Li Xue-Qi, Jin Bo, Liu Si-Xiu, Zhu Yan, Li Nan, Zhang Qing-Yan, Wan Cheng, Feng Yuan, Xing Yue-Xian, Ma Kun-Ling, Liu Jing, Jiang Chun-Ming, Lu Jian
Institute of Nephrology, Nanjing Drum Tower Hospital, School of Medicine, Southeast University, Nanjing, 210008, China.
Department of Nephrology, Nanjing Drum Tower Hospital, The Affiliated Hospital of Nanjing University Medical School, Nanjing, 210008, China.
Acta Pharmacol Sin. 2025 Jun;46(6):1692-1705. doi: 10.1038/s41401-024-01460-z. Epub 2025 Feb 3.
Diabetic nephropathy (DN) is a common and serious complication of diabetes, characterized by chronic fibro-inflammatory processes with an unclear pathogenesis. Renal fibrosis plays a significant role in the development and progression of DN. While recent research suggests that the neddylation pathway may influence fibrotic processes, its specific dysregulation in DN and the underlying mechanisms remain largely unexplored. This study identified the neddylation of RhoA as a novel post-translational modification that regulates its expression and promotes renal fibrosis in DN. We here demonstrated that two key components of the neddylation pathway-NEDD8-activating enzyme E1 subunit 1 (NAE1) and NEDD8-are significantly upregulated in human chronic kidney disease (CKD) specimens compared to healthy kidneys, implicating neddylation in CKD-associated fibrosis. Our findings further revealed that both pharmacological inhibition of neddylation using MLN4924 and genetic knockdown of NAE1 mitigate renal fibrosis in mouse models of streptozotocin-induced diabetes and unilateral ureteral obstruction (UUO). Immunoprecipitation-mass spectrometry (IP-MS) and subsequent function assays demonstrated a direct interaction between RhoA and NEDD8. Importantly, neddylation inhibition reduced RhoA protein expression, highlighting a potential therapeutic target. Additionally, a positive correlation was noted between elevated NEDD8 mRNA levels and RhoA mRNA expression in human CKD specimens. RhoA overexpression counteracted the antifibrotic effects of neddylation inhibition, underscoring its critical role in fibrosis progression. Mechanistically, we unveiled that neddylation enhances RhoA protein stability by inhibiting its ubiquitination-mediated degradation, which subsequently activates the ERK1/2 pathway. Collectively, this study provides novel insights into NAE1-dependent RhoA neddylation as a key contributor to renal fibrosis in DN. The NAE1 protein mediates RhoA protein hyper-neddylation and subsequent stabilization of the RhoA protein, which, in turn, contributes to the development of renal fibrosis and inflammation through an ERK1/2-dependent mechanism. Consequently, targeting neddylation inhibition represents a viable therapeutic approach for the treatment of renal fibrosis in DN.
糖尿病肾病（DN）是糖尿病常见且严重的并发症，其特征为慢性纤维炎症过程，发病机制尚不明确。肾纤维化在DN的发生和发展中起重要作用。虽然最近的研究表明NEDD化途径可能影响纤维化过程，但其在DN中的具体失调及潜在机制仍 largely 未被探索。本研究确定RhoA的NEDD化是一种新型的翻译后修饰，可调节其表达并促进DN中的肾纤维化。我们在此证明，与健康肾脏相比，NEDD化途径的两个关键成分——NEDD8激活酶E1亚基1（NAE1）和NEDD8在人类慢性肾脏病（CKD）标本中显著上调，提示NEDD化与CKD相关纤维化有关。我们的研究结果进一步表明，使用MLN4924对NEDD化进行药理学抑制以及对NAE1进行基因敲低，均可减轻链脲佐菌素诱导的糖尿病和单侧输尿管梗阻（UUO）小鼠模型中的肾纤维化。免疫沉淀-质谱（IP-MS）及后续功能测定表明RhoA与NEDD8之间存在直接相互作用。重要的是，NEDD化抑制降低了RhoA蛋白表达，突出了一个潜在的治疗靶点。此外，在人类CKD标本中，NEDD8 mRNA水平升高与RhoA mRNA表达之间存在正相关。RhoA过表达抵消了NEDD化抑制的抗纤维化作用，强调了其在纤维化进展中的关键作用。从机制上讲，我们发现NEDD化通过抑制RhoA的泛素化介导降解来增强其蛋白稳定性，进而激活ERK1/2途径。总体而言，本研究为NAE1依赖的RhoA NEDD化作为DN中肾纤维化的关键促成因素提供了新的见解。NAE1蛋白介导RhoA蛋白的过度NEDD化以及随后RhoA蛋白的稳定，这反过来又通过ERK1/2依赖机制促进肾纤维化和炎症的发展。因此，靶向NEDD化抑制是治疗DN中肾纤维化的一种可行治疗方法。
