Cryptotanshinone inhibits RANKL-induced osteoclastogenesis by regulating ERK and NF-κB signaling pathways.

Osteoporosis (OS) is one of the most common healthy problems characterized by low bone mass. Osteoclast, the primary bone-resorbing cell, is responsible for destructive bone diseases including osteoporosis (OS). Cryptotanshinone (CTS), an active component extracted from the root of Salvia miltiorrhiza bunge, has been shown to prevent the destruction of cartilage and the thickening of subchondral bone in mice osteoarthritis models. However, its molecular mechanism in osteoclastogenesis needs to be determined. The aim of the current study was to explore the effect of CTS on osteoclastogenesis and further evaluate the underlying mechanism. Our results showed that CTS inhibited receptor activator of NF-κB ligand (RANKL)-induced the increase in tartrate-resistant acid phosphatase (TRAP) activity in bone marrow-derived macrophages (BMMs). In addition, the expressions of osteoclastogenesis-related marker proteins and nuclear factor of activated T-cells (NFAT) activation were suppressed by CTS treatment in BMMs. Furthermore, CTS attenuated RANKL-induced ERK phosphorylation and NF-κB activation in BMMs. These findings indicated that CTS inhibited RANKL-induced osteoclastogenesis by inhibiting ERK phosphorylation and NF-κB activation in BMMs. Thus, CTS may function as an inhibitor of osteoclastogenesis and may be considered as an alternative medicine for the prevention and treatment of OS.

Down-regulation of miR-193a-3p promotes osteoblast differentiation through up-regulation of LGR4/ATF4 signaling.

Emerging evidence indicates that microRNAs (miRNAs) are crucial regulators of osteoblast differentiation. A previous study has reported that miR-193a-3p expression is altered during the induction of osteoblast differentiation. However, the precise biological function and regulatory mechanism of miR-193a-3p during osteoblast differentiation remains unclear. In this study, we aimed to investigate the precise role and underlying mechanism of miR-193a-3p in regulating osteoblast differentiation. The results showed that miR-193a-3p expression was significantly down-regulated during the induction of osteoblast differentiation. Functional experiments demonstrated that the overexpression of miR-193a-3p impeded osteoblast differentiation while miR-193a-3p inhibition promoted osteoblast differentiation. Bioinformatics analysis and a luciferase assay revealed that leucine-rich repeat-containing G-protein coupled receptor 4 (LGR4), a critical regulator of osteoblast differentiation, was a target gene of miR-193a-3p. We showed that miR-193a-3p negatively regulated the expression of LGR4 and activating transcription factor 4 (ATF4). Moreover, the knockdown of LGR4 or ATF4 significantly reversed the promotion effect of miR-193a-3p inhibition on osteoblast differentiation. Overall, these findings demonstrate that miR-193a-3p regulates osteoblast differentiation by modulating LGR4/ATF4 signaling and suggests that the miR-193a-3p/LGR4/ATF4 regulation axis may play an important role in regulating bone remodeling.

Lactotransferrin promotes intervertebral disc degeneration by regulating Fas and inhibiting human nucleus pulposus cell apoptosis.

BACKGROUND: In recent years, intervertebral disc (IVD) degeneration (IDD) has increased in age. There is still a lack of effective treatment in clinics, which cannot improve the condition of IDD at the level of etiology. OBJECTIVE: To explore IDD pathogenesis at the cellular and gene levels and investigate lactotransferrin (LTF) expression in IDD patients and its possible mechanism. METHODS: We downloaded the IDD data set from the Gene Expression Omnibus (GEO) database, screened the differentially expressed genes (DEGs) and hub genes and performed Kyoto Encyclopedia of Genes and Genomes (KEGG) analysis to construct a protein-protein interaction (PPI) network. Subsequently, we verified LTF's regulatory mechanism through cell experiments. IL-1ß was used to intervene in nucleus pulposus cells (NPCs) to construct the IDD cell model, and LTF and Fas expression was detected by qRT-PCR. LTF inhibitor, Fas inhibitor, LTF mimic, and Fas mimic were used to intervene in each group. Western blotting was used to detect Fas, Caspase-3, Bax, and Bcl-2 expression. RESULTS: A total of 131 DEGs and 10 hub genes were screened. LTF mRNA in the IDD model was significantly higher than that in the control group, while Fas' mRNA was significantly lower. When LTF was upregulated or downregulated in NPCs, apoptosis marker expression showed the opposite trend. The rescue test showed that LTF and Fas' overexpression greatly enhanced NPC apoptosis. CONCLUSION: LTF promotes IDD progression by regulating Fas in NPCs, and it may be an effective gene therapy target.