The glucagon gene is expressed along the GI tract in highly specialized gut endocrine cells, designated L cells. The origin of L cell or enteroendocrine cell lineages remains a challenging research issue. These studies suggest a developmental relationship between these cell types, possibly invoking a multipotential endocrine stem cell precursor that gives rise to multiple lineages.
Several genes appear important for both islet and endocrine cell development.
The Drucker lab has isolated and studied a mouse enteroendocrine cell line, designated GLUTag . GLUTag cells respond to the same secretagogues that normally regulate rat enteroendocrine cell function. Although admittedly rare, patients with autoimmune polyglandular endocrine failure may exhibit a deficiency of gut endocrine cells, leading to clinical disease.