Biology subjects

Lasconi, C.

Publications and source records attributed to Lasconi, C..

4 recordsLinked to original sources

bioRxiv2026

Intercellular Transfer of PTBP1 Drives Human Neural Stem Cell Fate

During fetal brain development, temporally defined alternative splicing (AS) programs control human neural stem cell (hNSC) self-renewal and differentiation, thereby regulating neurogenesis and gliogenesis. Polypyrimidine tract-binding protein 1 (PTBP1) is a master regulator of AS during neurogenesis; however, its functional role and dynamics in hNSCs remain largely unexplored. Here, we investigate the cellular and molecular functions, nucleocytoplasmic distribution, and intercellular trafficking of PTBP1 in primary hNSCs. We found that PTBP1 knockdown (KD) alters self-renewal capacity, mitochondrial dynamics and membrane potential, lipid droplet abundance, and PTBP2 expression. RNA sequencing analysis revealed that PTBP1 depletion affects the expression profiling of hundreds of coding and non-coding genes, collectively orchestrating a neuronal differentiation program. Super-resolution {tau}-STED microscopy and live-cell imaging demonstrated that PTBP1 localizes not only to the nucleus but also to the cytoplasm, tunneling nanotubes (TNTs), migrasomes, and extracellular vesicles (EVs). Co-culture experiments and EV uptake assays showed that cytosolic PTBP1 can be transferred between hNSCs and delivered to the nuclei of recipient cells via TNTs and EVs. Moreover, EVs were found to contain specific and previously uncharacterized PTBP1 isoforms and were efficiently transferred to PTBP1-KD cells, rescuing their proliferative capacity. Analysis of the mouse brain reveals the presence of PTBP1 in the V-SVZ and within TNT-like structures connecting NSCs, suggesting a role for TNT-mediated PTBP1 trafficking in vivo. Together, these findings uncover previously unrecognized roles for PTBP1 in hNSCs and provide the first evidence that PTBP1 can be transferred between hNSCs via TNTs and EVs, revealing a novel mechanism by which hNSCs may regulate fetal neurogenesis. Graphical AbstractA: PTBP1 regulates hNSC fate by controlling cell proliferation, lipid droplet dynamics, mitochondrial function, and post-transcriptional programs involved in neuronal commitment. B: Cytosolic PTBP1 is transferred between hNSCs via tunneling nanotubes (TNTs) and extracellular vesicles (EVs). Abbreviations: LV, lateral ventricle; aRG, apical radial glial cells; bRG, basal radial glial cells; V-SVZ, ventricular-subventricular zone; EVs, extracellular vesicles; TNTs, tunneling nanotubes.

neuroscience↗

bioRxiv2023

Perturbation of the insomnia WDR90 GWAS locus pinpoints rs3752495 as a causal variant influencing distal expression of neighboring gene, PIG-Q

Although genome wide association studies (GWAS) have been crucial for the identification of loci associated with sleep traits and disorders, the method itself does not directly uncover the underlying causal variants and corresponding effector genes. The overwhelming majority of such variants reside in non-coding regions and are therefore presumed to impact the activity of cis-regulatory elements, such as enhancers. Our previously reported variant-to-gene mapping effort in human induced pluripotent stem cell (iPSC)-derived neural progenitor cells (NPCs), combined with validation in both Drosophila and zebrafish, implicated PIG-Q as a functionally relevant gene at the insomnia WDR90 locus. However, importantly that effort did not characterize the corresponding underlying causal variant at this GWAS signal. Specifically, our genome-wide ATAC-seq and high-resolution promoter-focused Capture C datasets generated in this cell setting brought our attention to a shortlist of three tightly neighboring single nucleotide polymorphisms (SNPs) in strong linkage disequilibrium in a candidate intronic enhancer region of WDR90 that contacted the open PIG-Q promoter. The objective of this study was to investigate the influence of the proxy SNPs collectively and then individually on PIG-Q modulation and to pinpoint the causal "regulatory" variant among the three SNPs. Starting at a gross level perturbation, deletion of the entire region harboring all three SNPs in human iPSC-derived neural progenitor cells via CRISPR-Cas9 editing and subsequent RNA sequencing revealed expression changes in specific PIG-Q transcripts. Results from more refined individual luciferase reporter assays for each of the three SNPs in iPSCs revealed that the intronic region with the rs3752495 risk allele induced a [~]2.5-fold increase in luciferase expression (n=10). Importantly, rs3752495 also exhibited an allele specific effect, with the risk allele increasing the luciferase expression by [~]2-fold compared to the non-risk allele. In conclusion, our variant-to-function approach and subsequent in vitro validation implicates rs3752495 as a causal insomnia risk variant embedded at the WDR90-PIG-Q locus.

genomics↗

bioRxiv2021

Variant-to-gene-mapping followed by cross-species genetic screening identifies GPI-anchor biosynthesis as novel regulator of sleep

Sleep is nearly ubiquitous throughout the animal kingdom, with deficiencies in sleep having been linked to a wide range of human disorders and diseases. While genome wide association studies (GWAS) in humans have identified loci robustly associated with several heritable diseases or traits, little is known about the functional roles of the underlying causal variants in regulating sleep duration or quality. We applied an ATAC-seq/promoter focused Capture C strategy in human iPSC-derived neural progenitors to carry out a variant-to-gene mapping campaign that identified 88 candidate sleep effector genes connected to relevant GWAS signals. To functionally validate the role of the implicated effector genes in sleep regulation, we performed a neuron-specific RNAi screen in the fruit fly, Drosophila melanogaster. This approach identified a number of genes that regulated sleep, including phosphatidylinositol N-acetylglucosaminyltransferase subunit Q (PIG-Q), a gene that encodes an enzyme involved in the first step of glycosylphosphatidylinositol (GPI)- anchor biosynthesis. We show that flies deficient for PIG-Q have longer sleep during both day and night due to an increase in the total number of sleep bouts. Subsequent systematic investigation of other PIG-family genes identified increased sleep in flies for multiple different genes within the PIG pathway. We then mutated the PIG-Q locus in zebrafish and identified similar increases in sleep to those observed in Drosophila, confirming deep homology of PIG-Q mediated sleep regulation. These results provide the first physical variant-to-gene mapping of human sleep genes followed by a model organism-based prioritization, revealing a novel and conserved role for GPI-anchor biosynthesis in sleep regulation.

genetics↗

bioRxiv2020

Cis-regulatory architecture of human ESC-derived hypothalamic neuron differentiation aids in variant-to-gene mapping of relevant common complex traits

SummaryThe hypothalamus regulates metabolic homeostasis by influencing behavior, energy utilization and endocrine systems. Given its role governing health-relevant traits, such as body weight and reproductive timing, understanding the genetic regulation of hypothalamic development and function should yield insights into these traits and diseases. However, given its inaccessibility, studying human hypothalamic gene regulation has proven challenging. To address this gap, we generated a chromatin architecture atlas of an established embryonic stem cell (ESC)-derived hypothalamic-like neuron (HN) model across three stages of in vitro differentiation. We profiled accessible chromatin and identified physically interacting contacts between gene promoters and their putative cis-regulatory elements (cREs) to characterize changes in the gene regulatory landscape during hypothalamic differentiation. Next, we integrated these data with GWAS loci for multiple traits and diseases enriched for heritability in these cells, identifying candidate effector genes and cREs impacting transcription factor binding. Our results reveal common target genes for these traits, potentially identifying core hypothalamic developmental pathways. Our atlas will enable future efforts to determine precise mechanisms underlying hypothalamic development with respect to specific disease pathogenesis.Competing Interest StatementThe authors have declared no competing interest.View Full Text

genomics↗