Loss of reticulocalbin 2 lowers blood pressure and restrains ANG II-induced hypertension in vivo

Upregulation of RCN2 accelerates tumor progression and indicates poor prognosis in OSCC

OBJECTIVE

Oral squamous cell carcinoma (OSCC) is a prevalent cancer of the head and neck region. However, the potential role of RCN2 in OSCC is currently not well understood.

STUDY DESIGN

A series of molecular biology experiments were conducted to explore the mechanism by which RCN2 promotes OSCC growth through protein kinase A (PKA).

RESULTS

Our results revealed a significant increase in RCN2 levels in OSCC tissues. Moreover, OSCC patients with high RCN2 expression had a significantly worse prognosis than those with lower RCN2 expression. Interestingly, PKA activity was increased in RCN2-overexpressing YD-10B cells but reduced in RCN2-knockout Ca9-22 cells. These findings suggest that RCN2-mediated PKA activity is activated in OSCC cells. Moreover, the specific PKA inhibitor H89 significantly reduced the proliferation ability of RCN2-overexpressing Ca9-22 cells. Furthermore, we identified AKT/mTORC as a downstream pathway through which PKA promotes OSCC cell proliferation. The Tumor Immune Estimation Resource database revealed that the expression level of RCN2 was correlated with the infiltration levels of B cells, CD8+ T cells, CD4+ T cells, and neutrophils in the microenvironment of OSCC.

CONCLUSIONS

Our study revealed that RCN2 promotes tumor progression by activating PKA/AKT/mTORC signaling, which suggests that RCN2 may serve as a potential target for OSCC treatment.

The identification of key genes and pathways in polycystic ovary syndrome by bioinformatics analysis of next-generation sequencing data

Background

Polycystic ovary syndrome (PCOS) is a reproductive endocrine disorder. The specific molecular mechanism of PCOS remains unclear. The aim of this study was to apply a bioinformatics approach to reveal related pathways or genes involved in the development of PCOS.

Methods

The next-generation sequencing (NGS) dataset GSE199225 was downloaded from the gene expression omnibus (GEO) database and NGS dataset analyzed is obtained from in vitro culture of PCOS patients’ muscle cells and muscle cells of healthy lean control women. Differentially expressed gene (DEG) analysis was performed using DESeq2. The g:Profiler was utilized to analyze the gene ontology (GO) and REACTOME pathways of the differentially expressed genes. A protein–protein interaction (PPI) network was constructed and module analysis was performed using HiPPIE and cytoscape. The miRNA-hub gene regulatory network and TF-hub gene regulatory network were constructed. The hub genes were validated by using receiver operating characteristic (ROC) curve analysis.

Results

We have identified 957 DEG in total, including 478 upregulated genes and 479 downregulated gene. GO terms and REACTOME pathways illustrated that DEG were significantly enriched in regulation of molecular function, developmental process, interferon signaling and platelet activation, signaling, and aggregation. The top 5 upregulated hub genes including HSPA5, PLK1, RIN3, DBN1, and CCDC85B and top 5 downregulated hub genes including DISC1, AR, MTUS2, LYN, and TCF4 might be associated with PCOS. The hub gens of HSPA5 and KMT2A, together with corresponding predicted miRNAs (e.g., hsa-mir-34b-5p and hsa-mir-378a-5p), and HSPA5 and TCF4 together with corresponding predicted TF (e.g., RCOR3 and TEAD4) were found to be significantly correlated with PCOS.

Conclusions

These study uses of bioinformatics analysis of NGS data to obtain hub genes and key signaling pathways related to PCOS and its associated complications. Also provides novel ideas for finding biomarkers and treatment methods for PCOS and its associated complications.

Excessive mechanical loading promotes osteoarthritis development by upregulating Rcn2

Exposure of articular cartilage to excessive mechanical loading is closely related to the pathogenesis of osteoarthritis (OA). However, the exact molecular mechanism by which excessive mechanical loading drives OA remains unclear. In vitro, primary chondrocytes were exposed to cyclic tensile strain at 0.5 Hz and 10 % elongation for 30 min to simulate excessive mechanical loading in OA. In vivo experiments involved mice undergoing anterior cruciate ligament transection (ACLT) to model OA, followed by interventions on Rcn2 expression through adeno-associated virus (AAV) injection and tamoxifen-induced gene deletion. 10 μL AAV2/5 containing AAV-Rcn2 or AAV-shRcn2 was administered to the mice by articular injection at 1 week post ACLT surgery, and Col2a1-creERT: Rcn2flox/flox mice were injected with tamoxifen intraperitoneally to obtain Rcn2-conditional knockout mice. Finally, we explored the mechanism of Rcn2 affecting OA. Here, we identified reticulocalbin-2 (Rcn2) as a mechanosensitive factor in chondrocytes, which was significantly elevated in chondrocytes under mechanical overloading. PIEZO type mechanosensitive ion channel component 1 (Piezo1) is a critical mechanosensitive ion channel, which mediates the effect of mechanical loading on chondrocytes, and we found that increased Rcn2 could be suppressed through knocking down Piezo1 under excessive mechanical loading. Furthermore, chondrocyte-specific deletion of Rcn2 in adult mice alleviated OA progression in the mice receiving the surgery of ACLT. On the contrary, articular injection of Rcn2-expressing adeno-associated virus (AAV) accelerated the progression of ACLT-induced OA in mice. Mechanistically, Rcn2 accelerated the progression of OA through promoting the phosphorylation and nuclear translocation of signal transducer and activator of transcription 3 (Stat3).

Identification of Endoplasmic Reticulum Stress-Related Biomarkers in Coronary Artery Disease

Coronary artery disease (CAD) is caused by atherosclerotic lesions in the coronary vessels. Endoplasmic reticulum stress (ERS) acts in cardiovascular disease, and its role in CAD is not clear. A total of 13 differentially expressed ERS-related genes (DEERSRGs) in CAD were identified. Functional enrichment analysis demonstrated the DEERSRGs were mainly enriched in endoplasmic reticulum (ER)-related pathways. Then, eight genes (RCN2, HRC, DERL2, RNF183, CRH, TMED2, PPP1R15A, and IL1A) were authenticated as ERS-related biomarkers in CAD by least absolute shrinkage and selection operator (LASSO). The receiver operating characteristic (ROC) analysis showed that the LASSO logistic model constructed based on biomarkers had a better diagnostic effect, which was confirmed by the ANN and GSE23561 datasets. Also, ROC results showed that seven of the eight biomarkers had better diagnostic effects. The nomogram model had good predictive power, and biomarkers were mostly enriched in pathways associated with CAD. The biomarkers were significantly associated with 10 immune cells, and RCN2, DERL2, TMED2, and RNF183 were negatively correlated with most chemokines. Eight biomarkers had significant correlations with both immunoinhibitors and immunostimulators. In addition, eight biomarkers were significantly different in both CAD and control samples, CRH and HRC were upregulated in CAD. The quantitative reverse transcription-polymerase chain reaction (qRT-PCR) showed that RCN2, HRC, DERL2, CRH, and IL1A were consistent with the bioinformatics analysis. RCN2, HRC, DERL2, RNF183, CRH, TMED2, PPP1R15A, and IL1A were identified as biomarkers of CAD. Functional enrichment analysis and immunoassays for biomarkers provide new ideas for the treatment of CAD.

Gene and Protein Accumulation Changes Evoked in Porcine Aorta in Response to Feeding with Two Various Fructan Sources

In this study, two different ITFs sources were incorporated into a cereal-based diet to evaluate possible aortic protein and gene changes in nursery pigs. The animals were fed two different experimental diets from the 10th day of life, supplemented with either 4% of dried chicory root (CR) or with 2% of native inulin (IN). After a 40-day dietary intervention trial, pigs were sacrificed at day 50 and the aortas were harvested. Our data indicate that dietary ITFs have the potential to influence several structural and physiological changes that are reflected both in the mRNA and protein levels in porcine aorta. In contrast to our hypothesis, we could not show any beneficial effects of a CR diet on vascular functions. The direction of changes of several proteins and genes may indicate disrupted ECM turnover (COL6A1 and COL6A2, MMP2, TIMP3, EFEMP1), increased inflammation and lipid accumulation (FFAR2), as well as decreased activity of endothelial nitric oxide synthase (TXNDC5, ORM1). On the other hand, the IN diet may counteract a highly pro-oxidant environment through the endothelin-NO axis (CALR, TCP1, HSP8, PDIA3, RCN2), fibrinolytic activity (ANXA2), anti-atherogenic (CAVIN-1) and anti-calcification (LMNA) properties, thus contributing to the maintenance of vascular homeostasis.

Reticulocalbin 2 as a Potential Biomarker and Therapeutic Target for Atherosclerosis

Vascular inflammation initiated by oxidized lipoproteins drives initiation, progression, and even rupture of atherosclerotic plaques. Yet, to date, no biomarker is directly linked to oxidized lipid-induced vascular inflammation. Reticulocalbin 2 (RCN2) is a key regulator of basal and oxidized lipid-induced cytokine production in arterial wall cells. We evaluated the potential of circulating RCN2 to identify subjects with or at risk of developing atherosclerosis. Immunohistochemical analysis revealed abundant RCN2 expression in the endothelium and adventitia of normal arteries and in atherosclerotic lesions of both humans and mice. Atherosclerosis-susceptible C57BL/6 (B6) mice had higher plasma Rcn2 levels than resistant C3H mice. High-fat diet feeding raised plasma Rcn2 levels of both strains. In humans, patients with coronary artery disease (CAD) or peripheral artery disease (PAD) showed elevated serum RCN2 levels compared to healthy controls. In a cohort of 92 CAD patients, serum RCN2 exhibited a significant inverse correlation with HDL cholesterol and K+ levels and a trend toward association with white blood cell account, Na+, statin treatment, and diastolic blood pressure. HDL treatment suppressed Rcn2 expression in endothelial cells. This study suggests that circulating RCN2 is a potential non-invasive biomarker for identifying individuals with atherosclerosis and HDL protects against atherosclerosis by downregulation of RCN2 expression in endothelial cells.

The Programmed Cell Death of Macrophages, Endothelial Cells, and Tubular Epithelial Cells in Sepsis-AKI

Sepsis is a systemic inflammatory response syndrome caused by infection, following with acute injury to multiple organs. Sepsis-induced acute kidney injury (AKI) is currently recognized as one of the most severe complications related to sepsis. The pathophysiology of sepsis-AKI involves multiple cell types, including macrophages, vascular endothelial cells (ECs) and renal tubular epithelial cells (TECs), etc. More significantly, programmed cell death including apoptosis, necroptosis and pyroptosis could be triggered by sepsis in these types of cells, which enhances AKI progress. Moreover, the cross-talk and connections between these cells and cell death are critical for better understanding the pathophysiological basis of sepsis-AKI. Mitochondria dysfunction and oxidative stress are traditionally considered as the leading triggers of programmed cell death. Recent findings also highlight that autophagy, mitochondria quality control and epigenetic modification, which interact with programmed cell death, participate in the damage process in sepsis-AKI. The insightful understanding of the programmed cell death in sepsis-AKI could facilitate the development of effective treatment, as well as preventive methods.

Lipopolysaccharide induces vascular endothelial cell pyroptosis via the SP1/RCN2/ROS signaling pathway

Endothelial cell pyroptosis is a novel cause of endothelial dysfunction in sepsis. Reticulocalbin-2 (RCN2) is involved in regulating vascular inflammation and plays an important role in the cardiovascular system. However, the role of RCN2 in inflammation-induced endothelial cell pyroptosis remains to be explored. Here, we found that RCN2 was upregulated after lipopolysaccharide (LPS) treatment in a concentration- and time-dependent manner. RCN2 knockdown resulted in a significant decrease in pyroptosis, reduced LDH and IL-1β release and ROS production and inhibited the expression of pyroptosis-related proteins (NLRP3, cleaved caspase-1, and cleaved GSDMD) (all p < 0.05). N-acetyl-L-cysteine (NAC) counteracted the effects of RCN2 on pyroptosis (all p < 0.01). The silencing of RCN2 antagonized the inhibitory effect of LPS on the phosphorylation of eNOS (p < 0.05). We predicted and confirmed that specificity protein-1(SP1) could directly bind to the RCN2 promoter and regulate RCN2. RCN2 overexpression rescued the inhibitory effect of SP1 inhibitor on HUVEC pyroptosis induced by LPS (all p < 0.05). These findings suggested that the activation of the SP1/RCN2/ROS signaling pathway could promote LPS-induced endothelial cell pyroptosis.

Osteogenic differentiation and calcification of human aortic smooth muscle cells is induced by the RCN2/STAT3/miR-155-5p feedback loop

BACKGROUND

Vascular calcification (VC) is associated with the high morbidity and mortality of cardiovascular diseases in dialysis patients and is a process in which vascular smooth muscle cells (VSMCs) actively differentiate into osteoblast-like cells. Reticulocalbin-2 (RCN2) is involved in the process of osteogenic differentiation under diabetic conditions, but its regulatory role under hyperphosphatemic conditions and the related mechanisms remain unclear. In this study, the importance of the interactions among RCN2, STAT3 and miR-155-5p during the osteogenic differentiation and calcification of human aortic VSMCs (HASMCs) were investigated.

METHODS

RCN2 was measured in femoropopliteal artery plaque specimens from 6 peripheral arterial disease (PAD) patients with chronic kidney disease (CKD) and 6 PAD patients without CKD. RCN2 protein and mRNA expression were assessed in the high phosphate-induced aortic rings culture ex vivo model. In vitro calcification assays and molecular mechanism studies were performed in HASMCs.

RESULTS

Immunohistochemical staining results revealed increased RCN2 expression in the calcified plaques of femoral arteries of patients with CKD and in a high phosphate-induced aortic culture ex vivo model. RCN2 promoted HASMCs osteogenic differentiation and calcification by inducing STAT3 phosphorylation. Furthermore, inhibition of STAT3 activation by cryptotanshinone (CT) promoted miR-155-5p expression in HASMCs. In turn, miR-155-5p inhibited RCN2 mRNA expression, while RCN2 overexpression partially offset the miR-155-5p-mediated inhibition of HASMC calcification, acting as a positive feedback loop.

CONCLUSION

These results demonstrate that RCN2 is a crucial regulator of VC under hyperphosphatemic conditions. RCN2/STAT3/miR-155-5p feedback loop is important in VC and targeting each member of this feedback loop could potentially reverse high phosphate-induced VC.