Author
Despina Stamataki
Bio: Despina Stamataki is an academic researcher from London Research Institute. The author has an hindex of 1, co-authored 1 publications receiving 697 citations.
Papers
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TL;DR: A flurry of recent papers has clarified the key regulatory signals and brought us to the point where the authors can begin to give a coherent account, for at least one tissue, of how these signals collaborate to organize the architecture and behaviour of a stem-cell system.
Abstract: The lining of the intestine is renewed at an extraordinary rate, outpacing all other tissues in the vertebrate body. The renewal process is neatly organized in space, so that the whole production line, from the ever-youthful stem cells to their dying, terminally differentiated progeny, is laid out to view in histological sections. A flurry of recent papers has clarified the key regulatory signals and brought us to the point where we can begin to give a coherent account, for at least one tissue, of how these signals collaborate to organize the architecture and behaviour of a stem-cell system.
740 citations
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TL;DR: This Review provides a comprehensive overview of how IECs maintain host–commensal microbial relationships and immune cell homeostasis in the intestine.
Abstract: The abundance of innate and adaptive immune cells that reside together with trillions of beneficial commensal microorganisms in the mammalian gastrointestinal tract requires barrier and regulatory mechanisms that conserve host-microbial interactions and tissue homeostasis. This homeostasis depends on the diverse functions of intestinal epithelial cells (IECs), which include the physical segregation of commensal bacteria and the integration of microbial signals. Hence, IECs are crucial mediators of intestinal homeostasis that enable the establishment of an immunological environment permissive to colonization by commensal bacteria. In this Review, we provide a comprehensive overview of how IECs maintain host-commensal microbial relationships and immune cell homeostasis in the intestine.
2,046 citations
TL;DR: It is reported here that YAP1 increases organ size and causes aberrant tissue expansion in mice and that the Hippo signaling pathway regulates organ size in mammals and can act on stem cell compartments, indicating a potential link between stem/progenitor cells, organ size, and cancer.
1,144 citations
TL;DR: It is found that complete loss of the Lgr5-expressing cells did not perturb homeostasis of the epithelium, indicating that other cell types can compensate for the elimination of this population, and that in the absence of these cells, Bmi1- expressing cells can serve as an alternative stem cell pool.
Abstract: The small intestine epithelium renews every 2 to 5 days, making it one of the most regenerative mammalian tissues. Genetic inducible fate mapping studies have identified two principal epithelial stem cell pools in this tissue. One pool consists of columnar Lgr5-expressing cells that cycle rapidly and are present predominantly at the crypt base. The other pool consists of Bmi1-expressing cells that largely reside above the crypt base. However, the relative functions of these two pools and their interrelationship are not understood. Here we specifically ablated Lgr5-expressing cells in mice using a human diphtheria toxin receptor (DTR) gene knocked into the Lgr5 locus. We found that complete loss of the Lgr5-expressing cells did not perturb homeostasis of the epithelium, indicating that other cell types can compensate for the elimination of this population. After ablation of Lgr5-expressing cells, progeny production by Bmi1-expressing cells increased, indicating that Bmi1-expressing stem cells compensate for the loss of Lgr5-expressing cells. Indeed, lineage tracing showed that Bmi1-expressing cells gave rise to Lgr5-expressing cells, pointing to a hierarchy of stem cells in the intestinal epithelium. Our results demonstrate that Lgr5-expressing cells are dispensable for normal intestinal homeostasis, and that in the absence of these cells, Bmi1-expressing cells can serve as an alternative stem cell pool. These data provide the first experimental evidence for the interrelationship between these populations. The Bmi1-expressing stem cells may represent both a reserve stem cell pool in case of injury to the small intestine epithelium and a source for replenishment of the Lgr5-expressing cells under non-pathological conditions.
1,003 citations
TL;DR: It is shown that when enterocytes in the Drosophila midgut are subjected to apoptosis, enteric infection, or JNK-mediated stress signaling, they produce cytokines that activate Jak/Stat signaling in ISCs, promoting their rapid division and enabling stem cells to replace spent progeny as they are lost, thereby establishing gut homeostasis.
893 citations
TL;DR: Robust long-term methodology for small and large intestinal culture, incorporating an air-liquid interface and underlying stromal elements is described, indicating successful long- term intestinal culture within a microenvironment accurately recapitulating the Wnt- and Notch-dependent ISC niche.
Abstract: The in vitro analysis of intestinal epithelium has been hampered by a lack of suitable culture systems. Here we describe robust long-term methodology for small and large intestinal culture, incorporating an air-liquid interface and underlying stromal elements. These cultures showed prolonged intestinal epithelial expansion as sphere-like organoids with proliferation and multilineage differentiation. The Wnt growth factor family positively regulates proliferation of the intestinal epithelium in vivo. Accordingly, culture growth was inhibited by the Wnt antagonist Dickkopf-1 (Dkk1) and markedly stimulated by a fusion protein between the Wnt agonist R-spondin-1 and immunoglobulin Fc (RSpo1-Fc). Furthermore, treatment with the gamma-secretase inhibitor dibenzazepine and neurogenin-3 overexpression induced goblet cell and enteroendocrine cell differentiation, respectively, consistent with endogenous Notch signaling and lineage plasticity. Epithelial cells derived from both leucine-rich repeat-containing G protein-coupled receptor-5-positive (Lgr5(+)) and B lymphoma moloney murine leukemia virus insertion region homolog-1-positive (Bmi1(+)) lineages, representing putative intestinal stem cell (ISC) populations, were present in vitro and were expanded by treatment with RSpo1-Fc; this increased number of Lgr5(+) cells upon RSpo1-Fc treatment was subsequently confirmed in vivo. Our results indicate successful long-term intestinal culture within a microenvironment accurately recapitulating the Wnt- and Notch-dependent ISC niche.
753 citations