Project description:Physical exercise stimulates adult hippocampal neurogenesis in mammals, and is considered a relevant strategy for preventing age-related cognitive decline in aging humans. However, its mechanism is controversial. Here, by investigating microRNAs (miRNAs) and their downstream pathways, we uncover that downregulation of miR-135a-5p mediates exercise-induced proliferation of adult NPCs in adult neurogenesis in the mouse hippocampus, likely by activation of phosphatidylinositol (IP3) signaling. Specifically, while overexpression of miR-135 prevents exercise-induced proliferation in the adult mouse hippocampus in vivo and in NPCs in vitro, its inhibition activates NPCs proliferation in resting and aged mice. Label free proteomics and bioinformatics analysis identifies 11 potential targets of miR-135 in NPCs, several of them involved in phosphatidylinositol signaling. Thus, miR-135a is key in mediating exercise-induced adult neurogenesis and opens intriguing perspectives toward the therapeutic exploitation of miR-135 to delay or prevent pathological brain ageing.Physical exercise stimulates adult hippocampal neurogenesis in mammals, and is considered a relevant strategy for preventing age-related cognitive decline in aging humans. However, its mechanism is controversial. Here, by investigating microRNAs (miRNAs) and their downstream pathways, we uncover that downregulation of miR-135a-5p mediates exercise-induced proliferation of adult NPCs in adult neurogenesis in the mouse hippocampus, likely by activation of phosphatidylinositol (IP3) signaling. Specifically, while overexpression of miR-135 prevents exercise-induced proliferation in the adult mouse hippocampus in vivo and in NPCs in vitro, its inhibition activates NPCs proliferation in resting and aged mice. Label free proteomics and bioinformatics analysis identifies 11 potential targets of miR-135 in NPCs, several of them involved in phosphatidylinositol signaling. Thus, miR-135a is key in mediating exercise-induced adult neurogenesis and opens intriguing perspectives toward the therapeutic exploitation of miR-135 to delay or prevent pathological brain ageing.

Project description:Neonates are highly susceptible to repeat infection and respond poorly to vaccination; these attributes derive from intrinsic differences between neonatal and adult naïve CD8+ T cells. In contrast to adult cells, naïve neonatal cells exhibit a greatly limited ability to differentiate into memory cells, a fundamental property of their adult counterparts. Here, we describe the role of the miR-29 microRNA in naïve T cells, focusing on age-related differences in miR-29 expression and the consequences of these differences in adult and neonatal cells, from mice and humans. In adults, high expression of miR-29 licenses naïve cells towards eventual memory cell fates; whereas neonatal naïve cells, which lack high expression of miR-29, are predisposed towards effector cell fates in response to an infection. Multiple lines of evidence support this model, including analysis of a mouse model deficient in miR-29, which we examine with adoptive transfer experiments to define the functional consequences of reduction of miR-29, together with genomic assays to define the regulatory impact of miR-29. Adult miR 29 deficient naïve CD8+ T cells cell are primed for activation and therefore secrete elevated levels of cytolytic molecules, and express transcription factors at levels associated with effector cell differentiation; moreover, these cells exhibit an altered CD8+ T cell memory repertoire, akin to that of neonatal CD8+ T cells. Importantly, we use a method that exploits extracellular vesicles as a delivery vehicle with which to modulate levels of miR-29 in neonatal and adult naïve T cells, examining both human and mouse cells. For example, increasing miR 29 expression in mouse naïve neonatal CD8+ T cells significantly improved the memory response during infection, concomitant with alterations to the chromatin landscape characteristic of cells primed for memory differentiation. Delivery of miR-29 antagomirs to human adult naïve CD8+ T cells was sufficient to induce the adult cells to adopt phenotypes and gene expression signatures normally found in cells present in newborns. This study establishes miR-29 as a key conserved regulator in naïve CD8+ T cells, and by adjusting levels of miR-29, has the potential to underlie therapeutic strategies for controlling the balance of effector versus memory fates in human T cells.

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MiR-29 is an important driver of aging-related phenotypes

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