Biology subjects

Conforti, P.

Publications and source records attributed to Conforti, P..

6 recordsLinked to original sources

bioRxiv2022

Brain regional identity and cell type specificity landscape of human cortical organoid models

In vitro models of corticogenesis using mouse and human pluripotent stem cells (PSC) have greatly improved our understanding of human brain development and disease. Among these, 3D cortical organoid systems are able to recapitulate some aspects of in vivo cytoarchitecture of the developing cortex. Here, we tested three cortical organoid protocols for brain regional identity, cell type-specificity and neuronal maturation. Overall all protocols gave rise to organoids that displayed a time-dependent expression of neuronal maturation genes such as those involved in the establishment of synapses and neuronal function. We showed that three months old cortical organoids showed a pattern of gene expression that resembled late human embryonic cortex. Comparatively, directed differentiation methods without WNT activation gave rise to the highest degree of cortical regional identity in brain organoids. Whereas, default "intrinsic" brain organoid differentiation produced the broadest range of cell types such as neurons, astrocytes and hematopoietic-lineage derived microglia cells of the brain. These results suggest that cortical organoid models produce diverse outcomes in terms of brain regional identity and cell type specificity and emphasize the importance of selecting the correct model for the right application.

neuroscience↗

bioRxiv2020

SREBP2 delivery to striatal astrocytes normalizes transcription of cholesterol biosynthesis genes and ameliorates pathological features in Huntington's disease

Brain cholesterol is produced mainly by astrocytes and is important for neuronal function. Its biosynthesis is severely reduced in mouse models of Huntingtons Disease (HD). One possible mechanism is a diminished nuclear translocation of the transcription factor sterol regulatory element binding protein 2 (SREBP2) and, consequently, reduced activation of SREBP-controlled genes in the cholesterol biosynthesis pathway. Here we evaluated the efficacy of a gene therapy based on the unilateral intra-striatal injection of a recombinant adeno-associated virus 2/5 (AAV2/5) targeting astrocytes specifically and carrying the N-terminal fragment of human SREBP2 (hSREBP2). Robust hSREBP2 expression in striatal glial cells in HD mice activated the transcription of cholesterol biosynthesis pathway genes, restored synaptic transmission, reversed Drd2 transcript levels decline, cleared muHTT aggregates and attenuated behavioral deficits. We conclude that glial SREBP2 participates in HD brain pathogenesis in vivo and that AAV-based delivery of SREBP2 to astrocytes counteracts key features of HD.

neuroscience↗

bioRxiv2020

Dose-dependent and disease-modifying effects of striatal infusion of cholesterol in Huntington's disease

A variety of pathophysiological mechanisms are implicated in Huntingtons disease (HD). Among them, reduced cholesterol biosynthesis has been detected in the HD mouse brain from pre-symptomatic stages, leading to diminished cholesterol synthesis, particularly in the striatum. In addition, systemic injection of cholesterol-loaded brain-permeable nanoparticles ameliorates synaptic and cognitive function in a transgenic mouse model of HD. To identify an appropriate treatment regimen and gain mechanistic insights into the beneficial activity of exogenous cholesterol in the HD brain, we employed osmotic mini-pumps to infuse three escalating doses of cholesterol directly into the striatum of HD mice in a continuous and rate-controlled manner. All tested doses prevented cognitive decline, while amelioration of disease-related motor defects was dose-dependent. In parallel, we found morphological and functional recovery of synaptic transmission involving both excitatory and inhibitory synapses of striatal medium spiny neurons. The treatment also enhanced endogenous cholesterol biosynthesis and clearance of mutant Huntingtin aggregates. These results indicate that cholesterol infusion to the striatum can exert a dose-dependent, disease-modifying effect and may be therapeutically relevant in HD.

neuroscience↗

bioRxiv2020

The enhancement of activity rescues the establishment of Mecp2 null neuronal phenotypes

Mecp2 deficiency, the gene responsible for Rett syndrome (RTT), affects brain maturation by impairing neuronal activity, transcription and morphology. These three elements are physiologically linked in a feed-forward cycle where neuronal activity modulates transcription and morphology to further increase network maturity. We hypothesized that the reduced activity displayed by maturing Mecp2 null neurons during development could perturb such cycle, sustaining an improper transcriptional program that, ultimately, impairs neuronal maturation. Accordingly, we show that by enhancing activity within an early time window, Ampakine redirects, in vitro, the development of null neuronal networks towards more physiological routes. Similarly, the administration of the drug to newborn null offspring delays the progression of symptoms, significantly prolonging life span. Our data highlights the role of altered neuronal activity during the establishment of Mecp2 null networks and the importance of such early defects to the typically poor maturity of RTT brain functions in adulthood. We propose the existence of an "early molecular phase" of Rett syndrome, a detailed description of which might disclose relevant targets for new rescue treatments.

neuroscience↗

bioRxiv2018

Longitudinal dissection in brain organoids at single cell resolution uncovers the developmental role of GSK3 in human corticogenesis

The regulation of proliferation and polarity of neural progenitors is crucial for the development of the brain cortex, with modes and timings of cell division intimately related to the stereotypical acquisition of layer-specific neuronal identities. Animal studies have implicated glycogen synthase kinase 3 (GSK3) as a pivotal regulator of both proliferation and polarity, yet the functional relevance of its signaling for the unique features of human corticogenesis remain to be elucidated. Here we harness human cortical brain organoids to probe, at single cell resolution, the longitudinal impact of GSK3 inhibition through multiple developmental stages. Our results indicate that chronic GSK3 inhibition increases the proliferation of neural progenitors and causes massive derangement of cortical tissue architecture. Surprisingly, single cell transcriptome profiling revealed only a discrete impact on early neurogenesis and uncovered the outer radial glia and the astrogenic lineage as the main GSK3-dependent developmental domains. Through this first single cell-level dissection of the GSK3 regulatory network in human corticogenesis, our work uncovers a remarkably specific conduit between the architecture of progenitor niches and lineage specification.

developmental biology↗

bioRxiv2018

Interferon-alpha2 but not interferon-gamma serum levels are associated with intramuscular fat in obese patients with nonalcoholic fatty liver disease

BackgroundIntramuscular triglycerides (IMTGs) represent an important energy supply and a dynamic fat-storage depot that can expand during periods of elevated lipid availability and a fatty ac-id source. Ultrasonography (US) of human skeletal muscles is a practical and reproducible method to assess both IMTG presence and entity.\n\nAlthough a crosstalk between cytokines in skeletal muscle and adipose tissue has been suggested in obesity, condition leading to hepatic steatosis (HS) or better defined as nonalcoholic fatty liver disease and cancer, there are still questions to be answered about the role of interferons (IFNs), alpha as well as gamma, and IMTG in obesity. We aimed at discovering any correlation between IFNs and IMTG.\n\nMethodsWe analysed anthropometric data, metabolic parameters and imaging features of a population of obese subjects with low-prevalence of co-morbidities but HS. The levels of serum IFNs were detected by a magnetic bead-based multiplex immunoassays.\n\nResultsSerum concentrations of IFN-alpha2 were increased, while serum levels of IFN-gamma were decreased confronted with those of controls; the severity of IMTG, revealed at US as Heckmatt scores, was inversely predicted by IFN-alpha2 serum concentrations; IMTG scores were not predicted by serum levels of IFN-gamma; IMTG scores were predicted by HS severity, ascertained at US; HS severity was predicted by visceral adipose tissue, assessed by US, but the latter was not instrumental to IMTG.\n\nDiscussion & ConclusionThis study has added some pieces of observation about the cytokine network regulating the interplay between IMTG and obesity in obese patients with HS.

epidemiology↗