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Cytosine base editors have been reported to induce off-target mutations in DNA and RNA. Here the authors identify next-generation CBEs with reduced guide-independent off-target editing profiles and retain high on-target editing activity.

Metachromatic leukodystrophy (MLD) is a human neurodegenerative disorder characterized by progressive damage on the myelin band in the nervous system. MLD is caused by the impaired function of the lysosomal enzyme Arylsulphatase A (ARSA). The physiopathology mechanisms and the biochemical consequences in the brain of ARSA deficiency are not entirely understood. In recent years, the use of genome-scale metabolic (GEM) models has been explored as a tool for the study of the biochemical alterations in MLD. Previously, we modeled the metabolic consequences of different lysosomal storage diseases using single GEMs. In the case of MLD, using a glia GEM, we previously predicted that the metabolism of glycosphingolipids and neurotransmitters was altered. The results also suggested that mitochondrial metabolism and amino acid transport were the main reactions affected. In this study, we extended the modeling of the metabolic consequences of ARSA deficiency through the integration of neuron and glial cell metabolic models. Cell-specific models were generated from Recon2, and these were used to create a neuron-glial bi-cellular model. We propose a workflow for the integration of this type of model and its subsequent study. The results predicted the impairment pathways involved in the transport of amino acids, lipids metabolism, and catabolism of purines and pyrimidines. The use of this neuron-glial GEM metabolic reconstruction allowed to improve the prediction capacity of the metabolic consequences of ARSA deficiency, which might pave the way for the modeling of the biochemical alterations of other inborn errors of metabolism with central nervous system involvement.

The Sechium P. Br. genus composed of 11 species, which originated from the mountainous regions of Mesoamerica, have been domesticated and diversified. These species are clustered in two large groups: the Mexican clade and the Central American clade. Morphological and molecular studies have shown that species of the Mexican clade are formed through interspecific hybridizations and genetic flow, with the exception of S. mexicanum, which is strongly linked to the genus Sicyos. The objective of this review was to analyze the phylogenetics of Sechium based on morphological and molecular studies, which contributed to taxonomic knowledge and utilization, thereby favoring its conservation and improvement. The Central American clade is well supported with molecular data, but not so with morphological data. The species in this clade were geographically isolated and endemic. S. edule and S. tacaco are exploited species in the agricultural and industrial sectors, and both have an extensive genetic and phenotypic diversity that has allowed them to diversify and expand into different ecological niches. Finally, the Central American species of Sechium thrive in adverse environments of temperatures of mesophyll forest and high relative humidity, with characteristics that can give resistance to frosts and phytopathogenic agents, as well as cultivated species of this genus.

Abstract Background Tay-Sachs disease (TSD) is a rare neurodegenerative disorder caused by autosomal recessive mutations in the HEXA gene on chromosome 15 that encodes β-hexosaminidase. Deficiency in HEXA results in accumulation of GM2 ganglioside, a glycosphingolipid, in lysosomes. Currently, there is no effective treatment for TSD. Results We generated induced pluripotent stem cells (iPSCs) from two TSD patient dermal fibroblast lines and further differentiated them into neural stem cells (NSCs). The TSD neural stem cells exhibited a disease phenotype of lysosomal lipid accumulation. The Tay-Sachs disease NSCs were then used to evaluate the therapeutic effects of enzyme replacement therapy (ERT) with recombinant human Hex A protein and two small molecular compounds: hydroxypropyl-β-cyclodextrin (HPβCD) and δ-tocopherol. Using this disease model, we observed reduction of lipid accumulation by employing enzyme replacement therapy as well as by the use of HPβCD and δ-tocopherol. Conclusion Our results demonstrate that the Tay-Sachs disease NSCs possess the characteristic phenotype to serve as a cell-based disease model for study of the disease pathogenesis and evaluation of drug efficacy. The enzyme replacement therapy with recombinant Hex A protein and two small molecules (cyclodextrin and tocopherol) significantly ameliorated lipid accumulation in the Tay-Sachs disease cell model.

Abstract The use of specialized centers has been the main alternative for an appropriate diagnosis, management and follow up of patients affected by inborn errors of metabolism (IEM). These centers facilitate the training of different professionals, as well as the research at basic, translational and clinical levels. Nevertheless, few reports have described the experience of these centers and their local and/or global impact in the study of IEM. In this paper, we describe the experience of a Colombian reference center for the research, diagnosis, training and education on IEM. During the last 20 years, important advances have been achieved in the clinical knowledge of these disorders, as well as in the local availability of several diagnosis tests. Organic acidurias have been the most frequently detected diseases, followed by aminoacidopathies and peroxisomal disorders. Research efforts have been focused in the production of recombinant proteins in microorganisms towards the development of new enzyme replacement therapies, the design of gene therapy vectors and the use of bioinformatics tools for the understanding of IEM. In addition, this center has participated in the education and training of a large number professionals at different levels, which has contributed to increase the knowledge and divulgation of these disorders along the country. Noteworthy, in close collaboration with patient advocacy groups, we have participated in the discussion and construction of initiatives for the inclusion of diagnosis tests and treatments in the health system.

A rigorous understanding of off-target effects is necessary for SaCas9 to be used in therapeutic genome editing. Here the authors measure SaCas9 mismatch tolerance across a pairwise library screen of 88,000 guides and targets in human cells and develop a model which ranks off-target sites.

Abstract Background Understanding the diversity of repair outcomes after introducing a genomic cut is essential for realizing the therapeutic potential of genomic editing technologies. Targeted PCR amplification combined with Next Generation Sequencing (NGS) or enzymatic digestion, while broadly used in the genome editing field, has critical limitations for detecting and quantifying structural variants such as large deletions (greater than approximately 100 base pairs), inversions, and translocations. Results To overcome these limitations, we have developed a Uni-Directional Targeted Sequencing methodology, UDiTaS, that is quantitative, removes biases associated with variable-length PCR amplification, and can measure structural changes in addition to small insertion and deletion events (indels), all in a single reaction. We have applied UDiTaS to a variety of samples, including those treated with a clinically relevant pair of S. aureus Cas9 single guide RNAs (sgRNAs) targeting CEP290, and a pair of S. pyogenes Cas9 sgRNAs at T-cell relevant loci. In both cases, we have simultaneously measured small and large edits, including inversions and translocations, exemplifying UDiTaS as a valuable tool for the analysis of genome editing outcomes. Conclusions UDiTaS is a robust and streamlined sequencing method useful for measuring small indels as well as structural rearrangements, like translocations, in a single reaction. UDiTaS is especially useful for pre-clinical and clinical application of gene editing to measure on- and off-target editing, large and small.

CRISPR-Cas9 has rapidly become a common molecular biology tool for modifying genomes and has been modified to generate single-strand nicks as well as double-strand breaks. Here the authors explore the DNA repair pathways activated by the different variants of Cas9.

Background: Mucopolysaccharidoses (MPS) are a group of inherited metabolic diseases caused by impaired function or absence of lysosomal enzymes involved in degradation of glycosaminoglycans. Clinically, MPS are skeletal dysplasias, characterized by cartilage abnormalities and disturbances in the process of endochondral ossification. Histologic abnormalities of growth cartilage have been reported at advanced stages of the disease, but information regarding growth plate pathology progression either in humans or in animal models, as well as its pathophysiology, is limited. Methods: Histological analyses of distal femur growth plates of wild type (WT) and mucopolysaccharidosis type VI (MPS VI) rats at different stages of development were performed, including quantitative data. Experimental findings were then analyzed in a theoretical scenario. Results: Histological evaluation showed a progressive loss of histological architecture within the growth plate. Furthermore, in silico simulation suggest the abnormal cell distribution in the tissue may lead to alterations in biochemical gradients, which may be one of the factors contributing to the growth plate abnormalities observed, highlighting aspects that must be the focus of future experimental works. Conclusion: The results presented shed some light on the progression of growth plate alterations observed in MPS VI and evidence the potentiality of combined theoretical and experimental approaches to better understand pathological scenarios, which is a necessary step to improve the search for novel therapeutic approaches.

The nuclear factor κB (NF-κΒ) subunits RelA, RelB, cRel, p50, and p52 are each critical for B cell development and function. To systematically characterize their responses to canonical and noncanonical NF-κB pathway activity, we performed chromatin immunoprecipitation followed by high-throughput DNA sequencing (ChIP-seq) analysis in lymphoblastoid B cell lines (LCLs). We found a complex NF-κB-binding landscape, which did not readily reflect the two NF-κB pathway paradigms. Instead, 10 subunit-binding patterns were observed at promoters and 11 at enhancers. Nearly one-third of NF-κB-binding sites lacked κB motifs and were instead enriched for alternative motifs. The oncogenic forkhead box protein FOXM1 co-occupied nearly half of NF-κB-binding sites and was identified in protein complexes with NF-κB on DNA. FOXM1 knockdown decreased NF-κB target gene expression and ultimately induced apoptosis, highlighting FOXM1 as a synthetic lethal target in B cell malignancy. These studies provide a resource for understanding mechanisms that underlie NF-κB nuclear activity and highlight opportunities for selective NF-κB blockade.

Arid and semi-arid areas are highly productive ecosystems that have a great diversity of species, among which grasses stand out. These species have ecological, environmental, and economic importance. The objective was to identify the ecological descriptors of 15 native species of grasses and diversity patterns through multivariate analysis techniques (principal component analysis, PCA, and cluster analysis, CA), in addition to identifying potential distribution areas (current and future) and regions of high and low diversity from 3841 accessions and 21 climatic variables. Among the main results, the extreme values, coefficient of variation, and median for each species could be determined. PCA determined that, with 10 variables, it was possible to explain 54.36% of the variation between the analyzed species. CA resulted in the formation of four statistically significant groups, with specific climatic characteristics. Regarding potential distribution areas and climate change, a reduction in distribution is expected (2050) on most of the current surface, with a possible opportunity zone in the north of the country. Finally, two hotspots (high diversity areas) and four coldspots (low diversity areas) were identified among the analyzed species. These results can be used to create strategies for sustainable use and the conservation of these resources.

The original HTML version of this Article incorrectly listed an affiliation of Josh Tycko as ‘Department of Genetics, Stanford University School of Medicine, Stanford, CA 94305, USA’, instead of the correct ‘Present address: Department of Genetics, Stanford University School of Medicine, Stanford, CA 94305, USA’. It also incorrectly listed an affiliation of this author as ‘Present address: Arrakis Therapeutics, 35 Gatehouse Dr., Waltham, MA, 02451, USA’.The original HTML version incorrectly listed an affiliation of Luis A. Barrera as ‘Present address: Department of Molecular Biophysics and Biochemistry, Yale University, New Haven, CT, 06511, USA’, instead of the correct ‘Present address: Arrakis Therapeutics, 35 Gatehouse Dr., Waltham, MA 02451, USA’.Finally, the original HTML version incorrectly omitted an affiliation of Nicholas C. Huston: ‘Present address: Department of Molecular Biophysics and Biochemistry, Yale University, New Haven, CT 06511, USA’.This has been corrected in the HTML version of the Article. The PDF version was correct from the time of publication.

Introducción. El síndrome de Hunter o mucopolisacaridosis tipo II (MC KUSIK 309900) es causado por la deficiencia de la iduronato 2-sulfato sulfatasa humana (E.C. 3.1.6.13). La enzima no ha sido cristalizada y por tanto sus estructuras no se conocen por deducción experimental. Objetivo. Proponer un modelo computacional para la estructura tridimensional de la iduronato 2-sulfato sulfatasa humana. Materiales y métodos. Se realizó un análisis computacional de esta enzima empleando programas de libre acceso en internet como Comput pI/MW, JaMBW Chapter 3.1.7, SWISSMODEL, 3D-PSSM, ProSup. Los procesos de minimización de energía se realizaron con el programa Discover 3 del paquete Insight II (2004). Resultados. Se propone un modelo tridimensional de la iduronato 2-sulfato sulfatasa humana que presenta 33,3% en hélice, 7,2% en hoja plegada y 59,5% en enrollamiento al azar (coil). Se hallaron valores de RMS (del inglés Root Mean Square) de 0,78 y 0,86Å al compararla con otras enzimas de la misma familia. El modelo revela cinco sitios potenciales de N-glicosilación y una entrada al bolsillo que contiene los aminoácidos que componen el sitio activo. Usando este modelo se encontró una buena correlación entre el tipo de mutaciones y la gravedad de la enfermedad en 20 pacientes analizados. Conclusión. Los valores de RMS y la correlación genotipo-fenotipo en los pacientes analizados sugieren el modelo puede usarse para predecir ciertos aspectos del comportamiento biológico de la enzima.

Introducción. La enfermedad de Hunter es un trastorno lisosómico caracterizado por la deficiencia de la enzima iduronato-2-sulfato sulfatasa (IDS) (EC 3.1.6.13). Esta enfermedad, al igual que muchos trastornos metabólicos, son patologías intratables mediante la terapéutica convencional; sin embargo, existe la posibilidad de ser tratada alternativamente mediante terapia génica o terapia de reemplazo enzimático. Objetivo. El Instituto de Errores Innatos del Metabolismo (IEIM) ha desarrollado un sistema de expresión de sulfatasas para producir IDS humana recombinante (IDShr) en Escherichia coli y Pichia pastoris, con resultados favorables. El objetivo principal de este trabajo fue desarrollar un sistema de detección de IDS humana recombinante. Materiales y métodos. Para el efecto, se inmunizaron con IDS comercial de TKT (Cambridge, MA) dos conejos de raza Nueva Zelanda blanca y los anticuerpos purificados a partir del suero se utilizaron en el desarrollo de una técnica semicuantitativa por dot-blot. Diferentes muestras de extractos crudos de fermentaciones con P. pastoris y E. coli se procesaron con el fin de poder determinar la presencia de la enzima. Resultados. Se demostró que los anticuerpos eran específicos en el reconocimiento de la IDS sin presentar reactividad cruzada con proteínas contaminantes de los extractos crudos. Conclusión. Por consiguiente, los anticuerpos se podrán usar en el desarrollo de una técnica ELISA tipo sandwich como método de detección y cuantificación de la enzima y en procesos de purificación de la misma mediante cromatografía de afinidad.

Background: Azo pigments are widely used in the textile and leather industry, and they generate diverse contaminants (mainly in wastewater effluents) that affect biological systems, the rhizosphere community, and the natural activities of certain species. Methods: This review was performed according to the Systematic Reviews and Meta Analyses (PRISMA) methodology. Results: In the last decade, the use of Streptomyces species as biological azo-degraders has increased, and these bacteria are mainly isolated from mangroves, dye-contaminated soil, and marine sediments. Azo pigments such as acid orange, indigo carmine, Congo red, and Evans blue are the most studied compounds for degradation, and Streptomyces produces extracellular enzymes such as peroxidase, laccase, and azo reductase. These enzymes cleave the molecule through asymmetric cleavage, followed by oxidative cleavage, desulfonation, deamination, and demethylation. Typically, some lignin-derived and phenolic compounds are used as mediators to improve enzyme activity. The degradation process generates diverse compounds, the majority of which are toxic to human cells and, in some cases, can improve the germination process in some horticulture plants. Conclusions: Future research should include analytical methods to detect all of the molecules that are generated in degradation processes to determine the involved reactions. Moreover, future studies should delve into consortium studies to improve degradation efficiency and observe the relationship between microorganisms to generate scale-up biotechnological applications in the wastewater treatment industry.

Chronic hepatitis B virus (HBV) infection remains a global health problem due to the lack of treatments that prevent viral rebound from HBV covalently closed circular (ccc)DNA. In addition, HBV DNA integrates in the human genome, serving as a source of hepatitis B surface antigen (HBsAg) expression, which impairs anti-HBV immune responses. Cytosine base editors (CBEs) enable precise conversion of a cytosine into a thymine within DNA. In this study, CBEs were used to introduce stop codons in HBV genes, HBs and Precore. Transfection with mRNA encoding a CBE and a combination of two guide RNAs led to robust cccDNA editing and sustained reduction of the viral markers in HBV-infected HepG2-NTCP cells and primary human hepatocytes. Furthermore, base editing efficiently reduced HBsAg expression from HBV sequences integrated within the genome of the PLC/PRF/5 and HepG2.2.15 cell lines. Finally, in the HBV minicircle mouse model, using lipid nanoparticulate delivery, we demonstrated antiviral efficacy of the base editing approach with a >3log10 reduction in serum HBV DNA and >2log10 reduction in HBsAg, and 4/5 mice showing HBsAg loss. Combined, these data indicate that base editing can introduce mutations in both cccDNA and integrated HBV DNA, abrogating HBV replication and silencing viral protein expression.

Introducción. El tacrolimus es un medicamento inmunosupresor ampliamente usado en trasplante hepático, que presenta una gran variabilidad interindividual la cual se considera asociada a la frecuencia de polimorfismos de CYP3A5 y MDR-1. El objetivo de este estudio fue evaluar la frecuencia de los polimorfismos rs776746, rs2032582 y rs1045642 y su asociación con rechazo clínico y toxicidad farmacológica. Métodos. Se incluyeron pacientes inmunosuprimidos con tacrolimus a quienes se les realizó trasplante hepático en el Hospital San Vicente Fundación Rionegro entre 2020 y 2022, con supervivencia mayor a un mes. Se evaluaron las variables clínicas, rechazo agudo y toxicidad farmacológica. Se secuenciaron los genes de estudio mediante PCR, comparando la expresión o no en cada uno de los pacientes. Resultados. Se identificaron 17 pacientes. El 43 % de los pacientes se clasificaron como CYP3A5*1/*1 y CYP3A5*1/*3, entre los cuales se encontró asociación con aumento en la tasa de rechazo agudo clínico, al comparar con los pacientes no expresivos (100 % vs. 44 %, p=0,05); no hubo diferencias en cuanto a la toxicidad farmacológica u otros desenlaces. Se encontró el polimorfismo rs2032582 en un 50 % y el rs1045642 en un 23,5 % de los pacientes, sin embargo, no se identificó asociación con rechazo u otros eventos clínicos. Conclusiones. Se encontró una asociación entre el genotipo CYP3A5*1/*1 y CYP3A5*1/*3 y la tasa de rechazo clínico. Sin embargo, se requiere una muestra más amplia para validar estos datos y plantear modelos de medicina personalizada.

La levadura Pichia pastoris constituye un excelente modelo para la expresión de proteínas heterólogas, lo que se refleja en el gran número de proteínas que han sido obtenidas en este modelo biológico, bajo el control del promotor AOX1. Esto implica que el número de peroxisomas y la enzima alcohol oxidasa es regulada como respuesta a la inducción por metabolitos como el metanol, el glicerol, el etanol, el acetato y vías metabólica como la b-oxidación. En esta revisión, se discuten aspectos relacionados con el metabolismo de estos compuestos y su posible influencia en la producción de proteínas recombinantes, específicamente la Iduronato 2- sulfato sulfatasa humana (IDSh).

Tension and force propagation play a central role in tissue morphogenesis, as they enable sub- and supra-cellular shape changes required for the generation of new structures. Force is often generated by the cytoskeleton, which forms complex meshworks that reach cell–cell or cell–extracellular matrix junctions to induce cellular rearrangements. These mechanical properties can be measured through laser microdissection, which concentrates energy in the tissue of interest, disrupting its cytoskeleton. If the tissue is undergoing tension, this cut will induce a recoil in the surrounding regions of the cut. This protocol describes how one can perform laser microdissection experiments and subsequently measure the recoil speed of the sample of interest. While we explain how to carry out these experiments in Drosophila embryos, the recoil calibration and downstream analyses can be applied to other types of preparations. Key features• Allows measuring tension in live Drosophila embryos with a relatively simple approach. • Describes a quick way to mount a high number of embryos.• Includes a segmentation-free recoil quantification that reduces bias and speeds up analysis.Graphical overview

Currently, tuberculosis (TB) is a bacterial infection caused by Mycobacterium tuberculosis (Mtb) that primarily affects the lungs. The severity of active pulmonary TB (APTB) is an important determinant of transmission, morbidity, mortality, disease experience, and treatment outcomes. Several publications have shown a high prevalence of disabling complications in individuals who have had severe APTB. Furthermore, certain strains of Mtb were associated with more severe disease outcomes. The use of biomarkers to predict severe APTB patients who are candidates for host-directed therapies, due to the high risk of developing post-tuberculous lung disease (PTLD), has not yet been implemented in the management of TB patients. We followed 108 individuals with APTB for 6 months using clinical tools, flow cytometry, and whole-genome sequencing (WGS). The median age of the study population was 26.5 years, and the frequency of women was 53.7%. In this study, we aimed to identify biomarkers that could help us to recognize individuals with APTB and improve our understanding of the immunopathology in these individuals. In this study, we conducted a follow-up on the treatment progress of 121 cases of APTB. The follow-up process commenced at the time of diagnosis (T0), continued with a control visit at 2 months (T2), and culminated in an exit appointment at 6 months following the completion of medical treatment (T6). People classified with severe APTB showed significantly higher levels of IL-6 (14.7 pg/mL; p < 0.05) compared to those with mild APTB (7.7 pg/mL) at T0. The AUCs for the ROC curves and the Matthews correlation coefficient values (MCC) demonstrate correlations ranging from moderate to very strong. We conducted WGS on 88 clinical isolates of Mtb, and our analysis revealed a total of 325 genes with insertions and deletions (Indels) within their coding regions when compared to the Mtb H37Rv reference genome. The pattern of association was found between serum levels of CHIT1 and the presence of Indels in Mtb isolates from patients with severe APTB. A key finding in our study was the high levels of CHIT1 in severe APTB patients. We identified a biomarker profile (IL-6, IFN-γ, IL-33, and CHIT1) that allows us to identify individuals with severe APTB, as well as the identification of a panel of polymorphisms (125) in clinical isolates of Mtb from individuals with severe APTB. Integrating these findings into a predictive model of severity would show promise for the management of APTB patients in the future, to guide host-directed therapy and reduce the prevalence of PTLD.

Por definición, la colitis actínica incluye cambios inflamatorios de la mucosa colorrectal secundarios a radioterapia en cercanía a la región tratada. La localización más frecuente es el recto y la indicación más común de radioterapia corresponde a neoplasias de la región pélvica incluidos el recto, la próstata y el cérvix. Se estima que hasta la mitad de los pacientes que reciben radiación pélvica llega a desarrollar síntomas gastrointestinales asociados. Se presentan dos pacientes con metástasis óseas sacroilíacas y pélvicas secundarias a adenocarcinoma de próstata que recibieron radiación en la región lumbosacra y pélvica, ambos pacientes presentaron episodios de deposiciones con sangre que iniciaron tempranamente posterior a la radioterapia. La colonoscopia mostró eritema y ulceración. En el estudio histopatológico se observó un patrón de colitis isquémica, con núcleo y citomegalia, estroma fibroso con cambios reactivos y abundante infiltrado inflamatorio neutrofílico. Estos hallazgos son característicos de la colitis actínica aguda; sin embargo, la localización cecal no ha sido frecuentemente reportada. Aunque al ser el ciego y el íleon terminal móviles de localización pélvica, se convierten en un factor de riesgo para que estos segmentos anatómicos sean susceptibles al impacto directo de la radioterapia. Esta condición, en la fase aguda, es autolimitada y se suele resolver con medidas de soporte. Es indispensable que el personal involucrado en el manejo de estos pacientes conozca esta entidad y los posibles diagnósticos diferenciales.