The Journal of clinical investigation
Yadav, VK;Berger, JM;Singh, P;Nagarajan, P;Karsenty, G;
PMID: 34905510 | DOI: 10.1172/JCI153752
Through their ability to regulate gene expression in most organs, glucocorticoid hormones influence numerous physiological processes and therefore are key regulators of organismal homeostasis. In bone, glucocorticoid hormones inhibit the expression of the hormone Osteocalcin for poorly understood reasons. Here we show that in a classical endocrine feedback loop, osteocalcin in return enhances the biosynthesis of glucocorticoid but also mineralocorticoid hormones (adrenal steroidogenesis) in rodents and primates. Conversely, inactivating osteocalcin signalling in adrenal glands significantly impairs adrenal growth and steroidogenesis in mice. Embryo-made osteocalcin is necessary for normal Sf1 expression in foetal adrenal cells and adrenal cell steroidogenic differentiation, it therefore determines the number of steroidogenic cells present in adrenal glands of adult animals. Embryonic not postnatal osteocalcin also governs adrenal growth, adrenal steroidogenesis, blood pressure, electrolyte equilibrium and the rise of circulating corticosterone during the acute stress response in adult offspring. This osteocalcin-dependent regulation of adrenal development and steroidogenesis occurs even in the absence of a functional of hypothalamus-pituitary-adrenal axis; this explains why osteocalcin administration during pregnancy promotes adrenal growth and steroidogenesis and improves survival of adrenocorticotropic hormone signalling-deficient animals. This study reveals that a bone-derived, embryonic hormone influences lifelong adrenal functions and organismal homeostasis in the mouse.
Jarmas, AE;Brunskill, EW;Chaturvedi, P;Salomonis, N;Kopan, R;
PMID: 34732708 | DOI: 10.1038/s41467-021-26626-9
Mammalian nephron endowment is determined by the coordinated cessation of nephrogenesis in independent niches. Here we report that translatome analysis in Tsc1+/- nephron progenitor cells from mice with elevated nephron numbers reveals how differential translation of Wnt antagonists over agonists tips the balance between self-renewal and differentiation. Wnt agonists are poorly translated in young niches, resulting in an environment with low R-spondin and high Fgf20 promoting self-renewal. In older niches we find increased translation of Wnt agonists, including R-spondin and the signalosome-promoting Tmem59, and low Fgf20, promoting differentiation. This suggests that the tipping point for nephron progenitor exit from the niche is controlled by the gradual increase in stability and possibly clustering of Wnt/Fzd complexes in individual cells, enhancing the response to ureteric bud-derived Wnt9b inputs and driving synchronized differentiation. As predicted by these findings, removing one Rspo3 allele in nephron progenitors delays cessation and increases nephron numbers in vivo.
Thompson, MJ;Young, CA;Munnamalai, V;Umulis, DM;
PMID: 37237002 | DOI: 10.1038/s41598-023-34725-4
Positional information encoded in signaling molecules is essential for early patterning in the prosensory domain of the developing cochlea. The sensory epithelium, the organ of Corti, contains an exquisite repeating pattern of hair cells and supporting cells. This requires precision in the morphogen signals that set the initial radial compartment boundaries, but this has not been investigated. To measure gradient formation and morphogenetic precision in developing cochlea, we developed a quantitative image analysis procedure measuring SOX2 and pSMAD1/5/9 profiles in mouse embryos at embryonic day (E)12.5, E13.5, and E14.5. Intriguingly, we found that the pSMAD1/5/9 profile forms a linear gradient up to the medial ~ 75% of the PSD from the pSMAD1/5/9 peak in the lateral edge during E12.5 and E13.5. This is a surprising activity readout for a diffusive BMP4 ligand secreted from a tightly constrained lateral region since morphogens typically form exponential or power-law gradient shapes. This is meaningful for gradient interpretation because while linear profiles offer the theoretically highest information content and distributed precision for patterning, a linear morphogen gradient has not yet been observed. Furthermore, this is unique to the cochlear epithelium as the pSMAD1/5/9 gradient is exponential in the surrounding mesenchyme. In addition to the information-optimized linear profile, we found that while pSMAD1/5/9 is stable during this timeframe, an accompanying gradient of SOX2 shifts dynamically. Last, through joint decoding maps of pSMAD1/5/9 and SOX2, we see that there is a high-fidelity mapping between signaling activity and position in the regions that will become Kölliker's organ and the organ of Corti. Mapping is ambiguous in the prosensory domain precursory to the outer sulcus. Altogether, this research provides new insights into the precision of early morphogenetic patterning cues in the radial cochlea prosensory domain.
Bertozzi, A;Wu, CC;Hans, S;Brand, M;Weidinger, G;
PMID: 34748730 | DOI: 10.1016/j.ydbio.2021.11.001
Zebrafish can achieve scar-free healing of heart injuries, and robustly replace all cardiomyocytes lost to injury via dedifferentiation and proliferation of mature cardiomyocytes. Previous studies suggested that Wnt/β-catenin signaling is active in the injured zebrafish heart, where it induces fibrosis and prevents cardiomyocyte cell cycling. Here, via targeting the destruction complex of the Wnt/β-catenin pathway with pharmacological and genetic tools, we demonstrate that Wnt/β-catenin activity is required for cardiomyocyte proliferation and dedifferentiation, as well as for maturation of the scar during regeneration. Using cardiomyocyte-specific conditional inhibition of the pathway, we show that Wnt/β-catenin signaling acts cell-autonomously to promote cardiomyocyte proliferation. Our results stand in contrast to previous reports and rather support a model in which Wnt/β-catenin signaling plays a positive role during heart regeneration in zebrafish.
Opposing effects of Wnt/β-catenin signaling on epithelial and mesenchymal cell fate in the developing cochlea
Development (Cambridge, England)
Billings, SE;Myers, NM;Quiruz, L;Cheng, AG;
PMID: 34061174 | DOI: 10.1242/dev.199091
During embryonic development, the otic epithelium and surrounding periotic mesenchymal cells originate from distinct lineages and coordinate to form the mammalian cochlea. Epithelial sensory precursors within the cochlear duct first undergo terminal mitosis before differentiating into sensory and non-sensory cells. In parallel, periotic mesenchymal cells differentiate to shape the lateral wall, modiolus and pericochlear spaces. Previously, Wnt activation was shown to promote proliferation and differentiation of both otic epithelial and mesenchymal cells. Here, we fate-mapped Wnt-responsive epithelial and mesenchymal cells in mice and found that Wnt activation resulted in opposing cell fates. In the post-mitotic cochlear epithelium, Wnt activation via β-catenin stabilization induced clusters of proliferative cells that dedifferentiated and lost epithelial characteristics. In contrast, Wnt-activated periotic mesenchyme formed ectopic pericochlear spaces and cell clusters showing a loss of mesenchymal and gain of epithelial features. Finally, clonal analyses via multi-colored fate-mapping showed that Wnt-activated epithelial cells proliferated and formed clonal colonies, whereas Wnt-activated mesenchymal cells assembled as aggregates of mitotically quiescent cells. Together, we show that Wnt activation drives transition between epithelial and mesenchymal states in a cell type-dependent manner.
EGF and BMPs govern differentiation and patterning in human gastric glands
Wölffling, S;Daddi, A;Imai-Matsushima, A;Fritsche, K;Goosmann, C;Traulsen, J;Lisle, R;Schmid, M;del Mar Reines-Benassar, M;Pfannkuch, L;Brinkmann, V;Bornschein, J;Peter Malfertheiner, ;Ordemann, J;Link, A;Meyer, T;Boccellato, F;
| DOI: 10.1053/j.gastro.2021.04.062
Background & Aims The homeostasis of the gastrointestinal epithelium relies on cell regeneration and differentiation into distinct lineages organised inside glands and crypts. Regeneration depends on WNT/β-Catenin pathway activation, but to understand homeostasis and its dysregulation in disease we need to identify the signalling microenvironment governing cell differentiation. By using gastric glands as a model, we have identified the signals inducing differentiation of surface mucus-, zymogen- and gastric acid- producing cells. Methods We generated mucosoid cultures from the human stomach and exposed them to different growth factors to obtain cells with features of differentiated foveolar, chief and parietal cells. We localised the source of the growth factors in the tissue of origin. Results We show that EGF is the major fate determinant distinguishing the surface and inner part of human gastric glands. In combination with BMP/NOGGIN signals, EGF controls the differentiation of foveolar cells vs. parietal or chief cells. We also show that EGF is likely to underlie alteration of the gastric mucosa in the pre-cancerous condition atrophic gastritis. Conclusions Use of our recently established mucosoid cultures in combination with analysis of the tissue-of-origin provided a robust strategy to understand differentiation and patterning of human tissue and allowed us to draw a new, detailed map of the signalling microenvironment in the human gastric glands.
Wnt and Src signals converge on YAP-TEAD to drive intestinal regeneration
Guillermin, O;Angelis, N;Sidor, CM;Ridgway, R;Baulies, A;Kucharska, A;Antas, P;Rose, MR;Cordero, J;Sansom, O;Li, VSW;Thompson, BJ;
PMID: 33950519 | DOI: 10.15252/embj.2020105770
Wnt signalling induces a gradient of stem/progenitor cell proliferation along the crypt-villus axis of the intestine, which becomes expanded during intestinal regeneration or tumour formation. The YAP transcriptional co-activator is known to be required for intestinal regeneration, but its mode of regulation remains controversial. Here we show that the YAP-TEAD transcription factor is a key downstream effector of Wnt signalling in the intestine. Loss of YAP activity by Yap/Taz conditional knockout results in sensitivity of crypt stem cells to apoptosis and reduced cell proliferation during regeneration. Gain of YAP activity by Lats1/2 conditional knockout is sufficient to drive a crypt hyperproliferation response. In particular, Wnt signalling acts transcriptionally to induce YAP and TEAD1/2/4 expression. YAP normally localises to the nucleus only in crypt base stem cells, but becomes nuclear in most intestinal epithelial cells during intestinal regeneration after irradiation, or during organoid growth, in a Src family kinase-dependent manner. YAP-driven crypt expansion during regeneration involves an elongation and flattening of the Wnt signalling gradient. Thus, Wnt and Src-YAP signals cooperate to drive intestinal regeneration.
Walter, RJ;Sonnentag, SJ;Munoz-Sagredo, L;Merkel, M;Richert, L;Bunert, F;Heneka, YM;Loustau, T;Hodder, M;Ridgway, RA;Sansom, OJ;Mely, Y;Rothbauer, U;Schmitt, M;Orian-Rousseau, V;
PMID: 35190527 | DOI: 10.1038/s41419-022-04607-0
Enhancement of Wnt signaling is fundamental for stem cell function during intestinal regeneration. Molecular modules control Wnt activity by regulating signal transduction. CD44 is such a positive regulator and a Wnt target gene. While highly expressed in intestinal crypts and used as a stem cell marker, its role during intestinal homeostasis and regeneration remains unknown. Here we propose a CD44 positive-feedback loop that boosts Wnt signal transduction, thus impacting intestinal regeneration. Excision of Cd44 in Cd44fl/fl;VillinCreERT2 mice reduced Wnt target gene expression in intestinal crypts and affected stem cell functionality in organoids. Although the integrity of the intestinal epithelium was conserved in mice lacking CD44, they were hypersensitive to dextran sulfate sodium, and showed more severe inflammation and delayed regeneration. We localized the molecular function of CD44 at the Wnt signalosome, and identified novel DVL/CD44 and AXIN/CD44 complexes. CD44 thus promotes optimal Wnt signaling during intestinal regeneration.
The Journal of biological chemistry
Wei, W;Tang, X;Jiang, N;Ni, C;He, H;Sun, S;Yu, M;Yu, C;Qiu, M;Yan, D;Zhou, Z;Song, Y;Liu, H;Zhao, B;Lin, X;
PMID: 36115458 | DOI: 10.1016/j.jbc.2022.102490
Branching morphogenesis is a key process essential for lung and other organ development in which cellular and tissue architecture branch out to maximize surface area. While this process is known to be regulated by differential gene expression of ligands and receptors, how chromatin remodeling regulates this process remains unclear. Znhit1, acting as a chromatin remodeler, has previously been shown to control the deposition of the histone variant H2A.Z. Here, we demonstrate that Znhit1 also plays an important role in regulating lung branching. Using Znhit1 conditional knockout mice, we show that Znhit1 deficiency in the embryonic lung epithelium leads to failure of branching morphogenesis and neonatal lethality, which is accompanied by reduced cell proliferation and increased cell apoptosis of the epithelium. The results from the transcriptome and the ChIP assay reveal that this is partially regulated by the derepression of Bmp4, encoding bone morphogenetic protein 4, which is a direct target of H2A.Z. Furthermore, we show that inhibition of BMP signaling by the protein inhibitor Noggin rescues the lung branching defects of Znhit1 mutants ex vivo. Taken together, our study identifies the critical role of Znhit1/H2A.Z in embryonic lung morphogenesis via the regulation of BMP signaling.
Mitotic WNT signalling orchestrates neurogenesis in the developing neocortex
Da Silva, F;Zhang, K;Pinson, A;Fatti, E;Wilsch-Bräuninger, M;Herbst, J;Vidal, V;Schedl, A;Huttner, WB;Niehrs, C;
PMID: 34431536 | DOI: 10.15252/embj.2021108041
The role of WNT/β-catenin signalling in mouse neocortex development remains ambiguous. Most studies demonstrate that WNT/β-catenin regulates progenitor self-renewal but others suggest it can also promote differentiation. Here we explore the role of WNT/STOP signalling, which stabilizes proteins during G2/M by inhibiting glycogen synthase kinase (GSK3)-mediated protein degradation. We show that mice mutant for cyclin Y and cyclin Y-like 1 (Ccny/l1), key regulators of WNT/STOP signalling, display reduced neurogenesis in the developing neocortex. Specifically, basal progenitors, which exhibit delayed cell cycle progression, were drastically decreased. Ccny/l1-deficient apical progenitors show reduced asymmetric division due to an increase in apical-basal astral microtubules. We identify the neurogenic transcription factors Sox4 and Sox11 as direct GSK3 targets that are stabilized by WNT/STOP signalling in basal progenitors during mitosis and that promote neuron generation. Our work reveals that WNT/STOP signalling drives cortical neurogenesis and identifies mitosis as a critical phase for neural progenitor fate.
Gao, F;Li, C;Danopoulos, S;Al Alam, D;Peinado, N;Webster, S;Borok, Z;Kohbodi, GA;Bellusci, S;Minoo, P;
PMID: 35385750 | DOI: 10.1016/j.celrep.2022.110608
The lung alveolus is lined with alveolar type 1 (AT1) and type 2 (AT2) epithelial cells. During alveologenesis, increasing demand associated with expanding alveolar numbers is met by proliferating progenitor AT2s (pAT2). Little information exists regarding the identity of this population and their niche microenvironment. We show that during alveologenesis, Hedgehog-responsive PDGFRa(+) progenitors (also known as SCMFs) are a source of secreted trophic molecules that maintain a unique pAT2 population. SCMFs are in turn maintained by TGFβ signaling. Compound inactivation of Alk5 TβR2 in SCMFs reduced their numbers and depleted the pAT2 pool without impacting differentiation of daughter cells. In lungs of preterm infants who died with bronchopulmonary dysplasia, PDGFRa is reduced and the number of proliferative AT2s is diminished, indicating that an evolutionarily conserved mechanism governs pAT2 behavior during alveologenesis. SCMFs are a transient cell population, active only during alveologenesis, making them a unique stage-specific niche mesodermal cell type in mammalian organs.
Han, Y;Villarreal-Ponce, A;Gutierrez, G;Nguyen, Q;Sun, P;Wu, T;Sui, B;Berx, G;Brabletz, T;Kessenbrock, K;Zeng, YA;Watanabe, K;Dai, X;
PMID: 35021086 | DOI: 10.1016/j.celrep.2021.110240
Maintenance of undifferentiated, long-lived, and often quiescent stem cells in the basal compartment is important for homeostasis and regeneration of multiple epithelial tissues, but the molecular mechanisms that coordinately control basal cell fate and stem cell quiescence are elusive. Here, we report an epithelium-intrinsic requirement for Zeb1, a core transcriptional inducer of epithelial-to-mesenchymal transition, for mammary epithelial ductal side branching and for basal cell regenerative capacity. Our findings uncover an evolutionarily conserved role of Zeb1 in promoting basal cell fate over luminal differentiation. We show that Zeb1 loss results in increased basal cell proliferation at the expense of quiescence and self-renewal. Moreover, Zeb1 cooperates with YAP to activate Axin2 expression, and inhibition of Wnt signaling partially restores stem cell function to Zeb1-deficient basal cells. Thus, Zeb1 is a transcriptional regulator that maintains both basal cell fate and stem cell quiescence, and it functions in part through suppressing Wnt signaling.