title: Enhanced DNA synthesis accompanied by constitutive phosphorylation of the ERK pathway in human fibroblasts cultured on a polyelectrolyte complex.
abstract: In this study, we examined the cellular and molecular responses of fibroblasts cultured on a polyelectrolyte complex (PEC) derived from sulfated chitin as a polyanion and chitosan as a polycation. On PEC-coated dishes, the fibroblasts aggregated and then developed spheroid-like structures. At earlier stages of culture, DNA synthesis of cells cultured on PEC was stimulated approximately 75% higher than control cells. Among various signaling molecules examined, including mitogen-activated protein kinases, Akt/PKB and p53, an extracellular-signal-regulated kinase (ERK) was selectively and constitutively phosphorylated in cells cultured on PEC. The constitutive phosphorylation of ERK was derived from an activation of the ERK kinase MEK, but not from an inactivation of the ERK phosphatase MKP-1. Furthermore, ERK phosphorylation was almost abolished by a membrane receptor tyrosine kinase inhibitor. The enhanced phosphorylation of focal adhesion kinase, a downstream molecule of integrins, was also observed in cells cultured on PEC. These results suggest that fibroblasts recognize PEC as a continuous mitogenic stimulant which results in the constitutive activation of the MEK-ERK pathway toward mitogenesis. Further, PEC interacts with the cell membrane leading to activation of membrane molecules, including integrins and receptor tyrosine kinases. These responses may account, at least in part, for the potential use of PEC as a biomaterial for tissue regeneration.
authors.affiliation: Center for Frontier Life Sciences, Nagasaki University, 1-12-4 Sakamoto, Nagasaki 852-8523, Japan. nuric@net.nagasaki-u.ac.jp
authors.forename: Naoki
authors.initials: N
authors.lastname: Matsuda
authors.forename: Miwa
authors.initials: M
authors.lastname: Horikawa
authors.forename: Masahiro
authors.initials: M
authors.lastname: Yoshida
authors.forename: Masami
authors.initials: M
authors.lastname: Watanabe
authors.forename: Misao
authors.initials: M
authors.lastname: Nagahata
authors.forename: Akira
authors.initials: A
authors.lastname: Teramoto
authors.forename: Koji
authors.initials: K
authors.lastname: Abe
mesh_terms: D002449:Cell Aggregation / Q000502:physiology; D018929:Cell Culture Techniques / Q000379:methods*; D002454:Cell Differentiation / Q000502:physiology; D002460:Cell Line; D002686:Chitin / Q000031:analogs & derivatives* / Q000378:metabolism*; D048271:Chitosan; D020099:Coated Materials, Biocompatible / Q000378:metabolism; D004247:DNA / Q000096:biosynthesis*; D004573:Electrolytes / Q000378:metabolism; D005347:Fibroblasts / Q000166:cytology* / Q000502:physiology*; D006801:Humans; D020928:Mitogen-Activated Protein Kinases / Q000378:metabolism*; D010766:Phosphorylation; D017346:Protein Serine-Threonine Kinases; D011518:Proto-Oncogene Proteins / Q000378:metabolism; D051057:Proto-Oncogene Proteins c-akt; D015398:Signal Transduction / Q000502:physiology*; D023822:Tissue Engineering / Q000379:methods
chemical_list: D020099:Coated Materials, Biocompatible; D004573:Electrolytes; D011518:Proto-Oncogene Proteins; D002686:Chitin; D004247:DNA; D048271:Chitosan; C494918:AKT1 protein, human; D017346:Protein Serine-Threonine Kinases; D051057:Proto-Oncogene Proteins c-akt; D020928:Mitogen-Activated Protein Kinases