Biology subjects

Prischi, F.

Publications and source records attributed to Prischi, F..

4 recordsLinked to original sources

bioRxiv2025

Dissecting Annexin-A11 into its functional domains revealed calcium as a key regulator for RNA transport and its association with ALS

Recent studies reveal a "hitchhiking" mechanism in neurons, where organelles transported along microtubules carry other cargos via tethering molecules. Annexin A11 (ANXA11), a calcium-dependent phospholipid-binding protein, functions as a tether linking RNA granules to lysosomes, aiding mRNA transport for rapid neuronal responses. Structurally, its N-terminal (Nt) binds RNA, while the C-terminal (Ct) associates with lysosomal membranes. Mutations in ANXA11 linked to Amyotrophic lateral sclerosis (ALS) may disrupt this function. Here, applying a multidisciplinary approach, we revealed that Ca2+ acts as a master regulator of ANXAlls physiological function by modulating its conformational states. Specifically, Ca2+ influences a switch between two conformations: a close state, in which the Nt and Ct interact with each other, and an open state, which occurs in the presence of Ca2+ ions, where this self-interaction is disrupted, allowing the two domains to interact freely with RNA and liposomes. Surprisingly, we observed that both the Ct and Nt are capable of interacting with liposomes and RNA in a Ca2+-dependent manner, and these interactions can occur simultaneously. This dual binding and its calcium-regulated hierarchy finely tunes ANXAlls binding to RNA and lysosomes, promoting a large complex essential for overcoming transport steric hindrance. Moreover, our result showed that the p.D40G mutation, in the Nt domain, associated with ALS, displays destabilized interdomain interactions and bypass Ca2+ regulation, leading to aberrant aggregation. These insights advance our understanding of ANXAlls role in neuronal RNA transport and its disruption in neurodegeneration, highlighting potential targets for therapeutic intervention.

biochemistry↗

bioRxiv2024

Enhanced identification of small molecules binding to hnRNPA1 via cryptic pockets mapping coupled with X-Ray fragment screening

The human heterogeneous nuclear ribonucleoprotein (hnRNP) A1 is a prototypical RNA-binding protein essential in regulating a wide range of post-transcriptional events in cells. As a multifunctional protein with a key role in RNA metabolism, deregulation of its functions has been linked to neurodegenerative diseases, tumour aggressiveness and chemoresistance, which has fuelled efforts to develop novel therapeutics that modulates its RNA binding activities. Here, using a combination of Molecular Dynamics (MD) simulations and graph neural network pockets predictions, we showed that hnRNPA1 N-terminal RNA binding domain (UP1) contains several cryptic pockets capable of binding small molecules. To identify chemical entities for development of potent drug candidates and experimentally validate identified druggable hotspots, we carried out a large fragment screening on UP1 protein crystals. Our screen identified 36 hits which extensively samples UP1 functional regions involved in RNA recognition and binding, as well as mapping hotspots onto novel protein interaction surfaces. We observed a wide range of ligand-induced conformational variation, by stabilisation of dynamic protein regions. Our high-resolution structures, the first of an hnRNP in complex with a fragment or small molecule, provides rapid routes for the rational development of a range of different inhibitors and chemical tools for studying molecular mechanisms of hnRNPA1 mediated splicing regulation.

biochemistry↗

bioRxiv2024

The p90 Ribosomal S6 Kinases 2 and 4 promote Prostate Cancer cell proliferation in androgen-dependent and independent ways

Oncogenic activation of the phosphatidylinositol-3-kinase (PI3K) and mitogen-activated protein kinase (MAPK) pathways are frequent events in Prostate Cancer (PCa) that have been correlated to tumour formation, disease progression and therapeutic resistance. At the intersection of these two pathways lies the p90 ribosomal S6 kinase (RSKs) family, which regulates many proteins involved in cell survival, growth and proliferation. As such, deregulated RSKs activity has been associated with multiple cancer types, including PCa. However, the full extent of the RSKs involvement in prostate tumorigenesis remains to be determined. Here we have shown that RSKs levels are increased in PCa samples and cell lines. The RSKs were found to enhance Androgen Receptor (AR) activity, the key oncogenic driver in PCa. Indeed, all RSKs were found to interact in close proximity to the AR. However, RSK2/4, but not RSK1/3, showed changes in cell localisation following AR nuclear translocation. Consistently, silencing of RSK2/4, but not RSK1/3, inhibited PCa proliferation in an androgen-dependent and independent manner, respectively, and induced different signaling events downstream of the AR. The data suggests that RSK2 and RSK4 activity is required for PCa cell proliferation, but they are likely regulating growth via different mechanisms.

cancer biology↗

bioRxiv2019

Antibiotics select for novel pathways of resistance in biofilms

Most bacteria in nature exist in aggregated communities known as biofilms. Bacteria within biofilms are inherently highly resistant to antibiotics. Current understanding of the evolution and mechanisms of antibiotic resistance is largely derived from work from cells in liquid culture and it is unclear whether biofilms adapt and evolve in response to sub-inhibitory concentrations of drugs. Here we used a biofilm evolution model to show that biofilms of a model food borne pathogen, Salmonella Typhimurium rapidly evolve in response to exposure to three clinically important antibiotics. Whilst the model strongly selected for improved biofilm formation in the absence of any drug, once antibiotics were introduced the need to adapt to the drug was more important than the selection for improved biofilm formation. Adaptation to antibiotic stress imposed a marked cost in biofilm formation, particularly evident for populations exposed to cefotaxime and azithromycin. We identified distinct resistance phenotypes in biofilms compared to corresponding planktonic control cultures and characterised new mechanisms of resistance to cefotaxime and azithromycin. Novel substitutions within the multidrug efflux transporter, AcrB were identified and validated as impacting drug export as well as changes in regulators of this efflux system. There were clear fitness costs identified and associated with different evolutionary trajectories. Our results demonstrate that biofilms adapt rapidly to low concentrations of antibiotics and the mechanisms of adaptation are novel. This work will be a starting point for studies to further examine biofilm specific pathways of adaptation which inform future antibiotic use.

microbiology↗