Biology subjects

Beclin, C.

Publications and source records attributed to Beclin, C..

4 recordsLinked to original sources

bioRxiv2025

In Vivo AGO-APP For Cell-Type- and Compartment-Specific miRNA Profiling in the Mouse Brain

AGO-APP through the expression of the T6B peptide permits the isolation of Ago-bound miRNAs. Here we present the generation and characterization of two transgenic mouse lines allowing to perform AGO-APP in vivo. First, we generated mice for CRE-dependent expression of T6B in the cytoplasm. Using this line we performed Ago-APP in olfactory bulb (OB) inhibitory interneurons and cerebral cortex excitatory neurons. Bioinformatic analysis validated the high reproducibility of the approach. It also demonstrated that, despite global miRNome conservation between the two cell types, a set of miRNAs including the miR-200 family and the miR-183/96/182 cluster, is massively enriched in OB interneurons which is consistent with previous observations. In the second mouse line T6B is fused to the postsynaptic protein PSD95. Isolation of T6B-PSD95 fractions from OB and cortical neurons identified specific sets of post-synapse enriched miRNAs. Gene ontology analyses confirmed that these miRNAs preferentially target mRNAs related to synaptic functions. MotivationCollectively, miRNAs are required for all biological processes in eukaryotes. However, due to a lack of appropriate methodological tools, the actual mode of action of individual miRNAs in a given cell is currently poorly understood. In this article, we describe a novel approach to study the specific expression of miRNAs in vivo, at the level of cell type and in a specific cell compartment.

neuroscience↗

bioRxiv2023

In vivo AGO-APP identifies a module of microRNAs cooperatively controlling exit from neural stem cell state

MicroRNAs (miRNAs) are essential regulators of all developmental processes. Their function is particularly important during neurogenesis, when the production of large numbers of neurons from a limited number of neural stem cells depends on the precise control of determination, proliferation and differentiation. However, miRNA regulation of target mRNAs is highly promiscuous, one miRNA can target many mRNAs and vice versa, raising the question of how specificity is achieved to elicit a precise regulatory response. Here we introduce AGO-APP, a novel approach to purify Argonaute-bound miRNAs directly from cells and tissues in vivo, to isolate actively inhibiting miRNAs from different neural cell populations in the larval Drosophila central nervous system. We identify a defined group of miRNAs that redundantly target all iconic genes known to control the transition from neuroblasts to neurons. In vivo functional studies demonstrate that knockdown of individual miRNAs does not induce detectable cellular phenotypes. However, simultaneous knockdown of multiple miRNAs leads to precocious stem cell differentiation, demonstrating functional interdependence. Thus, miRNAs cooperate within a regulatory module to specify the targeted gene network.

developmental biology↗

bioRxiv2020

Regulatory interactions between Vax1, Pax6, and miR-7 regionalize the lateral Ventricular-Subventricular Zone during post-natal Olfactory Bulb neurogenesis in mice

Several subtypes of interneurons destined for the olfactory bulb are continuously generated after birth by neural stem cells located in the ventricular-subventricular zones of the lateral ventricles. Future neuronal identity depends on the positioning of pre-determined neural stem cells along the ventricle walls, which, in turn, depends on delimited expression domains of transcription factors and their cross regulatory interactions. However, mechanisms underlying positional identity of neural stem cells are still poorly understood. Here we show that the transcription factor Vax1 controls the production of two specific neuronal sub-types. First, it is directly necessary to generate Calbindin expressing interneurons from ventro-lateral progenitors. Second, it represses the generation of dopaminergic neurons by dorso-lateral progenitors through inhibiting Pax6 expression in the dorso-lateral wall. We provide evidence that this repression occurs via activation of microRNA miR-7, targeting Pax6 mRNA.

neuroscience↗

bioRxiv2018

Neuronal integration in the adult olfactory bulb is a non-selective addition process

Adult neurogenesis is considered a competition in which neurons scramble during a critical period for integration and survival. Moreover, newborn neurons are thought to replace preexisting ones that die. Despite a wealth of evidence supporting this model, systematic in vivo observations of the process are still scarce. We used 2-photon imaging to study neuronal integration and survival directly in the olfactory bulb (OB) of living mice. Long-term tracking of over 1400 neurons demonstrated that cell-loss in the OB is virtually absent. Neuronal death resembling a critical period was induced by standard doses of BrdU or EdU, but disappeared when low doses of EdU were used, demonstrating toxicity. Finally, we demonstrate that the OB grows throughout life. This shows that neuronal selection during OB-neurogenesis does not occur during integration and argues against the existence of a critical period. Moreover, the OB is not a \"turnover\" system but shows lifelong neuronal addition.

neuroscience↗