Biology subjects

Castillo-Azofeifa, D.

Publications and source records attributed to Castillo-Azofeifa, D..

4 recordsLinked to original sources

bioRxiv2025

Maladaptive inflammatory signaling in old mice impairs colonic regeneration by promoting a sustained fetal-like epithelial state

Aging is associated with a decline in the regenerative capacity of many tissues. Central to this decline is a complex interplay between inflammation and stem cell function. How these two processes are linked and influence regenerative capacity remains unclear. Here, we undertake a comprehensive assessment of age-related changes in the mouse colon at single-cell resolution. A survey of immune and epithelial compartments revealed a hyperactivated inflammatory state in the colon of old mice characterized by the induction of an interferon {gamma} (IFN{gamma}) response signature in immune cells. This does not result in increased inflammation under homeostasis, but triggers a disproportionate inflammatory response, disrupting regeneration after challenge with the enteropathogen Citrobacter rodentium. Colons of old mice exhibit higher production of IFN{gamma} by T and innate lymphoid cells (ILCs) that are associated with reduced Lgr5+ stem cells and decreased epithelial proliferation. Interestingly, we find aged intestinal epithelial cells to be hypersensitive to IFN{gamma} signaling, inducing a regeneration-associated fetal-like gene expression signature that, in turn, renders these cells more sensitive to IFN{gamma}-induced apoptosis. Our findings reveal an age-related imbalance in the interaction between the immune and epithelial compartments in the colon, priming the system for excessive inflammatory responses and the emergence of a hypersensitive epithelial cell state thus derailing proper repair of the intestinal epithelium after injury.

immunology↗

bioRxiv2021

Intracellular pH dynamics regulates intestinal stem cell fate

Intracellular pH (pHi) dynamics is increasingly recognized to regulate myriad cell behaviors, including proliferation, migration, differentiation, and transformation. Here we report a new finding that pHi dynamics also regulates adult stem cell lineage specification. In mouse small intestinal organoids, we identify a pHi gradient along the crypt axis, lower at the crypt base and higher toward the villus, and find that dissipating this gradient by inhibiting Na+-H+ exchanger 1 (NHE1) activity genetically or pharmacologically abolishes crypt budding. Using single-cell RNA sequencing and lineage tracing we demonstrate that pHi dynamics acts downstream of ATOH1, with increased pHi promoting differentiation toward the secretory lineage, while reduced pHi biases differentiation into the absorptive lineage. Consistent with these results, disrupting the pHi gradient blocks new Paneth cell differentiation. Paneth cells provide an essential WNT signal to ISCs in organoids, and we find that the loss of crypt budding with inhibiting NHE1 activity is rescued with exogenous WNTs. Our findings indicate that pHi dynamics is tightly regulated in the ISC lineage and that an increase in pHi is required for the specification of secretory lineage, including Paneth cell differentiation that contributes to crypt maintenance. These observations reveal a previously unreported role for pHi dynamics in cell fate decisions within an adult stem cell lineage.

cell biology↗

bioRxiv2019

Lgr5+ telocytes are a signaling hub at the intestinal villus tip

The intestinal epithelium is a structured organ composed of crypts harboring Lgr5+ stem cells, and villi harboring differentiated cells. Spatial transcriptomics have demonstrated profound zonation of epithelial gene expression along the villus axis, but the mechanisms shaping this spatial variability are unknown. Here, we combined laser capture micro-dissection and single cell RNA sequencing to uncover spatially zonated populations of mesenchymal cells along the crypt-villus axis. These included villus tip telocytes (VTTs) that express Lgr5, a gene previously considered a specific crypt epithelial stem cell marker. VTTs are elongated cells that line the villus tip epithelium and signal through Bmp morphogens and the non-canonical Wnt5a ligand. Their ablation strongly perturbs the zonation of enterocyte genes induced at the villus tip. Our study provides a spatially-resolved cell atlas of the small intestinal stroma and exposes Lgr5+ villus tip telocytes as regulators of the epithelial spatial expression programs along the villus axis.

cell biology↗

bioRxiv2018

SOX2 Regulation by Hedgehog Signaling Controls Adult Lingual Epithelium Homeostasis

The adult tongue epithelium is continuously renewed from epithelial progenitor cells, and this process relies on intact Hedgehog (HH) signaling. In mice, inhibition of the HH pathway using Smoothened antagonists (HH pathway inhibitors or HPIs) leads to taste bud loss over a span of several weeks. Previously, we demonstrated that overexpression of Sonic Hedgehog (SHH) in lingual epithelial progenitors induces formation of ectopic taste buds accompanied by locally increased SOX2 expression, consistent with the hypothesis that taste bud differentiation depends on SOX2 downstream of HH. To test this idea, we inhibited HH signaling by treating SOX2-GFP mice with HPI and found a rapid and drastic decline in SOX2-GFP expression in taste progenitors and taste buds. Using a conditional Cre-lox system to delete Sox2, we found that loss of SOX2 blocks differentiation of both taste buds and non-taste epithelium that comprises the majority of the tongue surface; progenitor cells increase in number at the expense of differentiated taste cells and lingual keratinocytes. In contrast to the normal pattern of basally restricted proliferation, dividing cells are overabundant, disorganized and present in suprabasal epithelial layers in Sox2 deleted tongues. Additionally, SOX2 loss in taste progenitors leads non-cell autonomously to rapid loss of taste bud cells via apoptosis, dramatically shortening taste cell lifespans. Finally, when Sox2 is conditionally deleted in mice with constitutive overexpression of SHH, ectopic taste buds fail to form and endogenous taste buds disappear; instead, robust hyperproliferation takes over the entire lingual epithelium. In sum, our experiments suggest that SOX2 functions downstream of HH signaling to regulate lingual epithelium homeostasis.

developmental biology↗