McCarthy, N;Tie, G;Madha, S;He, R;Kraiczy, J;Maglieri, A;Shivdasani, RA;
PMID: 36924771 | DOI: 10.1016/j.devcel.2023.02.012
Wnt and Rspondin (RSPO) signaling drives proliferation, and bone morphogenetic protein inhibitors (BMPi) impede differentiation, of intestinal stem cells (ISCs). Here, we identify the mouse ISC niche as a complex, multi-layered structure that encompasses distinct mesenchymal and smooth muscle populations. In young and adult mice, diverse sub-cryptal cells provide redundant ISC-supportive factors; few of these are restricted to single cell types. Niche functions refine during postnatal crypt morphogenesis, in part to oppose the dense aggregation of differentiation-promoting BMP+ sub-epithelial myofibroblasts at crypt-villus junctions. Muscularis mucosae, a specialized muscle layer, first appears during this period and supplements neighboring RSPO and BMPi sources. Components of this developing niche are conserved in human fetuses. The in vivo ablation of mouse postnatal smooth muscle increases BMP signaling activity, potently limiting a pre-weaning burst of crypt fission. Thus, distinct and progressively specialized mesenchymal cells together create the milieu that is required to propagate crypts during rapid organ growth and to sustain adult ISCs.
Disease models & mechanisms
Del-Pozo, J;Headon, DJ;Glover, JD;Azar, A;Schuepbach-Mallepell, S;Bhutta, MF;Riddell, J;Maxwell, S;Milne, E;Schneider, P;Cheeseman, M;
PMID: 35107126 | DOI: 10.1242/dmm.049034
In mice, rats, dogs and humans the growth and function of sebaceous glands and eyelid Meibomian glands depend on the ectodysplasin signalling pathway. Mutation of genes encoding the ligand EDA, its transmembrane receptor EDAR, and the intracellular signal transducer EDARADD leads to Hypohidrotic Ectodermal Dysplasia characterised by impaired development of teeth and hair as well as cutaneous glands. The rodent ear canal has a large auditory sebaceous gland, the Zymbal's gland, whose function in the health of the ear canal and tympanic membrane has not been determined. We report that the EDA deficient Tabby (EdaTa) mouse, the EDAR deficient mouse (EdarOVE1B/OVE1B) and the EDARADD deficient sparse and wavy hair rat (Edaraddswh/swh) have Zymbal's gland hypoplasia. EdaTa mice also have ear canal hypotrichosis and a 25% prevalence of otitis externa at P21. Treatment with agonist anti-EDAR antibodies rescues Zymbal's glands and ear canal pilosebaceous units. The aetiopathogenesis of otitis externa involves infection with Gram-positive cocci and dosing pregnant and lactating EdaTa females and pups with Enrofloxacin reduces the prevalence of otitis externa. We infer the deficit of sebum is the principal factor in predisposition to bacterial infection and the EdaTa mouse is a potentially useful microbial challenge model for human acute otitis externa, commonly known as swimmer's ear.
Pereira B, Amaral AL, Dias A, Mendes N, Muncan V, Silva AR, Thibert C, Radu AG, David L, M�ximo V, van den Brink GR, Billaud M, Almeida R
PMID: 32052574 | DOI: 10.15252/embr.201948938
Intestinal stem cells (ISCs) fuel the lifelong self-renewal of the intestinal tract and are paramount for epithelial repair. In this context, the Wnt pathway component LGR5 is the most consensual ISC marker to date. Still, the effort to better understand ISC identity and regulation remains a challenge. We have generated a Mex3a knockout mouse model and show that this RNA-binding protein is crucial for the maintenance of the Lgr5+ ISC pool, as its absence disrupts epithelial turnover during postnatal development and stereotypical organoid maturation ex vivo. Transcriptomic profiling of intestinal crypts reveals that Mex3a deletion induces the peroxisome proliferator-activated receptor (PPAR) pathway, along with a decrease in Wnt signalling and loss of the Lgr5+ stem cell signature. Furthermore, we identify PPAR? activity as a molecular intermediate of MEX3A-mediated regulation. We also show that high PPAR? signalling impairs Lgr5+ ISC function, thus uncovering a new layer of post-transcriptional regulation that critically contributes to intestinal homeostasis
Gupta K, Levinsohn J, Linderman G, Chen D, Sun TY, Dong D, Taketo MM, Bosenberg M, Kluger Y, Choate K, Myung P.
PMID: 30595533 | DOI: 10.1016/j.devcel.2018.11.032
Delineating molecular and cellular events that precede appendage morphogenesis has been challenging due to the inability to distinguish quantitative molecular differences between cells that lack histological distinction. The hair follicle (HF) dermal condensate (DC) is a cluster of cells critical for HF development and regeneration. Events that presage emergence of this distinctive population are poorly understood. Using unbiased single-cell RNA sequencing and in vivo methods, we infer a sequence of transcriptional states through which DC cells pass that begins prior to HF morphogenesis. Our data indicate that Wnt/β-catenin signaling is required to progress into an intermediate stage that precedes quiescence and differentiation. Further, we provide evidence that quiescent DC cells are recent progeny of selectively proliferating cells present prior to morphogenesis and that are later identified in the peri-DC zone during DC expansion. Together, these findings provide an inferred path of molecular states that lead to DC cell differentiation.
bioRxiv : the preprint server for biology
Bao, L;Fu, L;Su, Y;Chen, Z;Peng, Z;Sun, L;Gonzalez, FJ;Wu, C;Zhang, H;Shi, B;Shi, YB;
PMID: 36789439 | DOI: 10.1101/2023.01.24.524966
The intestine is critical for not only processing and resorbing nutrients but also protecting the organism from the environment. These functions are mainly carried out by the epithelium, which is constantly being self-renewed. Many genes and pathways can influence intestinal epithelial cell proliferation. Among them is mTORC1, whose activation increases cell proliferation. Here, we report the first intestinal epithelial cell-specific knockout ( ΔIEC ) of an amino acid transporter capable of activating mTORC1. We show that the transporter, SLC7A5, is highly expressed in mouse intestinal crypt and Slc7a5 ΔIEC reduces mTORC1 signaling. Surprisingly, Slc7a5 ΔIEC mice have increased cell proliferation but reduced secretory cells, particularly mature Paneth cells. scRNA-seq and electron microscopic analyses revealed dedifferentiation of Paneth cells in Slc7a5 ΔIEC mice, leading to markedly reduced secretory granules with little effect on Paneth cell number. We further show that Slc7a5 ΔIEC mice are prone to experimental colitis. Thus, SLC7A5 regulates secretory cell differentiation to affect stem cell niche and/or inflammatory response to regulate cell proliferation.
Glover, JD;Sudderick, ZR;Shih, BB;Batho-Samblas, C;Charlton, L;Krause, AL;Anderson, C;Riddell, J;Balic, A;Li, J;Klika, V;Woolley, TE;Gaffney, EA;Corsinotti, A;Anderson, RA;Johnston, LJ;Brown, SJ;Wang, S;Chen, Y;Crichton, ML;Headon, DJ;
PMID: 36764291 | DOI: 10.1016/j.cell.2023.01.015
Fingerprints are complex and individually unique patterns in the skin. Established prenatally, the molecular and cellular mechanisms that guide fingerprint ridge formation and their intricate arrangements are unknown. Here we show that fingerprint ridges are epithelial structures that undergo a truncated hair follicle developmental program and fail to recruit a mesenchymal condensate. Their spatial pattern is established by a Turing reaction-diffusion system, based on signaling between EDAR, WNT, and antagonistic BMP pathways. These signals resolve epithelial growth into bands of focalized proliferation under a precociously differentiated suprabasal layer. Ridge formation occurs as a set of waves spreading from variable initiation sites defined by the local signaling environments and anatomical intricacies of the digit, with the propagation and meeting of these waves determining the type of pattern that forms. Relying on a dynamic patterning system triggered at spatially distinct sites generates the characteristic types and unending variation of human fingerprint patterns.
Charting human development using a multi-endodermal organ atlas and organoid models
Yu, Q;Kilik, U;Holloway, EM;Tsai, YH;Harmel, C;Wu, A;Wu, JH;Czerwinski, M;Childs, CJ;He, Z;Capeling, MM;Huang, S;Glass, IA;Higgins, PDR;Treutlein, B;Spence, JR;Camp, JG;
PMID: 34019796 | DOI: 10.1016/j.cell.2021.04.028
Organs are composed of diverse cell types that traverse transient states during organogenesis. To interrogate this diversity during human development, we generate a single-cell transcriptome atlas from multiple developing endodermal organs of the respiratory and gastrointestinal tract. We illuminate cell states, transcription factors, and organ-specific epithelial stem cell and mesenchyme interactions across lineages. We implement the atlas as a high-dimensional search space to benchmark human pluripotent stem cell (hPSC)-derived intestinal organoids (HIOs) under multiple culture conditions. We show that HIOs recapitulate reference cell states and use HIOs to reconstruct the molecular dynamics of intestinal epithelium and mesenchyme emergence. We show that the mesenchyme-derived niche cue NRG1 enhances intestinal stem cell maturation in vitro and that the homeobox transcription factor CDX2 is required for regionalization of intestinal epithelium and mesenchyme in humans. This work combines cell atlases and organoid technologies to understand how human organ development is orchestrated.
