Induction of Expandable Tissue-Specific Stem/Progenitor Cells through Transient Expression of YAP/TAZ

Abstract

SummaryThe ability to induce autologous tissue-specific stem cells in culture could have a variety of applications in regenerative medicine and disease modeling. Here we show that transient expression of exogenous YAP or its closely related paralogue TAZ in primary differentiated mouse cells can induce conversion to a tissue-specific stem/progenitor cell state. Differentiated mammary gland, neuronal, and pancreatic exocrine cells, identified using a combination of cell sorting and lineage tracing approaches, efficiently convert to proliferating cells with properties of stem/progenitor cells of their respective tissues after YAP induction. YAP-induced mammary stem/progenitor cells show molecular and functional properties similar to endogenous MaSCs, including organoid formation and mammary gland reconstitution after transplantation. Because YAP/TAZ function is also important for self-renewal of endogenous stem cells in culture, our findings have implications for understanding the molecular determinants of the somatic stem cell state.

Derivation of a robust mouse mammary organoid system for studying tissue dynamics

“…Factors that likely contribute to these differences include the addition of FGF2 and heparin, the use of BME and the origin of cells (human versus mouse). Other studies did not describe the initial organoid-forming efficiency (Zhang et al, 2016b) or they initiated organoid cultures from tissue fragments (Jardé et al, 2016) or pre-formed 3D colonies (Panciera et al, 2016), rather than single cells. Here, we have discriminated between freshly isolated luminal and basal cells for organoid formation and show that ∼20% of basal cells exhibit stem cell potential, suggesting that the culture conditions recapitulate features of the MaSC niche.…”

“…S1E). Recent studies have shown organoid cells can repopulate the mammary fat pad in vivo even after prolonged passaging or CRISPR-mediated gene editing (Jardé et al, 2016;Panciera et al, 2016;Zhang et al, 2016b).…”

“…S3). In contrast to mammary organoid passaging via single cells, as previously reported (Jardé et al, 2016;Panciera et al, 2016;Zhang et al, 2016a,b), this method disaggregates organoids into smaller fragments and leaves the bi-layered structures intact.…”

“…Development of mammary organoid models is currently an area of intense interest. Several recent studies on mouse or human breast epithelial cells have used advanced culture medium and 3D scaffolds for the formation of budding or TDLU-like structures that comprise luminal and basal cells layered in the correct orientation (Jardé et al, 2016;Linnemann et al, 2015;Panciera et al, 2016;Sokol et al, 2016;Zhang et al, 2016a,b). In this study, we have established conditions that enable robust formation of organoids from single sorted mouse basal and luminal epithelial cells, with high efficiency and reproducibility.…”

Pituitary stem cell regulation: who is pulling the strings?

“…Genetic deletion of the YAP/TAZ-phosphorylating Mst1 and Mst2 leads to the increased emergence of liver stem cells (so-called oval cells) (Lu et al 2010). Moreover, transient YAP induction results in de-differentiation of various tissue cells into proliferating cells with stem/ progenitor cell characteristics (Panciera et al 2016). The Hippo network has also been implicated in tissue regeneration.…”