Transient receptor potential ankyrin 1 (trpa1) mediates il-1β-induced apoptosis in rat chondrocytes via calcium overload and mitochondrial dysfunction

Abstract

BackgroundChondrocyte apoptosis is a central feature in the progression of osteoarthritis (OA), and would be triggered by sustained elevation of intracellular calcium ion (Ca2+), also known as a cellular second messenger. Transient receptor potential ankyrin 1 (TRPA1) is a membrane-associated cation channel, and the activation of which causes an influx of cation ions, in particularly Ca2+, into the activated cells. Therefore, we investigate the potential role of TRPA1 in mediating Ca2+ influx to promote chondrocyte apoptosis in OA.MethodsThe expression of TRPA1 in interleukin (IL)-1β-treated rat chondrocytes was assessed by Polymerase chain reaction (PCR) and Western blot (WB), and the functionality of TRPA1 channel by Ca2+ influx measurements. Meanwhile, the chondrocyte apoptosis in IL-1β-treated cells was measured by TUNEL assay and flow cytometry. The measurement of mitochondrial membrane potential and apoptosis-associated proteins after inhibition of TRPA1 were also performed in IL-1β-treated rat chondrocytes.ResultsAfter being induced by IL-1β, the gene and protein expression of TRPA1 was increased in the dose-dependent manner. Meanwhile, Ca2+ influx mediated by TRPA1 in rat chondrocytes was also enhanced. Pharmacological inhibition of TRPA1 downregulated the apoptotic rate in IL-1β-treated rat chondrocytes. In addition, the membrane potential depolarization was improved and significantly increased expression of apoptosis-associated proteins also reduced by the TRPA1 antagonist.ConclusionsWe found the IL-1β caused the increased functional expression of TRPA1, the activation of which involved IL-1β-induced apoptosis in rat chondrocytes. The potential mechanism may be linked to the intracellular calcium overload mediated by TRPA1 and attendant mitochondrial dysfunction.

Hypoxia/reoxygenation activates the JNK pathway and accelerates synovial senescence

“…H/R can create a chronic anoxic environment in the joint organs (13,16). Furthermore, anoxia increases roS levels in FlS, which leads to mitochon- drial damage and induces the production of inflammatory factors (8). In addition, by inhibiting the synthesis of respiratory complexes iii and iV in synovial cells, mitochondrial dysfunction is worsened and inflammation is escalated (44).…”

“…Matrix conversion plays an important role in the joint microenvironment, and the synovial membrane can transform the matrix (7). Fibroblast-like synoviocytes (FlS) are located in the synovial lining layer and can secrete cytokines and catabolic factors, of which the latter can trigger articular cartilage degradation as a result of inflammatory trauma and oxidative stress (8). Synovial vascularization and synovial hyperplasia are observed in the early stage of oa (9).…”

Mitochondria: Potential Targets for Osteoarthritis

“…Calcium, a ubiquitous intracellular second messenger, is involved in numerous cellular processes ( 71 , 72 ). Calcium overload can lead to ROS overproduction, mitochondrial depolarization, MMP damage, and apoptosis ( 73 ). The maintenance of intracellular calcium homeostasis is achieved by mitochondrial uptake of calcium through a uniport transporter and the release of calcium through the inositol-1,4,5-trisphosphate receptor (IP 3 R), the sodium/calcium exchanger, or through the PTP, which is stimulated by excessive calcium in the mitochondrial matrix ( 72 , 74 ).…”

Interventional effects of the direct application of “Sanse powder” on knee osteoarthritis in rats as determined from lipidomics via UPLC-Q-Exactive Orbitrap MS

“…Western blotting was performed as previously described [12]. The blots were incubated with primary antibodies, including anti-IL-1β (1:1000, Abcam, Cambridge, UK), anti-pro-IL-1β (1:1000, Abcam, Cambridge, UK) and anti-TNF-α (1:1000, Abcam, Cambridge, UK).…”

“…qRT-PCR was performed as previously described [12]. Primer was designed and synthesized by Shanghai Biotechnology Service Company in accordance with Gene sequence in GenBank Gene sequence design, together with Oligo v6.6.…”