Biology subjects

Morenilla-Palao, C.

Publications and source records attributed to Morenilla-Palao, C..

4 recordsLinked to original sources

bioRxiv2024

ARID1A-BAF coordinates ZIC2 genomic occupancy for epithelial to mesenchymal transition in cranial neural crest lineage commitment

The BAF chromatin remodeler regulates lineage commitment including cranial neural crest cell (CNCC) specification. Variants in BAF subunits cause Coffin-Siris Syndrome (CSS), a congenital disorder characterized by coarse craniofacial features and intellectual disability. Approximately 50% of CSS patients carry variants in one of the mutually exclusive BAF subunits, ARID1A/ARID1B. While Arid1a deletion in mouse neural crest causes severe craniofacial phenotypes, little is known about the role of ARID1A in CNCC specification. Using CSS patient-derived ARID1A+/- iPSCs to model CNCC specification, we discovered ARID1A-haploinsufficiency impairs epithelial to mesenchymal transition (EMT), a process necessary for CNCC delamination and migration from the neural tube. Furthermore, wild-type ARID1A-BAF regulates enhancers associated with EMT genes. ARID1A-BAF binding at these enhancers is impaired in heterozygotes while binding at promoters is unaffected. At the sequence level, these EMT enhancers contain binding motifs for ZIC2, and ZIC2 binding at these sites is ARID1A-dependent. When excluded from EMT enhancers, ZIC2 relocates to neuronal enhancers, triggering aberrant neuronal gene activation. In mice, deletion of Zic2 impairs NCC delamination, while ZIC2 overexpression in chick embryos at pre-migratory neural crest stages elicits ectopic delamination from the neural tube. These findings reveal a novel ARID1A-ZIC2 axis essential for EMT and CNCC delamination.

developmental biology↗

bioRxiv2023

A novel regulatory mechanism of actin cytoskeleton dynamics through a neural microexon in DAAM1 is necessary for memory formation

Actin cytoskeleton dynamics is critical for nervous system development and function, yet the role of alternative splicing in controlling these processes is poorly understood. A highly conserved subset of neuronal-specific microexons coordinates fundamental aspects of nervous system biology. A subset of these exons is enriched in genes involved in actin cytoskeleton, yet their functions are unknown. Here, we focus on a microexon in DAAM1, a member of the formin-homology-2 (FH2) domain class of proteins, which have diverse functions associated with the reorganization of the actin cytoskeleton. Remarkably, splicing of the microexon extends the linker region of the DAAM1 FH2 domain and leads to qualitative and quantitative changes in actin polymerization. Deletion of the microexon results in neuritogenesis defects and increased calcium influx in differentiated neurons. Moreover, mice harboring the deletion exhibit postsynaptic defects, reduced number of immature dendritic spines, impaired long-term potentiation, and deficits in memory formation. These deficits are associated with increased RHOA/ROCK signaling, pivotal in controlling actin-cytoskeleton dynamics, and were rescued by treatment with a ROCK inhibitor. We thus demonstrate that a conserved neuronal microexon in DAAM1 is critical for controlling actin dynamics through the RHOA/ROCK signaling pathway and is necessary for normal cognitive functioning.

neuroscience↗

bioRxiv2022

Perinatal correlated retinal activity is required for the wiring of visual axons in non-image forming nuclei

The development of the visual system is an intricate and multi-step process involving the precise connection of retinal ganglion cell (RGC) axon terminals with their corresponding neurons in the visual nuclei of the brain. Upon reaching primary image-forming nuclei (IFN), such as the superior colliculus and the lateral geniculate nucleus, RGC axons undergo extensive arborization that refines over the first few postnatal weeks. The molecular mechanisms driving this activity-dependent remodeling process, which is influenced by spontaneous activity in the developing retina, are still not well understood. In this study, by manipulating the activity of RGCs in mice and analyzing their transcriptomic profiles before eye opening, we have identified gene programs involved in activity-dependent refinement. Furthermore, while RGC axons also target non-image forming nuclei (NIFN), the impact of spontaneous retinal activity on the development of these accessory nuclei, has not yet been elucidated. The analysis of visual terminals from mice with altered retinal activity revealed that spontaneous retinal waves occurring prior to visual experience also play a role in shaping the connectivity of the non-image forming circuit. Overall, these findings contribute to a deeper understanding of the mechanisms governing activity-dependent axon refinement during the establishment of the visual circuit.

neuroscience↗

bioRxiv2019

Zic2 abrogates an alternative Wnt signaling pathway to convert axon attraction into repulsion

Wnt signaling is involved in axon pathfinding during brain wiring but it is unknown how Wnt ligands promote attraction or repulsion. In addition, the participation of the canonical ({beta}catenin-dependent transcription) versus non-canonical ({beta}catenin-independent) Wnt pathways in this process remains controversial. Here we show that Wnt5a is expressed at the optic chiasm midline and promotes axon crossing by triggering an alternative Wnt pathway that depends on polarized accumulation of {beta}catenin at the axon terminal but does not activate the canonical pathway. Remarkably, this alternative pathway is silenced by the transcription factor Zic2 in the small subset of ipsilaterally projecting neurons. Zic2 directly regulates genes related to Wnt and Eph signaling that lead to global accumulation of {beta}catenin but triggers its asymmetric phosphorylation to facilitate the steering of the growth cone. This alternative Wnt pathway found in contralateral axons and its Zic2-mediated abrogation in ipsilateral neurons is likely operating in many other contexts requiring a two-way response to Wnt ligands.

developmental biology↗