Crypt density and recruited enhancers underlie intestinal tumour initiation.

Oncogenic mutations that drive colorectal cancer can be present in healthy intestines for long periods without overt consequence. Mutation of Adenomatous polyposis coli (Apc), the most common initiating event in conventional adenomas, activates Wnt signalling, hence conferring fitness on mutant intestinal stem cells (ISCs). Apc mutations may occur in ISCs that arose by routine self-renewal or by dedifferentiation of their progeny.

Distinct Mesenchymal Cell Populations Generate the Essential Intestinal BMP Signaling Gradient.

Intestinal stem cells (ISCs) are confined to crypt bottoms and their progeny differentiate near crypt-villus junctions. Wnt and bone morphogenic protein (BMP) gradients drive this polarity, and colorectal cancer fundamentally reflects disruption of this homeostatic signaling. However, sub-epithelial sources of crucial agonists and antagonists that organize this BMP gradient remain obscure.

Ketone Body Signaling Mediates Intestinal Stem Cell Homeostasis and Adaptation to Diet.

Little is known about how metabolites couple tissue-specific stem cell function with physiology. Here we show that, in the mammalian small intestine, the expression of Hmgcs2 (3-hydroxy-3-methylglutaryl-CoA synthetase 2), the gene encoding the rate-limiting enzyme in the production of ketone bodies, including beta-hydroxybutyrate (βOHB), distinguishes self-renewing Lgr5 stem cells (ISCs) from differentiated cell types. Hmgcs2 loss depletes βOHB levels in Lgr5 ISCs and skews their differentiation toward secretory cell fates, which can be rescued by exogenous βOHB and class I histone deacetylase (HDAC) inhibitor treatment.

A High-Throughput Organoid Microinjection Platform to Study Gastrointestinal Microbiota and Luminal Physiology.

Background & Aims: The human gut microbiota is becoming increasingly recognized as a key factor in homeostasis and disease. The lack of physiologically relevant in vitro models to investigate host-microbe interactions is considered a substantial bottleneck for microbiota research. Organoids represent an attractive model system because they are derived from primary tissues and embody key properties of the native gut lumen; however, access to the organoid lumen for experimental perturbation is challenging.

A high-throughput platform for stem cell niche co-cultures and downstream gene expression analysis.

Stem cells reside in 'niches', where support cells provide critical signalling for tissue renewal. Culture methods mimic niche conditions and support the growth of stem cells in vitro. However, current functional assays preclude statistically meaningful studies of clonal stem cells, stem cell-niche interactions, and genetic analysis of single cells and their organoid progeny.