Article ID | Journal | Published Year | Pages | File Type |
---|---|---|---|---|
9245593 | Gastroenterology | 2005 | 16 Pages |
Abstract
Background & Aims: Gap junctional communication was studied in quiescent and activated hepatic stellate cells. Methods: Connexin expression and intercellular dye transfer were studied in rat hepatic stellate cells in culture and in vivo. Results: Protein expression of connexin 43 was up-regulated in activated hepatic stellate cells in vivo and in vitro and was mainly localized on the cell surface, whereas connexin 26 was found intracellularly. In contrast to hepatocytes, hepatic stellate cells do not express connexin 32. Confluent hepatic stellate cells in culture communicate via gap junctions, resulting in lucifer yellow transfer and propagation of intracellular calcium signals. Phorbol ester induces a protein kinase C-dependent hyperphosphorylation and degradation of connexin 43 and inhibits intercellular communication on a short-term time scale. At the long-term level, vitamin D3, lipopolysaccharide, thyroid hormone T3, dexamethasone, platelet-derived growth factor, endothelin 1, and interleukin 1β up-regulate connexin 43 protein and messenger RNA expression and enhance intercellular communication. Slight down-regulation of connexin 43 is observed in response to vitamin A. Connexin 43 induction by endothelin 1 is inhibited by both endothelin A and endothelin B receptor antagonists. In coculture systems, hepatic stellate cells communicate with each other, which is suggestive of a syncytial organization, but no communication was found between hepatic stellate cells and other liver cell types. As shown by immunohistochemistry and electron microscopy, gap junctions are formed between activated hepatic stellate cells in vivo. Conclusions: Gap junctional communication occurs between hepatic stellate cells, is enhanced after activation, and underlies complex regulation by cytokines, hormones, and vitamins.
Keywords
GAPDHKrebs–Henseleit bufferpKaphorbol 12-myristate 13-acetateET-1KHBPDGFGFAPSECFITCSDSPKCDMEMLPSHSCPMAMAPKDulbecco’s modified Eagle mediumsmooth muscle actinendothelin 1interleukinSMAsodium dodecyl sulfateSinusoidal Endothelial CellHepatic stellate cellparenchymal cellKupffer cellplatelet-derived growth factorfluorescein isothiocyanatelipopolysaccharideGlial fibrillary acidic proteinprotein kinase AProtein kinase Cmitogen-activated protein kinaseconnexinglyceraldehyde-3-phosphate dehydrogenase
Related Topics
Health Sciences
Medicine and Dentistry
Gastroenterology
Authors
Richard Fischer, Roland Reinehr, Thuy Phung Lu, Alexandra Schönicke, Ulrich Warskulat, Hans Peter Dienes, Dieter Häussinger,