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NACC2 is a molecular effector of miR-132 regulation at the interface between adult neurogenesis and Alzheimer’s disease

ABSTRACT: The process of generating new neurons at the hippocampal neurogenic niche, also referred to as adult hippocampal neurogenesis (AHN), is impaired in Alzheimer’s disease (AD). MicroRNA-132 (miR-132), the most consistently downregulated microRNA (miRNA) in AD, was recently identified as a potent regulator of AHN, exerting multilayered proneurogenic effects in adult neural stem cells (NSCs) and their progeny. Supplementing miR-132 in AD mouse brain restores AHN and relevant memory deficits, yet the exact mechanisms involved are still unknown. Here, we identify NACC2 as a novel miR-132 target implicated in both AHN and AD. miR-132 deficiency in mouse hippocampus induces Nacc2 expression and inflammatory signaling in adult NSCs. We show that miR-132-dependent regulation of NACC2 is involved in the initial stages of human NSC differentiation towards astrocytes and neurons. Later, NACC2 function in astrocytic maturation becomes uncoupled from miR-132. We demonstrate that NACC2 is present in reactive astrocytes surrounding amyloid plaques in mouse and human AD hippocampus, and that there is an anticorrelation between miR-132 and NACC2 levels in AD and upon induction of inflammation. Unraveling the molecular mechanisms by which miR-132 regulates neurogenesis and cellular reactivity in AD, will provide valuable insights towards its possible application as a therapeutic target.

ORGANISM(S): Mus musculus

PROVIDER: GSE268144 | GEO | 2024/05/28

REPOSITORIES: GEO

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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:Mild exercise (ME) with an intensity below the lactate threshold (LT) is sufficient to enhance hippocampal function, while intense exercise (IE) above the LT negates such benefits. However, the question as to why ME more effectively enhances hippocampal function than does IE remains to be clarified. Here, we investigated adult hippocampal neurogenesis (AHN) as a mechanism of ME-induced cognitive improvement, and comprehensively delineated the transcriptomic profile of the hippocampus, using a rat whole-genome microarray approach through comparison with IE. Immunohistochemical results showed that less intense exercise (ME) is better suited to improve AHN, especially in regards to the survival and maturation of newborn neurons. DNA microarray analysis revealed that ME regulated more genes than did IE (ME: 604 genes, IE: 415 genes), and only 44 genes were modified with both exercise intensities. The identified molecular components did not comprise well-known factors related to exercise-induced AHN, such as brain-derived neurotrophic factor (BDNF) and insulin-like growth factor 1 (IGF1), probably due to the timing of hippocampal tissue collection after the last training session and the technical feature of microarray. Rather, network analysis of the microarray data using Ingenuity Pathway Analysis algorithms revealed that the ME-influenced genes were principally related to lipid metabolism, protein synthesis and inflammatory response, which are recognized as associated with hippocampal neuroadaptations including AHN. In contrast, IE-influenced genes linked to immune response, a negative regulatory system of AHN and hippocampal function, were identified. Collectively, these results support our hypothesis that AHN could explain why ME enhances hippocampal function, and provide the ME-specific gene list that contain some potential regulators of this positive regulation. The list will become a foundation to elucidate the molecular pathway involving the ME-induced cognitive gain.

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NACC2 is a molecular effector of miR-132 regulation at the interface between adult neurogenesis and Alzheimer’s disease

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