G-Protein Coupled Receptor 35 Induces Intervertebral Disc Degeneration by Mediating the Influx of Calcium Ions and Upregulating Reactive Oxygen Species

Abstract

Intervertebral disc degeneration (IDD) is a chronic disease affecting millions of patients; however, its specific etiology is unknown. G protein-coupled receptors (GPRs) are a superfamily of integral membrane receptors in cells, and the receptors respond to a diverse range of stimuli and participate in multiple cellular activities. Here, using RNA-sequencing (RNA-seq) methods and immunohistochemistry, we revealed that G protein-coupled receptor 35 (GPR35) may have a relationship with IDD. Then, we demonstrated that the deletion of GPR35 in nucleus pulposus cells (NPCs) with siRNA or in Gpr35-/- mice significantly alleviated IDD caused by senescence or mechanical stress, further validating the pathological role of GPR35 in IDD. In addition, GPR35 induced the influx of Ca2+ and upregulation of reactive oxygen species (ROS) under mechanical stress in NPCs, which we believe to be the mechanism of GPR35-induced IDD. Finally, GPR35 caused upregulation of ROS in NPCs under mechanical stress, while excessive ROS stimulated the NPCs to express more GPR35 with a significant dose or time response. The u-regulated GPR35 could sense mechanical stress to produce more ROS and perpetuate this harmful cycle. In summary, our study shows that GPR35 plays a critical role in mediating IDD via mediating the influx of calcium ions and upregulating ROS, which implies a strong potential advantage of GPR35 as a prevention and treatment target in IDD.

Cellular Senescence in Intervertebral Disc Aging and Degeneration: Molecular Mechanisms and Potential Therapeutic Opportunities

“…Prolonged exposure of cyclic mechanical tension led to DNA damage and induction of premature senescence of NP cells through the activation of the p53-p21-Rb pathway independent of oxidative stress [ 25 ]. The expression of membrane receptor G protein-coupled receptor 35 (GPR35) was higher in NP tissues from degenerated discs [ 26 ]. In NP cells, mechanical compression induced the intracellular calcium levels via GRP35 to upregulate ROS production, leading to disc cell oxidative damage [ 26 ].…”

“…The expression of membrane receptor G protein-coupled receptor 35 (GPR35) was higher in NP tissues from degenerated discs [ 26 ]. In NP cells, mechanical compression induced the intracellular calcium levels via GRP35 to upregulate ROS production, leading to disc cell oxidative damage [ 26 ]. Ke et al reported that compression stress in human NP cells induces the Rho/ROCK1/p-MLC pathway, which induces myosin IIA interaction with actin and reduces the interaction of myosin IIB and actin.…”

Constitutive and conditional gene knockout mice for the study of intervertebral disc degeneration: Current status, decision considerations, and future possibilities

“…Therefore, Ager KO may have protective effect on collagen in AF. In the study of disc degeneration, a disintegrin‐like and metallopeptidase with thrombospondin type 1 motif, 5 ( Adamts5 ) KO mice used by Ngo et al, 68 cyclin dependent kinase inhibitor 2A ( Cdkn2a ) KO mice used by Che et al, 69 G protein‐coupled receptor 35 ( Gpr35 ) KO mice used by Chen et al, 70 microRNA 141 ( Mir141 ) KO mice used by Ji et al 71 and sclerostin ( Sost ) KO mice used by Kroon et al 72 were also found that the target gene they studied could exacerbate disc degeneration (Table 2 ).…”

GPR35 acts a dual role and therapeutic target in inflammation

“…Under mechanical stress, GPR35 activation has been shown to enhance ROS production, and excessive ROS triggers further GPR35 expression ( 48 ). Conversely, GPR35 activation with Kynurenic acid in macrophages suppresses NLRP3 inflammasome activation and related inflammation by reducing mitochondrial damage and mitochondrial ROS production ( 49 ). These studies, despite showing divergent outcomes, reveal the significant role of GPR35 in modulating inflammation via ROS-mediated pathways.…”

“…There have been two diseases that are connected to the pro-inflammatory effects of GPR35. GPR35 plays a vital role in detecting bacteroides fragilis toxin and triggering an immune response in bacteroides fragilis toxin-induced colitis ( 89 ), and GPR35 loss in nucleus pulposus cells significantly reduces intervertebral disc degeneration typically triggered by inflammation induced by ROS or mechanical stress ( 49 ). In addition, encephalomyelitis (EAE) is worsened through the accumulation of GPR35 + /Ly6C + macrophages in the small intestine, while the blockage of KYNA-GPR35 signaling can alleviate EAE ( 75 ).…”