title: A novel arrangement of midgut epithelium and hepatic cells implies a novel regulation of the insulin signaling pathway in long-lived millipedes.
abstract: Nutrients absorbed by the epithelial cells of the millipede midgut are channeled to a contiguous population of hepatic cells where sugars are stored as glycogen. In insects and other arthropods, however, nutrients absorbed by midgut epithelia are first passed across the epithelial basal surface to the hemolymph before storage in fat body. The inter-digitation of cellular processes at the interface of hepatic and midgut epithelial cells offers a vast surface area for exchange of nutrients. At this interface, numerous small vesicles with the dimensions of exosomes (∼30nm) may represent the mediators of nutrient exchange. Longevity and the developmental arrest of diapause are associated with reduced insulin signaling. The long lifespans for which millipedes are known may be attributable to a novel pathway with reduced insulin signaling represented by the novel arrangement of hepatic storage cells and midgut epithelial absorbing cells.
authors.affiliation: Department of Entomology, University of Illinois, 320 Morrill Hall, 505 S. Goodwin Avenue, Urbana, IL 61801, United States. Electronic address: j-nardi@uiuc.edu.
authors.forename: James B
authors.initials: JB
authors.lastname: Nardi
authors.affiliation: Biological Electron Microscopy, Frederick Seitz Materials Research Laboratory, Room 125, University of Illinois, 104 South Goodwin Avenue, Urbana, IL 61801, United States. Electronic address: lamiller@illinois.edu.
authors.forename: Lou Ann
authors.initials: LA
authors.lastname: Miller
authors.affiliation: Imaging Technology Group, Beckman Institute for Advanced Science and Technology, University of Illinois, 405 N. Mathews Avenue, Urbana, IL 61801, United States. Electronic address: c-bee1@illinos.edu.
authors.forename: Charles M
authors.initials: CM
authors.lastname: Bee
mesh_terms: D000818:Animals; D001181:Arthropods / Q000166:cytology / Q000502:physiology*; D004847:Epithelial Cells / Q000166:cytology / Q000502:physiology; D041981:Gastrointestinal Tract / Q000166:cytology / Q000502:physiology; D022781:Hepatocytes / Q000166:cytology / Q000502:physiology; D007328:Insulin / Q000502:physiology*; D015398:Signal Transduction
chemical_list: D007328:Insulin
keywords: Diplopoda; Exosomes; Hepatic cells; Insulin signaling; Lifespan; Midgut epithelium