Biology subjects

Finer, G.

Publications and source records attributed to Finer, G..

3 recordsLinked to original sources

bioRxiv2024

The Transcription Factor TCF21 is necessary for adoption of cell fates by Foxd1+ stromal progenitors during kidney development.

Normal kidney development requires the coordinated interactions between multiple progenitor cell lineages. Among these, Foxd1+ stromal progenitors are essential for nephrogenesis, giving rise to diverse cell types including the renal stroma, capsule, mesangial cells, renin cells, pericytes, and vascular smooth muscle cells (VSMCs). However, the molecular mechanisms governing their differentiation remain poorly understood. This study investigates the role of Tcf21, a mesoderm-specific bHLH transcription factor, in Foxd1+ cell fate determination. Using single-cell RNA sequencing (scRNA-seq), we analyzed 32,461 GFP+ cells from embryonic day 14.5 (E14.5) Foxd1Cre/+;Rosa26mTmG;Tcf21f/fkidneys (Tcf21-cKO) and controls. Clustering identified a predominant stromal population, further divided into six subpopulations associated with healthy kidney development: nephrogenic zone-associated stroma, proliferating stroma, medullary/perivascular stroma, collecting duct-associated stroma, differentiating stroma, and ureteric stroma. Loss of Tcf21 resulted in marked depletion of medullary/perivascular stroma, collecting duct-associated stroma, proliferating stroma, and nephrogenic zone-associated stroma stromal subpopulations, confirmed by immunostaining, which revealed severe constriction of medullary and collecting duct stromal spaces. Additionally, we identified a novel cluster unique to Tcf21-cKO kidneys, characterized by high expression of Endomucin (Emcn), a vascular endothelial marker. These cells spanned across pseudotime trajectories and were distributed broadly across the mutant kidney. The emergence of Emcn-expressing cells in Tcf21-cKO kidneys coincided with a reduction in Acta2-expressing medullary stromal cells, suggesting a population shift. Our findings highlight the critical role of Tcf21 in directing Foxd1+ progenitor differentiation. Loss of Tcf21 disrupts stromal cell fates, leading to aberrant kidney development and providing new insights into the mechanisms underlying congenital kidney anomalies. TRANSLATIONAL STATEMENTThis study reveals critical insights into kidney development and congenital anomalies by identifying the developmental origins of stromal heterogeneity and the key role of Tcf21 in stromal progenitor differentiation. These findings enhance our understanding of stromal cell fate decisions and their relevance to congenital disorders. Additionally, this work provides valuable information for improving the recapitulation of the stromal compartment ex vivo, a current challenge in kidney organoid models. The role of Tcf21 in stromal phenotypic modulation underscores its broader significance in tissue repair and fibrotic diseases, suggesting potential avenues for therapeutic intervention.

developmental biology↗

bioRxiv2024

The transcription factor Tcf21 is required for specifying Foxd1 cells to the juxtaglomerular cell lineage

Renin is crucial for blood pressure regulation and electrolyte balance, and its expressing cells arise from Foxd1+ stromal progenitors. However, factors guiding these progenitors toward renin-secreting cell fate remain unclear. Tcf21, a basic helix-loop-helix (bHLH) transcription factor, is essential in kidney development. Utilizing Foxd1Cre/+;Tcf21f/f and Ren1dCre/+;Tcf21f/f mouse models, we investigated the role of Tcf21 in the differentiation of Foxd1+ progenitor cells into juxtaglomerular (JG) cells. Immunostaining and in-situ hybridization demonstrated fewer renin-positive areas and altered renal arterial morphology, including the afferent arteriole, in Foxd1Cre/+;Tcf21f/f kidneys compared to controls, indicating Tcf21s critical role in the emergence of renin-expressing cells. However, Tcf21 inactivation in renin-expressing cells (Ren1dCre/+;Tcf21f/f) did not recapitulate this phenotype, suggesting Tcf21 is dispensable once renin cell identity is established. Using an integrated analysis of single-cell RNA sequencing (scRNA-seq) and single-cell assay for transposase-accessible chromatin sequencing (scATAC-seq) on GFP+ cells (stromal lineage) from E12, E18, P5, and P30 Foxd1Cre/+;Rosa26mTmG control kidneys, we analyzed the temporal dynamics of Tcf21 expression in cells comprising the JG lineage (n=2,054). A pseudotime trajectory analysis revealed that Tcf21 expression is highest in metanephric mesenchyme and stromal cells at early developmental stages (E12), with a decline in expression as cells mature into renin-expressing JG cells. Motif enrichment analyses supported Tcf21s significant involvement in early kidney development. These findings underscore the critical role of Tcf21 in Foxd1+ cell differentiation into JG cells during early stages of kidney development, offering insights into the molecular mechanisms governing JG cell differentiation and highlight Tcf21s pivotal role in kidney development. NEW & NOTEWORTHYThis manuscript provides novel insights into the role of Tcf21 in the differentiation of Foxd1+ cells into JG cells. Utilizing integrated scRNA-seq and scATAC-seq, the study reveals that Tcf21 expression is crucial during early embryonic stages, with its peak at embryonic day 12. The findings demonstrate that inactivation of Tcf21 leads to fewer renin-positive areas and altered renal arterial morphology, underscoring the importance of Tcf21 in the specification of renin-expressing JG cells and kidney development.

developmental biology↗

bioRxiv2024

Non-endothelial expression of Endomucin in the mouse and human choroid

Endomucin (EMCN) is a 261 AA transmembrane glycoprotein that is highly expressed by venous and capillary endothelial cells where it plays a role in VEGF-mediated angiogenesis and regulation of immune cell recruitment. However, it is better known as a histological marker, where it has become widespread due to the commercial availability of high-quality antibodies that work under a wide range of conditions and in many tissues. The specificity of EMCN staining has been well-validated in retinal vessels, but while it has been used extensively as a marker in other tissues of the eye, including the choroid, the pattern of expression has not been described in detail. Here, in addition to endothelial expression in the choriocapillaris and deeper vascular layers, we characterize a population of EMCN-positive perivascular cells in the mouse choroid that did not co-localize with cells expressing other endothelial markers such as PECAM1 or PODXL. To confirm that these cells represented a new population of EMCN-expressing stromal cells, we then performed single cell RNA sequencing in choroids from adult wild-type mice. Analysis of this new dataset confirmed that, in addition to endothelial cells, Emcn mRNA expression was present in choroidal pericytes and a subset of fibroblasts, but not vascular smooth muscle cells. Besides Emcn, no known endothelial gene expression was detected in these cell populations, confirming that they did not represent endothelial-stromal doublets, a common technical artifact in single cell RNA seq datasets. Instead, choroidal Emcn-expressing fibroblasts exhibited high levels of chemokine and interferon signaling genes, while Emcn-negative fibroblasts were enriched in genes encoding extracellular matrix proteins. Emcn expressing fibroblasts were also detected in published datasets from mouse brain and human choroid, suggesting that stromal Emcn expression was not unique to the choroid and was evolutionarily conserved. Together, these findings highlight unique fibroblast and pericyte populations in the choroid and provide new context for the role of EMCN in angiogenesis and immune cell recruitment.

cell biology↗