MYC promotes tryptophan uptake and metabolism by the kynurenine pathway in colon cancer.

Tumors display increased uptake and processing of nutrients to fulfill the demands of rapidly proliferating cancer cells. Seminal studies have shown that the proto-oncogene MYC promotes metabolic reprogramming by altering glutamine uptake and metabolism in cancer cells. How MYC regulates the metabolism of other amino acids in cancer is not fully understood. Using high-performance liquid chromatography (HPLC)-tandem mass spectrometry (LC-MS/MS), we found that MYC increased intracellular levels of tryptophan and tryptophan metabolites in the kynurenine pathway. MYC induced the expression of the tryptophan transporters SLC7A5 and SLC1A5 and the enzyme arylformamidase (AFMID), involved in the conversion of tryptophan into kynurenine. SLC7A5, SLC1A5, and AFMID were elevated in colon cancer cells and tissues, and kynurenine was significantly greater in tumor samples than in the respective adjacent normal tissue from patients with colon cancer. Compared with normal human colonic epithelial cells, colon cancer cells were more sensitive to the depletion of tryptophan. Blocking enzymes in the kynurenine pathway caused preferential death of established colon cancer cells and transformed colonic organoids. We found that only kynurenine and no other tryptophan metabolite promotes the nuclear translocation of the transcription factor aryl hydrocarbon receptor (AHR). Blocking the interaction between AHR and kynurenine with CH223191 reduced the proliferation of colon cancer cells. Therefore, we propose that limiting cellular kynurenine or its downstream targets could present a new strategy to reduce the proliferation of MYC-dependent cancer cells.

The aryl hydrocarbon receptor regulates nucleolar activity and protein synthesis in MYC-expressing cells.

MYC enhances protein synthesis by regulating genes involved in ribosome biogenesis and protein translation. Here, we show that MYC-induced protein translation is mediated by the transcription factor aryl hydrocarbon receptor (AHR), which is induced by MYC in colonic cells. AHR promotes protein synthesis by activating the transcription of genes required for ribosome biogenesis and protein translation, including OGFOD1 and NOLC1. Using surface sensing of translation (SUnSET) to measure global protein translation, we found that silencing AHR or its targets diminishes protein synthesis. Therefore, targeting AHR or its downstream pathways could provide a novel approach to limit biomass production in MYC-driven tumors.

Nucleolar stress: From development to cancer.

The nucleolus is a large nuclear membraneless organelle responsible for ribosome biogenesis. Ribosomes are cytoplasmic macromolecular complexes comprising RNA and proteins that link amino acids together to form new proteins. The biogenesis of ribosomes is an intricate multistep process that involves the transcription of ribosomal DNA (rDNA), the processing of ribosomal RNA (rRNA), and the assembly of rRNA with ribosomal proteins to form active ribosomes. Nearly all steps necessary for ribosome production and maturation occur in the nucleolus. Nucleolar shape, size, and number are directly linked to ribosome biogenesis. Errors in the steps of ribosomal biogenesis are sensed by the nucleolus causing global alterations in nucleolar function and morphology. This phenomenon, known as nucleolar stress, can lead to molecular changes such as stabilization of p53, which in turn activates cell cycle arrest or apoptosis. In this review, we discuss recent work on the association of nucleolar stress with degenerative diseases and developmental defects. In addition, we highlight the importance of de novo nucleotide biosynthesis for the enhanced nucleolar activity of cancer cells and discuss targeting nucleotide biosynthesis as a strategy to activate nucleolar stress to specifically target cancer cells.

ZNF692 regulates nucleolar morphology by interacting with NPM1 and modifying its self-assembly properties.

The nucleolus, a membrane-less organelle, is responsible for ribosomal RNA transcription, ribosomal RNA processing, and ribosome assembly. Nucleolar size and number are indicative of a cell's protein synthesis rate and proliferative capacity, and abnormalities in the nucleolus have been linked to neurodegenerative diseases and cancer. In this study, we demonstrated that the nucleolar protein ZNF692 directly interacts with nucleophosmin 1 (NPM1). Knocking down ZNF692 resulted in the nucleolar redistribution of NPM1 in ring-like structures and reduced protein synthesis. Purified NPM1 forms spherical condensates in vitro but mixing it with ZNF692 produces irregular condensates more closely resembling living cell nucleoli. Our findings indicate that ZNF692, by interacting with NPM1, plays a critical role in regulating nucleolar architecture and function in living cells.

The AHR target gene scinderin activates the WNT pathway by facilitating the nuclear translocation of ß-catenin.

The ligand-activated transcription factor aryl hydrocarbon receptor (AHR) regulates cellular detoxification, proliferation and immune evasion in a range of cell types and tissues, including cancer cells. In this study, we used RNA-sequencing to identify the signature of the AHR target genes regulated by the pollutant 2,3,7,8-tetrachlorodibenzodioxin (TCDD) and the endogenous ligand kynurenine (Kyn), a tryptophan-derived metabolite. This approach identified a signature of six genes (CYP1A1, ALDH1A3, ABCG2, ADGRF1 and SCIN) as commonly activated by endogenous or exogenous ligands of AHR in multiple colon cancer cell lines. Among these, the actin-severing protein scinderin (SCIN) was necessary for cell proliferation; SCIN downregulation limited cell proliferation and its expression increased it. SCIN expression was elevated in a subset of colon cancer patient samples, which also contained elevated ß-catenin levels. Remarkably, SCIN expression promoted nuclear translocation of ß-catenin and activates the WNT pathway. Our study identifies a new mechanism for adhesion-mediated signaling in which SCIN, likely via its ability to alter the actin cytoskeleton, facilitates the nuclear translocation of ß-catenin. This article has an associated First Person interview with the first authors of the paper.

Can the Dose of Belimumab be Reduced in Patients with Systemic Lupus Erythematosus?

OBJECTIVES: The aims of this study were to investigate the prevalence of dose reduction in patients with SLE treated with belimumab (BEL) in Spain, analyze treatment modalities, and determine impact on control of disease activity. METHODS: Retrospective longitudinal and multicentre study of SLE patients treated with BEL. Data on disease activity, treatments and outcomes were recorded before and after reduction (6-12 months), and they were compared. RESULTS: A total of 324 patients were included. The dose was reduced in 29 patients (8.9%). The dosing interval was increased in 9 patients receiving subcutaneous BEL and in 6 patients receiving intravenous BEL. The dose per administration was reduced in 16 patients.Pre-reduction status was remission (2021 DORIS) in 15/26 patients (57.7%) and LLDAS in 23/26 patients (88.5%). After reduction, 2/24 patients (8.3%) and 3/22 patients (13.6%) lost remission at 6 months and 12 months, respectively (not statistically significant [NS]). As for LLDAS, 2/23 patients (8.7%) and 2/21 patients (9.5%) lost their status at 6 and 12 months, respectively (NS). Significantly fewer patients were taking glucocorticoids (GCs) at their 12-month visit, although the median dose of GCs was higher at the 12-month visit (5 [0.62-8.75] vs 2.5 [0-5] at baseline). CONCLUSION: Doses of BEL can be reduced with no relevant changes in disease activity-at least in the short term-in a significant percentage of patients, and most maintain the reduced dose. However, increased clinical or serologic activity may be observed in some patients. Consequently, tighter post-reduction follow-up is advisable.

Radiological characterization of the tailings of an abandoned copper mine using a neural network and geostatistical analysis through the Co-Kriging method.

The radiological characterization of soil contaminated with natural radionuclides enables the classification of the area under investigation, the optimization of laboratory measurements, and informed decision-making on potential site remediation. Neural networks (NN) are emerging as a new candidate for performing these tasks as an alternative to conventional geostatistical tools such as Co-Kriging. This study demonstrates the implementation of a NN for estimating radiological values such as ambient dose equivalent (H*(10)), surface activity and activity concentrations of natural radionuclides present in a waste dump of a Cu mine with a high level of natural radionuclides. The results obtained using a NN were compared with those estimated by Co-Kriging. Both models reproduced field measurements equivalently as a function of spatial coordinates. Similarly, the deviations from the reference concentration values obtained in the output layer of the NN were smaller than the deviations obtained from the multiple regression analysis (MRA), as indicated by the results of the root mean square error. Finally, the method validation showed that the estimation of radiological parameters based on their spatial coordinates faithfully reproduced the affected area. The estimation of the activity concentrations was less accurate for both the NN and MRA; however, both methods gave statistically comparable results for activity concentrations obtained by gamma spectrometry (Student's t-test and Fisher's F-test).

Nautilus Flap and Bullfighter Crutch Flap for the Repair of Periorificial Surgical Defects of the Face. / Colgajo nautilus y colgajo en muleta taurina para defectos quirúrgicos faciales periorificiales.

BACKGROUND: Reconstruction of surgical defects located close to eyelid edges, nostrils, or the mouth is challenging, as tension generated by direct closure or skin flaps in these sensitive regions tends to cause distortion. New repair techniques that prevent retraction may significantly improve outcomes. PATIENTS AND METHODS: Retrospective study of the use of 2 novel flap designs-the nautilus flap and the bullfighter crutch flap-to repair surgical defects in the peripalpebral, perivestibular, nasal, and perioral areas. The nautilus flap was used to repair 4 peripalpebral defects and 2 perioral defects, and the bullfighter crutch flap to repair 14 nasal ala defects. RESULTS: Cosmetic and functional outcomes were very satisfactory in all 20 patients, with no cases of ectropion, nasal vestibule collapse, or labial asymmetry. Necrosis did not occur in any of the cases. CONCLUSIONS: The nautilus and bullfighter crutch flaps appear to be excellent choices for reconstructing surgical defects in periorificial areas.

[Translated article] Nautilus Flap and Bullfighter Crutch Flap for the Repair of Periorificial Surgical Defects of the Face.

BACKGROUND: Reconstruction of surgical defects located close to eyelid edges, nostrils, or the mouth is challenging, as tension generated by direct closure or skin flaps in these sensitive regions tends to cause distortion. New repair techniques that prevent retraction may significantly improve outcomes. PATIENTS AND METHODS: Retrospective study of the use of 2 novel flap designs-the nautilus flap and the bullfighter crutch flap-to repair surgical defects in the peripalpebral, perivestibular, nasal, and perioral areas. The nautilus flap was used to repair 4 peripalpebral defects and 2 perioral defects, and the bullfighter crutch flap to repair 14 nasal ala defects. RESULTS: Cosmetic and functional outcomes were very satisfactory in all 20 patients, with no cases of ectropion, nasal vestibule collapse, or labial asymmetry. Necrosis did not occur in any of the cases. CONCLUSIONS: The nautilus and bullfighter crutch flaps appear to be excellent choices for reconstructing surgical defects in periorificial areas.

Increased risk of group B streptococcal sepsis and meningitis in HIV-exposed uninfected infants in a high-income country.

The purpose of this study is to compare group B Streptococcus (GBS) infection incidence in HIV-exposed uninfected (HEU) and HIV-unexposed (HU) infants in a Spanish cohort. We conducted a retrospective study in 5 hospitals in Madrid (Spain). Infants ≤ 90 days of life with a GBS infection were included from January 2008 to December 2017. Incidence of GBS infection in HEU and HU children was compared. HEU infants presented a sevenfold greater risk of GBS infection and a 29-fold greater risk of GBS meningitis compared to HU, with statistical significance. Early-onset infection was tenfold more frequent in HEU children, with statistical significance, and late-onset infection was almost fivefold more frequent in the HUE infants' group, without statistical significance. CONCLUSION: HEU infants presented an increased risk of GBS sepsis and meningitis. One in each 500 HEU infants of our cohort had a central nervous system infection and 1 in each 200, a GBS infection. Although etiological causes are not well understood, this should be taken into account by physicians when attending this population. WHAT IS KNOWN: • HIV-exposed uninfected infants are at higher risk of severe infections. • An increased susceptibility of these infants to group B Streptococcus infections has been described in low- and high-income countries, including a higher risk of meningitis in a South African cohort. WHAT IS NEW: • Group B Streptococcal meningitis is more frequent in HIV-exposed uninfected infants also in high-income countries. • Physicians should be aware of this increased risk when attending these infants.

Inhibition of the de novo pyrimidine biosynthesis pathway limits ribosomal RNA transcription causing nucleolar stress in glioblastoma cells.

Glioblastoma is the most common and aggressive type of cancer in the brain; its poor prognosis is often marked by reoccurrence due to resistance to the chemotherapeutic agent temozolomide, which is triggered by an increase in the expression of DNA repair enzymes such as MGMT. The poor prognosis and limited therapeutic options led to studies targeted at understanding specific vulnerabilities of glioblastoma cells. Metabolic adaptations leading to increased synthesis of nucleotides by de novo biosynthesis pathways are emerging as key alterations driving glioblastoma growth. In this study, we show that enzymes necessary for the de novo biosynthesis of pyrimidines, DHODH and UMPS, are elevated in high grade gliomas and in glioblastoma cell lines. We demonstrate that DHODH's activity is necessary to maintain ribosomal DNA transcription (rDNA). Pharmacological inhibition of DHODH with the specific inhibitors brequinar or ML390 effectively depleted the pool of pyrimidines in glioblastoma cells grown in vitro and in vivo and impaired rDNA transcription, leading to nucleolar stress. Nucleolar stress was visualized by the aberrant redistribution of the transcription factor UBF and the nucleolar organizer nucleophosmin 1 (NPM1), as well as the stabilization of the transcription factor p53. Moreover, DHODH inhibition decreased the proliferation of glioblastoma cells, including temozolomide-resistant cells. Importantly, the addition of exogenous uridine, which reconstitutes the cellular pool of pyrimidine by the salvage pathway, to the culture media recovered the impaired rDNA transcription, nucleolar morphology, p53 levels, and proliferation of glioblastoma cells caused by the DHODH inhibitors. Our in vivo data indicate that while inhibition of DHODH caused a dramatic reduction in pyrimidines in tumor cells, it did not affect the overall pyrimidine levels in normal brain and liver tissues, suggesting that pyrimidine production by the salvage pathway may play an important role in maintaining these nucleotides in normal cells. Our study demonstrates that glioblastoma cells heavily rely on the de novo pyrimidine biosynthesis pathway to generate ribosomal RNA (rRNA) and thus, we identified an approach to inhibit ribosome production and consequently the proliferation of glioblastoma cells through the specific inhibition of the de novo pyrimidine biosynthesis pathway.

Plasma Rich in Growth Factors as an Adjuvant Treatment for the Management of Frontal Fibrosing Alopecia: A Retrospective Observational Clinical Study.

BACKGROUND: Frontal fibrosing alopecia (FFA) is a scarring alopecia in which the exact etiopathogenesis has not been completely elucidated and the available treatments are not very effective. Plasma rich in growth factors (PRGF) has shown to induce folliculogenesis in hair loss related disorders. However, the scientific evidence when facing FFA is scarce. OBJECTIVES: The aim of this study was to retrospectively analyze the adjuvant use of PRGF compared to the conventional treatment in the management of FFA. METHODS: Participants with clinically diagnosed FFA who had been treated with either conventional therapy (Control Group) or conventional therapy combined with PRGF (PRGF Group) were identified from the center's medical records. The clinical assessment was based on the "Frontal Fibrosing Alopecia Severity Score" (FFASS), which was fulfilled during a period of two and 4 years. RESULTS: This study included 118 patients with clinically diagnosed FFA (Control Group: 57 and PRGF Group: 61). No adverse effects related to the treatments were observed. Both treatments showed to halt the steady progression of hair loss compared to baseline. PRGF treatment also induced significant hair regrowth compared to the Control Group. The scalp inflammation was reduced in response to treatments. The FFASS score indicated that PRGF Group improved the symptoms and severity of FFA in a significant manner. CONCLUSIONS: The adjuvant use of PRGF may exert long-term beneficial effects on hair loss reduction and might reduce the symptoms and severity of FFA.

Nutritional and Nutraceutical Properties of Selected Pulses to Promote Gluten-Free Food Products.

The market for gluten-free products is increasing with an estimated 7.6% annual growth rate from 2020 to 2027. It has been reported that most gluten-free products, such as bread, cookies, and pasta, contain great amounts of simple carbohydrates and are low in fiber and protein, affecting people's health. Pulses such as common beans, chickpeas, lentils, and peas have been studied as an alternative for developing gluten-free products because of their high protein and fiber content. In addition, they contain bioactive compounds with nutraceutical properties, such as phenolics, saponins, dietary fiber, and resistant starch, among others. Most studies carried out with pulses in vitro and in vivo have displayed health benefits, proving that pulse-based food products are better than their counterparts, even those containing wheat, with proper sensory acceptance. This work reviews pulse's nutritional and nutraceutical properties to promote the development and consumption of gluten-free products and improve their formulations to promote people's health.

[Multidisciplinary approach of the sequelae one month after hospital discharge in patients with severe bilateral COVID-19 pneumonia, are there differences depending on the respiratory therapy used during admission to intensive care?] / Valoración multidisciplinar de las secuelas al mes del alta hospitalaria por neumonía grave COVID-19, ¿existen diferencias en función de la terapia respiratoria empleada durante su ingreso en Cuidados Intensivos?

Objective: To describe the sequelae one month after hospital discharge in patients who required admission to intensive care for severe COVID-19 pneumonia and to analyze the differences between those who received therapy exclusively with high-flow oxygen therapy compared to those who required invasive mechanical ventilation. Design: Cohort, prospective and observational study. Setting: Post-intensive care multidisciplinary program. Patients or participants: Patients who survived admission to the intensive care unit (ICU) for severe COVID-19 pneumonia from April 2020 to October 2021. Interventions: Inclusion in the post-ICU multidisciplinary program. Main variables of interest: Motor, sensory, psychological/psychiatric, respiratory and nutritional sequelae after hospital admission. Results: One hundred and four patients were included. 48 patients received high-flow nasal oxygen therapy (ONAF) and 56 invasive mechanical ventilation (IMV). The main sequelae found were distal neuropathy (33.9% IMV vs. 10.4% ONAF); brachial plexopathy (10.7% IMV vs. 0% ONAF); decrease in grip strength: right hand 20.67 kg (± 8.27) in VMI vs. 31.8 kg (± 11.59) in ONAF and left hand 19.39 kg (± 8.45) in VMI vs. 30.26 kg (± 12.74) in ONAF; and limited muscle balance in the lower limbs (28.6% VMI vs. 8.6% ONAF). The differences observed between both groups did not reach statistical significance in the multivariable study. Conclusions: The results obtained after the multivariate study suggest that there are no differences in the perceived physical sequelae one month after hospital discharge depending on the respiratory therapy used, whether it was high-flow nasal oxygen therapy or prolonged mechanical ventilation, although more studies are needed to be able to draw conclusions.

bESC from cloned embryos do not retain transcriptomic or epigenetic memory from somatic donor cells.

In brief: Epigenetic reprogramming after mammalian somatic cell nuclear transfer is often incomplete, resulting in low efficiency of cloning. However, gene expression and histone modification analysis indicated high similarities in transcriptome and epigenomes of bovine embryonic stem cells from in vitro fertilized and somatic cell nuclear transfer embryos. Abstract: Embryonic stem cells (ESC) indefinitely maintain the pluripotent state of the blastocyst epiblast. Stem cells are invaluable for studying development and lineage commitment, and in livestock, they constitute a useful tool for genomic improvement and in vitro breeding programs. Although these cells have been recently derived from bovine blastocysts, a detailed characterization of their molecular state is lacking. Here, we apply cutting-edge technologies to analyze the transcriptomic and epigenomic landscape of bovine ESC (bESC) obtained from in vitro fertilized (IVF) and somatic cell nuclear transfer (SCNT) embryos. bESC were efficiently derived from SCNT and IVF embryos and expressed pluripotency markers while retaining genome stability. Transcriptome analysis revealed that only 46 genes were differentially expressed between IVF- and SCNT-derived bESC, which did not reflect significant deviation in cellular function. Interrogating histone 3 lysine 4 trimethylation, histone 3 lysine 9 trimethylation, and histone 3 lysine 27 trimethylation with cleavage under targets and tagmentation, we found that the epigenomes of both bESC groups were virtually indistinguishable. Minor epigenetic differences were randomly distributed throughout the genome and were not associated with differentially expressed or developmentally important genes. Finally, the categorization of genomic regions according to their combined histone mark signal demonstrated that all bESC shared the same epigenomic signatures, especially at gene promoters. Overall, we conclude that bESC derived from SCNT and IVF embryos are transcriptomically and epigenetically analogous, allowing for the production of an unlimited source of pluripotent cells from high genetic merit organisms without resorting to transgene-based techniques.

Equilibrium and symmetries of altitudinal magnetic rotors on a circle.

Macroscopic magnets can easily be manipulated and positioned so that interactions between themselves and with external fields induce interesting dynamics and equilibrium configurations. In this work, we use rotating magnets positioned in a line or at the vertices of a regular polygon. The rotation planes of the magnets can be modified at will. The rich structure of stable and unstable configurations is dictated by symmetry and the side of the polygon. We show that both symmetric solutions and their symmetry-breaking bifurcations can be explained with group theory. Our results suggest that the predicted magnetic textures should emerge at any length scale as long as the interaction is polar, and the system is endowed with the same symmetries.

Histopathological and virological features of lung, heart and liver percutaneous tissue core biopsy in patients with COVID-19: A clinicopathological case series.

INTRODUCTION: Data on pathological changes in COVID-19 are scarce. The aim of this study was to describe the histopathological and virological findings of postmortem biopsies, and the existing clinical correlations, in people who died of COVID-19. MATERIALS AND METHODS: We performed postmortem needle core biopsies of the chest in 11 people who died of COVID-19 pneumonia. Tissue examination was done by light microscopy and real-time polymerase chain reaction (RTPCR). RESULTS: The age of the patients were between 61 to 94 years. Of the 11 postmortem chest biopsies, lung tissue was obtained in 8, myocardium tissue in 7, and liver tissue in 5. Histologically of lung, the main findings pertaining to the lung were diffuse alveolar damage in proliferative phase (n = 4, 50%), diffuse alveolar damage in exudative and proliferative phase (n = 3, 37.5%), diffuse alveolar damage in exudative (n=1; 12.5%) and acute pneumonia (n = 2, 25%). Necrotising pneumonia, acute fibrinous and organising pneumonia, and neutrophils were detected in one sample each (12.5%). Another case presented myocarditis. RT-PCR showed RNA of SARS-CoV-2 in 7 of the 8 lung samples (87.5%), 2 of the 7 myocardial tissue samples (28.6%), and 1 of the 5 liver tissue samples (20%). CONCLUSION: The postmortem examinations show diffuse alveolar damage, as well as acute or necrotising pneumonia. RT-PCR of SARS-CoV-2 was positive in most lung samples.

The transcription factors aryl hydrocarbon receptor and MYC cooperate in the regulation of cellular metabolism.

The transcription factor AHR (aryl hydrocarbon receptor) drives the expression of genes involved in detoxification pathways in cells exposed to pollutants and other small molecules. Moreover, AHR supports transcriptional programs that promote ribosome biogenesis and protein synthesis in cells stimulated to proliferate by the oncoprotein MYC. Thus, AHR is necessary for the proliferation of MYC-overexpressing cells. To define metabolic pathways in which AHR cooperates with MYC in supporting cell growth, here we used LC-MS-based metabolomics to examine the metabolome of MYC-expressing cells upon AHR knockdown. We found that AHR knockdown reduced lactate, S-lactoylglutathione, N-acetyl-l-alanine, 2-hydroxyglutarate, and UMP levels. Using our previously obtained RNA sequencing data, we found that AHR mediates the expression of the UMP-generating enzymes dihydroorotate dehydrogenase (quinone) (DHODH) and uridine monophosphate synthetase (UMPS), as well as lactate dehydrogenase A (LDHA), establishing a mechanism by which AHR regulates lactate and UMP production in MYC-overexpressing cells. AHR knockdown in glioblastoma cells also reduced the expression of LDHA (and lactate), DHODH, and UMPS but did not affect UMP levels, likely because of compensatory mechanisms in these cells. Our results indicate that AHR contributes to the regulation of metabolic pathways necessary for the proliferation of transformed cells.

The MNT transcription factor autoregulates its expression and supports proliferation in MYC-associated factor X (MAX)-deficient cells.

The MAX network transcriptional repressor (MNT) is an MXD family transcription factor of the basic helix-loop-helix (bHLH) family. MNT dimerizes with another transcriptional regulator, MYC-associated factor X (MAX), and down-regulates genes by binding to E-boxes. MAX also dimerizes with MYC, an oncogenic bHLH transcription factor. Upon E-box binding, the MYC-MAX dimer activates gene expression. MNT also binds to the MAX dimerization protein MLX (MLX), and MNT-MLX and MNT-MAX dimers co-exist. However, all MNT functions have been attributed to MNT-MAX dimers, and no functions of the MNT-MLX dimer have been described. MNT's biological role has been linked to its function as a MYC oncogene modulator, but little is known about its regulation. We show here that MNT localizes to the nucleus of MAX-expressing cells and that MNT-MAX dimers bind and repress the MNT promoter, an effect that depends on one of the two E-boxes on this promoter. In MAX-deficient cells, MNT was overexpressed and redistributed to the cytoplasm. Interestingly, MNT was required for cell proliferation even in the absence of MAX. We show that in MAX-deficient cells, MNT binds to MLX, but also forms homodimers. RNA-sequencing experiments revealed that MNT regulates the expression of several genes even in the absence of MAX, with many of these genes being involved in cell cycle regulation and DNA repair. Of note, MNT-MNT homodimers regulated the transcription of some genes involved in cell proliferation. The tight regulation of MNT and its functionality even without MAX suggest a major role for MNT in cell proliferation.

Intrathecal AAVrh10 corrects biochemical and histological hallmarks of mucopolysaccharidosis VII mice and improves behavior and survival.

Mucopolysaccharidosis (MPS) type VII is a lysosomal storage disease caused by ß-glucuronidase deficiency, prompting glycosaminoglycan accumulation in enlarged vesicles, leading to peripheral and neuronal dysfunction. Here, we present a gene therapy strategy using lumbar puncture of AAVrh10 encoding human ß-glucuronidase (AAVrh10-GUSB) to adult MPS VII mice. This minimally invasive technique efficiently delivers the recombinant vector to the cerebrospinal fluid (CSF) with a single intrathecal injection. We show that AAVrh10 delivery to the CSF allows global, stable transduction of CNS structures. In addition, drainage of AAVrh10-GUSB from the CSF to the bloodstream resulted in the transduction of somatic organs such as liver, which provided a systemic ß-glucuronidase source sufficient to achieve serum enzyme activity comparable to wild type mice. ß-glucuronidase levels were enough to correct biochemical and histopathological hallmarks of the disease in the CNS and somatic organs at short and long term. Moreover, the progression of the bone pathology was also reduced. Importantly, the biochemical correction led to a significant improvement in the physical, cognitive and emotional characteristics of MPS VII mice, and doubling their life span. Our strategy may have implications for gene therapy in patients with lysosomal storage diseases.