Biology subjects

Pitasi, M.

Publications and source records attributed to Pitasi, M..

4 recordsLinked to original sources

bioRxiv2026

WT1 splice isoforms configure lineage bias during formative pluripotency

How transcriptional asymmetry first arises in the epiblast prior to gastrulation remains a central question in mammalian development. During the transition from naive to formative pluripotency, epiblast cells acquire responsiveness to lineage-inducing cues while already expressing lineage-associated transcriptional programmes. The molecular basis of these asymmetries and whether they reflect stochastic variation or regulated lineage-associated bias remain unclear. Here, using a targeted CRISPRa screen, we identify Wt1 (Wilms tumor 1) as a previously unrecognized regulator of lineage-associated transcriptional programmes during formative pluripotency. Wt1 is transiently induced during formative pluripotency in vitro and in the pre-gastrulation epiblast in vivo, with peak expression coinciding with the emergence of lineage-associated transcriptional biases. Precocious Wt1 induction overrides the naive transcriptional network and advances cells toward a post-implantation epiblast identity, whereas Wt1-deficient cells remain capable of naive exit but show impaired acquisition of formative and lineage-associated transcriptional programmes. Genome-wide binding analyses during formative state acquisition show that WT1 engages active regulatory elements of the emerging post-implantation gene regulatory network together with core formative transcription factors, including FOXO1, OTX2 and OCT4. Direct comparison of all four major Wt1 splice isoforms identifies KTS splice status as the major determinant of divergent anterior/neuroectodermal and posterior/mesodermal transcriptional programmes in vitro. In the E5.5 epiblast, Wt1 expression and splice composition align with lineage-biased transcriptional states, linking isoform usage to anterior transcriptional biases in vivo. Isoform-dependent gene expression modules are conserved in human pluripotent cells, indicating that this regulatory logic is preserved across species. Together, our findings indicate that lineage-associated transcriptional programmes diverge during formative pluripotency prior to gastrulation and identify alternative splicing as a mechanism that tunes lineage-associated transcriptional bias.

developmental biology↗

bioRxiv2025

Metabolic reprogramming and altered ATP content impair neuroprotective functions of microglia in β-glucocerebrosidase deficiency models

Mutations in the GBA gene, which reduce {beta}-glucocerebrosidase (GCase) activity, represent the most significant genetic risk factor for Parkinsons disease (PD). Decreased GCase activity has also been observed in sporadic PD cases, supporting a broader role for GCase in the poorly understood mechanisms underlying PD etiopathogenesis. While most studies on the relationship between GBA mutations and PD have focused on neurons, evidence suggests that PD pathology promoted by GCase deficiency involves other cell types and, in particular, interactions between neuronal and glial cells. Here, we identify microglia as primary players undergoing significant alterations at early stages of the pathological processes triggered by a GCase impairment. Using both pharmacological and genetic mouse models of GCase deficiency, we observed microglial morphological, transcriptional and metabolic changes. Interestingly, these changes were associated with a cell-specific, significant reduction of microglial ATP levels. When microglial ATP depletion was reproduced in an in vitro system of co-cultured microglial and neuronal cells, the neuroprotective properties of microglia were compromised and neuronal susceptibility to oxidative stress was enhanced. These findings underscore the role of microglia in PD pathogenesis and point to a pathogenetic mechanism by which microglial metabolic disturbances leading to ATP depletion enhance neuronal vulnerability to injury and neurodegeneration. This mechanism could be targeted for therapeutic intervention aimed at mitigating PD risk and counteracting the development of PD pathology. GRAPHICAL ABSTRACT O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=112 SRC="FIGDIR/small/656111v2_ufig1.gif" ALT="Figure 1"> View larger version (26K): org.highwire.dtl.DTLVardef@dfd3d7org.highwire.dtl.DTLVardef@ccf2c2org.highwire.dtl.DTLVardef@155d241org.highwire.dtl.DTLVardef@15ed00a_HPS_FORMAT_FIGEXP M_FIG C_FIG

neuroscience↗

bioRxiv2023

Enhancer cooperativity can compensate for loss of activity over large genomic distances

Enhancers are short DNA sequences that activate their target promoter from a distance; however, increasing the genomic distance between the enhancer and the promoter decreases expression levels. Many genes are controlled by combinations of multiple enhancers, yet the interaction and cooperation of individual enhancer elements is not well understood. Here, we developed a novel synthetic platform that allows building complex regulatory landscapes from the bottom up. We tested the system by integrating individual enhancers at different distances and revealed that the strength of an enhancer determines how strongly it is affected by increased genomic distance. Furthermore, synergy between two enhancer elements depends on the distance at which the two elements are integrated: introducing a weak enhancer between a strong enhancer and the promoter strongly increases reporter gene expression, allowing enhancers to activate from increased genomic distances.

molecular biology↗

bioRxiv2022

Bridging between mouse and human enhancer-promoter long-range interactions in neural stem cells, to understand enhancer function in neurodevelopmental disease

Non-coding variation in complex human disease has been well established by genome-wide association studies, and it is thought to involve regulatory elements, such as enhancers, whose variation affects the expression of the gene responsible for the disease. The regulatory elements often lie far from the gene they regulate, or within introns of genes differing from the regulated gene, making it difficult to identify the gene whose function is affected by a given enhancer variation. Enhancers are connected to their target gene promoters via long-range physical interactions (loops). In our study, we re-mapped, onto the human genome, more than 10,000 enhancers connected to promoters via long-range interactions, that we had previously identified in mouse brain-derived neural stem cells by RNApolII-ChIA-PET analysis, coupled to ChIP-seq mapping of DNA/chromatin regions carrying epigenetic enhancer marks. These interactions are thought to be functionally relevant. We discovered, in the human genome, thousands of DNA regions syntenic with the interacting mouse DNA regions (enhancers+connected promoters). We further annotated these human regions regarding their overlap with sequence variants (single nucleotide polymorphisms, SNPs; copy number variants, CNVs), that were previously associated with neurodevelopmental disease in human. We document various cases in which the genetic variant, associated in human to neurodevelopmental disease, affects an enhancer involved in long-range interactions: SNPs, previously identified by genome-wide association studies to be associated with schizophrenia, bipolar disorder, and intelligence, are located within our human syntenic enhancers, and alter transcription factors recognition sites. Similarly, CNVs associated to autism spectrum disease and other neurodevelopmental disorders overlap with our human syntenic enhancers. Some of these enhancers are connected (in mouse) to homologs of genes already associated to the human disease, strengthening the hypothesis that the gene is indeed involved in the disease. Other enhancers are connected to genes not previously associated with the disease, pointing to their possible pathogenetic involvement. Our observations provide a resource for further exploration of neural disease, in parallel with the now widespread genome-wide identification of DNA variants in patients with neural disease.

neuroscience↗