Biology subjects

Ulloa, F.

Publications and source records attributed to Ulloa, F..

3 recordsLinked to original sources

bioRxiv2022

Regulation of adult neurogenesis and neuronal differentiation by Neural Cell Adhesion Molecule 2 (NCAM2)

Adult neurogenesis persists in mammals in the neurogenic zones where newborn neurons are incorporated into existing neuronal circuits. Relevant molecular elements of the neurogenic niches include the family of Cell Adhesion Molecules (CAM), which participate in signal transduction and regulate radial glial progenitors (RGPs) survival, division and differentiation. The Neural Cell Adhesion Molecule 2 (NCAM2) is expressed in brain development and in adult stages, and controls dendrite arborisation and synaptic formation and maintenance during development. Nevertheless, the role of NCAM2 in neurogenesis and lineage progression is not well understood. Here we analyse the functions of NCAM2 in the regulation of RGPs in adult neurogenesis in the dentate gyrus and during corticogenesis, by using different lentiviral-mediated genetic approaches to modulate its expression, both in vivo and in vitro. First, we characterized the expression of NCAM2 among the main actors of the neurogenic process revealing different levels of NCAM2 amid the progression of RGPs and the formation of juvenile neurons. Further, we show that overexpression of NCAM2 arrest infected cells in a RGP-like state, with characteristic morphological, immunocytochemical and electron microscopy features. In contrast, NCAM2 overexpression in embryonic cortical progenitors does not seems to alter cell fate, but causes transient migration deficits. These results reveal a differential role of NCAM2 in the regulation of adult and embryonic RGPs, and specifically, a significant implication of NCAM2 in the regulation and progression of RGPs during adult neurogenesis in the hippocampus.

neuroscience↗

bioRxiv2021

A novel Alex3/Gαq protein complex regulating mitochondrial dynamics, dendritic complexity, and neuronal survival

In neurons, mitochondrial dynamics and trafficking are essential to provide the energy required for neurotransmission and neuronal activity. Recent studies point to GPCR and G proteins as important regulators of mitochondrial dynamics and energy metabolism. Here we show that activation of Gq negatively regulates mitochondrial dynamics and trafficking in neurons. Gq interacts with the mitochondrial trafficking protein Alex3. By generating a CNS-specific armcx3 knock-out mouse line, we demonstrate that Alex3 is required for Gq effects on mitochondrial dynamics and trafficking, and dendritic growth. Armcx3-deficient mice present decreased OXPHOS complex and ER stress response protein levels, which correlate with increased neuronal death, motor neuron and neuromuscular synaptic loss, and severe motor alterations. Finally, we show that Alex3 disassembles from the Miro1/Gq complex upon calcium rise. These data uncover a novel Alex3/Gq complex that regulates neuronal mitochondrial dynamics and neuronal death and allows the control of mitochondrial functions by GPCRs.

cell biology↗

bioRxiv2021

Syntaxin-1 is necessary for UNC5/Netrin-1-dependent macropinocytosis and chemorepulsion

Brain connectivity requires correct axonal guidance to drive axons to their appropriate targets. This process is orchestrated by guidance cues that exert attraction or repulsion to developing axons. However, the intricacies of the cellular machinery responsible for the correct response of growth cones are just being unveiled. Netrin-1 is a bifunctional molecule involved in axon pathfinding and cell migration that induces repulsion during postnatal cerebellar development. This process is mediated by Uncoordinated locomotion 5 (UNC5) receptors located on external granule layer (EGL) tracts. Here, we demonstrate that this response is characterized by enhanced membrane internalization through macropinocytosis, but not clathrin-mediated endocytosis. We show that UNC5 receptors form a protein complex with the t-SNARE syntaxin-1 (Stx1). By combining botulinum neurotoxins, a shRNA knock-down strategy and Stx1 knock-out mice, we demonstrate that this SNARE protein is required for Netrin-1-induced macropinocytosis and chemorepulsion, suggesting that Stx1 is crucial in regulating Netrin-1-mediated axonal guidance.

neuroscience↗