Biology subjects

Pellegrini, A.

Publications and source records attributed to Pellegrini, A..

4 recordsLinked to original sources

bioRxiv2026

Calcineurin B-mediated Ca2+ sensing translates stress signal intensity into the assembly of phase-separated condensates at PERK complexes.

Endoplasmic reticulum (ER) stress activates protein kinase RNA-like ER kinase (PERK), which initially promotes adaptive responses but remains the only active UPR branch during prolonged stress, mediating both early cytoprotective and chronic pro-apoptotic signaling. Recently, we identified translocon-generated Ca2+ microdomains that promote PERK phosphorylation during early UPR, revealing a mechanism by which local Ca2+ signals regulate UPR activation. However, the molecular mechanism linking these Ca2+ microdomains to PERK activation remains elusive. Previously, we showed that calcineurin (CN), a Ca2+ -dependent heterodimer composed of catalytic (CNA) and regulatory (CNB) subunits, exerts a non-canonical pro-survival function by promoting PERK autophosphorylation. Here, using super-resolution microscopy, CRISPR-Cas9 editing, in silico analyses, and optogenetic droplet assays, we identify CNB as a local Ca2+ sensor that couples translocon-generated Ca2+ signals to liquid condensate assembly, thereby promoting adaptive PERK phosphorylation. These findings establish CNB-mediated condensate assembly as a mechanism that translates local Ca2+ signals into spatially organized early adaptive PERK signaling.

cell biology↗

bioRxiv2025

GM1-oligosaccharide rescues rotenone-impaired neuronal polarization through RhoA/ROCK modulation and mitochondrial protection

Neuronal polarization is a fundamental process in the formation of functional neural circuits, relying on the precise coordination between cytoskeletal regulatory signals and mechanisms that sustain cellular integrity. Disruption of these processes compromises neuronal differentiation and survival, and various neurotoxic compounds, including certain pesticides, have been associated with such dysfunctions. In this context, identifying molecules that counteract these detrimental effects is of significant therapeutic interest. Neuronal polarization is essential for the establishment of functional neural circuits and relies on coordinated regulation of actin cytoskeleton dynamics, RhoA/ROCK signaling, and mitochondrial function. Here, we investigated the neuroprotective and neurorestorative potential of the ganglioside GM1 and its oligosaccharide derivative, osGM1, in primary hippocampal pyramidal neurons exposed to the mitochondrial neurotoxin rotenone. Rotenone induced a marked arrest of neuronal development, impaired axonal elongation, and disrupted mitochondrial organization and membrane potential. Both GM1 and osGM1 promoted recovery of neuronal polarity and axonal growth, exerting protective and restorative effects even under continuous toxin exposure, with osGM1 showing superior efficacy. Notably, osGM1 also reversed axonal growth deficits caused by pathological actin stabilization. Mechanistically, osGM1 normalized rotenone-induced hyperactivation of the RhoA/ROCK pathway without altering basal signaling and partially restored mitochondrial network integrity and function. Collectively, these findings identify osGM1 as a multi-target modulator of cytoskeletal and mitochondrial dysfunction and support its translational potential as a therapeutic strategy to counteract neurotoxin-induced neuronal damage.

neuroscience↗

bioRxiv2020

Decadal changes in fire frequencies shift tree communities and functional traits

Global change has resulted in chronic shifts in fire regimes, increasing fire frequency in some regions and decreasing it in others. Predicting the response of ecosystems to changing fire frequencies is challenging because of the multi-decadal timescales over which fire effects emerge and the variability in environmental conditions, fire types, and plant composition across biomes. Here, we address these challenges using surveys of tree communities across 29 sites that experienced multi-decadal alterations in fire frequencies spanning ecosystems and environmental conditions. Relative to unburned plots, more frequently burned plots had lower tree basal area and stem densities that compounded over multiple decades: average fire frequencies reduced basal area by only 4% after 16 years but 57% after 64 years, relative to unburned plots. Fire frequency had the largest effects on basal area in savanna ecosystems and in sites with strong wet seasons. Analyses of tree functional-trait data across North American sites revealed that frequently burned plots had tree communities dominated by species with low biomass nitrogen and phosphorus content and with more efficient nitrogen acquisition through ectomycorrhizal symbioses (rising from 85% to nearly 100%). Our data elucidate the impact of long-term fire regimes on tree community structure and composition, with the magnitude of change depending on climate, vegetation type, and fire history. The effects of widespread changes in fire regimes underway today will manifest in decades to come and have long-term consequences for carbon storage and nutrient cycling.

ecology↗

bioRxiv2018

Edge fires drive the shape and stability of tropical forests

In tropical regions, fires propagate readily in grasslands but typically consume only edges of forest patches. Thus forest patches grow due to tree propagation and shrink by fires in surrounding grasslands. The interplay between these competing edge effects is unknown, but critical in determining the shape and stability of individual forest patches, as well the landscape-level spatial distribution and stability of forests. We analyze high-resolution remote-sensing data from protected areas of the Brazilian Cerrado and find that forest shapes obey a robust perimeter-area scaling relation across climatic zones. We explain this scaling by introducing a heterogeneous fire propagation model for tropical forest-grassland ecotones. Deviations from this perimeter-area relation determine the stability of individual forest patches. At a larger scale, our model predicts that the relative rates of tree growth due to propagative expansion and long-distance seed dispersal determine whether collapse of regional-scale tree cover is continuous or discontinuous as fire frequency changes.

ecology↗