Histological Mapping and Subtype-Specific Functions of Galectins in Health and Disease

Galectins, beta-galactoside-binding lectins, consist of 15 members and are broadly distributed in the mammalian body in organand cell-specific manners. This minireview summarizes current knowledge on the cellular localization of galectin subtypes in various organs including the digestive tract, lymphatic system, respiratory system, urinary system, and reproductive system. We also summarize the specific localization of galectins in the epithelium with a focus on the characteristic morphologies of epithelia. In addition, we discuss the functions of galectins in the reproductive and endocrine systems, pathogenic angiogenesis, and the regulation of stem cells. The regulatory mechanism of galectin expression is also discussed based on findings obtained from luteal cells. Various glycoconjugate ligands for galectins have been identified, and notably the ligands for galectins differ in each galectin-expressing cell. The physiological and pathological states of cells affect the expression of galectin and glycoconjugate ligands, and the extracellular environment, such as the concentration of growth factors, nutrients, and oxygen also controls the expression levels. Future studies to identify the cellular and intracellular localization of galectins using histological analyses will provide a better understanding of the potential functions of galectins in healthy and disease states.