title: The Silk-protein Sericin Induces Rapid Melanization of Cultured Primary Human Retinal Pigment Epithelial Cells by Activating the NF-κB Pathway.
abstract: Restoration of the retinal pigment epithelial (RPE) cells to prevent further loss of vision in patients with age-related macular degeneration represents a promising novel treatment modality. Development of RPE transplants, however, requires up to 3 months of cell differentiation. We explored whether the silk protein sericin can induce maturation of primary human retinal pigment epithelial (hRPE) cells. Microarray analysis demonstrated that sericin up-regulated RPE-associated transcripts (RPE65 and CRALBP). Upstream analysis identified the NF-κB pathway as one of the top sericin-induced regulators. ELISA confirmed that sericin stimulates the main NF-κB pathway. Increased levels of RPE-associated proteins (RPE65 and the pigment melanin) in the sericin-supplemented cultures were confirmed by western blot, spectrophotometry and transmission electron microscopy. Sericin also increased cell density and reduced cell death following serum starvation in culture. Inclusion of NF-κB agonists and antagonists in the culture medium showed that activation of the NF-κB pathway appears to be necessary, but not sufficient, for sericin-induced RPE pigmentation. We conclude that sericin promotes pigmentation of cultured primary hRPE cells by activating the main NF-κB pathway. Sericin's potential role in culture protocols for rapid differentiation of hRPE cells derived from embryonic or induced pluripotent stem cells should be investigated.
authors.affiliation: Department of Ophthalmology, Oslo University Hospital, Oslo, Norway.
authors.forename: J R
authors.initials: JR
authors.lastname: Eidet
authors.affiliation: Department of Medical Biochemistry, Oslo University Hospital, Oslo, Norway.
authors.forename: S
authors.initials: S
authors.lastname: Reppe
authors.affiliation: Department of Medical Biochemistry, Oslo University Hospital, Oslo, Norway.|Faculty of Medicine, University of Oslo, Oslo, Norway.
authors.forename: L
authors.initials: L
authors.lastname: Pasovic
authors.affiliation: Department of Medical Biochemistry, Oslo University Hospital, Oslo, Norway.
authors.forename: O K
authors.initials: OK
authors.lastname: Olstad
authors.affiliation: Department of Medical Biochemistry, Oslo University Hospital, Oslo, Norway.
authors.forename: T
authors.initials: T
authors.lastname: Lyberg
authors.affiliation: Department of Medical Biochemistry, Oslo University Hospital, Oslo, Norway.|Faculty of Medicine, University of Oslo, Oslo, Norway.
authors.forename: A Z
authors.initials: AZ
authors.lastname: Khan
authors.affiliation: Department of Oral Biology, Faculty of Dentistry, University of Oslo, Oslo, Norway.
authors.forename: I G
authors.initials: IG
authors.lastname: Fostad
authors.affiliation: Schepens Eye Research Institute, Harvard Medical School/Massachusetts Eye and Ear, Boston, MA.
authors.forename: D F
authors.initials: DF
authors.lastname: Chen
authors.affiliation: Department of Medical Biochemistry, Oslo University Hospital, Oslo, Norway.|Department of Oral Biology, Faculty of Dentistry, University of Oslo, Oslo, Norway.
authors.forename: T P
authors.initials: TP
authors.lastname: Utheim
mesh_terms: D002454:Cell Differentiation / Q000187:drug effects*; D002478:Cells, Cultured; D004797:Enzyme-Linked Immunosorbent Assay; D004847:Epithelial Cells / Q000187:drug effects*; D020869:Gene Expression Profiling; D006801:Humans; D008543:Melanins / Q000378:metabolism*; D046228:Microarray Analysis; D016328:NF-kappa B / Q000378:metabolism*; D055213:Retinal Pigment Epithelium / Q000166:cytology*; D047030:Sericins / Q000378:metabolism*; D015398:Signal Transduction; D019745:cis-trans-Isomerases / Q000378:metabolism; D000099178:Retinoid Isomerohydrolase
chemical_list: D008543:Melanins; D016328:NF-kappa B; D047030:Sericins; D019745:cis-trans-Isomerases; D000099178:Retinoid Isomerohydrolase