Regulation of type II collagen expression by cyclin‐dependent kinase 6, cyclin D1, and p21 in articular chondrocytes

Hwang, Sang‐Gu; Song, Seung Jin; Kim, Jeong Ran; Park, Chun Shik; Song, Wookeun; Chun, Jang‐Soo

doi:10.1080/15216540701245022

Cited by 18 publications

(18 citation statements)

References 25 publications

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“…), but it also interferes with the ability of SOX9 to bind to promoter regions of target genes (Hwang et al. ). ACAN has been shown to be regulated by SOX9, thus CCND1 is a potential way that cytochalasin D may regulate ACAN expression levels.…”

Section: Discussionmentioning

confidence: 99%

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Interplay between cytoskeletal polymerization and the chondrogenic phenotype in chondrocytes passaged in monolayer culture

et al. 2016

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Tubulin and actin exist as monomeric units that polymerize to form either microtubules or filamentous actin. As the polymerization status (monomeric/polymeric ratio) of tubulin and/or actin have been shown to be important in regulating gene expression and phenotype in non-chondrocyte cells, the objective of this study was to examine the role of cytoskeletal polymerization on the chondrocyte phenotype. We hypothesized that actin and/or tubulin polymerization status modulates the chondrocyte phenotype during monolayer culture as well as in 3D culture during redifferentiation. To test this hypothesis, articular chondrocytes were grown and passaged in 2D monolayer culture. Cell phenotype was investigated by assessing cell morphology (area and circularity), actin/tubulin content, organization and polymerization status, as well as by determination of proliferation, fibroblast and cartilage matrix gene expression with passage number. Bovine chondrocytes became larger, more elongated, and had significantly (P < 0.05) increased gene expression of proliferation-associated molecules (cyclin D1 and ki67), as well as significantly (P < 0.05) decreased cartilage matrix (type II collagen and aggrecan) and increased fibroblast-like matrix, type I collagen (COL1), gene expression by passage 2 (P2). Although tubulin polymerization status was not significantly (P > 0.05) modulated, actin polymerization was increased in bovine P2 cells. Actin depolymerization, but not tubulin depolymerization, promoted the chondrocyte phenotype by inducing cell rounding, increasing aggrecan and reducing COL1 expression. Knockdown of actin depolymerization factor, cofilin, in these cells induced further P2 cell actin polymerization and increased COL1 gene expression. To confirm that actin status regulated COL1 gene expression in human P2 chondrocytes, human P2 chondrocytes were exposed to cytochalasin D. Cytochalasin D decreased COL1 gene expression in human passaged chondrocytes. Furthermore, culture of bovine P2 chondrocytes in 3D culture on porous bone substitute resulted in actin depolymerization, which correlated with decreased expression of COL1 and proliferation molecules. In 3D cultures, aggrecan gene expression was increased by cytochalasin D treatment and COL1 was further decreased. These results reveal that actin polymerization status regulates chondrocyte dedifferentiation. Reorganization of the cytoskeleton by actin depolymerization appears to be an active regulatory mechanism for redifferentiation of passaged chondrocytes.

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Section: Discussionmentioning

confidence: 99%

“…; Hwang et al. ). This is intriguing as actin depolymerization via cytochalasin D treatment favored proteoglycan deposition (Newman & Watt, ) or latrunculin treatment enhanced ACAN gene expression (Parreno et al.…”

Section: Introductionmentioning

confidence: 99%

Interplay between cytoskeletal polymerization and the chondrogenic phenotype in chondrocytes passaged in monolayer culture

et al. 2016

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“…CDKs are expressed and active in a cell cycle phase-specific manner, such that CDK4 and CDK6 activity is necessary for progression through the G 1 phase (23). Cyclin D1 forms complexes with CDK4 or CDK6, which play an important role in the G 1 /S transition by phosphorylating Rb (24).…”

Section: Discussionmentioning

confidence: 99%

Millimeter wave treatment promotes chondrocyte proliferation via G1/S cell cycle transition

et al. 2012

Int J Mol Med

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Abstract. Millimeter waves, high-frequency electromagnetic waves, can effectively alleviate the clinical symptoms in osteoarthritis patients, as a non-pharmaceutical and non-invasive physical therapy regimen. However, the molecular mechanisms of the therapeutic effects of millimeter wave treatment are not well understood. In the present study, the effect of millimeter waves on the G 1 /S cell cycle progression in chondrocytes and the underlying mecha nism was investigated. Chondrocytes isolated from the knee of SD rats were cultured and identified using toluidine blue staining. The second generation chondrocytes were collected and stimulated with or without millimeter waves for 48 h. Chondrocyte viability was analyzed using the MTT assay. The cell cycle distribution of chondrocytes was analyzed by flow cytometry. mRNA and protein expression levels of cyclin D1, cyclin-dependent kinases 4 and 6 (CDK4 and CDK6) and p21 were detected using real-time PCR and western blotting, respectively. Millimeter wave stimulation was found to significantly enhance chondrocyte viability. Moreover, the percentage of chondrocytes in the G 0 /G 1 phase was significantly decreased, whereas that in the S phase was significantly increased. In addition, following millimeter wave treatment, cyclin D1, CDK4 and CDK6 expression was significantly upregulated, whereas p21 expression was significantly downregulated. The results indicate that millimeter wave treatment promotes chondrocyte proliferation via cell cycle progression. IntroductionOsteoarthritis (OA), the most frequent arthropathy, is characterized by progressive degradation of hyaline articular cartilage and is associated with aging (1). A complex interplay of mechanical, and functional changes of chondrocytes could precipitate the imbalance between matrix anabolic and catabolic processes in articular cartilage and thus the pathogenesis of OA (2,3). Chondroctyes can rapidly respond to changes in the articular microenvironment and regulate the dynamic equilibrium between the anabolism and catabolism of the extracellular matrix (ECM), which plays a crucial role in the maintenance of the cartilage function (4). Therefore, enhancing chondrocyte function might be an efficient treatment to cure or even delay the progression of OA by promoting chondrocyte proliferation.The cell cycle plays an important role in the influence on chondrocyte function, which takes place in chondrocytes leading to its division and duplication. Cell cycle control is a highly regulated process that involves a complex cascade of events, in which regulation can be realized through a complicated network by cyclins, cyclin-dependent kinases (CDKs) and cyclin dependent kinase inhibitors (CDKI). G 1 /S transition, one of the two main checkpoints, is a rate-limiting step in the cell cycle and regulates cell proliferation (5,6). Cyclin D1 is a key cell cycle regulatory protein, which binds to CDK4 or CDK6 to control cell cycle progression from the G 1 to the S phase (7). Meanwhile, p21 competes with cyclin D1 for bindin...

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“…As a consequence, activated Cyclin D1 facilitates the G1/S transition, thus promoting the proliferation of chondrocytes (21,22). One checkpoint exists in the late G1 phase, and once the cells pass through this checkpoint, they are no longer dependent on an exogenous stimulation signal for proliferation, thus acquiring the capacity to independently complete the cell cycle (23). The DNA content of the cells reflects the specific processes of cell growth and proliferation.…”

Section: Discussionmentioning

confidence: 99%

BMP2 promotes chondrocyte proliferation via the Wnt/β-catenin signaling pathway

Peng

et al. 2011

Mol Med Report

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Abstract. Bone morphogenetic protein 2 (BMP2), a member of the transforming growth factor-β (TGF-β) superfamily, plays a key role in the induction of the differentiation of mesenchymal cells into chondrocytes to form cartilage tissue. However, it is not clear whether BMP2 regulates the proliferation of chondrocytes. In the present study, the effect of BMP2 on the proliferation of chondrocytes and its underlying mechanism was investigated. Chondrocytes isolated from the knee of SD rats were cultured and identified using toluidine blue staining. The second generation chondrocytes were collected and stimulated with or without BMP2 for 48 h. Cell viability was analyzed using the MTT assay. mRNA and protein expression levels of β-catenin, GSK-3β, Dvl1 and Cyclin D1 were detected using real-time RT-PCR and Western blotting, respectively. The cell cycle distribution of the chondrocytes was analyzed by flow cytometry. BMP2 stimulation was found to significantly increase cell viability. In addition, following BMP2 treatment, β-catenin, Cyclin D1 and Dvl1 expression was significantly increased, whereas GSK-3β expression was significantly decreased. Moreover, the percentage proportion of chondrocytes in the G0/G1 phase was significantly decreased, whereas that in the S phase was significantly increased. The results indicate that BMP2 promotes chondrocyte proliferation via the Wnt/β-catenin signaling pathway.

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Regulation of type II collagen expression by cyclin‐dependent kinase 6, cyclin D1, and p21 in articular chondrocytes

Cited by 18 publications

References 25 publications

Interplay between cytoskeletal polymerization and the chondrogenic phenotype in chondrocytes passaged in monolayer culture

Interplay between cytoskeletal polymerization and the chondrogenic phenotype in chondrocytes passaged in monolayer culture

Millimeter wave treatment promotes chondrocyte proliferation via G1/S cell cycle transition

BMP2 promotes chondrocyte proliferation via the Wnt/β-catenin signaling pathway

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