Meet the author: Laura Amaya.

We talk to first author Laura Amaya about her paper "Pathways for macrophage uptake of cell-free circular RNAs" (in this issue of Molecular Cell), her path to becoming a scientist, and some of the lessons she's learned along the way.

Pathways for macrophage uptake of cell-free circular RNAs.

Circular RNAs (circRNAs) are stable RNAs present in cell-free RNA, which may comprise cellular debris and pathogen genomes. Here, we investigate the phenomenon and mechanism of cellular uptake and intracellular fate of exogenous circRNAs. Human myeloid cells and B cells selectively internalize extracellular circRNAs. Macrophage uptake of circRNA is rapid, energy dependent, and saturable. CircRNA uptake can lead to translation of encoded sequences and antigen presentation. The route of internalization influences immune activation after circRNA uptake, with distinct gene expression programs depending on the route of RNA delivery. Genome-scale CRISPR screens and chemical inhibitor studies nominate macrophage scavenger receptor MSR1, Toll-like receptors, and mTOR signaling as key regulators of receptor-mediated phagocytosis of circRNAs, a dominant pathway to internalize circRNAs in parallel to macropinocytosis. These results suggest that cell-free circRNA serves as an "eat me" signal and danger-associated molecular pattern, indicating orderly pathways of recognition and disposal.

Organ- and Cell-Selective Delivery of mRNA In Vivo Using Guanidinylated Serinol Charge-Altering Releasable Transporters.

Selective RNA delivery is required for the broad implementation of RNA clinical applications, including prophylactic and therapeutic vaccinations, immunotherapies for cancer, and genome editing. Current polyanion delivery relies heavily on cationic amines, while cationic guanidinium systems have received limited attention due in part to their strong polyanion association, which impedes intracellular polyanion release. Here, we disclose a general solution to this problem in which cationic guanidinium groups are used to form stable RNA complexes upon formulation but at physiological pH undergo a novel charge-neutralization process, resulting in RNA release. This new delivery system consists of guanidinylated serinol moieties incorporated into a charge-altering releasable transporter (GSer-CARTs). Significantly, systematic variations in structure and formulation resulted in GSer-CARTs that exhibit highly selective mRNA delivery to the lung (∼97%) and spleen (∼98%) without targeting ligands. Illustrative of their breadth and translational potential, GSer-CARTs deliver circRNA, providing the basis for a cancer vaccination strategy, which in a murine model resulted in antigen-specific immune responses and effective suppression of established tumors.

Epigenetic signature and key transcriptional regulators of human antigen-specific type 1 regulatory T cells.

Human adaptive immunity is orchestrated by effector and regulatory T (Treg) cells. Natural Tregs arise in the thymus where they are shaped to recognize self-antigens, while type 1 Tregs or Tr1 cells are induced from conventional peripheral CD4 + T cells in response to peripheral antigens, such as alloantigens and allergens. Tr1 cells have been developed as a potential therapy for inducing antigen-specific tolerance, because they can be rapidly differentiated in vitro in response to a target antigen. However, the epigenetic landscape and the identity of transcription factors (TFs) that regulate differentiation, phenotype, and functions of human antigen-specific Tr1 cells is largely unknown, hindering Tr1 research and broader clinical development. Here, we reveal the unique epigenetic signature of antigen-specific Tr1 cells, and TFs that regulate their differentiation, phenotype and function. We showed that in vitro induced antigen-specific Tr1 cells are distinct both clonally and transcriptionally from natural Tregs and other conventional CD4 + T cells on a single-cell level. An integrative analysis of Tr1 cell epigenome and transcriptome identified a TF signature unique to antigen-specific Tr1 cells, and predicted that IRF4, BATF, and MAF act as their transcriptional regulators. Using functional genomics, we showed that each of these TFs play a non-redundant role in regulating Tr1 cell differentiation, suppressive function, and expression of co-inhibitory and cytotoxic proteins. By using the Tr1-specific TF signature as a molecular fingerprint, we tracked Tr1 cells in peripheral blood of recipients of allogeneic hematopoietic stem cell transplantation treated with adoptive Tr1 cell therapy. Furthermore, the same signature identified Tr1 cells in resident CD4 + T cells in solid tumors. Altogether, these results reveal the epigenetic signature and the key transcriptional regulators of human Tr1 cells. These data will guide mechanistic studies of human Tr1 cell biology and the development and optimization of adoptive Tr1 cell therapies.

Factores de predisposición genéticos y epigenéticos de los trastornos de ansiedad / Genetic and epigenetic predisposing factors of anxiety disorders

Los trastornos de ansiedad constituyen un grupo de alteraciones psicológicas y neurológicas que representan varias formas de miedo y ansiedad anormales o patológicas (Orozco & Baldares, 2012). Aun cuando alrededor del 14% de la población del planeta ha sufrido algún trastorno de ansiedad, las causas que desencadenan el mismo no son del todo claras (Posada, 2013). La aproximación clásica de los estudios para la identificación de los factores de predisposición de estos trastornos neuropsiquiátricos se ha orientado a las teorías de la personalidad como la Teoría de Eysenck (Mitchell & Kumari, 2016) y la Teoría Bio-Psicológica de la personalidad (Knyazev, Pylkova, Slobodskoj-Plusnin, Bocharov, & Ushakov, 2015). Sin embargo, a partir de estos estudios, han surgido nuevas propuestas involucrando los aspectos neuroanatómicos y neurofuncionales. La transmisión eléctrica y química de la información y como esta se asocia a distintas conductas demuestran la relevación de la regulación de la producción y recaptación de neurotransmisores en sistema nervioso central (SNC). Aunque esta regulación se encuentra directamente relacionada con la expresión genética, em tanto se han identificado ciertos genes candidatos que aportan un porcentaje a esta predisposición, estos no son totalmente determinantes. Actualmente, dado a este vacío, se ha comenzado a investigar la influencia de factores epigenéticos que en conjunto con los factores genéticos permitirían ampliar la explicación de los factores de predisposición de ciertos trastornos neuropsiquiátricos que anteriormente eran considerados de etiología ambiental

Anxiety disorders are a group of psychological and neurological disorders that represent various forms of abnormal or pathological fear and anxiety (Orozco & Baldares, 2012). Even though around 14% of the planet's population has suffered from an anxiety disorder, the causes that trigger it are not entirely clear (Posada, 2013). The classical approach of studies for the identification of the predisposing factors of these neuropsychiatric disorders has been oriented to personality theories such as the Eysenck Theory (Mitchell & Kumari, 2016) and the Bio-Psychological Theory of Personality (Knyazev, Pylkova, Slobodskoj-Plusnin, Bocharov, & Ushakov, 2015). However, from these studies, new proposals involving neuroanatomical and neurofunctional aspects have emerged. The electrical and chemical transmission of the information and how it is associated with different behaviors demonstrate the relief of the regulation of the production and reuptake of neurotransmitters in the central nervous system (CNS). This regulation is directly related to genetic expression, however, although certain candidate genes that contribute a percentage to this predisposition have been identified, these are not totally determinant (Montag, Reuter, Newport, Elger & Weber, 2008). Currently, given this gap, we have begun to investigate the influence of epigenetic factors that, together with genetic factors, would allow us to expand the explanation of the predisposing factors of certain neuropsychiatric disorders that were previously considered to be of environmental etiology

Hábitos de higiene bucal y caries dental en escolares de primer año de tres escuelas públicas / Oral hygiene habits and dental caries in first-grade school children of three public schools

Introducción: los factores asociados a la producción de caries en la infancia son dietéticos y ambientales. Los primeros incluyen el alto consumo de dulces y líquidos endulzados, y en los segundos se circunscriben el bajo nivel educativo, la ausencia de hábitos higiénicos y la falta de accesibilidad a los servicios de salud. Objetivo: establecer la relación entre los hábitos de higiene bucal y caries dental en escolares de primer año de primaria de tres escuelas públicas. Metodología: estudio correlacional-analítico, se aplicó una encuesta a 259 niños y a sus padres sobre hábitos de higiene bucal. Se valoró clínicamente la boca y dentadura de los infantes. La prueba de hipótesis fue con coeficiente de correlación de Pearson y análisis de regresión lineal. Resultados: la prevalencia de caries fue del 51%, la presencia de caries clase I fue mayor en escolares de la escuela de nivel socioeconómico bajo (33%). La frecuencia de cepillado dental es de dos veces o menos al día, con omisión del cepillado nocturno. Conclusiones: el consumo de dulces, aunado a la menor frecuencia de cepillado, se asoció a caries, sobre todo en la población de la escuela primaria de nivel socioeconómico bajo.

Introduction: The factors associated with the production of caries in childhood are dietary and environmental. The former include the high consumption of sweets and sweetened liquids and in the latter, the low educational level, the absence of hygienic habits and the lack of accessibility to health services are circumscribed. Objective: To establish the relationship between oral hygiene habits and dental caries in first-grade public elementary school students. Methods: Correlational-analytical study, a survey was applied to 259 children and their parents on oral hygiene habits. The mouth and teeth of the infants were clinically evaluated. The hypothesis test was with a Pearson correlation coefficient and linear regression analysis. Results: The prevalence of caries was 51%, the presence of class I caries was higher in school children of low socioeconomic level (33%). The frequency of tooth brushing is twice or less per day with omission of night brushing. Conclusions: The consumption of sweets combined with a lower frequency of brushing was associated with caries, especially in the population of the primary school of low socioeconomic status.