Calreticulin Promotes Proliferation and Migration But Inhibits Apoptosis in Schwann Cells

Downregulation of Calreticulin and Annexin A2 Expression in Acquired Middle Ear Cholesteatoma by 2-DE Analysis

BACKGROUND

Many factors are thought to be associated with the development of cholesteatoma, while the mechanisms of its formation remain unclear. This study aimed to identify the potential mechanisms of the proliferation and growth of cholesteatoma by analysis of the differential expressions of proteins in cholesteatoma and retroauricular skin tissue collected from the same patients.

METHODS

The present study is a retrospective study performed in an academic medical center. Comparative proteomics analyses using two-dimensional gel electrophoresis (2-DE) and liquid chromatography-tandem mass spectrometry (LC-MS/MS), in addition to immunohistochemical analysis, were conducted to identify differentially-expressed proteins in cholesteatoma tissue as compared with retroauricular skin tissue. Western blotting was also employed to verify the expression patterns of the specific proteins identified by 2-DE and to measure the changes in potential modulators related to cholesteatoma proliferation and growth.

RESULTS

Calreticulin (CRT) and annexin A2 (AnxA2) were identified as being differentially-expressed in cholesteatoma by 2-DE and LC-MS/MS, the results of which were in agreement with the results of immunohistochemical analysis and western blotting. Downregulation of CRT and AnxA2 were observed in cholesteatoma.

CONCLUSION

Our data suggests that CRT and AnxA2 downregulation are seen in cholesteatoma compared to retroauricular skin. We speculate that the reduced expression of CRT and the persistent inflammatory response play important roles in the epithelial proliferation of cholesteatoma.

Advances in Intracellular Calcium Signaling Reveal Untapped Targets for Cancer Therapy

Intracellular Ca2+ distribution is a tightly regulated process. Numerous Ca2+ chelating, storage, and transport mechanisms are required to maintain normal cellular physiology. Ca2+-binding proteins, mainly calmodulin and calbindins, sequester free intracellular Ca2+ ions and apportion or transport them to signaling hubs needing the cations. Ca2+ channels, ATP-driven pumps, and exchangers assist the binding proteins in transferring the ions to and from appropriate cellular compartments. Some, such as the endoplasmic reticulum, mitochondria, and lysosomes, act as Ca2+ repositories. Cellular Ca2+ homeostasis is inefficient without the active contribution of these organelles. Moreover, certain key cellular processes also rely on inter-organellar Ca2+ signaling. This review attempts to encapsulate the structure, function, and regulation of major intracellular Ca2+ buffers, sensors, channels, and signaling molecules before highlighting how cancer cells manipulate them to survive and thrive. The spotlight is then shifted to the slow pace of translating such research findings into anticancer therapeutics. We use the PubMed database to highlight current clinical studies that target intracellular Ca2+ signaling. Drug repurposing and improving the delivery of small molecule therapeutics are further discussed as promising strategies for speeding therapeutic development in this area.

Cox4i2 Triggers an Increase in Reactive Oxygen Species, Leading to Ferroptosis and Apoptosis in HHV7 Infected Schwann Cells

Emerging evidence suggests that reactive oxygen species (ROS) play a significant role in the pathogenesis of peripheral nerve damage. Our previous study indicated that human herpesvirus 7 (HHV7) induces Bell’s palsy. However, the specific mechanism underlying the effects of ROS in HHV7 infection-induced facial nerve damage is unknown. In this study, we established a rat FN model by inoculating an HHV7 virus solution. The facial grading score and LuxolFastBlue (LFB) staining were used to assess the success of the model. Using mRNA-sequencing analysis, we found that the expression of Complex IV Subunit 4 Isoform 2 (Cox4i2) increased in infected Schwann cells (SCs). Cox4i2 was suggested to increase COX activity, thereby promoting ROS production. The changes in the endogenous oxidant and antioxidant system were assessed, and the results showed that oxidative stress increased after HHV7 infection in vivo and in vitro. However, we found that oxidative injury was relieved after the transfection of shCox4i2 in HHV7-treated SCs by evaluating cell death, cell proliferation, and the ROS level as well as the levels of malondialdehyde (MDA), superoxide dismutase (SOD), and glutathione (GSH). Furthermore, we hypothesised that Cox4i2 loss would attenuate HHV7-induced ferroptosis and apoptosis, which are closely related to ROS in SCs. Our research illustrated that the knockdown of Cox4i2 suppresses HHV7-induced RSC96 cell ferroptosis as well as apoptosis via the ERK signalling pathway. Overall, several in vitro and in vivo methods were adopted in this study to reveal the new mechanism of ROS-induced and Cox4i2-mediated apoptosis and ferroptosis in HHV7 infected SCs.

Nogo-C Inhibits Peripheral Nerve Regeneration by Regulating Schwann Cell Apoptosis and Dedifferentiation

While Nogo protein demonstrably inhibits nerve regeneration in the central nervous system (CNS), its effect on Schwann cells in peripheral nerve repair and regeneration following sciatic nerve injury remains unknown. In this research, We assessed the post-injury expression of Nogo-C in an experimental mouse model of sciatic nerve-crush injury. Nogo-C knockout (Nogo-C^–/–) mouse was generated to observe the effect of Nogo-C on sciatic nerve regeneration, Schwann cell apoptosis, and myelin disintegration after nerve injury, and the effects of Nogo-C on apoptosis and dedifferentiation of Schwann cells were observed in vitro. We found that the expression of Nogo-C protein at the distal end of the injured sciatic nerve increased in wild type (WT) mice. Compared with the injured WT mice, the proportion of neuronal apoptosis was significantly diminished and the myelin clearance rate was significantly elevated in injured Nogo-C^–/– mice; the number of nerve fibers regenerated and the degree of myelination were significantly elevated in Nogo-C^–/– mice on Day 14 after injury. In addition, the recovery of motor function was significantly accelerated in the injured Nogo-C^–/– mice. The overexpression of Nogo-C in primary Schwann cells using adenovirus-mediated gene transfer promoted Schwann cells apoptosis. Nogo-C significantly reduced the ratio of c-Jun/krox-20 expression, indicating its inhibition of Schwann cell dedifferentiation. Above all, we hold the view that the expression of Nogo-C increases following peripheral nerve injury to promote Schwann cell apoptosis and inhibit Schwann cell dedifferentiation, thereby inhibiting peripheral nerve regeneration.

Mechanism of miR-148b inhibiting cell proliferation and migration of Schwann cells by regulating CALR

The aim of this study is to investigate the effect of miR-148b on cell proliferation and migration of Schwann cells and explore its mechanism. The miR-148b group, miR-con group and the anti-miR-148b group, anti-miR-con group, si-con group, si-CALR group, Ctrl group, CALR group were transfected into Schwann cells by liposome method; the expression of miR-148b was detected by qRT-PCR; the cell viability was detected by MTT assay; the migration of cells was detected by Transwell method; WB assay was used to detect the protein expression of CALR. Firstly, we found that compared with miR-con group and si-con group, the proliferation and migration of miR-148b group and si-CALR group were significantly down-regulated (P < .05). Moreover, compared with anti-miR-con group and Ctrl group, anti-miR-148b group and CALR group cells proliferation and migration were significantly up-regulated (P < .05). In addition, miR-148b was targeted to CALR, and silencing CALR could reverse the inhibitory effect of miR-148b on Schwann cell proliferation and migration. In conclusion, miR-148b can regulate the proliferation and migration of Schwann cells. The mechanism may be related to the targeted negative regulation of CALR, which will provide a basis for targeted therapy of peripheral nerve injury.

Transcriptional inhibition of TCDD-mediated induction of cytochrome P450 1A1 and alteration of protein expression in a zebrafish hepatic cell line following the administration of TCDD and Cd2

We studied the effects of Cd²⁺ on TCDD-mediated induction of the cytochrome P450 1A1 (cyp1a1) gene using a zebrafish liver cell line (ZFL). Our results showed that Cd²⁺ inhibited the TCDD-mediated induction of the cyp1a1 protein, enzyme activity, and mRNA expression level. Cd²⁺ also down-regulated levels of the aryl hydrocarbon receptor (ahr2) and the aryl hydrocarbon receptor nuclear translocator 2b (arnt2b) mRNAs. Compared with TCDD (3nM) treatment alone, co-treatment with Cd²⁺ (0-30μM) and TCDD (3nM) significantly inhibited the activity of the luciferase reporter gene constructs harboring the distal promoter region (P-2626/-2009) of CYP1A1 and the synthetic 3XRE gene promoter. This indicates that Cd²⁺ decreased the level of TCDD-induced cyp1a1 through transcriptional inhibition. Proteomic analysis was also used to evaluate the effect of Cd²⁺ on TCDD-altered protein expression in ZFL cells. The identified proteins are mainly enzymes of the glycolysis pathway and proteasomes, and have anti-oxidative and anti-stress effects.