Production of Nurr-1 Specific Polyclonal Antibodies Free of Cross-reactivity Against Its Close Homologs, Nor1 and Nur77

Identification of Oxidative Stress-Related Biomarkers in Diabetic Kidney Disease

Background

Diabetic kidney disease (DKD) is a leading cause of end-stage renal disease throughout the world. In kidney disease, oxidative stress has been linked to both antioxidant depletions and increased reactive oxygen species (ROS) production. Thus, the objective of this study was to identify biomarkers related to oxidative stress in DKD.

Methods

The gene expression profile of the DKD was extracted from the Gene Expression Omnibus (GEO) database. The identification of the differentially expressed genes (DEGs) was performed using the "limma" R package, and weighted gene coexpression network analysis (WGCNA) was used to find the gene modules that were most related to DKD. Gene ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway enrichment analysis was performed using "Org.Hs.eg.db" R package. The protein-protein interaction (PPI) network was constructed using the STRING database. The hub genes were identified by the Molecular Complex Detection (MCODE) plug-in of Cytoscape software. The diagnostic capacity of hub genes was verified using the receiver operating characteristic (ROC) curve. Correlations between diagnostic genes were analyzed using the "corrplot" package. In addition, the miRNA gene transcription factor (TF) network was used to explain the regulatory mechanism of hub genes in DKD.

Results

DEGs analysis and WGCNA-identified 160 key genes were identified in DKD patients. Among them, nine oxidative stress-related genes were identified as candidate hub genes for DKD. Using the PPI network, five hub genes, NR4A2, DUSP1, FOS, JUN, and PTGS2, were subsequently identified. All the hub genes were downregulated in DKD and had a high diagnostic value of DKD. The regulatory mechanism of hub genes was analyzed from the miRNA gene-TF network.

Conclusion

Our study identified NR4A2, DUSP1, FOS, JUN, and PTGS2 as hub genes of DKD. These genes may serve as potential therapeutic targets for DKD patients.

Nurr1 (NR4A2) regulates Alzheimer's disease-related pathogenesis and cognitive function in the 5XFAD mouse model

The orphan nuclear receptor Nurr1 (also known as NR4A2) is critical for the development and maintenance of midbrain dopaminergic neurons, and is associated with Parkinson's disease. However, an association between Nurr1 and Alzheimer's disease (AD)‐related pathology has not previously been reported. Here, we provide evidence that Nurr1 is expressed in a neuron‐specific manner in AD‐related brain regions; specifically, it is selectively expressed in glutamatergic neurons in the subiculum and the cortex of both normal and AD brains. Based on Nurr1’s expression patterns, we investigated potential functional roles of Nurr1 in AD pathology. Nurr1 expression was examined in the hippocampus and cortex of AD mouse model and postmortem human AD subjects. In addition, we performed both gain‐of‐function and loss‐of‐function studies of Nurr1 and its pharmacological activation in 5XFAD mice. We found that knockdown of Nurr1 significantly aggravated AD pathology while its overexpression alleviated it, including effects on Aβ accumulation, neuroinflammation, and neurodegeneration. Importantly, 5XFAD mice treated with amodiaquine, a highly selective synthetic Nurr1 agonist, showed robust reduction in typical AD features including deposition of Aβ plaques, neuronal loss, microgliosis, and impairment of adult hippocampal neurogenesis, leading to significant improvement of cognitive impairment. These in vivo and in vitro findings suggest that Nurr1 critically regulates AD‐related pathophysiology and identify Nurr1 as a novel AD therapeutic target.