Biology subjects

Pelicci, S.

Publications and source records attributed to Pelicci, S..

4 recordsLinked to original sources

bioRxiv2026

Decoding EGFR ligand bias through an endocytic organelle platform

How growth factor receptors decode ligand identity into distinct cellular responses remains a fundamental question in cell signaling. Here, we identify a receptor-proximal mechanism that links ligand-specific EGFR activation to distinct endocytic and biological outputs. We show that EGF, but not TGF, selectively engages a RAC1-PLC{gamma}2-IP3R signaling axis that supports EGFR non-clathrin endocytosis (NCE). PLC{gamma}2, but not PLC{gamma}1, localizes to RTN3-dependent PM-ER contact sites, where it generates localized Ca{superscript 2} signals required for completion of NCE, mitochondrial activation and cell motility. This specificity requires the RAC-binding interface of PLC{gamma}2 and is associated with RAC1-dependent formation of CTxB-positive PM regions, indicating that spatial organization contributes to signaling specificity. TGF fails to efficiently assemble the EGFR-associated organelle platform and instead favors clathrin-dependent EGFR uptake, prolonged proliferative signaling, greater organoid yield, and reduced migration compared with EGF. Together, our findings identify the RAC1-PLC{gamma}2 axis as the key determinant that decodes EGFR ligand bias by coupling receptor trafficking to the metabolic program that supports cell migration.

cell biology↗

bioRxiv2025

Endocytic control of cell-autonomous and non-cell-autonomous functions of p53

NUMB is an endocytic protein with tumor suppressor activity, largely mediated by its ability to inhibit p53 degradation. This function depends on the inclusion of a short alternatively spliced exon (Ex3) in NUMB, although the mechanistic link between endocytosis and p53 regulation remains unclear. Here, we show that the Ex3-encoded sequence directs NUMB to the plasma membrane, where it forms a complex with the endocytic adaptor SNX9. This complex recruits p53 in a SNX9-dependent manner and is internalized and trafficked to multivesicular bodies, culminating in exosomal secretion, in a process requiring both SNX9 and NUMB. Exosomal p53 is taken up by recipient cells and translocated to the nucleus, where it activates p53-dependent transcriptional and phenotypic programs. These findings suggest that exosome-mediated p53 transfer may contribute to the establishment of a tumor-suppressive microenvironment.

cancer biology↗

bioRxiv2019

Nanoscale distribution of nuclear sites analyzed by superresolution STED-ICCS

Deciphering the spatiotemporal coordination between nuclear functions is important to understand its role in the maintenance of human genome. In this context, superresolution microscopy has gained considerable interest as it can be used to probe the spatial organization of functional sites in intact single cell nuclei in the 20-250 nm range. Among the methods that quantify colocalization from multicolor images, image cross-correlation spectroscopy (ICCS) offers several advantages, namely it does not require a pre-segmentation of the image into objects and can be used to detect dynamic interactions. However, the combination of ICCS with super-resolution microscopy has not been explored yet.\n\nHere we combine dual color stimulated emission depletion (STED) nanoscopy with ICCS (STED-ICCS) to quantify the nanoscale distribution of functional nuclear sites. We show that STED-ICCS provides not only a value of colocalized fraction but also the characteristic distances associated to correlated nuclear sites. As a validation, we quantify the nanoscale spatial distribution of three different pairs of functional nuclear sites in MCF10A cells. As expected, transcription foci and a transcriptionally repressive histone marker (H3K9me3) are not correlated. Conversely, nascent DNA replication foci and the Proliferating cell nuclear antigen (PCNA) protein have a high level of proximity and are correlated at a nanometer distance which is close to the limit of our experimental approach. Finally, transcription foci are found at a distance of 130 nm from replication foci, indicating a spatial segregation at the nanoscale. Overall, our data demonstrate that STED-ICCS can be a powerful tool for the analysis of nanoscale distribution of functional sites in the nucleus.\n\nStatement of significanceSeveral methods are available to quantify the proximity of two labeled molecules from dual color images. Among them, image cross-correlation spectroscopy (ICCS) is attractive as it does not require a pre-segmentation of the image into objects and can be used to detect dynamic interactions. Here, we combine for the first time ICCS with superresolution stimulated emission depletion (STED) microscopy (STED-ICCS) to quantify the spatial distribution of functional sites in the nucleus. Our results show that STED-ICCS, in addition to quantifying the colocalized fraction, detects characteristic nanometer distances associated to correlated nuclear sites. This work shows that STED-ICCS can be a powerful tool to quantify the nanoscale distribution of functional sites in the nucleus.

biophysics↗

bioRxiv2019

Chromatin nanoscale compaction in live cells visualized by acceptor-donor ratio corrected FRET between DNA dyes

Chromatin nanoscale architecture in live cells can be studied by Forster Resonance Energy Transfer (FRET) between fluorescently labeled chromatin components, such as histones. A higher degree of nanoscale compaction is detected as a higher FRET level, since this corresponds to a higher degree of proximity between donor and acceptor molecules. However, in such a system the stoichiometry of the donors and acceptors engaged in the FRET process is not well defined and, in principle, FRET variations could be caused by variations in the acceptor-donor ratio rather than distance. Here we show that a FRET value independent of the acceptor-donor ratio can be obtained by Fluorescence Lifetime Imaging (FLIM) detection of FRET combined with a normalization of the FRET level to a pixel-wise estimation of the acceptor-donor ratio. We use this method to study FRET between two DNA binding dyes staining the nuclei of live cells. We show that acceptor-donor ratio corrected FRET imaging reveals variations of nanoscale compaction in different chromatin environments. As an application, we monitor the rearrangement of chromatin in response to laser-induced micro-irradiation and reveal that DNA is rapidly decompacted, at the nanoscale, in response to DNA damage induction.

biophysics↗