Identifying the protective effects of miR-874-3p/ATF3 axis in intervertebral disc degeneration by single-cell RNA sequencing and validation.

Intervertebral disc degeneration (IVDD) severely affects the work and the quality of life of people. We previously demonstrated that silencing activation transcription factor 3 (ATF3) blocked the IVDD pathological process by regulating nucleus pulposus cell (NPC) ferroptosis, apoptosis, inflammation, and extracellular matrix (ECM) metabolism. Nevertheless, whether miR-874-3p mediated the IVDD pathological process by targeting ATF3 remains unclear. We performed single-cell RNA sequencing (scRNA-seq) and bioinformatics analysis to identify ATF3 as a key ferroptosis gene in IVDD. Then, Western blotting, flow cytometry, ELISA, and animal experiments were performed to validate the roles and regulatory mechanisms of miR-874-3p/ATF3 signalling axis in IVDD. ATF3 was highly expressed in IVDD patients and multiple cell types of IVDD rat, as revealed by scRNA-seq and bioinformatics analysis. GO analysis unveiled the involvement of ATF3 in regulating cell apoptosis and ECM metabolism. Furthermore, we verified that miR-874-3p might protect against IVDD by inhibiting NPC ferroptosis, apoptosis, ECM degradation, and inflammatory response by targeting ATF3. In vivo experiments displayed the protective effect of miR-874-3p/ATF3 axis on IVDD. These findings propose the potential of miR-874-3p and ATF3 as biomarkers of IVDD and suggest that targeting the miR-874-3p/ATF3 axis may be a therapeutic target for IVDD.

Silencing ATF3 Might Delay TBHP-Induced Intervertebral Disc Degeneration by Repressing NPC Ferroptosis, Apoptosis, and ECM Degradation.

Intervertebral disc degeneration (IDD), being the predominant root cause of lower back pain, has led to an enormous socioeconomic burden in the world. Ferroptosis is an iron-dependent nonapoptotic and nonpyroptotic programmed cell death associated with an increase in reactive oxygen species (ROS), which has been implicated in the pathogenesis of IDD. Activation transcription factor 3 (ATF3) is widely reported to promote ferroptosis and apoptosis in multiple diseases, but its roles and underlying regulatory mechanism in IDD have not been identified. FAoptosis is defined as a mixed cell death consisting of ferroptosis and apoptosis. The loss- and gain-of-function experiments demonstrated that ATF3 positively regulated tert-butyl hydroperoxide- (TBHP-) induced nucleus pulposus cell (NPC) FAoptosis, ROS production, inflammatory response, and extracellular matrix (ECM) degradation. Furthermore, silencing ATF3 ameliorated the progression of IDD in vivo, whereas its overexpression showed the opposite phenotype. Bioinformatics analysis and molecular experiments corroborated that ATF3 is a direct target of miR-874-3p, suggesting that the upregulation of ATF3 in IDD might be caused at least in part due to the downregulation of miR-874-3p in IDD, thereby relieving the inhibition of ATF3 by miR-874-3p. The findings revealed that ATF3 has the potential to be used as a promising therapeutic target against IDD.

Circ_0004354 might compete with circ_0040039 to induce NPCs death and inflammatory response by targeting miR-345-3p-FAF1/TP73 axis in intervertebral disc degeneration.

The abnormal function of nucleus pulposus cells (NPCs) plays a crucial role in the pathogenesis of intervertebral disc degeneration (IVDD). Recent studies have demonstrated that circular RNAs (circRNAs) are involved in the pathological process of IVDD by regulating NPCs' function. Nevertheless, the investigation on circRNA-circRNA interaction has not yet been reported. Here, we identified the top upregulated circ_0040039 and circ_0004354 in IVDD, derived from the syntrophin beta 2 gene but had different degrees of biological functions. Accumulating studies have reported PANoptosis is composed of apoptosis, pyroptosis, and necroptosis. Based on this, we think there should be a new pro-inflammatory cell death PAoptosis in the form of apoptosis and pyroptosis. Circ_0004354 might compete with circ_0040039 to induce the development of IVDD by modulating miR-345-3p-FAF1/TP73 axis-mediated PAoptosis, inflammatory response, growth inhibition, and ECM degradation of NPCs. Thus, these findings offer a novel insight into the circRNAs-mediated posttranscriptional regulatory network in IVDD, contributing to further clarification of the pathological mechanism of IVDD to develop a promising therapeutic target for IVDD diseases.

Circ_0040039 May Aggravate Intervertebral Disk Degeneration by Regulating the MiR-874-3p-ESR1 Pathway.

The functional alteration of nucleus pulposus cells (NPCs) exerts a crucial role in the occurrence and progression of intervertebral disk degeneration (IDD). Circular RNAs and microRNAs (miRs) are critical regulators of NPC metabolic processes such as growth and apoptosis. In this study, bioinformatics tools, encompassing Gene Ontology pathway and Venn diagrams analysis, and protein-protein interaction (PPI) network construction were used to identify functional molecules related to IDD. PPI network unveiled that ESR1 was one of the most critical genes in IDD. Then, a key IDD-related circ_0040039-miR-874-3p-ESR1 interaction network was predicted and constructed. Circ_0040039 promoted miR-874-3p and repressed ESR1 expression, and miR-874-3p repressed ESR1 expression in NPCs, suggesting ESR1 might be a direct target of miR-874-3p. Functionally, circ_0040039 could enhance NPC apoptosis and inhibit NPC growth, revealing that circ_0040039 might aggravate IDD by stabilizing miR-874-3p and further upregulating the miR-874-3p-ESR1 pathway. This signaling pathway might provide a novel therapeutic strategy and targets for the diagnosis and therapy of IDD-related diseases.

Emerging role of circular RNA in intervertebral disc degeneration: Knowns and unknowns (Review).

Lower back pain (LBP) is one of the predominant factors contributing to dyskinesia and remains a serious social and economic burden worldwide. Intervertebral disc degeneration (IDD) is the leading cause of LBP; the existing IDD treatments cannot completely prevent IDD. Circular RNAs (circRNAs) are non­coding RNAs resulting from back­splicing with unique structural characteristics and functions. Accumulating evidence suggests that circRNAs are involved in the pathological process of IDD and modulate a range of IDD­related genes or proteins. However, the underlying circRNA­mediated regulatory mechanisms remain poorly understood. The aim of the present review is to describe the current understanding of circRNA characteristics, classification, biogenesis and function in relation to its specific roles in IDD. Additionally, the limitations on the current knowledge in the field and the future direction of IDD­related research are also discussed.

Epidemiology of traumatic spinal fractures: experience from medical university-affiliated hospitals in Chongqing, China, 2001-2010.

OBJECT: The main objective of this study was to analyze the epidemiological data obtained from patients with traumatic spinal fracture at 2 university-affiliated hospitals in Chongqing, China. METHODS: The authors retrospectively reviewed the hospital records of all patients who suffered traumatic spinal fracture and were treated at Xinqiao Hospital and Southwest Hospital (both affiliated with The Third Military Medical University) between January 2001 and December 2010. The demographic characteristics, injury characteristics, and clinical outcomes of patients over this 10-year period were compared. RESULTS: A total of 3142 patients (mean age 45.7 years, range 1-92 years) with traumatic spinal fractures were identified; 65.5% of the patients were male. The peak frequency of these injuries occurred in the 31- to 40-year-old age group. Accidental falls and traffic accidents were the most common causes of spinal fractures (58.9% and 20.9%, respectively). Traffic accidents tended to occur in younger patients, whereas accidental falls tended to occur in older patients. The most common area of fracture was the thoracolumbar spine (54.9%). Cervical spinal fractures were significantly more common in patients injured in traffic accidents, while lumbar spinal fractures were more common in accidental fall patients. Using the American Spinal Injury Association (ASIA) classification, 479 (15.3%) patients were classified as having ASIA A injuries; 913 (29.1%), ASIA B, ASIA C, or ASIA D; and 1750 (55.7%), ASIA E. ASIA A injuries were more common in patients who suffered thoracic spinal fractures (15.09%) than in those with fractures in other areas of the spine. A total of 954 (30.4%) patients had associated nonspinal injuries. Of these patients, 389 (40.78%) suffered a thoracic injury, and 191 (20.02%) sustained a head and neck injury. The length of hospitalization differed significantly between the accidental falls from high heights and falls from low heights, as did the mean cost of hospitalization (p < 0.05), but no significant difference was found between accidental falls from high heights and traffic accidents (p > 0.05). The length of hospitalization differed significantly among the 3 groups according to the ASIA classification, as did the mean cost of hospitalization (p < 0.05). Of patients with incomplete lesions, 39.3% improved 1 or more grades in ASIA classification during hospitalization. CONCLUSIONS: Accidental falls emerged as the leading cause of traumatic spinal fracture in this study, and the numbers of fall-induced and sports-related injuries increased steadily with age. These results indicate that there should be increased concern for the consequences of fall- and sports-related injuries among the elderly.