Person: Yilmaz, Omer
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Publication mTORC1 in the Paneth Cell Niche Couples Intestinal Stem Cell Function to Calorie Intake
(Nature Publishing Group, 2012) Katajisto, Pekka; Lamming, Dudley W.; Gültekin, Yetis; Bauer-Rowe, Khristian E.; Sengupta, Shomit; Birsoy, Kivanc; Dursun, Abdulmetin; Yilmaz, V. Onur; Selig, Martin; Nielson, G. Petur; Sabatini, David M.; Yilmaz, Omer; Mino-Kenudson, Mari; Zukerberg, Lawrence; Bhan, Atul; Deshpande, VikramHow adult tissue stem and niche cells respond to the nutritional state of an organism is not well understood. Here we find that Paneth cells, a key constituent of the mammalian intestinal stem-cell (ISC) niche, augment stem-cell function in response to calorie restriction. Calorie restriction acts by reducing mechanistic target of rapamycin complex 1 (mTORC1) signalling in Paneth cells, and the ISC-enhancing effects of calorie restriction can be mimicked by rapamycin. Calorie intake regulates mTORC1 in Paneth cells, but not ISCs, and forced activation of mTORC1 in Paneth cells during calorie restriction abolishes the ISC-augmenting effects of the niche. Finally, increased expression of bone stromal antigen 1 (Bst1) in Paneth cells—an ectoenzyme that produces the paracrine factor cyclic ADP ribose—mediates the effects of calorie restriction and rapamycin on ISC function. Our findings establish that mTORC1 non-cell-autonomously regulates stem-cell self-renewal, and highlight a significant role of the mammalian intestinal niche in coupling stem-cell function to organismal physiology.
Publication High fat diet enhances stemness and tumorigenicity of intestinal progenitors
(2016) Beyaz, Semir; Mana, Miyeko D.; Roper, Jatin; Kedrin, Dmitriy; Saadatpour, Assieh; Hong, Sue-Jean; Bauer-Rowe, Khristian E.; Xifaras, Michael E.; Akkad, Adam; Arias, Erika; Pinello, Luca; Katz, Yarden; Shinagare, Shweta; Abu-Remaileh, Monther; Mihaylova, Maria M.; Lamming, Dudley W.; Dogum, Rizkullah; Guo, Guoji; Bell, George W.; Selig, Martin; Nielsen, G. Petur; Gupta, Nitin; Ferrone, Cristina; Deshpande, Vikram; Yuan, Guo-Cheng; Orkin, Stuart; Sabatini, David M.; Yilmaz, OmerLittle is known about how pro-obesity diets regulate tissue stem and progenitor cell function. Here we find that high fat diet (HFD)-induced obesity augments the numbers and function of Lgr5+ intestinal stem-cells (ISCs) of the mammalian intestine. Mechanistically, HFD induces a robust peroxisome proliferator-activated receptor delta (PPAR-d) signature in intestinal stem and (non-ISC) progenitor cells, and pharmacologic activation of PPAR-d recapitulates the effects of a HFD on these cells. Like a HFD, ex vivo treatment of intestinal organoid cultures with fatty acid constituents of the HFD enhances the self-renewal potential of these organoid bodies in a PPAR-d dependent manner. Interestingly, HFD- and agonist-activated PPAR-d signaling endow organoid-initiating capacity to progenitors, and enforced PPAR-d signaling permits these progenitors to form in vivo tumors upon loss of the tumor suppressor Apc. These findings highlight how diet-modulated PPAR-d activation alters not only the function of intestinal stem and progenitor cells, but also their capacity to initiate tumors.