Biology subjects

Lilao-Garzon, J.

Publications and source records attributed to Lilao-Garzon, J..

7 recordsLinked to original sources

bioRxiv2025

Imp1 acts as a dosage- and stage-dependent temporal rheostat orchestrating radial glial fate transitions and cortical morphogenesis

Cortical neurogenesis proceeds through a precise temporal program in which radial glia sequentially generate distinct neuronal subtypes and later glia, yet how post-transcriptional regulators coordinate these transitions remain poorly understood. We previously identified that a decreasing temporal gradient of the RNA-binding protein Imp encodes neural stem cell age in Drosophila. In this work, we extend our investigation to Imp1, a mammalian homologue of Imp, and its role in murine neocortical development. Using TEMPO to track birth-order dynamics, we demonstrate that sustained Imp1 overexpression during early neurogenesis arrests temporal fate progression, shifting neuronal populations toward deeper cortical layers V-VI. Immunostaining with layer-specific transcription factors Cux1 and Ctip2 confirmed that laminar repositioning results from genuine changes in neuronal identity rather than migratory defects, with neurons adopting molecular identities matching their final positions. Temporal window-specific manipulations reveal distinct stage-specific effects where early-stage Imp1 induction produces cascading effects on fate specification and moderately delays the neuronal-to-gliogenic transition, while mid-stage induction induces neuronal accumulation in the subplate region. Live imaging of organotypic cultures reveals continuous neuronal recruitment within intermediate and ventricular zones, with mid-stage-born neurons accumulating at significantly faster rates than earlier cohorts. Strikingly, mid-stage Imp1 overexpression also induces ectopic glial-like foci distributed throughout the cortical plate, featuring dramatic cellular expansion and morphological heterogeneity. These findings establish Imp1 as a dosage- and stage-dependent temporal rheostat orchestrating developmental transitions in radial glial progenitors, controlling neuronal fate decisions and spatial organization. This work advances our understanding of molecular timing mechanisms governing neuronal diversity in the mammalian cortex.

developmental biology↗

bioRxiv2025

Regulation of mouse blastocyst primitive endoderm differentiation by p38-mitogen-activated-kinases (p38-MAPKs) is inner-cell-mass (ICM) autonomous and unrelated to cavity expansion defects in ICM specification.

During early mouse blastocyst ICM maturation, we previously described that pharmacological inhibition of p38-MAPK (p38-MAPKi) significantly impairs primitive endoderm (PrE) differentiation from an initially uncommitted population of ICM cells but does not affect pluripotent epiblast (EPI) specification. A recent report details a positive role for blastocyst cavity expansion in assisting ICM lineage formation and marker gene expression. As p38-MAPKi also results in smaller cavity volumes, we addressed to what extent p38-MAPKi mediated impaired PrE differentiation is driven by ICM autonomous or cavity expansion mechanisms. We compared ICM differentiation phenotypes associated with either chemically inhibited cavity volume expansion and p38-MAPKi, on the individual cell and ICM lineage population levels. Whilst recapitulating previously observed decreases in expression of both EPI and PrE markers, we discovered cavity expansion phenotypes are manifest in impaired numbers of specified EPI and increased numbers of uncommitted cells; rather than impaired PrE differentiation, as observed after p38-MAPKi. Moreover, using both 2D ES-cell and 3D ICM organoid models, we show PrE differentiation is also significantly impaired by p38-MAPKi in the absence of a blastocyst cavity; a result recapitulated in cultured immuno-surgically isolated early blastocyst ICMs, in which an outer PrE and inner EPI population are ordinarily formed. These data confirm the early blastocyst requirement for p38-MAPK activity to permit PrE differentiation from uncommitted ICM progenitors is primarily ICM autonomous rather than caused by impaired cavity expansion.

developmental biology↗

bioRxiv2025

Wnt/β-catenin signalling assists cell fate decision making in the early mouse embryo

Cell fate choice is a key event happening during preimplantation mouse development. From embryonic day 3.5 (E3.5) to E4.5, the inner cell mass (ICM) differentiates into epiblast (Epi, NANOG expressing cells) and primitive endoderm (PrE, GATA6, SOX17 and/or GATA4 expressing cells). The mechanism by which ICM cells differentiate into Epi cells and PrE cells remains partially unknown. FGF/ERK has been proposed as the main signalling pathway for this event, but it does not explain co-expression of NANOG and GAT6 or how the cell fate choice is initiated. In this study, we investigate whether Wnt/{beta}-catenin signalling also plays a role. To this end, we use two in vitro models based on inducible GATA6 expression: one in 2D, and another in 3D, namely ICM organoids. By combining these in vitro models with in vivo mouse embryos, chemical and classical genetics, and quantitative 3D immunofluorescence analyses, we propose a dual role for Wnt/{beta}-catenin signalling. We find that {beta}-catenin, acting alongside FGF/ERK signalling, helps to guide the cell fate choice towards PrE. Additionally, by regulating GATA6 and GATA4 stability, {beta}-catenin further facilitates this choice. To summarise, we observe that pathway activation promotes PrE differentiation, while its inhibition stalls it. SUMMARY STATEMENTWnt/{beta}-catenin signalling promotes PrE fate in mouse preimplantation embryos.

developmental biology↗

bioRxiv2023

The salt-and-pepper pattern in mouse blastocysts is compatible with signalling beyond the nearest neighbours.

Embryos develop in a concerted sequence of spatio-temporal arrangements of cells. In the preimplantation mouse embryo, the distribution of the cells in the inner cell mass evolves from a salt-and-pepper pattern to spatial segregation of two distinct cell types. The exact properties of the salt-and-pepper pattern have not been analysed so far. We investigate the spatio-temporal distribution of NANOG and GATA6 expressing cells in the ICM of the mouse blastocysts with quantitative three-dimensional single cell-based neighbourhood analyses. A combination of spatial statistics and agent-based modelling reveals that the cell fate distribution follows a local clustering pattern. Using ordinary differential equations modelling, we show that this pattern can be established by a distance-based signalling mechanism enabling cells to integrate information from the whole inner cell mass into their cell fate decision. Our work highlights the importance of longer-range signalling to ensure coordinated decisions in groups of cells to successfully build embryos.

developmental biology↗

bioRxiv2022

Maternal age, obesity and hyperglycaemia are associated with a delay in preimplantation development in a mouse model of type 2 diabetes

Aims/hypothesisDelayed maternal age, obesity and diabetes are associated with reduced fertility. We investigated how age and obesity/metabolic syndrome impact fertility and hypothesized that its decrease is due to defects in preimplantation embryo development. MethodsThree groups of female C57Bl6 mice (12 weeks, 9 months and 1 year old) were fed either a high fat diet for 8 weeks, to induce obesity and the metabolic syndrome, or a control chow diet. Body weight and composition, glucose tolerance and insulin resistance were assessed. Fecundity was evaluated by mating and pregnancy rates, as well as number of embryos. Embryo quality was assessed morphologically, and cell fate composition was analysed in preimplantation embryos by state-of-the-art single cell quantitative confocal image analysis. ResultsThe high fat diet was associated with increased adiposity, glucose intolerance and insulin resistance, especially in the older mice. Fecundity was affected by age, more than by the diet. Both age and high fat diet were associated with reduced cell fate allocation, indicating a delay in preimplantation embryo development, and with increased expression of GATA3, an inhibitor of placentation. Conclusion/InterpretationThese results support that age and the metabolic syndrome reduce fertility through mechanisms which are present at conception very early in pregnancy. What is already known about this subject?O_LILifestyle changes in modern societies have led to an increase in obesity and type 2 diabetes, and women tend to become pregnant later than ever. These factors have a negative influence on female fecundity. C_LIO_LIIn mice, diet induced obesity is associated with poor quality oocytes that affect overall embryonic development. C_LI What is the key question?O_LIDo age and high fat diet influence cell fate differentiation during preimplantation embryo development? C_LI What are the new findings?O_LIBody composition and glucose metabolism are altered due to high fat diet even when weight is not affected in young animals. C_LIO_LIAlthough there are no differences in mating and fertilization rates, embryo quality is lower with high fat diet. C_LIO_LICells not fully committed to a cell fate (epiblast or primitive endoderm) are increased in embryos from mature dams or fed a high fat diet, indicating a delay in preimplantation embryo development. C_LI How might this impact on clinical practice in the foreseeable future?O_LIOur findings show a delay in early embryo development associated to obesity and maternal age. This delay could be responsible for the low fertility observed in women with type 2 diabetes and obesity. C_LI

developmental biology↗

bioRxiv2022

Exploring the link between Parkinson's disease and Diabetes Mellitus in Drosophila

Parkinsons disease (PD) is the second most common neurodegenerative disease. Diabetes mellitus (DM) is a metabolic disease characterized by high levels of glucose in blood. Recent epidemiological studies are highlighting the link between both diseases; it is even considered that DM might be a risk factor for PD. To further investigate the likely relation of these diseases, we have used a Drosophila PD model based on inactivation of the DJ-1{beta} gene (ortholog of human DJ-1), and diet-induced Drosophila and mouse T2DM models, together with human neuron-like cells. T2DM models were obtained by feeding flies with a high sugar containing medium, and mice with a high fat diet. Our results showed that both fly models exhibit common phenotypes such as alterations in carbohydrate homeostasis, mitochondrial dysfunction or motor defects, among others. In addition, we demonstrated that T2DM might be a risk factor of developing PD since our diet-induced fly and mouse T2DM models present DA neurodegeneration, a hallmark of PD. We have also confirmed that neurodegeneration is caused by increased glucose levels, which has detrimental effects in human neuron-like cells by triggering apoptosis and leading to cell death. Besides, the observed phenotypes were exacerbated in DJ-1{beta} mutants cultured in the high sugared medium, indicating that DJ-1 might have a role in carbohydrate homeostasis. Finally, we have confirmed that metformin, an antidiabetic drug, is a potential candidate for PD treatment and that it could prevent PD onset in T2DM model flies. This result supports antidiabetic drugs as promising PD therapeutics.

neuroscience↗

bioRxiv2017

Three-dimensional cell neighbourhood impacts differentiation in the inner mass cells of the mouse blastocyst

During mammalian blastocyst development, inner cell mass (ICM) cells differentiate into epiblast (Epi) or primitive endoderm (PrE). These two fates are characterised by the transcription factors NANOG and GATA6, respectively. Here, we present quantitative three-dimensional single cell-based neighbourhood analyses to investigate the spatial distribution of NANOG and GATA6 expression in the ICM of the mouse blastocyst. The cell neighbourhood is characterised by the expression levels of the fate markers in the surrounding cells, together with the number of surrounding cells and cell position. We find that cell neighbourhoods are established in early blastocysts and different for cells expressing different levels of NANOG and GATA6. Highest NANOG expressing cells occupy specific positions within the ICM and are surrounded by 9 neighbours, while GATA6 expressing cells cluster according to their GATA6 levels. The analysis of mutants reveals that NANOG local neighbourhood is regulated by GATA6.\n\nSummary statementThree-dimensional cell neighbourhood, which includes fate marker levels, number of neighbouring cells and cell position, determines cell fate decision in early mouse embryos.

developmental biology↗