Biology subjects

Fernandez-Vallone, V.

Publications and source records attributed to Fernandez-Vallone, V..

3 recordsLinked to original sources

bioRxiv2024

An Lgr5-independent developmental lineage is involved in mouse intestinal regeneration

Collagenase/dispase treatment of intestinal tissue from adult mice generates cells growing in matrigel as stably replatable cystic spheroids in addition to differentiated organoids. Contrary to classical EDTA-derived organoids, these spheroids display poor intestinal differentiation and are independent of Rspondin/Noggin/EGF for growth. Their transcriptome resembles strikingly that of fetal intestinal spheroids, with downregulation of crypt base columnar cell (CBC) markers (Lgr5, Ascl2, Smoc2, Olfm4). In addition, they display upregulation of inflammatory and mesenchymal genetic programs, together with robust expression of YAP target genes. Lineage tracing, cell-sorting and single cell RNA sequencing experiments demonstrate that adult spheroid-generating cells belong to a hitherto undescribed developmental lineage, independent of Lgr5+ve CBCs, and are involved in regeneration of the epithelium following CBC ablation. O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=153 SRC="FIGDIR/small/584399v3_ufig1.gif" ALT="Figure 1"> View larger version (32K): org.highwire.dtl.DTLVardef@c8d67corg.highwire.dtl.DTLVardef@1799ca2org.highwire.dtl.DTLVardef@11a7d92org.highwire.dtl.DTLVardef@2a1c9b_HPS_FORMAT_FIGEXP M_FIG C_FIG

developmental biology↗

bioRxiv2023

Spatiotemporal expression of thyroid hormone transporter MCT8 and THRA mRNA in human cerebral organoids recapitulating first trimester cortex development

Thyroid hormones (TH) play critical roles during nervous system development and patients carrying coding variants of MCT8 (Monocarboxylate transporter 8) or THRA (Thyroid hormone receptor alpha) present a spectrum of neurological phenotypes resulting from perturbed local TH action during early brain development. Recently, human cerebral organoids (hCOs) emerged as powerful three-dimensional in vitro tools for disease modelling recapitulating key aspects of early human cerebral cortex development. To begin exploring prospects of this model for thyroid research, we performed a detailed characterization of the spatiotemporal expression of the TH transporter MCT8 and TH receptor THRA in developing hCOs. Immunostaining of hCOs showed MCT8 membrane expression in neuronal progenitor cell types including early neuroepithelial cells, SOX2+/Nestin+ radial glia cells (RGCs), TBR2+ intermediate progenitors and HOPX+ outer RGCs. In addition, we detected robust MCT8 protein expression in CTIP2+ deep layer neurons and at later developmental stages in SATB2+ upper layer neurons. Spatiotemporal SLC16A2 mRNA expression, detected by fluorescent in situ hybridization (FISH), was highly concordant with MCT8 protein expression across cortical cell layers. FISH detected THRA mRNA expression already in neuroepithelium before the onset of neurogenesis and THRA expression was maintained in RGCs of the ventricular zone. Increased THRA expression was later detected in the subventricular zone whereas highest THRA expression was observed in excitatory neurons in peripheral hCO regions. In combination with strong up-regulation of known T3 response genes following short-term T3 treatment of hCOs, these observations show that hCOs provide a promising and experimentally tractable model to probe local TH action during human cortical neurogenesis and eventually to model the consequences of impaired TH function for early cortex development.

neuroscience↗

bioRxiv2019

Lgr5 Controls Extracellular Matrix Production By Stem Cells In The Developing Intestine

The Lgr5 receptor is a marker of intestinal stem cells (ISCs) that regulates Wnt/b-catenin signaling. In this study, phenotype analysis of knockin/knockout Lgr5-eGFP-IRES-Cre and Lgr5-DTReGFP embryos revealed that Lgr5 deficiency during Wnt-mediated cytodifferentiation results in amplification of ISCs and early differentiation into Paneth cells, which can be counteracted by in utero treatment with the Wnt inhibitor LGK974. Conditional ablation of Lgr5 postnatally, but not in adults, altered stem cell fate towards the Paneth lineage. Together, these in vivo studies suggest that Lgr5 is part of a feedback loop to adjust the Wnt tone in ISCs. Moreover, transcriptome analyses revealed that fetal ISCs generate their own extracellular matrix components, a property lost in adult ISCs, which adopt a definitive epithelialized phenotype and an inflammatory response signature. Absence of Lgr5 in fetal ISCs resulted in reduced extracellular matrix production and accelerated ISC maturation, indicating that Lgr5 regulates the ISC niche. Finally, evidences are provided that Rspondin 2 negatively regulates the pool of ISCs in organoids via Lgr5, revealing a sophisticated regulatory process for Wnt signaling in ISC.

developmental biology↗