CaSR and calpain contribute to the ischemia reperfusion injury of spinal cord

Calcium-Sensing Receptor (CaSR)-Mediated Intracellular Communication in Cardiovascular Diseases

The calcium-sensing receptor (CaSR), a G-protein-coupled receptor (GPCR), is a cell-surface-located receptor that can induce highly diffusible messengers (IP3, Ca²⁺, cAMP) in the cytoplasm to activate various cellular responses. Recently, it has also been suggested that the CaSR mediates the intracellular communications between the endoplasmic reticulum (ER), mitochondria, nucleus, protease/proteasome, and autophagy-lysosome, which are involved in related cardiovascular diseases. The complex intracellular signaling of this receptor challenges it as a valuable therapeutic target. It is, therefore, necessary to understand the mechanisms behind the signaling characteristics of this receptor in intracellular communication. This review provides an overview of the recent research progress on the various regulatory mechanisms of the CaSR in related cardiovascular diseases and the heart-kidney interaction; the associated common causes are also discussed.

Identification of Regeneration and Hub Genes and Pathways at Different Time Points after Spinal Cord Injury

Spinal cord injury (SCI) is a neurological injury that can cause neuronal loss around the lesion site and leads to locomotive and sensory deficits. However, the underlying molecular mechanisms remain unclear. This study aimed to verify differential gene time-course expression in SCI and provide new insights for gene-level studies. We downloaded two rat expression profiles (GSE464 and GSE45006) from the Gene Expression Omnibus database, including 1 day, 3 days, 7 days, and 14 days post-SCI, along with thoracic spinal cord data for analysis. At each time point, gene integration was performed using "batch normalization." The raw data were standardized, and differentially expressed genes at the different time points versus the control were analyzed by Gene Ontology enrichment analysis, the Kyoto Encyclopedia of Genes and Genomes pathway analysis, and gene set enrichment analysis. A protein-protein interaction network was then built and visualized. In addition, ten hub genes were identified at each time point. Among them, Gnb5, Gng8, Agt, Gnai1, and Psap lack correlation studies in SCI and deserve further investigation. Finally, we screened and analyzed genes for tissue repair, reconstruction, and regeneration and found that Anxa1, Snap25, and Spp1 were closely related to repair and regeneration after SCI. In conclusion, hub genes, signaling pathways, and regeneration genes involved in secondary SCI were identified in our study. These results may be useful for understanding SCI-related biological processes and the development of targeted intervention strategies.

Proanthocyanidin promotes functional recovery of spinal cord injury via inhibiting ferroptosis

Improving the microenvironment of lesioned spinal cord to minimize the secondary injury is one important strategy to treat spinal cord injury (SCI). The ensuing hemorrhage after SCI has tight connection with ferroptosis. This study investigated the effects of proanthocyanidins (PACs) on SCI repair and the underlying mechanisms. Adult female mice were divided into four groups, including sham, SCI, PACs5 and PACs10 (i.p. 5 and 10 mg/kg PACs after SCI respectively). The impacts of SCI and PACs treatment on redox parameters (iron contents, TBARS, GSH, and GPX activities) and ferroptosis essential factors such as ACSL4, LPCAT3, Alox15B, Nrf2, HO-1, GPX4 were investigated. The results demonstrated that PACs treatment significantly decreased the levels of iron, TBARS, ACSL4, and Alox15B, while increased the levels of GSH, GPX4, Nrf2, and HO-1 in traumatic spinal cords. Above all, PACs improved the locomotive function of SCI mice. These results suggest that PACs might be potential therapeutics for SCI repair by inhibiting ferroptosis in SCI.

Angiopoietin-1 Protects Spinal Cord Ischemia and Reperfusion Injury by Inhibiting Autophagy in Rats

Spinal cord ischemia and reperfusion (SCIR) injury can induce autophagy, which is involved in the survival of neurons. However, whether autophagy plays a neuroprotective or a detrimental role in SCIR injury remains controversial. Angiopoietin-1 (Ang-1), an endothelial growth factor, has been shown to have neuroprotective effects. The present study aimed to explore the neuroprotective mechanisms of Ang-1 in neuronal cells in a rat model of SCIR injury in vivo. Ang-1 protein and rapamycin were injected intrathecally. Basso Beattie Bresnahan (BBB) scoring and hematoxylin and eosin staining were used to assess the degree of SCIR injury. Proteins that reflected the level of autophagy expression, such as Beclin-1 and LC3, were evaluated by western blotting. The results indicated that SCIR injury resulted in loss in lower limb motor function. Ang-1 protein inhibited the expression of Beclin-1 and LC3, which improved the BBB score and alleviated spinal cord injury. In contrast, rapamycin, an autophagy activator, caused the opposite effect. This study provides evidence that Ang-1 plays a neuroprotective role by inhibiting of autophagy expression in SCIR injury. Overall, findings could be useful for the treatment of SCIR injury.

Dexmedetomidine attenuates neuronal injury after spinal cord ischaemia-reperfusion injury by targeting the CNPY2-endoplasmic reticulum stress signalling

Dexmedetomidine (Dex) has been proven to exert protective effects on multiple organs in response to ischaemia-reperfusion injury, but the specific mechanism by which this occurs has not been fully elucidated. The purpose of this study was to investigate whether Dex attenuates spinal cord ischaemia-reperfusion injury (SCIRI) by inhibiting endoplasmic reticulum stress (ERS). Our team established a model of SCIRI and utilized the endoplasmic reticulum agonist thapsigargin. Dex (25 g/kg) was intraperitoneally injected 30 minutes before spinal cord ischaemia. After 45 minutes of ischaemia, the spinal cord was reperfused for 24 hours. To evaluate the neuroprotective effect of Dex on SCIRI, neurological function scores were assessed in rats and apoptosis of spinal cord cells was determined by TUNEL staining. To determine whether the endoplasmic reticulum apoptosis pathway CNPY2-PERK was involved in the neuroprotective mechanism of Dex, the expression levels of related proteins (CNPY2, GRP78, PERK, CHOP, caspase-12, caspase-9 and caspase-3) were detected by western blot analysis and RT-PCR. We observed that Dex significantly increased the neurological function scores after SCIRI and decreased apoptosis of spinal cord cells. The expression of ERS-related apoptosis proteins was significantly increased by SCIRI but was significantly decreased in response to Dex administration. Taken together, the results of this study indicate that Dex may attenuate SCIRI by inhibiting the CNPY2-ERS apoptotic pathway.

Local application of MDL28170-loaded PCL film improves functional recovery by preserving survival of motor neurons after traumatic spinal cord injury

Neuronal death and organization degeneration can happen inordinately after spinal cord injury (SCI), which lead to nerve dysfunction. We aimed to determine whether local application of a cell permeable calpain I inhibitor (MDL28170) can promote SCI recovery by increasing neuronal cell viability. MDL28170-loaded polycaprolactone (PCL) film was fabricated. Scanning electron microscopy showed the surface of PCL film was smooth with holes (diameter at μM level). The PCL film was non-toxic, biological compatibility, and had good neuron adhension and slow release characteristic. MDL28170 increased VSC4.1 motor neurons' viability under tunicamycin (an endoplasmic reticulum stress) induced injury. In a traumatic SCI rat model, MDL28170-loaded PCL film reduced the area of lesion cavity, and promoted recovery of locomotor behavior. Moreover, the expression of GAP-43 was upregulated after MDL28170-loaded PCL film treatment. Thus, our findings demonstrated that localized delivery of MDL28170 could promote SCI recovery by inhibiting endoplasmic reticulum stress, preserving survival of the motor neurons, which may point out a promising therapeutic target for treating SCI patient.

Impacts of Bone Marrow Stem Cells on Caspase-3 Levels after Spinal Cord Injury in Mice

Spinal cord injury (SCI) is a drastic disability that leads to spinal cord impairment. This study sought to determine the effects of bone marrow stem cells (BMSCs) on caspase-3 levels after acute SCI in mice. Forty-two mice were randomly divided into 3 groups: control (2 subcategories), subjected to no intervention; sham (3 subcategories), subjected to acute SCI; and experimental (2 subcategories), subjected to SCI and cell transplantation. In the experimental group, 2×10⁵ BMSCs were injected intravenously 1 day after SCI. The mesenchymal property of the cells was assessed. The animals in the 3 groups were sacrificed 1, 21, and 35 days after the induction of injury and caspase-3 levels were evaluated using a caspase-3 assay kit. The obtained values were analyzed with ANOVA and Tukey tests using GraphPad and SPSS. Based on the assessments, the transplanted cells were spindle-shaped and were negative for the hematopoietic markers of CD34 and CD45 and positive for the expression of the mesenchymal marker of CD90 and osteogenic induction. The caspase-3 levels showed a significant increase in the sham and experimental groups in comparison to the control group. One day after SCI, the caspase-3 level was significantly higher in the sham group (1.157±0.117) than in the other groups (P<0.000). Twenty-one days after SCI, the caspase-3 level was significantly lower in the experimental group than in the sham group (0.4±0.095 vs. 0.793±0.076; P˂0.000). Thirty-five days following SCI, the caspase-3 level was lower in the experimental group than in the sham group (0.223±0.027 vs. 0.643±0.058; P˂0.000). We conclude that BMSC transplantation was able to downregulate the caspase-3 level after acute SCI, underscoring the role of caspase-3 as a marker for the assessment of treatment efficacy in acute SCI.