfusion is a high-risk process due to its complexity and possible consequences in case of error. Preventing mistakes and acting promptly if they occur is a duty of healthcare organizations. The Italian Ministry of Health has drafted a specific recommendation with the aim of reducing transfusion errors.

Description of the problem

Following a transfusion error occurred in July 2018, a multidisciplinary group including professionals from Clinical Risk Unit (CRU) and Transfusion Department of the Academic Hospital of Udine, carried out an analysis of the blood components issuing process. The 20 most critical steps were identified and grouped into 3 areas: 1)single samples processed individually, 2)appropriate application compliance, 3)environmental interferences. For each step shared solutions were identified and then implemented as new standard practices. From February to March 2019, CRU randomly observed 23 blood components assignments using tracer methodology, evaluating staff’s compliance with the new recommended practices (NRP).

Results

For the sample processing (area 1, n.10 practices), adherence to all ten NRP was 100% (26/26). For the appropriate application compliance (area 2, n.8 practices), adherence to 7 NRP was 100% (11/11), whereas for one (punctual registration of non-conformities) adherence was 86% (6/7). For the environmental interferences (area 3, n.2 practices), adherence to one practice was 100% (2/2), whereas for the other one (avoid answering to incoming phone calls) adherence was 75% (3/4). Overall, professionals behaviour was consistent with the NRP in the observed period.

Lessons

Identification of critical issues by a multidisciplinary team and measuring the adherence to new practices is crucial in managing the complexity of blood transfusion process.

Tracer methodology, used by CRU to verify adherence to new standard, also allows the hospital to monitor the progress of the achieved performances over time.

Key messages

Multidisciplinary analysis of the blood transfusion process and shared development of new standard by all professionals favours their compliance in the practice. Tracer methodology is a useful tool to evaluate adherence to recommended practices and monitor the complexity of transfusion process over time.

Recording educational information in medical record: the experience of a Rehabilitation Hospital

Issue/Problem

Healthcare organizations have the responsibility to provide education to patients and families so that they have the knowledge to participate in the care process and make decisions. Rehabilitative organizations, on account of the long hospitalization period and the specific care plans, have to organize education resources in the most effective manner, ensuring the registration of what has been done in the medical record (MR).

Description of the problem

During the accreditation process, IMFR (Medical and Physical Rehabilitation Institute - an hospital part of the Udine Healthcare Trust) launched a MR-quality program. A dedicated team of 3 doctors, 4 nurses and 4 therapists changed the way in recording educational information in MR, introducing in April 2018 a specific, independent form, part of the MR, where documenting the achievement of two educational phases: assessment and delivery. The aim of this project is to determine if the introduction of this specific educational form and its sharing process, included in the wider MR-quality program, would improve the recording behavior. Twenty MRs were quarterly analyzed from December 2017 to December 2018, assessing educational forms completeness. Significance (p < 0.01) was assessed by Cochran-Armitage test for trends.

Results

The recording behavior improved significantly from 53% (21/40; Dec-17) to 88% (30/34) in June 2018, after the introduction of the specific education form and remained high also in Sept.2018 (90%, 34/38) and in Dec.2018 (82%, 31/38), with an overall trend of + 29%.

Lessons

Sharing elements in the creation of the specific educational form with a multidisciplinary approach, within a wider MR-quality program, allows to improve the recording behavior of educational information in it. Hopefully this method would help healthcare professionals and organizations to ensure the education needed to patients and families.

Key messages

A multidisciplinary approach is a good model to deal with specific aspects of quality programs. A specific form, part of the MR, allows to improve behavior in recording educational information.

DNA Base Excision Repair: The Achilles' Heel of Tumour Cells and their Microenvironment?

Our current understanding of cancer suggests that every tumour has individual features. Approaches to cancer treatment require thorough comprehension of the mechanisms triggering genomic instability and protecting cancer cells from therapeutic treatments. Base excision repair (BER) is a frontline DNA repair system that is responsible for maintaining genome integrity. The BER pathway prevents the occurrence of disease, including cancer, by constantly repairing DNA base lesions and DNA single strand breaks caused by endogenous and exogenous mutagens. BER is an important DNA repair system for cancer cell survival, as it can affect both chemoand radio-resistance of tumours. Variations in BER capacity are likely responsible for a number of cases of sporadic cancer and may also modulate cancer sensitivity and resistance to therapeutic treatments. For these reasons, it is broadly accepted that targeting BER enzymes might be a promising approach to personalised anti-cancer therapy. However, recent advances in both treatment strategies and the comprehension of cancer development call for a better understanding of the consequences of BER inhibition. Indeed, the impact on both the tumour microenvironment and healthy tissues is still unclear. This review will summarise the current status of the approaches exploiting BER targeting, describing the most promising small molecule inhibitors and synthetic lethality strategies, as well as potential limitations of these approaches.

Interplay between base excision repair protein XRCC1 and ALDH2 predicts overall survival in lung and liver cancer patients

BACKGROUND

To deliver efficacious personalised cancer treatment, it is essential to characterise the cellular metabolism as well as the genetic stability of individual tumours. In this study, we describe a new axis between DNA repair and detoxification of aldehyde derivatives with important implications for patient prognosis and treatment.

METHODS

Western blot and qPCR analyses were performed in relevant non-transformed and cancer cell lines from lung and liver tissue origin in combination with bioinformatics data mining of The Cancer Genome Atlas database from lung and hepatocellular cancer patients.

RESULTS

Using both biochemical and bioinformatics approaches, we revealed an association between the levels of expression of the aldehyde detoxifying enzyme aldehyde dehydrogenase 2 (ALDH2) and the key DNA base excision repair protein XRCC1. Across cancer types, we found that if one of the corresponding genes exhibits a low expression level, the level of the other gene is increased. Surprisingly, we found that low ALDH2 expression levels associated with high XRCC1 expression levels are indicative for a poor overall survival, particularly in lung and liver cancer patients. In addition, we found that Mithramycin A, a XRCC1 expression inhibitor, efficiently kills cancer cells expressing low levels of ALDH2.

CONCLUSIONS

Our data suggest that lung and liver cancers require efficient single-strand break repair for their growth in order to benefit from a low aldehyde detoxification metabolism. We also propose that the ratio of XRCC1 and ALDH2 levels may serve as a useful prognostic tool in these cancer types.

Persistent DNA strand breaks induce a CAF-like phenotype in normal fibroblasts

Cancer-associated fibroblasts (CAFs) are an emerging target for cancer therapy as they promote tumour growth and metastatic potential. However, CAF targeting is complicated by the lack of knowledge-based strategies aiming to selectively eliminate these cells. There is a growing body of evidence suggesting that a pro-inflammatory microenvironment (e.g. ROS and cytokines) promotes CAF formation during tumorigenesis, although the exact mechanisms involved remain unclear. In this study, we reveal that a prolonged pro-inflammatory stimulation causes a de facto deficiency in base excision repair, generating unrepaired DNA strand breaks and thereby triggering an ATF4-dependent reprogramming of normal fibroblasts into CAF-like cells. Based on the phenotype of in vitro-generated CAFs, we demonstrate that midostaurin, a clinically relevant compound, selectively eliminates CAF-like cells deficient in base excision repair and prevents their stimulatory role in cancer cell growth and migration.

Sp1 phosphorylation by ATM downregulates BER and promotes cell elimination in response to persistent DNA damage

ATM (ataxia-telangiectasia mutated) is a central molecule for DNA quality control. Its activation by DNA damage promotes cell-cycle delay, which facilitates DNA repair prior to replication. On the other hand, persistent DNA damage has been implicated in ATM-dependent cell death via apoptosis; however, the mechanisms underlying this process remain elusive. Here we find that, in response to persistent DNA strand breaks, ATM phosphorylates transcription factor Sp1 and initiates its degradation. We show that Sp1 controls expression of the key base excision repair gene XRCC1, essential for DNA strand break repair. Therefore, degradation of Sp1 leads to a vicious cycle that involves suppression of DNA repair and further aggravation of the load of DNA damage. This activates transcription of pro-apoptotic genes and renders cells susceptible to elimination via both apoptosis and natural killer cells. These findings constitute a previously unrecognized 'gatekeeper' function of ATM as a detector of cells with persistent DNA damage.

Modulation of proteostasis counteracts oxidative stress and affects DNA base excision repair capacity in ATM-deficient cells

Ataxia telangiectasia (A-T) is a syndrome associated with loss of ATM protein function. Neurodegeneration and cancer predisposition, both hallmarks of A-T, are likely to emerge as a consequence of the persistent oxidative stress and DNA damage observed in this disease. Surprisingly however, despite these severe features, a lack of functional ATM is still compatible with early life, suggesting that adaptation mechanisms contributing to cell survival must be in place. Here we address this gap in our knowledge by analysing the process of human fibroblast adaptation to the lack of ATM. We identify profound rearrangement in cellular proteostasis occurring very early on after loss of ATM in order to counter protein damage originating from oxidative stress. Change in proteostasis, however, is not without repercussions. Modulating protein turnover in ATM-depleted cells also has an adverse effect on the DNA base excision repair pathway, the major DNA repair system that deals with oxidative DNA damage. As a consequence, the burden of unrepaired endogenous DNA lesions intensifies, progressively leading to genomic instability. Our study provides a glimpse at the cellular consequences of loss of ATM and highlights a previously overlooked role for proteostasis in maintaining cell survival in the absence of ATM function.

p53 coordinates base excision repair to prevent genomic instability

DNA constantly undergoes chemical modification due to endogenous and exogenous mutagens. The DNA base excision repair (BER) pathway is the frontline mechanism handling the majority of these lesions, and primarily involves a DNA incision and subsequent resealing step. It is imperative that these processes are extremely well-coordinated as unrepaired DNA single strand breaks (SSBs) can be converted to DNA double strand breaks during replication thus triggering genomic instability. However, the mechanism(s) governing the BER process are poorly understood. Here we show that accumulation of unrepaired SSBs triggers a p53/Sp1-dependent downregulation of APE1, the endonuclease responsible for the DNA incision during BER. Importantly, we demonstrate that impaired p53 function, a characteristic of many cancers, leads to a failure of the BER coordination mechanism, overexpression of APE1, accumulation of DNA strand breaks and results in genomic instability. Our data provide evidence for a previously unrecognized mechanism for coordination of BER by p53, and its dysfunction in p53-inactivated cells.

Inhibitors of the apurinic/apyrimidinic endonuclease 1 (APE1)/nucleophosmin (NPM1) interaction that display anti-tumor properties

The apurinic/apyrimidinic endonuclease 1 (APE1) is a protein central to the base excision DNA repair pathway and operates in the modulation of gene expression through redox-dependent and independent mechanisms. Aberrant expression and localization of APE1 in tumors are recurrent hallmarks of aggressiveness and resistance to therapy. We identified and characterized the molecular association between APE1 and nucleophosmin (NPM1), a multifunctional protein involved in the preservation of genome stability and rRNA maturation. This protein-protein interaction modulates subcellular localization and endonuclease activity of APE1. Moreover, we reported a correlation between APE1 and NPM1 expression levels in ovarian cancer, with NPM1 overexpression being a marker of poor prognosis. These observations suggest that tumors that display an augmented APE1/NPM1 association may exhibit increased aggressiveness and resistance. Therefore, targeting the APE1/NPM1 interaction might represent an innovative strategy for the development of anticancer drugs, as tumor cells relying on higher levels of APE1 and NPM1 for proliferation and survival may be more sensitive than untransformed cells. We set up a chemiluminescence-based high-throughput screening assay in order to find small molecules able to interfere with the APE1/NPM1 interaction. This screening led to the identification of a set of bioactive compounds that impair the APE1/NPM1 association in living cells. Interestingly, some of these molecules display anti-proliferative activity and sensitize cells to therapeutically relevant genotoxins. Given the prognostic significance of APE1 and NPM1, these compounds might prove effective in the treatment of tumors that show abundant levels of both proteins, such as ovarian or hepatic carcinomas.

Nucleophosmin modulates stability, activity, and nucleolar accumulation of base excision repair proteins

Nucleophosmin (NPM1) is a multifunctional protein that controls cell growth and genome stability via a mechanism that involves nucleolar-cytoplasmic shuttling. It is clear that NPM1 also contributes to the DNA damage response, yet its exact function is poorly understood. We recently linked NPM1 expression to the functional activation of the major abasic endonuclease in mammalian base excision repair (BER), apurinic/apyrimidinic endonuclease 1 (APE1). Here we unveil a novel role for NPM1 as a modulator of the whole BER pathway by 1) controlling BER protein levels, 2) regulating total BER capacity, and 3) modulating the nucleolar localization of several BER enzymes. We find that cell treatment with the genotoxin cisplatin leads to concurrent relocalization of NPM1 and BER components from nucleoli to the nucleoplasm, and cellular experiments targeting APE1 suggest a role for the redistribution of nucleolar BER factors in determining cisplatin toxicity. Finally, based on the use of APE1 as a representative protein of the BER pathway, our data suggest a function for BER proteins in the regulation of ribogenesis.

Expression and prognostic significance of APE1/Ref-1 and NPM1 proteins in high-grade ovarian serous cancer

OBJECTIVES

To correlate the expression profile of human apurinic endonuclease/redox factor 1 (APE1/Ref-1) with that of nucleolar/nucleoplasmic protein nucleophosmin 1 (NPM1) in association with the aggressiveness and progression of high-grade ovarian serous cancer.

METHODS

Retrospective study analyzing a tissue microarray of 73 women affected by high-grade ovarian serous cancer. Protein expression was assessed by immunohistochemistry on primary tumor masses and synchronous peritoneal metastases if present.

RESULTS

APE1/Ref-1 and NPM1 showed a significant correlation in ovarian serous cancer. Patients with a poorer outcome showed a significant overexpression of nuclear NPM1 protein. A Cox proportional hazards multivariate regression model revealed NPM1 expression to be independently significant for overall survival in high-grade ovarian serous cancers after correcting for stage, age, cytoreduction completeness, and platinum resistance.

CONCLUSIONS

APE1/Ref-1 interacts with NPM1 to control the DNA damage repair system, and it is likely that this interaction plays a defining role in high-grade ovarian serous carcinoma. A high NPM1 immunohistochemical expression was independently correlated with a shorter survival period and thus appears to be an important prognostic factor.

Emerging roles of the nucleolus in regulating the DNA damage response: the noncanonical DNA repair enzyme APE1/Ref-1 as a paradigmatical example

SIGNIFICANCE

An emerging concept in DNA repair mechanisms is the evidence that some key enzymes, besides their role in the maintenance of genome stability, display also unexpected noncanonical functions associated with RNA metabolism in specific subcellular districts (e.g., nucleoli). During the evolution of these key enzymes, the acquisition of unfolded domains significantly amplified the possibility to interact with different partners and substrates, possibly explaining their phylogenetic gain of functions.

RECENT ADVANCES

After nucleolar stress or DNA damage, many DNA repair proteins can freely relocalize from nucleoli to the nucleoplasm. This process may represent a surveillance mechanism to monitor the synthesis and correct assembly of ribosomal units affecting cell cycle progression or inducing p53-mediated apoptosis or senescence.

CRITICAL ISSUES

A paradigm for this kind of regulation is represented by some enzymes of the DNA base excision repair (BER) pathway, such as apurinic/apyrimidinic endonuclease 1 (APE1). In this review, the role of the nucleolus and the noncanonical functions of the APE1 protein are discussed in light of their possible implications in human pathologies.

FUTURE DIRECTIONS

A productive cross-talk between DNA repair enzymes and proteins involved in RNA metabolism seems reasonable as the nucleolus is emerging as a dynamic functional hub that coordinates cell growth arrest and DNA repair mechanisms. These findings will drive further analyses on other BER proteins and might imply that nucleic acid processing enzymes are more versatile than originally thought having evolved DNA-targeted functions after a previous life in the early RNA world.

Interactome map uncovers phosphatidylserine transport by oxysterol-binding proteins

The internal organization of eukaryotic cells into functionally specialized, membrane-delimited organelles of unique composition implies a need for active, regulated lipid transport. Phosphatidylserine (PS), for example, is synthesized in the endoplasmic reticulum and then preferentially associates--through mechanisms not fully elucidated--with the inner leaflet of the plasma membrane. Lipids can travel via transport vesicles. Alternatively, several protein families known as lipid-transfer proteins (LTPs) can extract a variety of specific lipids from biological membranes and transport them, within a hydrophobic pocket, through aqueous phases. Here we report the development of an integrated approach that combines protein fractionation and lipidomics to characterize the LTP-lipid complexes formed in vivo. We applied the procedure to 13 LTPs in the yeast Saccharomyces cerevisiae: the six Sec14 homology (Sfh) proteins and the seven oxysterol-binding homology (Osh) proteins. We found that Osh6 and Osh7 have an unexpected specificity for PS. In vivo, they participate in PS homeostasis and the transport of this lipid to the plasma membrane. The structure of Osh6 bound to PS reveals unique features that are conserved among other metazoan oxysterol-binding proteins (OSBPs) and are required for PS recognition. Our findings represent the first direct evidence, to our knowledge, for the non-vesicular transfer of PS from its site of biosynthesis (the endoplasmic reticulum) to its site of biological activity (the plasma membrane). We describe a new subfamily of OSBPs, including human ORP5 and ORP10, that transfer PS and propose new mechanisms of action for a protein family that is involved in several human pathologies such as cancer, dyslipidaemia and metabolic syndrome.

Functional regulation of the apurinic/apyrimidinic endonuclease 1 by nucleophosmin: impact on tumor biology

Nucleophosmin 1 (NPM1) is a nucleolar protein involved in ribosome biogenesis, stress responses and maintaining genome stability. One-third of acute myeloid leukemias (AMLs) are associated with aberrant localization of NPM1 to the cytoplasm (NPM1c+). This mutation is critical during leukemogenesis and constitutes a good prognostic factor for chemotherapy. At present, there is no clear molecular basis for the role of NPM1 in DNA repair and the tumorigenic process. We found that the nuclear apurinic/apyrimidinic endonuclease 1 (APE1), a core enzyme in base excision DNA repair (BER) of DNA lesions, specifically interacts with NPM1 within nucleoli and the nucleoplasm. Cytoplasmic accumulation of APE1 is associated with cancers including, as we show, NPM1c+ AML. Here we show that NPM1 stimulates APE1 BER activity in cells. We provide evidence that expression of the NPM1c+ variant causes cytoplasmic accumulation of APE1 in: (i) a heterologous cell system (HeLa cells); (ii) the myeloid cell line OCI/AML3 stably expressing NPM1c+; and (iii) primary lymphoblasts of NPM1c+ AML patients. Consistent with impaired APE1 localization, OCI/AML3 cells and blasts of AML patients have impaired BER activity. Cytoplasmic APE1 in NPM1c+ myeloid cells is truncated due to proteolysis. Thus, the good prognostic response of NPM1c+ AML to chemotherapy may result from the cytoplasmic relocalization of APE1 and the consequent BER deficiency. NPM1 thus has an indirect but significant role in BER in vivo that may also be important for NPM1c+ tumorigenesis.

Abstract 3337: Modulating the APE1/NPM1 interaction in cancer

DNA repair pathways protect the genome from endogenous and environmental DNA damage. Such defensive mechanisms, however, enable tumor cells to survive DNA damage caused by chemo- and radio-therapy. Moreover, alterations of DNA repair pathways that may occur during tumorigenesis can make cancer cells reliant on a subset of repair enzymes for survival. Hence, knowledge of the mechanisms involved in the control of DNA repair proteins is of great interest for cancer diagnosis and treatment.

The Apurinic/apyrimidinc endonuclease 1 (APE1) is an essential protein in eukaryotic cells. As the main AP-endonuclease in mammals, this protein is central to the base excision DNA repair pathway (BER). Beside its role in the maintenance of genomic stability, APE1 modulates gene expression by tuning the redox status of several transcription factors. Moreover, recent reports suggest that APE1 may take part in RNA processing and degradation, thus controlling the transcriptional output of the cell. Overexpression and aberrant localization of APE1 are recurrent phenotypes in tumors. Both situations are prognostic indicators of aggressiveness and onset of resistance. Interestingly, downregulation or inhibition of APE1 sensitizes cells to pharmacologically relevant gentoxins.

We identified and characterized the molecular association between APE1 and Nucleophosmin (NPM1), a multifunctional protein involved in the preservation of genome stability, rRNA maturation and chromatin remodeling. The association with NPM1 modulates subcellular localization and endonuclease activity of APE1. Accordingly, NPM1−/− cells show lower BER capacity, and expression of an APE1 mutant unable to interact with NPM1 severely impairs cell proliferation. We recently reported a correlation between APE1 and NPM1 expression levels in ovarian cancer, along with a poorer prognosis for patients having higher NPM1 levels. These observations suggest that tumors that display an augmented APE1/NPM1 association may exhibit increased aggressiveness and resistance. Targeting the APE1/NPM1 interaction therefore represents a novel strategy for the development of anticancer drugs, as tumor cells which rely on higher levels of APE1 and NPM1 for proliferation and survival may be more sensitive than normal cells.

We exploited the AlphaScreen technology to screen for small molecules that act as inhibitors of the APE1/NPM1 interaction. Our approach detected a set of compounds able to interfere with the APE1/NPM1 association in vivo. Interestingly, some of these molecules display anti-proliferative activity and sensitize cells to genotoxins. To the best of our knowledge, this is the first attempt to target the APE1 interactome. Given the prognostic significance of the APE1 and NPM1 overexpression, these compounds might prove particularly effective in the treatment of tumors that show abundant levels of both proteins, such as ovarian or hepatic carcinomas.

Citation Format: Mattia Poletto, Dorjbal Dorjsuren, Lisa Lirussi, Carlo Vascotto, Pasqualina L. Scognamiglio, Daniela Marasco, Ajit Jadhav, David J. Maloney, Anton Simeonov, David M. Wilson, Gianluca Tell. Modulating the APE1/NPM1 interaction in cancer. [abstract]. In: Proceedings of the 104th Annual Meeting of the American Association for Cancer Research; 2013 Apr 6-10; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2013;73(8 Suppl):Abstract nr 3337. doi:10.1158/1538-7445.AM2013-3337

Nucleolar accumulation of APE1 depends on charged lysine residues that undergo acetylation upon genotoxic stress and modulate its BER activity in cells

The functional importance of APE1 nucleolar accumulation is described. It is shown that acetylation of Lys27–35, affecting local conformation, regulates APE1 function by 1) controlling its interaction with NPM1 and rRNA and its nucleolar accumulation, 2) modulating K6/K7 acetylation status, and 3) promoting APE1 BER activity in cells.

Apurinic/apyrimidinic endonuclease 1 (APE1) is the main abasic endonuclease in the base excision repair (BER) pathway of DNA lesions caused by oxidation/alkylation in mammalian cells; within nucleoli it interacts with nucleophosmin and rRNA through N-terminal Lys residues, some of which (K²⁷/K³¹/K³²/K³⁵) may undergo acetylation in vivo. Here we study the functional role of these modifications during genotoxic damage and their in vivo relevance. We demonstrate that cells expressing a specific K-to-A multiple mutant are APE1 nucleolar deficient and are more resistant to genotoxic treatment than those expressing the wild type, although they show impaired proliferation. Of interest, we find that genotoxic treatment induces acetylation at these K residues. We also find that the charged status of K²⁷/K³¹/K³²/K³⁵ modulates acetylation at K⁶/K⁷ residues that are known to be involved in the coordination of BER activity through a mechanism regulated by the sirtuin 1 deacetylase. Of note, structural studies show that acetylation at K²⁷/K³¹/K³²/K³⁵ may account for local conformational changes on APE1 protein structure. These results highlight the emerging role of acetylation of critical Lys residues in regulating APE1 functions. They also suggest the existence of cross-talk between different Lys residues of APE1 occurring upon genotoxic damage, which may modulate APE1 subnuclear distribution and enzymatic activity in vivo.

Critical lysine residues within the overlooked N-terminal domain of human APE1 regulate its biological functions

Apurinic/apyrimidinic endonuclease 1 (APE1), an essential protein in mammals, is involved in base excision DNA repair (BER) and in regulation of gene expression, acting as a redox co-activator of several transcription factors. Recent findings highlight a novel role for APE1 in RNA metabolism, which is modulated by nucleophosmin (NPM1). The results reported in this article show that five lysine residues (K24, K25, K27, K31 and K32), located in the APE1 N-terminal unstructured domain, are involved in the interaction of APE1 with both RNA and NPM1, thus supporting a competitive binding mechanism. Data from kinetic experiments demonstrate that the APE1 N-terminal domain also serves as a device for fine regulation of protein catalytic activity on abasic DNA. Interestingly, some of these critical lysine residues undergo acetylation in vivo. These results suggest that protein–protein interactions and/or post-translational modifications involving APE1 N-terminal domain may play important in vivo roles, in better coordinating and fine-tuning protein BER activity and function on RNA metabolism.

Gene transcription in Lactarius quietus-Quercus petraea ectomycorrhizas from a forest soil

Extracting fungal mRNA from ectomycorrhizas (ECMs) and forest soil samples for monitoring in situ metabolic activities is a significant challenge when studying the role of ECMs in biogeochemical cycles. A robust, simple, rapid, and effective method was developed for extracting RNA from rhizospheric soil and ECMs by adapting previous grinding and lysis methods. The quality and yield of the extracted RNA were sufficient to be used for reverse transcription. RNA extracted from ECMs of Lactarius quietus in a 100-year-old oak stand was used to construct a cDNA library and sequence expressed sequence tags. The transcripts of many genes involved in primary metabolism and in the degradation of organic matter were found. The transcription levels of four targeted fungal genes (glutamine synthase, a general amino acid transporter, a tyrosinase, and N-acetylhexosaminidase) were measured by quantitative reverse transcription-PCR in ECMs and in the ectomycorrhizospheric soil (the soil surrounding the ECMs containing the extraradical mycelium) in forest samples. On average, levels of gene expression for the L. quietus ECM root tips were similar to those for the extraradical mycelium, although gene expression varied up to 10-fold among the samples. This study demonstrates that gene expression from ECMs and soil can be analyzed. These results provide new perspectives for investigating the role of ectomycorrhizal fungi in the functioning of forest ecosystems.

Mud bath therapy influences nitric oxide, myeloperoxidase and glutathione peroxidase serum levels in arthritic patients

Nitric oxide (NO) has recently been proposed as an important mediator in inflammatory phases and in loss of cartilage. In inflammatory arthritis NO levels are correlated with disease activity and articular cartilage is able to produce large amounts of NO with the appropriate inducing factors such as cytokines and/or endotoxin. Neutrophils also play an important role in inflammatory reactions and the level of myeloperoxidase, a constituent of neutrophil granules, is related to the intensity of the inflammation. Because there is evidence that suggests that mud packs influence the main cytokines involved in cartilage damage, we tried to determine whether NO and myeloperoxidase are involved in the mechanisms of action of mud bath treatment. We enrolled 37 subjects and randomly assigned them to two groups: 19 patients underwent mud bath treatment (group A) while 18 patients underwent bath treatment alone. Blood samples were obtained before and after the treatment cycles to assay serum levels of NO, myeloperoxidase (MPO) and glutathione (GSH)-peroxidase. The results showed a statistically significant decrease in NO and myeloperoxidase serum values in groups A and B, while GSH-peroxidase was not significantly increase in either of the groups; no correlation was found between NO, myeloperoxidase and GSH-peroxidase serum values. Mud bath treatment can exert beneficial effects on cartilage homeostasis and inflammatory reactions, influencing NO and decreasing myeloperoxidase serum values. The increase in GSH-peroxidase was not correlated with the reduction of other biochemical markers, suggesting that mud bath treatment has different mechanisms of action.