Biology subjects

Fusca, D.

Publications and source records attributed to Fusca, D..

5 recordsLinked to original sources

bioRxiv2025

An in vivo parallelized reporter assay to uncover tissue-specific splicing regulatory sequences in a multicellular animal

Introns play a critical role in regulating alternative splicing. However, identifying functional intronic motifs is challenging due to their short and degenerate sequence composition. Massively parallel reporter assays have provided insights into cis-regulatory logic governing alternative splicing, but these approaches are generally performed in cell culture, limiting their ability to capture tissue-specific contexts. Here, we implemented in vivo Parallelized Reporter Assays in C. elegans neurons and muscle cells to screen for intronic enhancer and silencer motifs among thousands of randomized sequences. We identified nearly 200 sequences regulating splicing in these tissues. We uncovered core sub-sequences with tissue-biased enhancing and silencing activity, including motifs recognized by well-characterized RNA-binding proteins, and orphan motifs with no obvious cognate binding protein. Mapping our PRA-derived motifs to native introns flanking tissue-biased alternative exons revealed their conservation across nematodes, supporting their functional relevance. Additionally, individual intronic regions frequently contained diverse combinations of these motifs, indicative of complex engagement of these sequences by RNA-binding proteins. Finally, we performed targeted mutagenesis of PRA-derived intronic enhancers flanking a neuronal microexon, identifying key cis-regulatory determinants of microexon splicing. Together, our study provides a framework to explore the role of intronic regions in tissue-specific splicing regulation within a multicellular organism. Graphical Abstract O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=107 SRC="FIGDIR/small/670696v1_ufig1.gif" ALT="Figure 1"> View larger version (24K): org.highwire.dtl.DTLVardef@84d5daorg.highwire.dtl.DTLVardef@f3f625org.highwire.dtl.DTLVardef@a53739org.highwire.dtl.DTLVardef@ccbb03_HPS_FORMAT_FIGEXP M_FIG C_FIG

molecular biology↗

bioRxiv2023

Genome-wide profiling reveals a dual role for histone H2A monoubiquitylation at Polycomb-repressed and enhancer chromatin

Histone modifications are an integral component of eukaryotic genome regulation. Polycomb Repressive Complex 1 (PRC1) is responsible for depositing histone H2A lysine 119 monoubiquitylation (H2AK119ub) and can work cooperatively with PRC2-mediated histone H3 lysine 27 trimethylation (H3K27me3) to maintain gene repression. However, H3K27me3-independent functions and roles in gene activation have also been described for PRC1. Thus, the extent to which Polycomb complexes and their corresponding histone modifications function together or independently and the conservation of these roles in different organisms is unclear. Using C. elegans as a model, we investigated the relationship between H2AK119ub and H3K27me3. Here we show that the majority of H2AK119ub and H3K27me3 enrichment across the genome in embryos is distinct, and that the bulk levels of these modifications are regulated independently. We identify many genes related to nervous system development and functionality that have H2AK119ub-enriched promoters and are misregulated in H2AK119ub-deficient mutants, including a subset of genes that are normally H3K27me3-repressed. Surprisingly, we also find an enrichment of H2AK119ub at enhancers, including enhancers proximal to genes which are both up-regulated and down-regulated following the loss of this histone modification. Together, our results indicate a dual role for H2AK119ub in the regulation of both H3K27me3-repressed and enhancer chromatin states.

genomics↗

bioRxiv2023

Development of a genetically-encoded sensor for probing endogenous nociceptin opioid peptide release

Nociceptin/orphanin-FQ (N/OFQ) is a recently appreciated critical opioid peptide with key regulatory functions in several central behavioral processes including motivation, stress, feeding, and sleep. The functional relevance of N/OFQ action in the mammalian brain remains unclear due to a lack of high-resolution approaches to detect this neuropeptide with appropriate spatial and temporal resolution. Here we develop and characterize NOPLight, a genetically encoded sensor that sensitively reports changes in endogenous N/OFQ release. We characterized the affinity, pharmacological profile, spectral properties, kinetics, ligand selectivity, and potential interaction with intracellular signal transducers of NOPLight in vitro. Its functionality was established in acute brain slices by exogeneous N/OFQ application and chemogenetic induction of endogenous N/OFQ release from PNOC neurons. In vivo studies with fibre photometry enabled direct recording of NOPLight binding to exogenous N/OFQ receptor ligands, as well as detection of endogenous N/OFQ release within the paranigral ventral tegmental area (pnVTA) during natural behaviors and chemogenetic activation of PNOC neurons. In summary, we show here that NOPLight can be used to detect N/OFQ opioid peptide signal dynamics in tissue and freely behaving animals.

neuroscience↗

bioRxiv2021

ToxoNet: A high confidence map of protein-protein interactions in Toxoplasma gondii reveals novel virulence factors implicated in host cell invasion

The apicomplexan intracellular parasite Toxoplasma gondii is a major food borne pathogen with significant impact in children and during pregnancy. The majority of the T. gondii proteome remains uncharacterized and the organization of proteins into complexes is unclear. To overcome this knowledge gap, we utilize a biochemical fractionation strategy coupled with mass spectrometry to predict interactions by correlation profiling. Key to this approach is the integration of additional datasets based on gene co-expression as well as phylogenetic profiles that eliminate poorly supported interactions and reduce the number of false positive interactions. In addition to a supervised machine learning strategy, we employed an unsupervised approach in data integration, based on similarity network fusion, to overcome the deficit of high-quality training data in non-model organisms. The resulting high confidence network, we term ToxoNet, comprises 2,063 interactions connecting 652 proteins. Clustering of this network identifies 93 protein complexes, predicting both novel complexes as well as new components for previously known complexes. In particular, we identified clusters enriched in mitochondrial machinery that include previously uncharacterized proteins that likely represent novel adaptations to oxidative phosphorylation. Furthermore, complexes enriched in proteins localized to secretory organelles and the inner membrane complex, predict additional novel components representing novel targets for detailed functional characterization. We present ToxoNet as a publicly available resource with the expectation that it will help drive future hypotheses within the research community.

microbiology↗

bioRxiv2020

Task-specific roles of local interneurons for inter -and intraglomerular signaling in the insect antennal lobe

Local interneurons (LNs) mediate complex interactions within the antennal lobe, the primary olfactory system of insects, and the functional analog of the vertebrate olfactory bulb. In the cockroach Periplaneta Americana, as in other insects, several types of LNs with distinctive physiological and morphological properties can be defined. Here, we combined whole-cell patch clamp recordings and Ca2+ imaging of individual LNs to analyze the role of spiking and nonspiking LNs in inter- and intraglomerular signaling during olfactory information processing. Spiking GABAergic LNs reacted to odorant stimulation with a uniform rise in [Ca2+]i in the ramifications of all innervated glomeruli. In contrast, in nonspiking LNs, glomerular Ca2+ signals were odorant specific and varied between glomeruli, resulting in distinct, glomerulus-specific tuning curves. The cell type-specific differences in Ca2+ dynamics support the idea that spiking LNs play a primary role in interglomerular signaling, while they assign nonspiking LNs an essential role in intraglomerular signaling.

neuroscience↗