Epsilon cell

Islets of Langerhans.^[1] Epsilon cells produce the hormone ghrelin that induces hunger. They were first discovered in mice. In humans, these cells compose less than 1% of all islet cells. They are connected by tight junctions that allow impermeability to water-soluble compounds.^[2]

cytokeratin 20, a marker of duct cells and islet precursor cells, hinting that these islet cells originate from the ductal epithelium. The development of these cells derive from the Ngn3 transcription factor. Mice with mutant Nkx2.2 genes show an increase of ε-cells.^[4] On a cellular level, ε-cells co-produce both NKX2-2 and ISL1, but not NKS6-1 and PAX6 as was previously hypothesized.^[5] Furthermore, this type of cell co-produces ISL1 which plays a role in the development of the mesenchyme of the dorsal pancreatic bud, and the differentiation of the dorsal pancreatic epithelium into endocrine cells. A total of 36 genes are significantly enriched in ε-cells that aid in proteinase inhibition, processing of hormones, cell migration, and immune activity that differentiates them from α-, β-, δ- and PP-cells.^[7] Additionally, the secretory vesicles of ε-cells (110±3 nm) are much smaller than those of α-cells (185±7 nm).^[5] Unlike the other pancreatic islet cells, ε-cells also do not produce other pancreatic hormones (insulin, glucagon, homeostatic) and they do not express the CART peptide. Examples of specific genes that influence ε-cells are acyl-coenzyme A synthetase long chain family member 1 (ACSL1) and defensin beta 1.^[7] ACSL1 is thought to play a role in the processing of ghrelin while defensin beta 1 produces a protein that can kill bacteria, viruses, and yeast to regulate immunity. ^[5]

plasminogen receptor, and a CD320 receptor. The variety of receptors allow hormones, nutrients, lipids, and cytokine ligands to bind. The primary cellular metabolic pathway factor present in ε-cells are members that compose the fatty acid metabolism pathway, ACSL1