title: PEP-1-SIRT2 causes dedifferentiation and COX-2 expression via the MAPK pathways in rabbit articular chondrocytes.
abstract: SIRT2 is a member of the mammalian sirtuin protein family, primarily found in the cytoplasm. It regulates numerous cellular processes including aging, DNA repair, cell cycle, and survival under stress conditions. However, the biological function and mechanism of the SIRT2 protein was not well understood in normal cells such as primary chondrocytes. In this study, we examined the effects of SIRT2 on differentiation and inflammation in rabbit articular chondrocytes by using a cell-permeative PEP-1-SIRT2 protein. Our results indicate that PEP-1-SIRT2-induced a loss of type II collagen and decreased sulfate proteoglycan levels in a dose- and time-dependent manner, as examined by Western blotting, alcian blue staining, and immunohistochemistry. Furthermore, PEP-1-SIRT2 caused an inflammatory response by inducing the expression of cyclooxygenase-2 (COX-2) and prostaglandin E2 (PGE2). In addition, after treatment with PEP-1-SIRT2, phosphorylation of both p38 and ERK was observed. Inhibition of ERK with PD98059 (PD) suppressed PEP-1-SIRT2-induced dedifferentiation and COX-2 expression. Reduction in PEP-1-SIRT2-induced inflammatory response was observed upon inhibition of p38 by SB203580 (SB). The same pattern was demonstrated in PEP-1-SIRT2-induced dedifferentiation and inflammatory response during culture with serial passages. During expansion to four passages, levels of type II collagen decreased, whereas levels of COX-2 and SIRT2 increased and activated ERK and p38. Furthermore, PEP-1-SIRT2 enhances dedifferentiation through the ERK pathway and inflammatory response through the ERK and p38 pathways in rabbit chondrocytes in vitro. These findings suggest that PEP-1-SIRT2 induces dedifferentiation via the ERK pathway and inflammation through the p38 and ERK pathways in rabbit articular chondrocytes.
authors.affiliation: Department of Biological Sciences, College of Natural Sciences, Kongju National University, 182 Shinkwan-Dong, Gongju, Chungnam 314-701, Republic of Korea. Electronic address: eoseonghee@kongju.ac.kr.
authors.forename: Seong-Hui
authors.initials: SH
authors.lastname: Eo
authors.affiliation: Department of Biochemistry and Molecular Biology, Research Institute of Oral Sciences, College of Dentistry, Gangnung-Wonju National University, Gangneung, Republic of Korea. Electronic address: kimdw@gwnu.ac.kr.
authors.forename: Dae Won
authors.initials: DW
authors.lastname: Kim
authors.affiliation: Department of Biomedical Science and Research Institute of Bioscience and Biotechnology, Hallym University, Chunchon, Republic of Korea. Electronic address: sychoi@hallym.ac.kr.
authors.forename: Soo Young
authors.initials: SY
authors.lastname: Choi
authors.affiliation: Division of rheumatology, Department of Internal Medicine, Hallym University Sacred Heart Hospital, Kyunggi, Republic of Korea; 2nd Affiliate: Institute for Skeletal Aging, Hallym University, Chunchun, Republic of Korea. Electronic address: kimha@hallym.ac.kr.
authors.forename: Hyun Ah
authors.initials: HA
authors.lastname: Kim
authors.affiliation: Department of Biological Sciences, College of Natural Sciences, Kongju National University, 182 Shinkwan-Dong, Gongju, Chungnam 314-701, Republic of Korea. Electronic address: ksj85@kongju.ac.kr.
authors.forename: Song-Ja
authors.initials: SJ
authors.lastname: Kim
mesh_terms: D000818:Animals; D002358:Cartilage, Articular / Q000166:cytology* / Q000378:metabolism; D054337:Cell Dedifferentiation; D049109:Cell Proliferation; D002470:Cell Survival; D002478:Cells, Cultured; D019902:Chondrocytes / Q000166:cytology / Q000201:enzymology / Q000378:metabolism*; D051546:Cyclooxygenase 2 / Q000096:biosynthesis*; D003543:Cysteamine / Q000031:analogs & derivatives* / Q000378:metabolism; D020928:Mitogen-Activated Protein Kinases / Q000378:metabolism*; D010455:Peptides / Q000378:metabolism*; D011817:Rabbits; D056565:Sirtuin 2 / Q000378:metabolism*
chemical_list: C503924:Pep-1 peptide; D010455:Peptides; D003543:Cysteamine; D051546:Cyclooxygenase 2; D020928:Mitogen-Activated Protein Kinases; D056565:Sirtuin 2
keywords: Chondrocytes; Dedifferentiation; Inflammation; MAPK pathway; PEP-1-SIRT2