IGF-1 induces growth, survival and morphological change of primary hepatocytes on a galactose-bared polymer through both MAPK and beta-catenin pathways.
PVLA poly-(N-p-vinylbenzyl-O-beta-D-galactopyranosyl-D-gluconamide) is a glycopolymer composed of hydrophilic carbohydrate side chain and hydrophobic styrene polymer. The hydrophilic carbohydrate residue of PVLA can be recognized as a ligand for hepatocytes asialoglycoprotein receptor (ASGP-R), which is abundant on the hepatocyte cell surface. Adhering to the PVLA coated dishes, hepatocytes try to form aggregates that have a long time survival and also cells in these aggregates exhibit better maintenance of specific hepatocyte functions. Stimulation of the cells with IGF-1 in this culture condition results in the formation of lower aggregates. In addition to the morphological influences of IGF-1 to these cells, we have also found that IGF-1 transmits growth stimulatory responses to hepatocytes on PVLA through both mitogen activated protein kinase (MAPK) pathway and beta-catenin pathways. The phosphorylation of MAPK can take place within 5 min of stimulation with IGF-1 and within at least 10 ng/ml of IGF-1 concentration. Inhibition of MAPK activation by MEK-1 inhibitor PD98059 reduces IGF-1 induced MAPK phosphorylation, and also IGF-1 stimulated DNA synthesis. Similarly, the use of PI3-K inhibitor LY294002 also inhibits IGF-1 stimulated DNA synthesis. IGF-1 stimulation enhances the migration of beta-catenin from the cytoskeleton and cell membrane to the cytoplasm which also is the reason behind formation of spheroids and lower aggregates. IGF-1 stimulation also shows increased translocalization of beta-catenin to the nucleus that is essentially important to produce beta-catenin responsive effects to the cells. These studies thus suggest that IGF-1 can stimulate the growth and survival of hepatocytes on PVLA through both MAPK and beta-catenin signaling pathways, and that the activation of beta-catenin signaling pathway produces the morphological changes of IGF-1 induced cells.
Department of Biomolecular Engineering, Graduate School of Bioscience and Biotechnology, Tokyo Institute of Technology, Yokohama, Japan.
Anup Kumer
AK
Kundu
Masato
M
Nagaoka
Ezharul Hoque
EH
Chowdhury
Shinichi
S
Hirose
Tadashi
T
Sasagawa
Toshihiro
T
Akaike
D000818:Animals; D037263:Asialoglycoprotein Receptor / Q000378:metabolism; D002455:Cell Division / Q000502:physiology*; D048429:Cell Size / Q000502:physiology; D002470:Cell Survival / Q000502:physiology*; D002478:Cells, Cultured; D002867:Chromones / Q000494:pharmacology; D003598:Cytoskeletal Proteins / Q000378:metabolism; D004261:DNA Replication; D004791:Enzyme Inhibitors / Q000494:pharmacology; D005419:Flavonoids / Q000494:pharmacology; D022781:Hepatocytes / Q000378:metabolism*; D007334:Insulin-Like Growth Factor I / Q000494:pharmacology*; D007785:Lactose / Q000031:analogs & derivatives* / Q000737:chemistry*; D020935:MAP Kinase Signaling System / Q000187:drug effects / Q000502:physiology; D008297:Male; D051379:Mice; D009025:Morpholines / Q000494:pharmacology; D019869:Phosphatidylinositol 3-Kinases / Q000378:metabolism; D000081082:Phosphoinositide-3 Kinase Inhibitors; D011137:Polystyrenes / Q000737:chemistry*; D015398:Signal Transduction / Q000502:physiology; D015534:Trans-Activators / Q000378:metabolism; D051176:beta Catenin
D037263:Asialoglycoprotein Receptor; D002867:Chromones; D003598:Cytoskeletal Proteins; D004791:Enzyme Inhibitors; D005419:Flavonoids; D007334:Insulin-Like Growth Factor I; D007785:Lactose; D009025:Morpholines; D019869:Phosphatidylinositol 3-Kinases; D000081082:Phosphoinositide-3 Kinase Inhibitors; D011137:Polystyrenes; D015534:Trans-Activators; D051176:beta Catenin; C495267:CTNNB1 protein, mouse; C085911:2-(4-morpholinyl)-8-phenyl-4H-1-benzopyran-4-one; C074112:poly-N-4-vinylbenzyllactonamide; C093973:2-(2-amino-3-methoxyphenyl)-4H-1-benzopyran-4-one