Related Experiment Video
Updated: Jan 10, 2026
A 5-mC Dot Blot Assay Quantifying the DNA Methylation Level of Chondrocyte Dedifferentiation In Vitro
Published on: May 17, 2017
Dexamethasone regulates gene expression in chondrocytes through MKP-1 and downregulates cholesterol hydroxylases
Tiina Lehtola1, Antti Pemmari1, Elina Nummenmaa1
1The Immunopharmacology Research Group, Faculty of Medicine and Health Technology, Tampere University and Tampere University Hospital in Wellbeing Services County of Pirkanmaa, 33014, Tampere, Finland.
Objective:
Mitogen-activated protein kinase phosphatase-1 (MKP-1) is an anti-inflammatory enzyme whose expression is increased by glucocorticoids (GCs). MKP-1 dephosphorylates and thereby inactivates mitogen-activated protein kinases (MAP kinases) which are major signaling pathways mediating proinflammatory effects of various extracellular factors to gene expression. In this study, we examined the regulatory effects of the synthetic glucocorticoid dexamethasone on the expression of a panel of genes previously identified as the top 15 critical mediators in the pathogenesis of osteoarthritis (OA). Furthermore, we investigated the hypothesis that MKP-1 is involved in mediating these glucocorticoid-induced effects in chondrocytes.
Methods:
The effects of dexamethasone on the interleukin-1β-induced expression of OA target genes were investigated with RNA-seq and quantitative RT-PCR in primary cultured chondrocytes from wild-type and MKP-1 deficient mice, and from OA patients undergoing joint replacement surgery.
Results:
Under these conditions, dexamethasone was found to significantly alter the expression of seven out of the 15 OA-related genes including two cholesterol hydroxylases, namely cholesterol 25-hydroxylase (CH25H) and 25-hydroxycholesterol 7-hydroxylase (also known as cytochrome P450 family 7 subfamily B member 1, CYP7B1). Dexamethasone attenuated the interleukin-1β -induced expression of CH25H and CYP7B1 in primary chondrocytes of wild-type mice and in primary human OA chondrocytes, but the dexamethasone effect was absent (CYP7B1) or reduced (CH25H) in chondrocytes from MKP-1 deficient mice. Furthermore, the p38 MAP kinase inhibitor BIRB796 significantly inhibited CH25H expression while the JNK MAP kinase inhibitor SP600125 attenuated CYP7B1 expression in human OA chondrocytes.
Conclusions:
In conjunction with previous findings, the current data substantiate the role of MKP-1 as a protective factor in chondrocytes and highlight its potential as a therapeutic target for the treatment of osteoarthritis, because increased levels of cholesterol and its metabolism by CH25H and CYP7B1 are involved in the pathogenesis of OA, particularly in its obesity-associated phenotype.
Insights
Glucocorticoids like dexamethasone reduce osteoarthritis gene expression via MKP-1. This highlights MKP-1 as a potential therapeutic target for osteoarthritis, especially its obesity-associated form.
Area of Science:
- Molecular Biology
- Biochemistry
- Immunology
Background:
- Mitogen-activated protein kinase phosphatase-1 (MKP-1) is an anti-inflammatory enzyme induced by glucocorticoids (GCs).
- MKP-1 inactivates MAP kinases, crucial signaling pathways in inflammatory gene expression.
- Osteoarthritis (OA) pathogenesis involves specific gene mediators and inflammatory processes.
Purpose of the Study:
- To investigate dexamethasone's regulatory effects on key OA-associated genes.
- To determine the role of MKP-1 in mediating dexamethasone's effects on chondrocytes.
- To explore the link between cholesterol metabolism genes and OA pathogenesis.
Main Methods:
- Primary chondrocytes from wild-type and MKP-1 deficient mice, and OA patients were used.
- RNA-sequencing and quantitative RT-PCR analyzed gene expression changes.
- Specific MAP kinase inhibitors (BIRB796, SP600125) were employed.
Main Results:
- Dexamethasone altered seven of the 15 studied OA-related genes.
- Expression of cholesterol hydroxylases CH25H and CYP7B1 was attenuated by dexamethasone.
- Dexamethasone's effects on CH25H and CYP7B1 were reduced or absent in MKP-1 deficient chondrocytes.
Conclusions:
- MKP-1 plays a protective role in chondrocytes, suggesting it's a therapeutic target for OA.
- Increased cholesterol and its metabolism by CH25H and CYP7B1 are implicated in OA pathogenesis.
- Targeting MKP-1 may be beneficial for treating osteoarthritis, particularly obesity-associated OA.
Related Concept Videos
02:23Master Transcription Regulators
01:23Regulation of Expression at Multiple Steps
01:37Epigenetic Regulation
X-chromosome...
01:46Epigenetic Regulation
01:29Cholesterol: Significance and Regulation
Considering cholesterol and...
01:23Role of Matrix Metalloproteases in Degradation of ECM