Biology subjects

Hurtado, A.

Publications and source records attributed to Hurtado, A..

8 recordsLinked to original sources

bioRxiv2026

Differential vulnerability of CA1 pyramidal neuron cell types in the 5xFAD Alzheimer's disease mouse model

Selective neuronal vulnerability is a defining feature of Alzheimers disease, yet how neurodegeneration unfolds across defined hippocampal CA1 pyramidal neuron populations remains unresolved. Previously, we showed that CA1 pyramidal neurons are organized into molecularly defined laminar cell types that form stable spatial signatures along the longitudinal axis (Pachicano et al., 2025). Here, we investigated how vulnerability manifests across CA1 pyramidal cell types in the 5xFAD mouse model of amyloid pathology. HiPlex single-molecule fluorescence in situ hybridization was used to quantify gene expression at single-cell resolution across hippocampal CA1 subregions across disease progression. Cells were classified into molecularly defined CA1 pyramidal cell types based on marker gene expression, and changes in density, proportion, and molecular state were assessed. Amyloid-associated pathology differentially affected CA1 pyramidal cell types, revealing distinct trajectories of vulnerability and resilience. Specific populations exhibited early and progressive susceptibility, while other populations demonstrated relative preservation across disease timepoints. These effects were consistent across CA1 subregions, indicating that vulnerability follows cell type identity rather than regional anatomy alone. Together, these findings demonstrate that neurodegeneration in Alzheimers disease is structured by intrinsic cell type identity and provide a cellular framework for understanding selective vulnerability.

neuroscience↗

bioRxiv2026

Supporting-like cells constitute an alternative steroidogenic lineage conserved in amniotes

In mammals, the production of sex hormones is widely considered to depend on the interstitial lineage of the gonad, which differentiates into Leydig cells in males or theca cells in females. However, certain mammalian species evidence gonadal steroidogenic activity prior to the specialization of these interstitial lineages, suggesting that alternative cell types may assume this function. Here we reveal a previously unrecognized role for supporting-like cells (SLCs), which can act as a major steroidogenic lineage during mammalian embryonic development. Through comparative single-cell transcriptomics, steroidomics and in toto organ imaging we find that in rabbits, SLCs not only contribute to the formation of gonadal rete structures, as described for other mammals, but also differentiate into a steroid-producing population. The steroidogenic program of SLCs is initially activated in both sexes but selectively maintained in ovaries, whereas in testes it is progressively replaced by that of interstitially derived Leydig cells. Evolutionary comparisons indicate that SLCs may represent an ancestral lineage that is homologous to the steroidogenic cells of non-mammalian species, which also derive from supporting precursors and share expression of cell fate regulators such as PAX2/8 and TBX1. Altogether, our findings redefine current models of gonadal lineages, revealing an unexpected plasticity in sex differentiation and exemplifying how distinct cell types can converge on analogous functions during evolution.

developmental biology↗

bioRxiv2026

Flexibility of cell fates and functions across sex determination systems revealed by comparative single-cell analyses

Sex determination in vertebrates can be initiated by a wide range of genetic or environmental triggers. Yet, the degree to which gonadal cell types and genetic programs are conserved remains unresolved. Here we employed single-cell transcriptomics to characterize the temperature-dependent sex determination (TSD) program in gonads from the turtle species Trachemys scripta. Comparative analyses against species with genetic sex determination, like mouse (XY) and chicken (ZW), revealed a marked divergence in cell type repertoires and functions during vertebrate evolution. Unlike mammals, fetal Leydig cells are absent from the early gonads of T. scripta, where the supporting lineage expresses genes required for androgen synthesis. Evolutionary reconstructions show that this lineage derives from a Pax2-positive mesenchymal population, suggesting an ancestral condition in Archelosauria that differs from the primarily coelomic epithelium origin in the mammalian clade. Transcriptional dynamics and co-expression analyses revealed the recruitment of lineage-specific transcription factors, including Twist1 or Runx1, into the genetic programs of vertebrate clades. Our findings reveal extensive plasticity of the cellular and genetic mechanisms of vertebrate sex determination and suggest that this flexibility is a key feature of gonadal evolution.

evolutionary biology↗

bioRxiv2024

Sox9 prevents retinal degeneration and is required for limbal stem cell differentiation in the adult mouse eye

Sox9 is a transcription factor with multiple roles during development and in adult organ homeostasis. In the adult eye, Sox9 expression persists in several cell types, including the retinal pigmented epithelium cells and the Muller glial cells, as well as in the limbal and corneal basal epithelia. To uncover the role of Sox9 in these cell types, we induced the deletion of the gene in adult mice. We found that, after Sox9 ablation, mutant mice undergo a severe process of retinal degeneration characterized by the loss of Muller glial cells and complete depletion of the photoreceptors layer. Moreover, by combining single-cell RNA sequencing and Sox9 lineage tracing, we found that Sox9 is expressed in a basal limbal stem cell population with the ability to form two types of long-lived cell clones involved in stem cell maintenance and homeostasis. Mosaic analysis of Sox9 positive and negative cells confirmed that the gene is essential for limbal stem cell differentiation. Our results show that Sox9 is required for the maintenance of retinal integrity and for limbal stem cell differentiation in the adult mouse eye.

developmental biology↗

bioRxiv2023

Complete male-to-female sex reversal in XY mice lacking the miR-17~92 cluster

In mammals, sex determination is controlled by antagonistic gene cascades operating in embryonic undifferentiated gonads1 2. The expression of the Y-linked gene SRY is sufficient to trigger the testicular pathway, whereas its absence in XX embryos leads to ovarian differentiation3 4 5. Despite this strong genetic component, the involvement of non-coding regulation in determining mammalian sex remains unclear6. Here we show that the deletion of a single microRNA cluster, miR-17[~]92, induces complete primary male-to-female sex reversal in XY mice. Time-course analyses revealed that Sry is heterochronically expressed, showing a delay in XY miR-17[~]92 knockout gonads, which subsequently activate the ovarian genetic program. Bulk and single cell RNA-seq analyses showed that Sertoli cell differentiation is reduced, delayed and unable to sustain the testicular fate. This disrupted differentiation results from a transient state of sex ambiguity in pre-supporting cells, which is later resolved towards the ovarian fate. Consistent with known mechanisms of miRNA-mediated gene regulation, the expression of miR-17[~]92 target genes is not stabilized in undifferentiated XY mutant gonads, affecting concomitantly the fine regulation of gene networks with critical roles in developing gonads. Our results demonstrate that microRNAs are key components for mammalian sex determination, controlling the timing of Sry expression and Sertoli cell differentiation.

developmental biology↗

bioRxiv2022

Sex-determining 3D regulatory hubs revealed by genome spatial auto-correlation analysis

Mammalian sex is determined by opposing networks of ovarian and testicular genes that are well characterized. However, its epigenetic regulation is still largely unknown, thus limiting our understanding of a fundamental process for species propagation. Here we explore the 3D chromatin landscape of sex determination in vivo, by profiling FACS-sorted embryonic mouse gonadal populations, prior and after sex determination, in both sexes. We integrate Hi-C with ChIP-seq experiments using METALoci, a novel genome spatial auto-correlation analysis that identifies 3D enhancer hubs across the genome. We uncover a prominent rewiring of chromatin interactions during sex determination, affecting the enhancer hubs of hundreds of genes that display temporal- and sex-specific expression. Moreover, the identification of the 3D enhancer hubs allows the reconstruction of regulatory networks, revealing key transcription factors involved in sex determination. By combining predictive approaches and validations in transgenic mice we identify a novel Fgf9 regulatory hub, deletion of which results in male-to-female sex reversal with the upregulation of ovarian-specific markers and the initiation of meiosis. Thus, spatial auto-correlation analysis is an effective strategy to identify regulatory networks associated to biological processes and to further characterize the functional role of the 3D genome.

developmental biology↗

bioRxiv2021

Combination of a Sindbis-SARS-CoV-2 spike vaccine and αOX40 antibody elicits protective immunity against SARS-CoV-2 induced disease and potentiates long-term SARS-CoV-2-specific humoral and T-cell immunity

The COVID-19 pandemic caused by the coronavirus SARS-CoV-2 is a major global public threat. Currently, a worldwide effort has been mounted to generate billions of effective SARS-CoV-2 vaccine doses to immunize the worlds population at record speeds. However, there is still demand for alternative effective vaccines that rapidly confer long-term protection and rely upon cost-effective, easily scaled-up manufacturing. Here, we present a Sindbis alphavirus vector (SV), transiently expressing the SARS-CoV-2 spike protein (SV.Spike), combined with the OX40 immunostimulatory antibody (OX40) as a novel, highly effective vaccine approach. We show that SV.Spike plus OX40 elicits long-lasting neutralizing antibodies and a vigorous T-cell response in mice. Protein binding, immunohistochemical and cellular infection assays all show that vaccinated mice sera inhibits spike functions. Immunophenotyping, RNA Seq transcriptome profiles and metabolic analysis indicate a reprogramming of T-cells in vaccinated mice. Activated T-cells were found to mobilize to lung tissue. Most importantly, SV.Spike plus OX40 provided robust immune protection against infection with authentic coronavirus in transgenic mice expressing the human ACE2 receptor (hACE2-Tg). Finally, our immunization strategy induced strong effector memory response, potentiating protective immunity against re-exposure to SARS-CoV-2 spike protein. Our results show the potential of a new Sindbis virus-based vaccine platform to counteract waning immune response that can be used as a new candidate to combat SARS-CoV-2. Given the strong T-cell responses elicited, our vaccine is likely to be effective against variants that are proving challenging, as well as, serve as a platform to develop a broader spectrum pancoronavirus vaccine. Similarly, the vaccine approach is likely to be applicable to other pathogens.

immunology↗

bioRxiv2017

Signs of host genetic regulation in the microbiome composition in cattle

Previous studies have revealed certain genetic control by the host over the microbiome composition, although in many species the host genetic link controlling microbial composition is yet unknown. This potential association is important in livestock to study all factors and interactions that rule the effect of the microbiome in complex traits. This report aims to study whether the host genotype exerts any genetic control on the microbiome composition of the rumen in cattle. Data on 16S and 18S rRNA gene-based analysis of the rumen microbiome in 18 dairy cows from two different breeds (Holstein and Brown Swiss) were used. The effect of the genetic background of the animal (through the breed and Single Nucleotide Polymorphisms; SNP) on the relative abundance (RA) of archaea, bacteria and ciliates (with average relative abundance per breed >0.1%) was analysed using Bayesian statistics. In total, 13 genera were analysed for bacteria (5), archaea (1), and ciliates (7). All these bacteria and archaea genera showed association to the host genetic background both for breed and SNP markers, except RA for the genera Butyrivibrio and Ruminococcus that showed association with the SNP markers but not with the breed composition. Relative abundance of 57% (4/7) of ciliate analysed showed to be associated to the genetic background of the host. This host genetic link was observed in some genus of Trichostomatia family. For instance, the breed had a significant effect on Isotricha, Ophryoscolex and Polyplastron, and the SNP markers on Entodinium, Ophryoscolex and Polyplastron. In total, 77% (10/13) of microbes analysed showed to be associated to the host genetic background (either by breed or SNP genotypes). Further, the results showed a significant association between DGAT1, ACSF3, AGPAT3 and STC2 genes with the relative abundance Prevotella genus with a false discovery rate lower than 15%. The results in this study support the hypothesis and provide some evidence that there exist a host genetic component in cattle that can partially regulate the composition of the microbiome.

genomics↗