Transcription Factor 21 Is Required for Branching Morphogenesis and Regulates the Gdnf-Axis in Kidney Development

Tcf21 as a Founder Transcription Factor in 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 Foxd1 Cre/+ ;Tcf21 f/f and Ren1 dCre/+ ;Tcf21 f/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 Foxd1 Cre/+ ;Tcf21 f/f kidneys compared to controls, indicating Tcf21's critical role in the emergence of renin-expressing cells. However, Tcf21 inactivation in renin-expressing cells ( Ren1 dCre/+ ;Tcf21 f/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 Foxd1 Cre/+ ;Rosa26 mTmG 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 Tcf21's 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 Tcf21's pivotal role in kidney development.

NEW & NOTEWORTHY

This 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.

Aberrant TCF21 upregulation in adenomyosis impairs endometrial decidualization by increasing PDE4C expression

BACKGROUND

Impaired decidualization is a major cause of infertility in patients with adenomyosis (AM). However, the effect of transcription factor 21 (TCF21) on AM and the underlying mechanism of associated-impaired decidualization remain unclear. The aim of this study was to investigate the expression of TCF21 in endometrial tissues of AM patients and the specific mechanisms by which it impairs the decidualization of human endometrial stromal cells (HESCs), with a view to improving the reproductive outcome of AM infertile patients.

METHODS

We compared gene expressions via transcriptomics between the control and AM-associated recurrent implantation failure (RIF) groups. qRT-PCR, western blot, and IHC were performed to confirm the expression and location of TCF21 in the endometrium. Furthermore, we confirmed that high expression of TCF21 impairs decidualization by qRT-PCR, immunofluorescence, and western blot. RNA-seq following overexpression of TCF21 in HESCs was conducted to identify TCF21-related molecular changes during in vitro decidualization. Then we performed ChIP-seq/qPCR and dual-luciferase reporter assay to explore the exact interaction between TCF21 and PDE4C. The related downstream mechanisms were further proved using IHC, qRT-PCR, western blot, and ELISA.

RESULTS

According to the RNA-seq analysis, TCF21 expression was remarkably higher in the endometrium of the AM-related RIF group compared to the control group. We confirmed the same results using samples from patients with AM and controls. TCF21 overexpression in HESCs impaired decidualization through suppression of decidual markers and cytoskeleton alterations. The mechanistic analysis revealed that TCF21 inhibited intracellular cAMP levels by directly increasing PDE4C expression and suppressing FOXO1 expression.

CONCLUSIONS

TCF21 compromises decidualization in patients with AM via the PDE4C/cAMP-FOXO1 axis, which offers valuable insights on the pathology of decidualization-related infertility and indicates a potential treatment to improve endometrial receptivity in AM.

Single-cell transcriptomic profiling of the neonatal oviduct and uterus reveals new insights into upper Müllerian duct regionalization

The upper Müllerian duct (MD) is patterned and specified into two morphologically and functionally distinct organs, the oviduct and uterus. It is known that this regionalization process is instructed by inductive signals from the adjacent mesenchyme. However, the interaction landscape between epithelium and mesenchyme during upper MD development remains largely unknown. Here, we performed single-cell transcriptomic profiling of mouse neonatal oviducts and uteri at the initiation of MD epithelial differentiation (postnatal day 3). We identified major cell types including epithelium, mesenchyme, pericytes, mesothelium, endothelium, and immune cells in both organs with established markers. Moreover, we uncovered region-specific epithelial and mesenchymal subpopulations and then deduced region-specific ligand-receptor pairs mediating mesenchymal-epithelial interactions along the craniocaudal axis. Unexpectedly, we discovered a mesenchymal subpopulation marked by neurofilaments with specific localizations at the mesometrial pole of both the neonatal oviduct and uterus. Lastly, we analyzed and revealed organ-specific signature genes of pericytes and mesothelial cells. Taken together, our study enriches our knowledge of upper MD development, and provides a manageable list of potential genes, pathways, and region-specific cell subtypes for future functional studies.

Isthmin-1: A critical regulator of branching morphogenesis and metanephric mesenchyme condensation during early kidney development

Isthmin-1 (Ism1) was first described to be syn-expressed with Fgf8 in Xenopus. However, its biological role has not been elucidated until recent years. Despite of accumulated evidence that Ism1 participates in angiogenesis, tumor invasion, macrophage apoptosis, and glucose metabolism, the cognate receptors for Ism1 remain largely unknown. Ism1 deficiency in mice results in renal agenesis (RA) with a transient loss of Gdnf transcription and impaired mesenchyme condensation at E11.5. Ism1 binds to and activates Integrin α8β1 to positively regulate Gdnf/Ret signaling, thus promoting mesenchyme condensation and ureteric epithelium branching morphogenesis. Here, we propose the hypothesis underlying the mechanism by which Ism1 regulates branching morphogenesis during early kidney development.

Transcription factor Tcf21 modulates urinary bladder size and differentiation

Urinary bladder organogenesis requires coordinated cell growth, specification, and patterning of both mesenchymal and epithelial compartments. Tcf21, a gene that encodes a helix-loop-helix transcription factor, is specifically expressed in the mesenchyme of the bladder during development. Here we show that Tcf21 is required for normal development of the bladder. We found that the bladders of mice lacking Tcf21 were notably hypoplastic and that the Tcf21 mutant mesenchyme showed increased apoptosis. There was also a marked delay in the formation of visceral smooth muscle, accompanied by a defect in myocardin (Myocd) expression. Interestingly, there was also a marked delay in the formation of the basal cell layer of the urothelium, distinguished by diminished expression of Krt5 and Krt14. Our findings suggest that Tcf21 regulates the survival and differentiation of mesenchyme cell-autonomously and the maturation of the adjacent urothelium non-cell-autonomously during bladder development.

Single-cell transcriptomic profiling of the neonatal oviduct and uterus reveals new insights into upper Müllerian duct regionalization

The upper Müllerian duct (MD) is patterned and specified into two morphologically and functionally distinct organs, the oviduct and uterus. It is known that this regionalization process is instructed by inductive signals from the adjacent mesenchyme. However, the interaction landscape between epithelium and mesenchyme during upper MD development remains largely unknown. Here, we performed single-cell transcriptomic profiling of mouse neonatal oviducts and uteri at the initiation of MD epithelial differentiation (postnatal day 3). We identified major cell types including epithelium, mesenchyme, pericytes, mesothelium, endothelium, and immune cells in both organs with established markers. Moreover, we uncovered region-specific epithelial and mesenchymal subpopulations and then deduced region-specific ligand-receptor pairs mediating mesenchymal-epithelial interactions along the craniocaudal axis. Unexpectedly, we discovered a mesenchymal subpopulation marked by neurofilaments with specific localizations at the mesometrial pole of both the neonatal oviduct and uterus. Lastly, we analyzed and revealed organ-specific signature genes of pericytes and mesothelial cells. Taken together, our study enriches our knowledge of upper Müllerian duct development, and provides a manageable list of potential genes, pathways, and region-specific cell subtypes for future functional studies.

Stromal netrin 1 coordinates renal arteriogenesis and mural cell differentiation

The kidney vasculature has a complex architecture that is essential for renal function. The molecular mechanisms that direct development of kidney blood vessels are poorly characterized. We identified a regionally restricted, stroma-derived signaling molecule, netrin 1 (Ntn1), as a regulator of renal vascular patterning in mice. Stromal progenitor (SP)-specific ablation of Ntn1 (Ntn1SPKO) resulted in smaller kidneys with fewer glomeruli, as well as profound defects of the renal artery and transient blood flow disruption. Notably, Ntn1 ablation resulted in loss of arterial vascular smooth muscle cell (vSMC) coverage and in ectopic SMC deposition at the kidney surface. This was accompanied by dramatic reduction of arterial tree branching that perdured postnatally. Transcriptomic analysis of Ntn1SPKO kidneys revealed dysregulation of vSMC differentiation, including downregulation of Klf4, which we find expressed in a subset of SPs. Stromal Klf4 deletion similarly resulted in decreased smooth muscle coverage and arterial branching without, however, the disruption of renal artery patterning and perfusion seen in Ntn1SPKO. These data suggest a stromal Ntn1-Klf4 axis that regulates stromal differentiation and reinforces stromal-derived smooth muscle as a key regulator of renal blood vessel formation.

Senescence-associated inflammation and inhibition of adipogenesis in subcutaneous fat in Werner syndrome

Werner syndrome (WS) is a hereditary premature aging disorder characterized by visceral fat accumulation and subcutaneous lipoatrophy, resulting in severe insulin resistance. However, its underlying mechanism remains unclear. In this study, we show that senescence-associated inflammation and suppressed adipogenesis play a role in subcutaneous adipose tissue reduction and dysfunction in WS. Clinical data from four Japanese patients with WS revealed significant associations between the decrease of areas of subcutaneous fat and increased insulin resistance measured by the glucose clamp. Adipose-derived stem cells from the stromal vascular fraction derived from WS subcutaneous adipose tissues (WSVF) showed early replicative senescence and a significant increase in the expression of senescence-associated secretory phenotype (SASP) markers. Additionally, adipogenesis and insulin signaling were suppressed in WSVF, and the expression of adipogenesis suppressor genes and SASP-related genes was increased. Rapamycin, an inhibitor of the mammalian target of rapamycin (mTOR), alleviated premature cellular senescence, rescued the decrease in insulin signaling, and extended the lifespan of WS model of C. elegans. To the best of our knowledge, this study is the first to reveal the critical role of cellular senescence in subcutaneous lipoatrophy and severe insulin resistance in WS, highlighting the therapeutic potential of rapamycin for this disease.

β-Catenin in the kidney stroma modulates pathways and genes to regulate kidney development

BACKGROUND

Kidney development is regulated by cellular interactions between the ureteric epithelium, mesenchyme, and stroma. Previous studies demonstrate essential roles for stromal β-catenin in kidney development. However, how stromal β-catenin regulates kidney development is not known. We hypothesize that stromal β-catenin modulates pathways and genes that facilitate communications with neighboring cell populations to regulate kidney development.

RESULTS

We isolated purified stromal cells with wild type, deficient, and overexpressed β-catenin by fluorescence-activated cell sorting and conducted RNA Sequencing. A Gene Ontology network analysis demonstrated that stromal β-catenin modulates key kidney developmental processes, including branching morphogenesis, nephrogenesis and vascular formation. Specific stromal β-catenin candidate target genes that may mediate these effects included secreted, cell-surface and transcriptional factors that regulate branching morphogenesis and nephrogenesis (Wnts, Bmp, Fgfr, Tcf/Lef) and secreted vascular guidance cues (Angpt1, VEGF, Sema3a). We validated established β-catenin targets including Lef1 and novel candidate β-catenin targets including Sema3e which have unknown roles in kidney development.

CONCLUSIONS

These studies advance our understanding of gene and biological pathway dysregulation in the context of stromal β-catenin misexpression during kidney development. Our findings suggest that during normal kidney development, stromal β-catenin may regulate secreted and cell-surface proteins to communicate with adjacent cell populations.

scRNA-Seq of Cultured Human Amniotic Fluid from Fetuses with Spina Bifida Reveals the Origin and Heterogeneity of the Cellular Content

Amniotic fluid has been proposed as an easily available source of cells for numerous applications in regenerative medicine and tissue engineering. The use of amniotic fluid cells in biomedical applications necessitates their unequivocal characterization; however, the exact cellular composition of amniotic fluid and the precise tissue origins of these cells remain largely unclear. Using cells cultured from the human amniotic fluid of fetuses with spina bifida aperta and of a healthy fetus, we performed single-cell RNA sequencing to characterize the tissue origin and marker expression of cultured amniotic fluid cells at the single-cell level. Our analysis revealed nine different cell types of stromal, epithelial and immune cell phenotypes, and from various fetal tissue origins, demonstrating the heterogeneity of the cultured amniotic fluid cell population at a single-cell resolution. It also identified cell types of neural origin in amniotic fluid from fetuses with spina bifida aperta. Our data provide a comprehensive list of markers for the characterization of the various progenitor and terminally differentiated cell types in cultured amniotic fluid. This study highlights the relevance of single-cell analysis approaches for the characterization of amniotic fluid cells in order to harness their full potential in biomedical research and clinical applications.

The transcriptional and regulatory identity of erythropoietin producing cells

Erythropoietin (Epo) is the master regulator of erythropoiesis and oxygen homeostasis. Despite its physiological importance, the molecular and genomic contexts of the cells responsible for renal Epo production remain unclear, limiting more-effective therapies for anemia. Here, we performed single-cell RNA and transposase-accessible chromatin (ATAC) sequencing of an Epo reporter mouse to molecularly identify Epo-producing cells under hypoxic conditions. Our data indicate that a distinct population of kidney stroma, which we term Norn cells, is the major source of endocrine Epo production in mice. We use these datasets to identify the markers, signaling pathways and transcriptional circuits characteristic of Norn cells. Using single-cell RNA sequencing and RNA in situ hybridization in human kidney tissues, we further provide evidence that this cell population is conserved in humans. These preliminary findings open new avenues to functionally dissect EPO gene regulation in health and disease and may serve as groundwork to improve erythropoiesis-stimulating therapies.

Determinants of renin cell differentiation: a single cell epi-transcriptomics approach

Rationale

Renin cells are essential for survival. They control the morphogenesis of the kidney arterioles, and the composition and volume of our extracellular fluid, arterial blood pressure, tissue perfusion, and oxygen delivery. It is known that renin cells and associated arteriolar cells descend from FoxD1 + progenitor cells, yet renin cells remain challenging to study due in no small part to their rarity within the kidney. As such, the molecular mechanisms underlying the differentiation and maintenance of these cells remain insufficiently understood.

Objective

We sought to comprehensively evaluate the chromatin states and transcription factors (TFs) that drive the differentiation of FoxD1 + progenitor cells into those that compose the kidney vasculature with a focus on renin cells.

Methods and Results

We isolated single nuclei of FoxD1 + progenitor cells and their descendants from FoxD1 ^cre/+ ; R26R-mTmG mice at embryonic day 12 (E12) (n _cells =1234), embryonic day 18 (E18) (n _cells =3696), postnatal day 5 (P5) (n _cells =1986), and postnatal day 30 (P30) (n _cells =1196). Using integrated scRNA-seq and scATAC-seq we established the developmental trajectory that leads to the mosaic of cells that compose the kidney arterioles, and specifically identified the factors that determine the elusive, myo-endocrine adult renin-secreting juxtaglomerular (JG) cell. We confirm the role of Nfix in JG cell development and renin expression, and identified the myocyte enhancer factor-2 (MEF2) family of TFs as putative drivers of JG cell differentiation.

Conclusions

We provide the first developmental trajectory of renin cell differentiation as they become JG cells in a single-cell atlas of kidney vascular open chromatin and highlighted novel factors important for their stage-specific differentiation. This improved understanding of the regulatory landscape of renin expressing JG cells is necessary to better learn the control and function of this rare cell population as overactivation or aberrant activity of the RAS is a key factor in cardiovascular and kidney pathologies.

Human theca arises from ovarian stroma and is comprised of three discrete subtypes

Theca cells serve multiple essential functions during the growth and maturation of ovarian follicles, providing structural, metabolic, and steroidogenic support. While the function of theca during folliculogenesis is well established, their cellular origins and the differentiation hierarchy that generates distinct theca sub-types, remain unknown. Here, we performed single cell multi-omics analysis of primary cell populations purified from human antral stage follicles (1-3 mm) to define the differentiation trajectory of theca/stroma cells. We then corroborated the temporal emergence and growth kinetics of defined theca/stroma subpopulations using human ovarian tissue samples and xenografts of cryopreserved/thawed ovarian cortex, respectively. We identified three lineage specific derivatives termed structural, androgenic, and perifollicular theca cells, as well as their putative lineage-negative progenitor. These findings provide a framework for understanding the differentiation process that occurs in each primordial follicle and identifies specific cellular/molecular phenotypes that may be relevant to either diagnosis or treatment of ovarian pathologies.

An integrated co-expression network analysis reveals novel genetic biomarkers for immune cell infiltration in chronic kidney disease

Background

Chronic kidney disease (CKD) is characterized by persistent damage to kidney function or structure. Progression to end-stage leads to adverse effects on multiple systems. However, owing to its complex etiology and long-term cause, the molecular basis of CKD is not completely known.

Methods

To dissect the potential important molecules during the progression, based on CKD databases from Gene Expression Omnibus, we used weighted gene co-expression network analysis (WGCNA) to identify the key genes in kidney tissues and peripheral blood mononuclear cells (PBMC). Correlation analysis of these genes with clinical relevance was evaluated based on Nephroseq. Combined with a validation cohort and receiver operating characteristic curve (ROC), we found the candidate biomarkers. The immune cell infiltration of these biomarkers was evaluated. The expression of these biomarkers was further detected in folic acid-induced nephropathy (FAN) murine model and immunohistochemical staining.

Results

In total, eight genes (CDCP1, CORO1C, DACH1, GSTA4, MAFB, TCF21, TGFBR3, and TGIF1) in kidney tissue and six genes (DDX17, KLF11, MAN1C1, POLR2K, ST14, and TRIM66) in PBMC were screened from co-expression network. Correlation analysis of these genes with serum creatinine levels and estimated glomerular filtration rate from Nephroseq showed a well clinical relevance. Validation cohort and ROC identified TCF21, DACH1 in kidney tissue and DDX17 in PBMC as biomarkers for the progression of CKD. Immune cell infiltration analysis revealed that DACH1 and TCF21 were correlated with eosinophil, activated CD8 T cell, activated CD4 T cell, while the DDX17 was correlated with neutrophil, type-2 T helper cell, type-1 T helper cell, mast cell, etc. FAN murine model and immunohistochemical staining confirmed that these three molecules can be used as genetic biomarkers to distinguish CKD patients from healthy people. Moreover, the increase of TCF21 in kidney tubules might play important role in the CKD progression.

Discussion

We identified three promising genetic biomarkers which could play important roles in the progression of CKD.

Stromal Transcription Factor 21 Regulates Development of the Renal Stroma via Interaction with Wnt/β-Catenin Signaling

Background

Kidney formation requires coordinated interactions between multiple cell types. Input from the interstitial progenitor cells is implicated in multiple aspects of kidney development. We previously reported that transcription factor 21 (Tcf21) is required for ureteric bud branching. Here, we show that Tcf21 in Foxd1+ interstitial progenitors regulates stromal formation and differentiation via interaction with β-catenin.

Methods

We utilized the Foxd1Cre;Tcf21f/f murine kidney for morphologic analysis. We used the murine clonal mesenchymal cell lines MK3/M15 to study Tcf21 interaction with Wnt/β-catenin.

Results

Absence of Tcf21 from Foxd1+ stromal progenitors caused a decrease in stromal cell proliferation, leading to marked reduction of the medullary stromal space. Lack of Tcf21 in the Foxd1+ stromal cells also led to defective differentiation of interstitial cells to smooth-muscle cells, perivascular pericytes, and mesangial cells. Foxd1Cre;Tcf21f/f kidney showed an abnormal pattern of the renal vascular tree. The stroma of Foxd1Cre;Tcf21f/f kidney demonstrated marked reduction in β-catenin protein expression compared with wild type. Tcf21 was bound to β-catenin both upon β-catenin stabilization and at basal state as demonstrated by immunoprecipitation in vitro. In MK3/M15 metanephric mesenchymal cells, Tcf21 enhanced TCF/LEF promoter activity upon β-catenin stabilization, whereas DNA-binding deficient mutated Tcf21 did not enhance TCF/LEF promoter activity. Kidney explants of Foxd1Cre;Tcf21f/f showed low mRNA expression of stromal Wnt target genes. Treatment of the explants with CHIR, a Wnt ligand mimetic, restored Wnt target gene expression. Here, we also corroborated previous evidence that normal development of the kidney stroma is required for normal development of the Six2+ nephron progenitor cells, loop of Henle, and the collecting ducts.

Conclusions

These findings suggest that stromal Tcf21 facilitates medullary stroma development by enhancing Wnt/β-catenin signaling and promotes stromal cell proliferation and differentiation. Stromal Tcf21 is also required for the development of the adjacent nephron epithelia.

Single-Cell Chromatin and Gene-Regulatory Dynamics of Mouse Nephron Progenitors

BACKGROUND

We reasoned that unraveling the dynamic changes in accessibility of genomic regulatory elements and gene expression at single-cell resolution will inform the basic mechanisms of nephrogenesis.

METHODS

We performed single-cell ATAC-seq and RNA-seq both individually (singleomes; Six2GFP cells) and jointly in the same cells (multiomes; kidneys) to generate integrated chromatin and transcriptional maps in mouse embryonic and neonatal nephron progenitor cells.

RESULTS

We demonstrate that singleomes and multiomes are comparable in assigning most cell states, identification of new cell type markers, and defining the transcription factors driving cell identity. However, multiomes are more precise in defining the progenitor population. Multiomes identified a "pioneer" bHLH/Fox motif signature in nephron progenitor cells. Moreover, we identified a subset of Fox factors exhibiting high chromatin activity in podocytes. One of these Fox factors, Foxp1, is important for nephrogenesis. Key nephrogenic factors are distinguished by strong correlation between linked gene regulatory elements and gene expression.

CONCLUSION

Mapping the regulatory landscape at single-cell resolution informs the regulatory hierarchy of nephrogenesis. Paired single-cell epigenomes and transcriptomes of nephron progenitors should provide a foundation to understand prenatal programming, regeneration after injury, and ex vivo nephrogenesis.

The relationship between free fatty acids and mitochondrial oxidative stress damage to trophoblast cell in preeclampsia

Aim

To investigate the effects of free fatty acids on mitochondrial oxidative stress and the pathogenesis of preeclampsia.

Methods

Human primary trophoblast cells at 6–8 weeks of gestation were retrieved and cultured to 70–80% confluence, then incubated in serum from women with a normal pregnancy (normal pregnancy group), women with preeclampsia (PE group), and a combination of serum from women with 24 h preeclampsia-like symptoms and free fatty acids (FFA group). Mitochondrial membrane potential was assessed by fluorescent dye concurrent with detection of membrane channel conversion pore activity by fluorescence microscope. Enzyme labeling instruments and RT-PCR were used to detect mitochondrial DNA (mtDNA) levels.

Results

The preeclampsia and free fatty acids groups both exhibited significantly higher levels of mitochondria oxidative stress damage when compared to the normal pregnancy group. However, no significant differences in mitochondrial oxidative stress damage were observed between the FFA and PE groups.

Conclusions

Serum free fatty acids might play an important role in the pathogenesis of preeclampsia by enhancing mitochondrial oxidative stress damage.

Transcription Factor 21 Promotes Chicken Adipocyte Differentiation at Least in Part via Activating MAPK/JNK Signaling

The molecular mechanisms of transcription factor 21 (TCF21) in regulating chicken adipogenesis remain unclear. Thus, the current study was designed to investigate the signaling pathway mediating the effect of TCF21 on chicken adipogenesis. Immortalized chicken preadipocytes cell line (ICP), a preadipocyte cell line stably overexpressing TCF21 (LV-TCF21) and a control preadipocyte cell line (LV-control) were used in the current study. We found that the phosphorylation of c-Jun N-terminal kinases (JNK) was significantly elevated in LV-TCF21 compared to LV-control. After treating ICP cells with a JNK inhibitor SP600125, the differentiation of ICP was inhibited, as evidenced by decreased accumulation of lipid droplets and reduced expression of peroxisome proliferator-activated receptor γ (PPARγ), CCAAT/enhancer binding protein α (C/EBPα), adipocyte fatty acid binding protein (A-FABP), and lipoprotein lipase (LPL). Moreover, we found that the inhibition of JNK by SP600125 remarkably impaired the ability of TCF21 to drive adipogenesis. Taken together, our results suggest that TCF21 promotes the differentiation of adipocytes at least in part via activating MAPK/JNK pathway.

Role of the bHLH transcription factor TCF21 in development and tumorigenesis

Transcription factors control, coordinate, and separate the functions of distinct network modules spatially and temporally. In this review, we focus on the transcription factor 21 (TCF21) network, a highly conserved basic-helix-loop-helix (bHLH) protein that functions to integrate signals and modulate gene expression. We summarize the molecular and biological properties of TCF21 control with an emphasis on molecular and functional TCF21 interactions. We suggest that these interactions serve to modulate the development of different organs at the transcriptional level to maintain growth homeostasis and to influence cell fate. Importantly, TCF21 expression is epigenetically inactivated in different types of human cancers. The epigenetic modification or activation and/or loss of TCF21 expression results in an imbalance in TCF21 signaling, which may lead to tumor initiation and, most likely, to progression and tumor metastasis. This review focuses on research on the roles of TCF21 in development and tumorigenesis systematically considering the physiological and pathological function of TCF21. In addition, we focus on the main molecular bases of its different roles whose importance should be clarified in future research. For this review, PubMed databases and keywords such as TCF21, POD-1, capsulin, tumors, carcinomas, tumorigenesis, development, and mechanism of action were utilized. Articles were selected within a historical context as were a number of citations from journals with relevant impact.

Development of the metanephric kidney

The kidney plays an integral role in filtering the blood-removing metabolic by-products from the body and regulating blood pressure. This requires the establishment of large numbers of efficient and specialized blood filtering units (nephrons) that incorporate a system for vascular exchange and nutrient reabsorption as well as a collecting duct system to remove waste (urine) from the body. Kidney development is a dynamic process which generates these structures through a delicately balanced program of self-renewal and commitment of nephron progenitor cells that inhabit a constantly evolving cellular niche at the tips of a branching ureteric "tree." The former cells build the nephrons and the latter the collecting duct system. Maintaining these processes across fetal development is critical for establishing the normal "endowment" of nephrons in the kidney and perturbations to this process are associated both with mutations in integral genes and with alterations to the fetal environment.

Fibroblasts from different body parts exhibit distinct phenotypes in adult progeria Werner syndrome

Werner syndrome (WS), also known as adult progeria, is characterized by accelerated aging symptoms from a young age. Patients with WS experience painful intractable skin ulcers with calcifications in their extremities, subcutaneous lipoatrophy, and sarcopenia. However, there is no significant abnormality in the trunk skin, where the subcutaneous fat relatively accumulates. The cause of such differences between the limbs and trunk is unknown. To investigate the underlying mechanism behind these phenomena, we established and analyzed dermal fibroblasts from the foot and trunk of two WS patients. As a result, WS foot-derived fibroblasts showed decreased proliferative potential compared to that from the trunk, which correlated with the telomere shortening. Transcriptome analysis showed increased expression of genes involved in osteogenesis in the foot fibroblasts, while adipogenic and chondrogenic genes were downregulated in comparison with the trunk. Consistent with these findings, the adipogenic and chondrogenic differentiation capacity was significantly decreased in the foot fibroblasts in vitro. On the other hand, the osteogenic potential was mutually maintained and comparable in the foot and trunk fibroblasts. These distinct phenotypes in the foot and trunk fibroblasts are consistent with the clinical symptoms of WS and may partially explain the underlying mechanism of this disease phenotype.

Integration of GWAS Summary Statistics and Gene Expression Reveals Target Cell Types Underlying Kidney Function Traits

BACKGROUND

Genetic variants identified in genome-wide association studies (GWAS) are often not specific enough to reveal complex underlying physiology. By integrating RNA-seq data and GWAS summary statistics, novel computational methods allow unbiased identification of trait-relevant tissues and cell types.

METHODS

The CKDGen consortium provided GWAS summary data for eGFR, urinary albumin-creatinine ratio (UACR), BUN, and serum urate. Genotype-Tissue Expression Project (GTEx) RNA-seq data were used to construct the top 10% specifically expressed genes for each of 53 tissues followed by linkage disequilibrium (LD) score-based enrichment testing for each trait. Similar procedures were performed for five kidney single-cell RNA-seq datasets from humans and mice and for a microdissected tubule RNA-seq dataset from rat. Gene set enrichment analyses were also conducted for genes implicated in Mendelian kidney diseases.

RESULTS

Across 53 tissues, genes in kidney function-associated GWAS loci were enriched in kidney (P=9.1E-8 for eGFR; P=1.2E-5 for urate) and liver (P=6.8·10^-5 for eGFR). In the kidney, proximal tubule was enriched in humans (P=8.5E-5 for eGFR; P=7.8E-6 for urate) and mice (P=0.0003 for eGFR; P=0.0002 for urate) and confirmed as the primary cell type in microdissected tubules and organoids. Gene set enrichment analysis supported this and showed enrichment of genes implicated in monogenic glomerular diseases in podocytes. A systematic approach generated a comprehensive list of GWAS genes prioritized by cell type-specific expression.

CONCLUSIONS

Integration of GWAS statistics of kidney function traits and gene expression data identified relevant tissues and cell types, as a basis for further mechanistic studies to understand GWAS loci.

Crosstalk between DNA methylation and histone acetylation triggers GDNF high transcription in glioblastoma cells

BACKGROUND

Glial cell line-derived neurotrophic factor (GDNF) is highly expressed in glioblastoma (GBM) and blocking its expression can inhibit the initiation and development of GBM. GDNF is a dual promoter gene, and the promoter II with two enhancers and two silencers plays a major role in transcription initiation. We had previously reported that histone hyperacetylation and DNA hypermethylation in GDNF promoter II region result in high transcription of GDNF in GBM cells, but the mechanism remains unclear. In this study, we investigated whether these modifications synergistically regulate high GDNF transcription in GBM.

RESULTS

Cyclic AMP response element binding protein (CREB) expression and phosphorylation at S133 were significantly increased in human GBM tissues and GBM cell lines (U251 and U343). In U251 GBM cells, high expressed CREB significantly enhanced GDNF transcription and promoter II activity. CREB regulated GDNF transcription via the cyclic AMP response elements (CREs) in enhancer II and silencer II of GDNF promoter II. However, the two CREs played opposite regulatory roles. Interestingly, hypermethylation of CRE in silencer II occurred in GBM tissues and cells which led to decreased and increased phosphorylated CREB (pCREB) binding to silencer II and enhancer II, respectively. Moreover, pCREB recruited CREB binding protein (CBP) with histone acetylase activity to the CRE of GDNF enhancer II, thereby increasing histone H3 acetylation and RNA polymerase II recruitment there and at the transcription start site (TSS), and promoted GDNF high transcription in U251 cells. The results indicated that high GDNF transcription was attributable to DNA hypermethylation in CRE of GDNF silencer II increasing pCREB binding to CRE in enhancer II, which enhanced CBP recruitment, histone H3 acetylation, and RNA polymerase II recruitment there and at the TSS.

CONCLUSIONS

Our results demonstrate that pCREB-induced crosstalk between DNA methylation and histone acetylation at the GDNF promoter II enhanced GDNF high transcription, providing a new perspective for GBM treatment.