FMRP regulates mRNAs encoding distinct functions in the cell body and dendrites of CA1 pyramidal neurons.

Neurons rely on translation of synaptic mRNAs in order to generate activity-dependent changes in plasticity. Here, we develop a strategy combining compartment-specific crosslinking immunoprecipitation (CLIP) and translating ribosome affinity purification (TRAP) in conditionally tagged mice to precisely define the ribosome-bound dendritic transcriptome of CA1 pyramidal neurons. We identify CA1 dendritic transcripts with differentially localized mRNA isoforms generated by alternative polyadenylation and alternative splicing, including many that have altered protein-coding capacity. Among dendritic mRNAs, FMRP targets were found to be overrepresented. Cell-type-specific FMRP-CLIP and TRAP in microdissected CA1 neuropil revealed 383 dendritic FMRP targets and suggests that FMRP differentially regulates functionally distinct modules in CA1 dendrites and cell bodies. FMRP regulates ~15-20% of mRNAs encoding synaptic functions and 10% of chromatin modulators, in the dendrite and cell body, respectively. In the absence of FMRP, dendritic FMRP targets had increased ribosome association, consistent with a function for FMRP in synaptic translational repression. Conversely, downregulation of FMRP targets involved in chromatin regulation in cell bodies suggests a role for FMRP in stabilizing mRNAs containing stalled ribosomes in this compartment. Together, the data support a model in which FMRP regulates the translation and expression of synaptic and nuclear proteins within different compartments of a single neuronal cell type.

The brain has over 100 billion neurons that together form vast networks to relay electrical signals. A neuron receives electrical signals from other neurons via branch-like structures known as dendrites. The signals then travel into the cell body of the neuron. If their sum reaches a threshold, they fire a new signal through a single outgoing projection known as the axon, which is connected to the dendrites of other neurons. A single neuron has thousands of dendrites that each receive inputs from different axons, and it is thought that the strengthening and weakening of these dendritic connections enables us to learn and store memories. Dendrites are filled with molecules known as messenger ribonucleic acids (mRNAs) that act as templates to make proteins. Axonal signals reaching the dendrites can trigger these mRNAs to make new proteins that strengthen or weaken the connections between the two neurons, which is believed to be necessary for generating long-term memories. A protein called FMRP is found in both the cell body and dendrites and is able to bind to and regulate the ability of mRNAs to make proteins. A loss of the gene encoding FMRP is the most common cause of inherited intellectual disability and autism in humans, but it remains unclear precisely what role this protein plays in learning and memory. Hale et al. used genetic and bioinformatics approaches to specifically study mRNAs in the dendrites and the cell body of a specific type of neuron involved in memory in mice. The experiments revealed that FMRP played different roles in the dendrites and cell body. In the dendrites, FMRP interacted with mRNAs encoding proteins that can change how the neuron responds to a signal from a neighboring neuron and may alter how strong the connections between the neurons are. On the other hand, FMRP in the cell body modulated the activities of mRNAs encoding proteins that in turn regulate the activities of genes. These findings change the way we think about how memory may work by suggesting that groups of mRNAs encoding proteins with certain activities are found in distinct parts of a single neuron. These observations offer new ways to approach intellectual disabilities and autism spectrum disorder.

DRUL for school: Opening Pre-K with safe, simple, sensitive saliva testing for SARS-CoV-2.

To address the need for simple, safe, sensitive, and scalable SARS-CoV-2 tests, we validated and implemented a PCR test that uses a saliva collection kit use at home. Individuals self-collected 300 µl saliva in vials containing Darnell Rockefeller University Laboratory (DRUL) buffer and extracted RNA was assayed by RT-PCR (the DRUL saliva assay). The limit of detection was confirmed to be 1 viral copy/µl in 20 of 20 replicate extractions. Viral RNA was stable in DRUL buffer at room temperature up to seven days after sample collection, and safety studies demonstrated that DRUL buffer immediately inactivated virus at concentrations up to 2.75x106 PFU/ml. Results from SARS-CoV-2 positive nasopharyngeal (NP) swab samples collected in viral transport media and assayed with a standard FDA Emergency Use Authorization (EUA) test were highly correlated with samples placed in DRUL buffer. Direct comparison of results from 162 individuals tested by FDA EUA oropharyngeal (OP) or NP swabs with co-collected saliva samples identified four otherwise unidentified positive cases in DRUL buffer. Over six months, we collected 3,724 samples from individuals ranging from 3 months to 92 years of age. This included collecting weekly samples over 10 weeks from teachers, children, and parents from a pre-school program, which allowed its safe reopening while at-risk pods were quarantined. In sum, we validated a simple, sensitive, stable, and safe PCR-based test using a self-collected saliva sample as a valuable tool for clinical diagnosis and screening at workplaces and schools.

Caracterización sociodemográfica, clínica y terapéutica de pacientes con falla cardiaca con fracción de eyección intermedia: cohorte MED-ICAi / Sociodemographic, clinical and therapeutic characteristics of patients with heart failure with mid-range ejection fraction: MED-ICAi cohort

Resumen Antecedentes: Clásicamente, la falla cardiaca se ha clasificado en dos grupos, según tengan fracción de eyección preservada o reducida; no obstante, en fecha reciente se ha añadido el grupo de fracción intermedia, y aún existe gran desconocimiento sobre sus características fisiopatológicas y clínicas. Objetivo: Caracterizar el grupo de pacientes con fracción intermedia en cuanto a sus variables sociodemográficas, clínicas y de tratamiento. Método: Se realizó un estudio descriptivo, retrospectivo, en el que se analizaron historias clínicas de pacientes con falla cardiaca hospitalizados por agudización en el periodo comprendido entre enero de 2015 y diciembre de 2017. Resultados: Se revisaron 1536 historias clínicas, de las cuales 864 cumplían los criterios de inclusión. El grupo con fracción intermedia correspondió a 83 (9.6%) pacientes, en quienes se encontró predominio del sexo femenino (53%) y una edad mediana de 77 años. La coronariopatía fue la etiología más frecuente (26.5%), mientras que la falta de adherencia a los medicamentos fue la causa principal de descompensación (14.5%). Los medicamentos más usados fueron los betabloqueadores y la furosemida, tanto al ingreso como al egreso. El grupo con mayor mortalidad fue el de fracción de eyección reducida (4.1%). La estancia hospitalaria, el ingreso y la estancia en la unidad de cuidados intensivos fueron similares en todos los grupos, independientemente de la fracción de eyección. Conclusiones: Los hallazgos son similares a los descritos en otras poblaciones internacionales y en algunas nacionales, y avalan la hipótesis de un fenotipo intermedio con un comportamiento etiológico semejante al de la fracción de eyección reducida.

Abstract Background: Classically, heart failure has been classified in two groups, depending on a preserved or reduced ejection fraction, but a mid-range ejection fraction group has been introduced recently, and there is still great ignorance about its physiopathological and clinical characteristics. Objective: To characterize this group of patients as for their sociodemographic, clinical and treatment variables. Method: We carried out a descriptive, retrospective study, by analyzing medical records from patients hospitalized with acute heart failure between January 2015 and December 2017. Results: We reviewed 1536 medical records of which 864 met the inclusion criteria. The mid-range ejection fraction group corresponded to 83 (9.6%) of patients, of which the majority were women (53%), with a median age of 77 years, coronary heart disease as the most frequent etiology (26.5%) and lack of adherence to medications as the main cause of decompensation (14.5%). The most frequently used drugs were betablockers and furosemide, both upon admission and discharge. Mortality was higher between patients with reduced ejection fraction (4.1%). Hospital stay, admission to and length of stay in an ICU, were similar between all groups regardless of ejection fraction. Conclusions: Our findings are similar to those described in previous international and national cohorts, and support the hypothesis of an intermediate phenotype with an etiology similar to that seen with a reduced ejection fraction.