Overexpression of Nrdp1/FLRF sensitizes cells to oxidative stress

Nrdp1-mediated Macrophage Phenotypic Regulation Promotes Functional Recovery in Mice with Mild Neurological Impairment after Intracerebral Hemorrhage

Neuregulin receptor degradation protein 1 (Nrdp1) is a ring finger E3 ubiquitin ligase involved in some inflammation through ubiquitination, including macrophage polarization following cerebral hemorrhage. However, there is limited understanding regarding the mechanisms through which Nrdp1 modulates macrophage polarization and the potential impact of this modulation on neurological function. Using stereotactic injection and adenoviral transfection techniques, the corresponding animal models were constructed through injecting adenovirus, saline, or blood into the mouse striatum at different periods of time in this research. The alteration in the ratio of various M1/M2 phenotype-associated markers (e.g., CD86, CD206, IL-6, IL-10, etc.) was evaluated through immunohistochemistry, immunofluorescence, western blotting, and elisa assays. Additionally, neurological function scores and behavioral tests were utilized to evaluate changes in neurological function in mice after cerebral hemorrhage. Our results show that overexpression of Nrdp1 promotes the expression of a variety of M2 macrophage-associated markers and enhance transcriptional activity of arginase-1 (Arg1) protein through ubiquitination for early regulation M2 macrophage polarization. Additionally, Nrdp1 promotes hematoma absorption, increases IL-10 expression, inhibits inducible nitric oxide synthase (iNOS), IL-6, and TNF-α production, alleviates neurological impairment and brain edema, and accelerates functional recovery. These findings suggest that modulating macrophage polarization through Nrdp1 could be a therapeutic strategy for neurofunctional impairment in cerebral hemorrhage.

Nrdp1 increases neuron apoptosis via downregulation of Bruce following intracerebral haemorrhage

Background

Neuregulin receptor degradation protein-1 (Nrdp1) is an E3 ubiquitin ligase that plays an important role in regulating cell growth, apoptosis and oxidative stress. However, the data regarding its expression and exact mechanism in neuronal injury following ICH has not been well identified.

Methods

In this study, primary cortical neurons from C57BL/6 mice were subjected to erythrocyte lysates. Nrdp1 expression, cell apoptosis, caspase-3 and BRUCE levels were detected. In addition, inflammatory response, brain edema, and neurological injury in ICH mice were also assessed.

Results

We found that the expression of Nrdp1 was significantly increased in neuron cells accompanied by up-regulation of active caspase-3 and decreased expression of BRUCE (an inhibitor of apoptosis protein). However, inhibiting Nrdp1 levels of neurons reduced caspase-3 activity but induced up-regulation of BRUCE. In vivo, inhibiting Nrdp1 levels increased pro-inflammatory cytokines, brain edema, and neurological injury following ICH.

Conclusions

Taken together, the data suggested that Nrdp1 might play a crucial role in neuronal apoptosis via inhibiting BRUCE following ICH.

Reduced expression of Nrdp1 predicts a poor prognosis in human hepatocellular carcinoma

Background

Hepatocellular carcinoma (HCC) is an aggressive form of liver cancer with particularly poor survival rates for patients. Targeted molecular therapies are lacking, and current treatment is generally limited to surgical resection or liver transplantation. Overexpression and aberrant signaling of the ErbB family of receptors has been implicated in HCC, but the mechanisms underlying ErbB overexpression are unclear. In this study, we investigated the potential role of neuregulin receptor degradation protein-1 (Nrdp1), a regulator of ErbB3 protein stability, in HCC progression.

Methods

We compared the expression of Nrdp1 in various HCC cell lines and in 8 pairs of tumor and peritumor tissue samples using Western blot analysis. Changes in the degree of proliferation were determined before and after small interfering RNA (siRNA)-induced knockdown of Nrdp1 using a cell counting Kit-8 (ccK-8) assay and cell-cycle analysis. The correlation between Nrdp1 expression and prognosis was determined in specimens of 89 HCC patients.

Results

Nrdp1 expression is significantly reduced in HCC tissues compared with adjacent healthy tissues. Higher Nrdp1 expression corresponds to lower maximal tumor size (χ², P<0.05), lower histological grade (χ², P<0.05), and higher survival rates by Kaplan–Meier estimate (P<0.05). Higher Nrdp1 expression also corresponds to reduced expression of Ki-67, a marker of cell proliferation (Spearman, r²=0.734; P<0.05). Nrdp1 accumulates in serum-starved HepG2 cancer cells and progressively decreases in expression after re-feeding. Furthermore, depletion of Nrdp1 in healthy L02 cells by siRNA results in enhanced cell proliferation and a greater proportion of cells in S phase.

Conclusions

Our findings suggest an inhibitory role for Nrdp1 in HCC tumorigenesis, and we propose that Nrdp1 may serve as a prognostic biomarker for HCC and as a potential therapeutic target for the treatment of HCC.