PICH deficiency limits the progression of MYC-induced B-cell lymphoma.

Plk1-interacting checkpoint helicase (PICH) is a DNA translocase involved in resolving ultrafine anaphase DNA bridges and, therefore, is important to safeguard chromosome segregation and stability. PICH is overexpressed in various human cancers, particularly in lymphomas such as Burkitt lymphoma, which is caused by MYC translocations. To investigate the relevance of PICH in cancer development and progression, we have combined novel PICH-deficient mouse models with the Eµ-Myc transgenic mouse model, which recapitulates B-cell lymphoma development. We have observed that PICH deficiency delays the onset of MYC-induced lymphomas in Pich heterozygous females. Moreover, using a Pich conditional knockout mouse model, we have found that Pich deletion in adult mice improves the survival of Eµ-Myc transgenic mice. Notably, we show that Pich deletion in healthy adult mice is well tolerated, supporting PICH as a suitable target for anticancer therapies. Finally, we have corroborated these findings in two human Burkitt lymphoma cell lines and we have found that the death of cancer cells was accompanied by chromosomal instability. Based on these findings, we propose PICH as a potential therapeutic target for Burkitt lymphoma and for other cancers where PICH is overexpressed.

NPCs and APBs: two HUBs of non-canonical homology-based recombination at telomeres?

Apart from a few rare exceptions, the maintenance of functional telomeres by recombination-based mechanisms is restricted to accidental and/or pathological situations. Originally described in the yeast S. cerevisiae, this mode of telomere repair has gained interest with the discovery of telomerase negative cancers that use alternative lengthening of telomeres (ALT cancer) dependent on homologous recombination. In both yeast and humans, it has been shown that recombination at telomeres is spatially regulated and occurs preferentially at the nuclear pore complexes (NPCs) in yeast and at ALT-associated promyelocytic leukemia nuclear bodies (APBs) in human cells. Here, we discuss the potential relationships between these two membrane-less structures and their role in enabling unconventional recombination pathways.

Pancreatic Cancer Surveillance in Carriers of a Germline Pathogenic Variant in CDKN2A.

Three percent of patients with pancreatic ductal adenocarcinoma (PDAC) present a germline pathogenic variant (GPV) associated with an increased risk of this tumor, CDKN2A being one of the genes associated with the highest risk. There is no clear consensus on the recommendations for surveillance in CDKN2A GPV carriers, although the latest guidelines from the International Cancer of the Pancreas Screening Consortium recommend annual endoscopic ultrasound (EUS) or magnetic resonance imaging (MRI) regardless of family history. Our aim is to describe the findings of the PDAC surveillance program in a cohort of healthy CDKN2A GPV heterozygotes. This is an observational analysis of prospectively collected data from all CDKN2A carriers who underwent screening for PDAC at the high-risk digestive cancer clinic of the "Hospital Clínic de Barcelona" between 2013 and 2021. A total of 78 subjects were included. EUS or MRI was performed annually with a median follow-up of 66 months. Up to 17 pancreatic findings were described in 16 (20.5%) individuals under surveillance, although most of them were benign. No significant precursor lesions were identified, but an early PDAC was detected and treated. While better preventive strategies are developed, we believe that annual surveillance with EUS and/or MRI in CDKN2A GPV heterozygotes may be beneficial.

The MC1R r allele does not increase melanoma risk in MITF E318K carriers.

BACKGROUND: Population-wide screening for melanoma is not cost-effective, but genetic characterization could facilitate risk stratification and targeted screening. Common Melanocortin-1 receptor (MC1R) red hair colour (RHC) variants and Microphthalmia-associated transcription factor (MITF) E318K separately confer moderate melanoma susceptibility, but their interactive effects are relatively unexplored. OBJECTIVES: To evaluate whether MC1R genotypes differentially affect melanoma risk in MITF E318K+ vs. E318K- individuals. MATERIALS AND METHODS: Melanoma status (affected or unaffected) and genotype data (MC1R and MITF E318K) were collated from research cohorts (five Australian and two European). In addition, RHC genotypes from E318K+ individuals with and without melanoma were extracted from databases (The Cancer Genome Atlas and Medical Genome Research Bank, respectively). χ2 and logistic regression were used to evaluate RHC allele and genotype frequencies within E318K+/- cohorts depending on melanoma status. Replication analysis was conducted on 200 000 general-population exomes (UK Biobank). RESULTS: The cohort comprised 1165 MITF E318K- and 322 E318K+ individuals. In E318K- cases MC1R R and r alleles increased melanoma risk relative to wild type (wt), P < 0.001 for both. Similarly, each MC1R RHC genotype (R/R, R/r, R/wt, r/r and r/wt) increased melanoma risk relative to wt/wt (P < 0.001 for all). In E318K+ cases, R alleles increased melanoma risk relative to the wt allele [odds ratio (OR) 2.04 (95% confidence interval 1.67-2.49); P = 0.01], while the r allele risk was comparable with the wt allele [OR 0.78 (0.54-1.14) vs. 1.00, respectively]. E318K+ cases with the r/r genotype had a lower but not significant melanoma risk relative to wt/wt [OR 0.52 (0.20-1.38)]. Within the E318K+ cohort, R genotypes (R/R, R/r and R/wt) conferred a significantly higher risk compared with non-R genotypes (r/r, r/wt and wt/wt) (P < 0.001). UK Biobank data supported our findings that r did not increase melanoma risk in E318K+ individuals. CONCLUSIONS: RHC alleles/genotypes modify melanoma risk differently in MITF E318K- and E318K+ individuals. Specifically, although all RHC alleles increase risk relative to wt in E318K- individuals, only MC1R R increases melanoma risk in E318K+ individuals. Importantly, in the E318K+ cohort the MC1R r allele risk is comparable with wt. These findings could inform counselling and management for MITF E318K+ individuals.

ATRX, a guardian of chromatin.

ATRX (alpha-thalassemia mental retardation X-linked) is one of the most frequently mutated tumor suppressor genes in human cancers, especially in glioma, and recent findings indicate roles for ATRX in key molecular pathways, such as the regulation of chromatin state, gene expression, and DNA damage repair, placing ATRX as a central player in the maintenance of genome stability and function. This has led to new perspectives about the functional role of ATRX and its relationship with cancer. Here, we provide an overview of ATRX interactions and molecular functions and discuss the consequences of its impairment, including alternative lengthening of telomeres and therapeutic vulnerabilities that may be exploited in cancer cells.

Transcriptomic study in explanted liver from a patient with acute intermittent porphyria.

Acute intermittent porphyria (AIP) is a rare disease caused by a deficiency of hydroxymethylbilane synthase (HMBS), the third enzyme of the heme-synthesis pathway. Decreased enzymatic activity in the liver induces an overproduction of heme-precursors and acute neurological attacks. We report a 36-years-old female with AIP with a long-term history of severe, disabling, recurrent attacks, who underwent curative liver transplantation. Tissue samples from the explant were obtained for transcriptome analysis. Whole RNA was extracted and 16 gene-transcripts were selected and investigated by quantitative polymerase chain reaction. These included nine genes encoding enzymes that consecutively catalyze heme-synthesis and catabolism in the liver (ALAS1; ALAD; HMBS; UROS; UROD; CPOX; PPOX; FECH; HMOX1). Additionally, we studied genes related to inflammation (IL6; TNF) insulin signaling (PGC-1α; IGF-1; FOXO-1) and tryptophan metabolism (TDO2; IDO). Transcripts of eight house-keeping genes were co-measured for normalization. All transcripts were also measured in five control samples from healthy living liver donors. The transcriptome of the controls showed important differences between the various genes, with the first two genes of the heme-synthesis pathway, ALAS1 and ALAD showing strikingly high mRNA levels compared to the consecutive HMBS gene. Transcripts of several genes significantly differed in the AIP liver compared to controls. Transcripts of HMOX1 and UROS were increased in the AIP liver whereas transcripts of UROD; CPOX, PPOX, and TDO2 were decreased. ALAS1 expression was not increased, possibly due to hemin administered to the patient before transplantation. These results highlight several transcriptomic changes related to heme homeostasis in AIP.

Arbuscular mycorrhizal fungi enhance monoterpene production in red clover (Trifolium pratense L.): a potential tool for pest control.

The possibility of modifying terpene production in plants is a defensive strategy that has been studied in conjunction with their biosynthetic pathways. A biotic factor such as Arbuscular Mycorrhizal Fungi (AMF) could modify terpene production in Trifolium pratense L. In this work, the enzymatic production of monoterpenes in Superqueli INIA cultivar with two AMF was evaluated via HeadSpace-Gas Chromatography (HS-GC). A significant increase of (S)-limonene was found in plants inoculated with Claroideoglomus claroideum as well as with the AMF mix (genera Scutellospora, Acaulospora and Glomus). Moreover, significant increases in other monoterpenes such as (-)-ß-pinene, myrcene, linalool, were observed. Results showed higher monoterpene production capacities in the Superqueli-INIA cultivar, suggesting the participation of monoterpene synthases (MTS). The significant rise of (S)-limonene in red clover plants inoculated with AMF suggests this strategy could be implemented in an agronomical manage for controlling the H. obscurus, the primary pest.

ATRX-Deficient High-Grade Glioma Cells Exhibit Increased Sensitivity to RTK and PDGFR Inhibitors.

High-grade glioma, including anaplastic astrocytoma and glioblastoma (GBM) patients, have a poor prognosis due to the lack of effective treatments. Therefore, the development of new therapeutic strategies to treat these gliomas is urgently required. Given that high-grade gliomas frequently harbor mutations in the SNF2 family chromatin remodeler ATRX, we performed a screen to identify FDA-approved drugs that are toxic to ATRX-deficient cells. Our findings reveal that multi-targeted receptor tyrosine kinase (RTK) and platelet-derived growth factor receptor (PDGFR) inhibitors cause higher cellular toxicity in high-grade glioma ATRX-deficient cells. Furthermore, we demonstrate that a combinatorial treatment of RTKi with temozolomide (TMZ)-the current standard of care treatment for GBM patients-causes pronounced toxicity in ATRX-deficient high-grade glioma cells. Our findings suggest that combinatorial treatments with TMZ and RTKi may increase the therapeutic window of opportunity in patients who suffer high-grade gliomas with ATRX mutations. Thus, we recommend incorporating the ATRX status into the analyses of clinical trials with RTKi and PDGFRi.

Evaluation of Metabolic Changes in Acute Intermittent Porphyria Patients by Targeted Metabolomics.

Acute intermittent porphyria (AIP) is an inherited rare hepatic disorder due to mutations within the hydroxymethylbilane gene. AIP patients with active disease overproduce aminolevulinic acid (ALA) and porphobilinogen (PBG) in the liver which are exported inducing severe neurological attacks. Different hepatic metabolic abnormalities have been described to be associated with this condition. The goal of this research was to explore the metabolome of symptomatic AIP patients by state-of-the art liquid chromatography-tandem mass spectrometry (LC-MS/MS). A case versus control study including 18 symptomatic AIP patients and 33 healthy controls was performed. Plasmatic levels of 51 metabolites and 16 ratios belonging to four metabolic pathways were determined. The results showed that the AIP patients presented significant changes in the two main areas of the metabolome under study: (a) the tryptophan/kynurenine pathway with an increase of tryptophan in plasma together with increase of the kynurenine/tryptophan ratio; and (b) changes in the tricarboxylic acid cycle (TCA) including increase of succinic acid and decrease of the fumaric acid/succinic acid ratio. We performed a complementary in vitro study adding ALA to hepatocytes media that showed some of the effects on the TCA cycle were parallel to those observed in vivo. Our study confirms in plasma previous results obtained in urine showing that AIP patients present a moderate increase of the kynurenine/tryptophan ratio possibly associated with inflammation. In addition, it also reports changes in the mitochondrial TCA cycle that, despite requiring further research, could be associated with an energy misbalance due to sustained overproduction of heme-precursors in the liver.

Application of Arbuscular Mycorrhizal Fungi in Vineyards: Water and Biotic Stress Under a Climate Change Scenario: New Challenge for Chilean Grapevine Crop.

The crop Vitis vinifera (L.) is of great economic importance as Chile is one of the main wine-producing countries, reaching a vineyard area of 145,000 ha. This vine crop is usually very sensitive to local condition changes and agronomic practices; therefore, strategies to counteract the expected future decrease in water level for agricultural irrigation, temperature increase, extreme water stress (abiotic stress), as well as increase in pathogenic diseases (biotic stress) related to climate change will be of vital importance for this crop. Studies carried out in recent years have suggested that arbuscular mycorrhizal fungi (AMF) can provide key ecosystem services to host plants, such as water uptake implementation and enhanced absorption of nutrients such as P and N, which are key factors for improving the nutritional status of the vine. AMF use in viticulture will contribute also to sustainable agronomic management and bioprotection against pathogens. Here we will present (1) the current status of grapevines in Chile, (2) the main problems in grapevines related to water stress and associated with climate change, (3) the importance of AMF to face water stress and pathogens, and (4) the application of AMF as a biotechnological and sustainable tool in vineyards.

Telomeric C-circles localize at nuclear pore complexes in Saccharomyces cerevisiae.

As in human cells, yeast telomeres can be maintained in cells lacking telomerase activity by recombination-based mechanisms known as ALT (Alternative Lengthening of Telomeres). A hallmark of ALT human cancer cells are extrachromosomal telomeric DNA elements called C-circles, whose origin and function have remained unclear. Here, we show that extrachromosomal telomeric C-circles in yeast can be detected shortly after senescence crisis and concomitantly with the production of survivors arising from "type II" recombination events. We uncover that C-circles bind to the nuclear pore complex (NPC) and to the SAGA-TREX2 complex, similar to other non-centromeric episomal DNA. Disrupting the integrity of the SAGA/TREX2 complex affects both C-circle binding to NPCs and type II telomere recombination, suggesting that NPC tethering of C-circles facilitates formation and/or propagation of the long telomere repeats characteristic of type II survivors. Furthermore, we find that disruption of the nuclear diffusion barrier impairs type II recombination. These results support a model in which concentration of C-circles at NPCs benefits type II telomere recombination, highlighting the importance of spatial coordination in ALT-type mechanisms of telomere maintenance.

Remote heart failure management using the HeartLogic algorithm. RE-HEART registry.

INTRODUCTION AND OBJECTIVES: HeartLogic is a multiparametric algorithm incorporated into implantable cardioverter-defibrillators (ICD). The associated alerts predict impending heart failure (HF) decompensations. Our objective was to analyze the association between alerts and clinical events and to describe the implementation of a protocol for remote management in a multicenter registry. METHODS: We evaluated study phase 1 (the investigators were blinded to the alert state) and phases 2 and 3 (after HeartLogic activation, managed as per local practice and with a standardized protocol, respectively). RESULTS: We included 288 patients from 15 centers. In phase 1, the median observation period was 10 months and there were 73 alerts (0.72 alerts/patient-y), with 8 hospitalizations and 2 emergency room admissions for HF (0.10 events/patient-y). There were no HF hospitalizations outside the alert period. In the active phases, the median follow-up was 16 (95%CI, 15-22) months and there were 277 alerts (0.89 alerts/patient-y); 33 were associated with HF hospitalizations or HF death (n=6), 46 with minor decompensations, and 78 with other events. The unexplained alert rate was 0.39 alerts/patient-y. Outside the alert state, there was only 1 HF hospitalization and 1 minor HF decompensation. Most alerts (82% in phase 2 and 81% in phase 3; P=.861) were remotely managed. The median NT-proBNP value was higher within than outside the alert state (7378 vs 1210 pg/mL; P <.001). CONCLUSIONS: The HeartLogic index was frequently associated with HF-related events and other clinically relevant situations, with a low rate of unexplained events. A standardized protocol allowed alerts to be safely and remotely detected and appropriate action to be taken on them.

Arbuscular mycorrhizal fungi from acidic soils favors production of tomatoes and lycopene concentration.

BACKGROUND: Tomato is widely consumed throughout the world for its flavor and nutritional value. This functional food largely depends on the implementation of new strategies to maintain the nutraceutical value, e.g. lycopene concentration, and overcome the challenges of sustainable production and food security. The use of arbuscular mycorrhizal fungi (AMF)-based biostimulants represents one of the most promising tools for sustainable management of agricultural soils, being fundamental for organic food production, reducing fertilizers and pesticides use, and decreasing environmental damage. This study aimed at elucidating whether native arbuscular mycorrhizal fungi (AMF) could positively affect tomato yield and lycopene concentration. RESULTS: Native AMF inoculum consisted of two inoculum types: the single species Claroideoglomus claroideum, and a mix of Scutellospora calospora, Acaulospora laevis, Claroideoglomus claroideum, and Claroideoglomus etunicatum. At the end of the study up to 78% of the root system was colonized by single inoculum. Tomato diameters in single and mix mycorrhizal plants showed increases of 80% and 35% respectively. Fresh weights were 84% and 38% higher with single and mix inocula compared with the controls, respectively. The lycopene concentration in tomato fruits of plants with single and mix inoculum was higher than controls. The lycopene concentration was 124.5% and 113.9% greater in single and mix than non-inoculated plants. CONCLUSION: Tomato diameters, fresh weight and lycopene concentration was significantly higher in plants colonized by AMF compared with uninoculated plants. Results suggest that the role of single species Claroideoglomus claroideum could generate better plant performance due to its high production of extraradical mycelium. © 2021 Society of Chemical Industry.

DNA Repair and Immune Response Pathways Are Deregulated in Melanocyte-Keratinocyte Co-cultures Derived From the Healthy Skin of Familial Melanoma Patients.

Familial melanoma accounts for 10% of cases, being CDKN2A the main high-risk gene. However, the mechanisms underlying melanomagenesis in these cases remain poorly understood. Our aim was to analyze the transcriptome of melanocyte-keratinocyte co-cultures derived from healthy skin from familial melanoma patients vs. controls, to unveil pathways involved in melanoma development in at-risk individuals. Accordingly, primary melanocyte-keratinocyte co-cultures were established from the healthy skin biopsies of 16 unrelated familial melanoma patients (8 CDKN2A mutant, 8 CDKN2A wild-type) and 7 healthy controls. Whole transcriptome was captured using the SurePrint G3 Human Microarray. Transcriptome analyses included: differential gene expression, functional enrichment, and protein-protein interaction (PPI) networks. We identified a gene profile associated with familial melanoma independently of CDKN2A germline status. Functional enrichment analysis of this profile showed a downregulation of pathways related to DNA repair and immune response in familial melanoma (P < 0.05). In addition, the PPI network analysis revealed a network that consisted of double-stranded DNA repair genes (including BRCA1, BRCA2, BRIP1, and FANCA), immune response genes, and regulation of chromosome segregation. The hub gene was BRCA1. In conclusion, the constitutive deregulation of BRCA1 pathway genes and the immune response in healthy skin could be a mechanism related to melanoma risk.

Genetic insights into biological mechanisms governing human ovarian ageing.

Reproductive longevity is essential for fertility and influences healthy ageing in women1,2, but insights into its underlying biological mechanisms and treatments to preserve it are limited. Here we identify 290 genetic determinants of ovarian ageing, assessed using normal variation in age at natural menopause (ANM) in about 200,000 women of European ancestry. These common alleles were associated with clinical extremes of ANM; women in the top 1% of genetic susceptibility have an equivalent risk of premature ovarian insufficiency to those carrying monogenic FMR1 premutations3. The identified loci implicate a broad range of DNA damage response (DDR) processes and include loss-of-function variants in key DDR-associated genes. Integration with experimental models demonstrates that these DDR processes act across the life-course to shape the ovarian reserve and its rate of depletion. Furthermore, we demonstrate that experimental manipulation of DDR pathways highlighted by human genetics increases fertility and extends reproductive life in mice. Causal inference analyses using the identified genetic variants indicate that extending reproductive life in women improves bone health and reduces risk of type 2 diabetes, but increases the risk of hormone-sensitive cancers. These findings provide insight into the mechanisms that govern ovarian ageing, when they act, and how they might be targeted by therapeutic approaches to extend fertility and prevent disease.

Inherited duplications of PPP2R3B predispose to nevi and melanoma via a C21orf91-driven proliferative phenotype.

PURPOSE: Much of the heredity of melanoma remains unexplained. We sought predisposing germline copy-number variants using a rare disease approach. METHODS: Whole-genome copy-number findings in patients with melanoma predisposition syndrome congenital melanocytic nevus were extrapolated to a sporadic melanoma cohort. Functional effects of duplications in PPP2R3B were investigated using immunohistochemistry, transcriptomics, and stable inducible cellular models, themselves characterized using RNAseq, quantitative real-time polymerase chain reaction (qRT-PCR), reverse phase protein arrays, immunoblotting, RNA interference, immunocytochemistry, proliferation, and migration assays. RESULTS: We identify here a previously unreported genetic susceptibility to melanoma and melanocytic nevi, familial duplications of gene PPP2R3B. This encodes PR70, a regulatory unit of critical phosphatase PP2A. Duplications increase expression of PR70 in human nevus, and increased expression in melanoma tissue correlates with survival via a nonimmunological mechanism. PPP2R3B overexpression induces pigment cell switching toward proliferation and away from migration. Importantly, this is independent of the known microphthalmia-associated transcription factor (MITF)-controlled switch, instead driven by C21orf91. Finally, C21orf91 is demonstrated to be downstream of MITF as well as PR70. CONCLUSION: This work confirms the power of a rare disease approach, identifying a previously unreported copy-number change predisposing to melanocytic neoplasia, and discovers C21orf91 as a potentially targetable hub in the control of phenotype switching.

Dysregulation of homocysteine homeostasis in acute intermittent porphyria patients receiving heme arginate or givosiran.

Acute intermittent porphyria (AIP) is a rare metabolic disease caused by mutations within the hydroxymethylbilane synthase gene. Previous studies have reported increased levels of plasma total homocysteine (tHcy) in symptomatic AIP patients. In this study, we present long-term data for tHcy and related parameters for an AIP patient cohort (n = 37) in different clinical disease-states. In total, 25 patients (68%) presented with hyperhomocysteinemia (HHcy; tHcy > 15 µmol/L) during the observation period. HHcy was more frequent in AIP patients with recurrent disease receiving heme arginate, than in nonrecurrent (median tHcy: 21.6 µmol/L; range: 10-129 vs median tHcy: 14.5 µmol/L; range 6-77). Long-term serial analyses showed a high within-person tHcy variation, especially among the recurrent patients (coefficient of variation: 16.4%-78.8%). HHcy was frequently associated with low blood concentrations of pyridoxal-5'-phosphate and folate, while cobalamin concentration and the allele distribution of the methylene-tetrahydrofolate-reductase gene were normal. Strikingly, 6 out of the 9 recurrent patients who were later included in a regime of givosiran, a small-interfering RNA that effectively reduced recurrent attacks, showed further increased tHcy (median tHcy in 9 patients: 105 µmol/L; range 16-212). Screening of amino acids in plasma by liquid-chromatography showed co-increased levels of methionine (median 71 µmol/L; range 23-616; normal <40), suggestive of acquired deficiency of cystathionine-ß-synthase. The kynunerine/tryptophan ratio in plasma was, however, normal, indicating a regular metabolism of tryptophan by heme-dependent enzymes. In conclusion, even if HHcy was observed in AIP patients receiving heme arginate, givosiran induced an aggravation of the dysregulation, causing a co-increase of tHcy and methionine resembling classic homocystinuria.

Unexpected findings before hospital discharge in a patient implanted with a dual-chamber pacemaker.

A case of a patient implanted with a dual-chamber pacemaker in which routine ECG before discharge shown unexpected findings.