Upregulated miR-154 promotes ECM degradation in intervertebral disc degeneration

Intervertebral disc degeneration (IDD), a common global health issue, is a major cause for low back pain (LBP). Given the complex etiology of IDD, micro RNA (miRNA) recently has been demonstrated to play essential roles in the progression of IDD. Therefore, this study aims to investigate functions of the miR-154, which is well-documented in a series of cell activities, IDD, and other relevant mechanisms. Lumbar nucleus pulposus (NP) samples were collected from patients with IDD and the control group. After solexa sequencing and bioinformatical analysis, the results showed that miR-154 was increased in NP cells of patients with IDD. Inhibition of miR-154 increased type II collagen and aggrecan and decreased mRNA expressions of collagenase-3 (MMP13) and aggrecanase-1 (ADAMTS4), whereas overexpression of miR-154 reversed such effects in NP cells. In addition, the luciferase reporter assay revealed that fibroblast growth factor 14 (FGF14) is a direct target of miR-154 and that the overexpression of FGF14 leads to similar effects as inhibition of miR-154 did. In conclusion, the results suggested that miR-154 participates in the development of IDD and its effects are mediated via targeting FGF14. Thus, miR-154 may be thought as a potential etiological factor for IDD and may provide insights into a therapeutic target to treat IDD.     

Calcitonin inhibits intervertebral disc degeneration by regulating protein kinase C

Intervertebral disc degeneration (IVDD) is the most critical factor that causes low back pain. Molecular biotherapy is a fundamental strategy for IVDD treatment. Calcitonin can promote the proliferation of chondrocytes, stimulate the synthesis of matrix and prevent cartilage degeneration. However, its effect and the underlying mechanism for IVDD have not been fully revealed. Chondrogenic specific matrix components’ mRNA expression of nucleus pulposus cell (NPC) was determined by qPCR. Protein expression of NPC matrix components and protein kinase C was determined by Western blotting. A rat caudal intervertebral disc degeneration model was established and tested for calcitonin in vivo. IL‐1 induced NPC change via decreasing protein kinase C (PKC)‐ε phosphorylation, while increasing PKC‐δ phosphorylation. Calcitonin treatment could prevent or reverse IL‐1‐induced cellular change on PKC signalling associated with degeneration. The positive effect of calcitonin on IVDD in vivo was verified on a rat caudal model. In summary, this study, for the first time, elucidated the important role of calcitonin in the regulation of matrix components in the nucleus of the intervertebral disc. Calcitonin can delay degeneration of the intervertebral disc nucleus by activating the PKC‐ε pathway and inhibiting the PKC‐δ pathway.     

Cardiac specific expression of the green fluorescent protein during early murine embryonic development

We demonstrate the establishment of transgenic mice, where the expression of the green fluorescent protein (GFP) is under control of the human cardiac α-actin promoter. These mice display cardiac specific GFP expression already during early embryonic development. Prominent GFP fluorescence was observed at the earliest stage of the murine heart anlage (E8). Cardiomyocytes of different developmental stages proved GFP positive, but the intensity varied between cells. We further show that contractions of single GFP positive cardiomyocytes can be monitored within the intact embryo. At later stages of embryonic development, the skeletal musculature was also GFP positive, in line with the known expression pattern of cardiac α-actin. The tissue specific labeling of organs is a powerful new tool for embryological as well as functional investigations in vivo.     

Angiopoietin‐like protein 8 expression and association with extracellular matrix metabolism and inflammation during intervertebral disc degeneration

Intervertebral disc degeneration (IDD) is considered the primary culprit for low back pain. Although the underlying mechanisms remain unknown, hyperactive catabolism of the extracellular matrix (ECM) and inflammation are suggested to play critical roles in IDD progression. This study was designed to elucidate the role of angiopoietin‐like protein 8 (ANGPTL8) in the progression of IDD, especially the relationship of ANGPTL8 with ECM metabolism and inflammation. A positive association between ANGPTL8 expression and degenerative grades of IDD was detected in the analysis of human nucleus pulposus tissue samples. Silencing of ANGPTL8 attenuated the degradation of the anabolic protein type collagen II, and reduced the expression of the catabolic proteins MMP3 and MMP9, and the inflammatory cytokine IL‐6 through inhibition of NF‐κB signalling activation. In addition, the effect of ANGPTL8 was evaluated in a rat model of puncture‐induced IDD. Based on the imaging results and histological examination in animal study, knockdown of ANGPTL8 was demonstrated to ameliorate the IDD progression. These results demonstrate the detrimental role of ANGPTL8 expression in the pathogenesis of IDD and may provide a new therapeutic target for IDD treatment.