Project description:The gut and liver are recognized to mutually communicate through the biliary tract, portal vein and systemic circulation, but it remains unclear how this gut-liver axis regulates intestinal physiology. Through hepatectomy, transcriptomic and proteomic profiling, we identified pigment epithelium-derived factor (PEDF), a liver-derived soluble Wnt inhibitor, that restrains intestinal stem cell (ISC) hyperproliferation to maintain gut homeostasis by suppressing the Wnt/b-catenin signaling pathway. Further, we found that microbial danger signals occurring as a result of intestinal inflammation can be sensed by the liver to repress PEDF production via peroxisome proliferator-activated receptor-a (PPARa), liberating ISC proliferation to accelerate tissue repair in the gut. Finally, treatment of mice with fenofibrate, a clinical agent of PPARa agonist for hypolipidemia enhances the susceptibility of colitis via PEDF activity. Therefore, we have identified a distinct role for PEDF in calibrating ISC expansion for intestinal homeostasis via reciprocal interactions between the gut and liver.
Project description:The gut and liver have been recognized to mutually communicate through the biliary tract, portal vein and systemic circulation, but it remains unclear how this gut-liver axis regulates intestinal physiology. Through hepatectomy, transcriptomics and proteomics profiling, we identified pigment epithelium-derived factor (PEDF), as a liver-derived soluble Wnt inhibitor, that can restrain intestinal stem cells (ISC) hyperproliferation for gut homeostasis by competing with Wnt ligands and suppressing Wnt/beta-catenin signaling pathway. In turn, microbial danger signals from intestinal inflammation can be sensed by the liver to repress PEDF production via peroxisome proliferator-activated receptor-alpha (PPAR alpha), liberating ISC proliferation to accelerate tissue repair in the gut. Further, treatment of mice with fenofibrate, a clinical agent of PPARalpha agonist for hypolipidemia enhances the susceptibility of colitis via PEDF activity. Therefore, we identified a distinct role of PEDF to calibrate ISC expansion for intestinal homeostasis via reciprocal interactions between the gut and liver.
Project description:A central hallmark of brain aging is the alteration of neuronal functions in the hippocampus, leading to a progressive decline in learning and memory. Multiple reports have shown the importance of blood-borne factors in inter-tissue communication for the maintenance of cognitive fitness and proper regulation of neuronal homeostasis throughout life. Among these blood-borne factors, we identified Osteocalcin (OCN), a bone-derived hormone. OCN induces autophagy machinery in hippocampal neurons which is essential for activity-dependent synaptic plasticity. However, the way in which blood-borne factors like OCN communicate with neurons, including their regulatory mechanisms, remains largely elusive. Here, we show the importance of a core primary cilium (PC)-proteins/autophagy machinery axis in hippocampal neurons that mediate the effects of the pro-youthful blood factor OCN on neuronal homeostasis and cognitive fitness. We found that OCN’s receptor, GPR158, is present at the PC of hippocampal neurons and mediates the regulation of autophagy machinery by OCN. During aging, PC-core proteins are reduced in hippocampal neurons and associated with neuronal PC morphological abnormalities. Restoring their levels is sufficient to improve neuronal autophagy and cognitive impairments in aged mice. Mechanistically, we found that OCN promotes neuronal autophagy in the hippocampus by the induction of PC-dependent cAMP response element-binding protein (CREB) signaling pathway. Altogether, this study proposes a novel paradigm for blood factor-neuron communication dependent on a neuronal PC/autophagy axis by identifying a novel regulatory pathway fostering cognitive fitness and providing the foundation for autophagy-based therapeutic strategies to treat age-related cognitive dysfunction.
Project description:We demonstrated that Lepr+ mesenchymal cells surround intestinal crypts where ISCs and transit-amplifying (TA) cells localize. The abundance of these cells increased upon administration of a high-fat diet (HFD) but dramatically decreased upon fasting. Depletion of Lepr+ mesenchymal cells resulted in fewer ISCs, compromised architecture of crypt-villi axis and impaired intestinal regeneration. Furthermore, Lepr+ cell-derived Igf1 has been identified as an important effector that promotes the proliferation of ISCs and TA cells. Deletion of Igf1 in Lepr+ cells partially recapitulated Lepr+ cell-ablated intestinal phenotypes during both homeostasis and regeneration. Overall, Lepr+ mesenchymal cells sense diet alteration and function as a novel niche for ISCs via the stromal Igf1 - epithelial Igf1r axis, which is critical for intestinal homeostasis and regeneration. These findings revealed that Lepr+ mesenchymal cells are an important mediator that links diet to ISC function and might provide a novel therapeutic target for gut diseases.
Project description:Peritoneal dissemination of ovarian cancer (OC) correlates with poor prognosis, but the mechanisms underlying the escape of OC cells from the intraperitoneal immune system have remained unknown. We here identify pigment epithelium–derived factor (PEDF) as a regulator of OC cell dissemination, which functions through induction of CD206+ IL-10–producing macrophages. High PEDF gene expression was associated with poor prognosis in OC patients. Concentrations of PEDF in ascites and serum were significantly higher in OC patients than those with more benign tumors and correlated with early recurrence of OC patients, suggesting that PEDF might serve as a prognostic biomarker. Bromodomain and extraterminal (BET) inhibitors were found to reduce PEDF expression and limit both OC cell survival and CD206+ macrophage induction in the peritoneal cavity. Our results thus implicate PEDF as a driver of OC dissemination and identify a BET protein–PEDF–IL-10 axis as a promising therapeutic target for OC.
Project description:Intestinal epithelial cells (IECs) are pivotal for maintaining intestinal homeostasis through self-renewal, proliferation, differentiation, and regulated cell death. While apoptosis and necroptosis are recognized as distinct pathways, their intricate interplay remains elusive. In this study, we report that Mettl3-mediated m6A modification maintains intestinal homeostasis by impeding epithelial cell death. Mettl3 knockout induces both apoptosis and necroptosis in IECs. Targeting different modes of cell death with specific inhibitors unveils that RIPK1 kinase activity is critical for the cell death triggered by Mettl3 knockout. Mechanistically, this occurs via the m6A-mediated transcriptional regulation of Atf3, a transcription factor that directly binds to Cflar, the gene encoding the anti-cell death protein cFLIP. cFLIP inhibits RIPK1 activity, thereby suppressing downstream apoptotic and necroptotic signaling. Together, these findings delineate the essential role of the METTL3-ATF3-cFLIP axis in homeostatic regulation of the intestinal epithelium by blocking RIPK1 activity.