Golgi organization regulates stem cell function in the small intestine.

Cell-to-cell signaling between niche and stem cells regulates tissue renewal. While the identity of many mediating factors is known, it is largely unknown whether stem cells optimize their receptiveness to niche signals according to the niche organization. Here, we show that Lgr5+ small intestinal stem cells (ISCs) regulate the morphology and orientation of their secretory apparatus to match the niche architecture, and to increase transport efficiency of niche signal receptors. ISCs orient their Golgi apparatus laterally towards Paneth cells of the epithelial niche, and divide Golgi into multiple stacks. Stem cells with multiple lateral Golgi transport stem cell receptors with a higher efficiency than cells with one single Golgi. The lateral Golgi orientation and enhanced receptor transport requires A-kinase anchor protein 9 (Akap9), and is necessary for normal renewal capacity. Moreover, reduced Akap9 in aged ISCs renders ISCs insensitive to niche-dependent modulation of Golgi stack number and transport efficiency. Our results reveal a stem cell-specific Golgi complex configuration that facilitates efficient niche signal reception and tissue renewal, which is compromised in the aged epithelium.