Control of matrix synthesis in isolated bovine chondrocytes by extracellular and intracellular pH

Wilkins, Robert J.; Hall, Andrew C.

doi:10.1002/jcp.1041640305

Cited by 93 publications

(93 citation statements)

References 27 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…For both disc and cartilage cells cultured for 48 h in alginate beads, the production of matrix components showed a biphasic response to pH (Fig. 1), as seen previously after short exposures of disc explants and cartilage cells in suspension culture to changes in extracellular pH [39,54]. Rates were highest at around pH 7.0-7.2 (the estimated pH in normal discs [19]), where they were 10-20% greater than at pH 7.4 (the extracellular pH of most body fluids).…”

Section: Discussionsupporting

confidence: 75%

See 1 more Smart Citation

The effect of extracellular pH on matrix turnover by cells of the bovine nucleus pulposus

Razaq

Wilkins

Urban

2003

European Spine Journal

Self Cite

168

164

View full text Add to dashboard Cite

IntroductionNucleus pulposus cells are solely responsible for the production and maintenance of the extracellular matrix of the nucleus throughout life [31]. The cells have no direct contact with each other and rely on cell-matrix interactions and signals from the environment to maintain the function of the tissue. The cells synthesize all the matrix components [10,37,38,50] and also produce degradative enzymes including metalloproteinases (MMPs) and their inhibitors (tissue inhibitors of metalloproteinases or TIMPs), involved in matrix turnover [7,45,53]. The fine balance between synthesis of components and the breakdown of tissue determines the composition of the matrix; tissue integrity is thus dependent on the activity of the nucleus pulposus cells [53]. In vivo [20,43] and in vitro [14] environmental factors such as mechanical stress [30,34] and nutrient levels have been found to affect matrix composition, presumably by affecting macromolecule biosyntheAbstract It has long been known that very acidic conditions can be found in degenerate discs. The effect of these acid conditions on matrix turnover are, however, unknown. This study aimed to examine the effect of acidity on production of matrix components and on agents which break down the matrix in order to gain insight into the effect of pathological values of pH on matrix turnover. Cells were isolated from the nucleus of bovine discs and from bovine articular cartilage, embedded in alginate beads and cultured at pH levels maintained within the ranges seen in normal and pathological discs: pH 7.4-pH 6.3 for 48 h. Rates of sulphated glycosaminoglycan (GAG) and protein synthesis were measured, as well as rates of production of some agents involved in matrix breakdown, i.e. total and activated matrix metalloproteinases (MMPs) and their inhibitors (TIMPs). The results showed that acid conditions had a profound effect on cell matrix turnover; at pH 6.4, total production of most species measured was inhibited by more than 50% compared to production at pH 7.2; production of sulphated GAGs and of TIMP-1 fell by >90%. However production of active metalloproteinases by disc cells was relatively insensitive to pH, with activity at pH 6.3 not statistically different from that at pH 7.2. These findings indicate that exposure to acid conditions appears particularly deleterious for the disc matrix, as it inhibits the disc cells from synthesising functionally important molecules such as the sulphated GAGs but does not prevent the production of agents able to degrade matrix components. The low values of pH seen in some degenerate discs are thus likely to be involved in breakdown of the disc matrix.

show abstract

Section: Discussionsupporting

confidence: 75%

“…1a). Protein synthesis appeared less sensitive to pH, as observed in similar systems [39,54], but was still strongly inhibited under acid conditions (Fig. 1b).…”

Section: Discussionsupporting

confidence: 72%

The effect of extracellular pH on matrix turnover by cells of the bovine nucleus pulposus

Razaq

Wilkins

Urban

2003

European Spine Journal

Self Cite

168

164

View full text Add to dashboard Cite

show abstract

“…Flow diagram representing the key stages of live cell volume buffered Dulbecco's modified Eagle's medium (DMEM), and imaging (square boxes). Each phase required optimization steps this initially provided a solution of 280 mosM (140 mM NaCl) (rounded boxes) that were necessary to both extract and view at pH 7.4; hence it was not necessary to supply C02 during the course of the experiment (11,34). Explants were posi tively labeled with 4.5 p.M 5-chloromethylfluorescein diacIn this paper we demonstrate a series of protocols for etate Molecular Probes, Eugene, OR) at 37 C for 15…”

Section: Methodsmentioning

confidence: 99%

Four-dimensional imaging of living chondrocytes in cartilage using confocal microscopy: a pragmatic approach

Errington

Fricker

Wood

et al. 1997

American Journal of Physiology-Cell Physiology

View full text Add to dashboard Cite

“…Each of these physical phenomena may potentially act as a "mechano-ligand" activating or inhibiting one or more signaling pathways. Prior studies have often focused on the effects of one or a few of these components of compressive loading such as negative fixed charge density (26) or interstitial pH (22,29,30). Recent studies have also demonstrated that mechanical stretching of chondrocytes can increase nitric oxide production (31) and alter membrane transport phenomena, resulting in proliferative changes (32).…”

mentioning

confidence: 99%

Mechanical Regulation of Mitogen-activated Protein Kinase Signaling in Articular Cartilage

Fanning

Emkey

Smith

et al. 2003

Journal of Biological Chemistry

118

View full text Add to dashboard Cite

Articular chondrocytes respond to mechanical forces by alterations in gene expression, proliferative status, and metabolic functions. Little is known concerning the cell signaling systems that receive, transduce, and convey mechanical information to the chondrocyte interior. Here, we show that ex vivo cartilage compression stimulates the phosphorylation of ERK1/2, p38 MAPK, and SAPK/ERK kinase-1 (SEK1) of the JNK pathway. Mechanical compression induced a phased phosphorylation of ERK consisting of a rapid induction of ERK1/2 phosphorylation at 10 min, a rapid decay, and a sustained level of ERK2 phosphorylation that persisted for at least 24 h. Mechanical compression also induced the phosphorylation of p38 MAPK in strictly a transient fashion, with maximal phosphorylation occurring at 10 min. Mechanical compression stimulated SEK1 phosphorylation, with a maximum at the relatively delayed time point of 1 h and with a higher amplitude than ERK1/2 and p38 MAPK phosphorylation. These data demonstrate that mechanical compression alone activates MAPK signaling in intact cartilage. In addition, these data demonstrate distinct temporal patterns of MAPK signaling in response to mechanical loading and to the anabolic insulin-like growth factor-I. Finally, the data indicate that compression coactivates distinct signaling pathways that may help define the nature of mechanotransduction in cartilage.

show abstract

Control of matrix synthesis in isolated bovine chondrocytes by extracellular and intracellular pH

Cited by 93 publications

References 27 publications

The effect of extracellular pH on matrix turnover by cells of the bovine nucleus pulposus

The effect of extracellular pH on matrix turnover by cells of the bovine nucleus pulposus

Four-dimensional imaging of living chondrocytes in cartilage using confocal microscopy: a pragmatic approach

Mechanical Regulation of Mitogen-activated Protein Kinase Signaling in Articular Cartilage

Contact Info

Product

Resources

About