Project description:Nonalcoholic fatty liver disease (NAFLD) is the most common liver disorder with high morbidity and mortality. The current study aims to explore the role of Cullin-associated and neddylation-dissociated protein 1 (CAND1) in the development of NAFLD and the underlying mechanisms. CAND1 is reduced in the liver of NAFLD male patients and high fat diet (HFD)-fed male mice. CAND1 alleviates palmitate (PA) induced lipid accumulation in vitro. Hepatocyte-specific knockout of CAND1 exacerbates HFD-induced liver injury in HFD-fed male mice, while hepatocyte-specific knockin of CAND1 ameliorates these pathological changes. Mechanistically, deficiency of CAND1 enhances the assembly of Cullin1, F-box only protein 42 (FBXO42) and acetyl-CoA acyltransferase 2 (ACAA2) complexes, and thus promotes the ubiquitinated degradation of ACAA2. ACAA2 overexpression abolishes the exacerbated effects of CAND1 deficiency on NAFLD. Additionally, androgen receptor binds to the -187 to -2000 promoter region of CAND1. Collectively, CAND1 mitigates NAFLD by inhibiting Cullin1/FBXO42 mediated ACAA2 degradation
Project description:The cytosolic DNA sensor cyclic GMP-AMP (cGAMP) synthetase (cGAS) has emerged as a fundamental component fueling the anti-pathogen immunity. Because of its pivotal role in initiating innate immune response, the activity of cGAS must be tightly fine-tuned to maintain immune homeostasis in antiviral response. Here, we reported that neddylation modification was indispensable for appropriate cGAS-STING signaling activation. Blocking neddylation pathway using neddylation inhibitor MLN4924 substantially impaired the induction of type I interferon and proinflammatory cytokines, which was selectively dependent on Nedd8 E2 enzyme Ube2m. We further found that deficiency of the Nedd8 E3 ligase Rnf111 greatly attenuated DNA-triggered cGAS activation while not affecting cGAMP induced activation of STING, demonstrating that Rnf111 was the Nedd8 E3 ligase of cGAS. We further identified Lys231 and Lys421 as the key neddylation sites in human cGAS. Mechanistically, Rnf111 interacted with and polyneddylated cGAS, which in turn promoted its dimerization and enhanced the DNA-binding ability, leading to proper cGAS-STING pathway activation. In the same line, the Ube2m or Rnf111 deficiency mice exhibited severe defects in innate immune response and were susceptible to HSV-1 infection. Collectively, our study uncovered a vital role of the Ube2m-Rnf111 neddylation axis in promoting the activity of the cGAS-STING pathway and highlighted the importance of neddylation modification in antiviral defense.
Project description:Background: Polycystic liver diseases (PLD) are genetic disorders characterized by progressive growth of numerous liver cysts, causing significant morbidity. Previous studies revealed genes affecting protein biogenesis and more recently, protein SUMOylation, a posttranslational modification (PTM), has been implicated in PLD pathobiology. On the other hand, protein NEDDylation is a newly-characterized PTM, modulating a plethora of biological processes and its dysregulation is associated with development and progression of several human diseases. In this regard, the role of NEDDylation in PLD remains elusive and unraveling its role in the pathogenesis of these genetic disorders could open new avenues for the development of novel treatments in the future. Objective: To explore the role of protein NEDDylation in PLD and its potential therapeutic regulatory value. Methods: Expression and function of NEDDylation, including response to Pevonedistat (first-in-class selective inhibitor of the NEDDylation E1 enzyme NAE1), were assessed in vitro. Proteomic analyses of immunoprecipitated NEDDylated proteins were performed by mass spectrometry.
Project description:The heart undergoes significant structural, metabolic, gene expression and functional alterations during the perinatal to postnatal transition. While recent studies have identified multiple epigenetic and transcriptional regulators of cardiac maturation, post-transcriptional mechanisms regulating this process remain poorly understood. Neddylation is a post-translational modification that conjugates a small ubiquitin-like protein, NEDD8, to protein substrates via an E1-E2-E3 enzymatic cascade. The goal of this study was to define the role of neddylation in perinatal cardiac development and cardiac maturation. Neddylation was inhibited in adult mouse hearts by cardiac-specific deletion of NAE1 gene, a regulatory subunit of NEDD8 E1 enzyme, or in neonatal cardiomyocytes (CMs) with a pharmacological neddylation inhibitor, MLN4924. The impact on cardiac transcriptome, metabolism, maturation and function was assessed. Mosaic deletion of NAE1 in ~40% neonatal CMs disrupted aspects of maturation, including transverse-tubule formation, cellular hypertrophy and fetal/adult isoform switching, whereas deletion of NAE1 in over 80% CMs led to rapid development of cardiomyopathy and heart failure. Transcriptome analysis demonstrated an association of metabolic derangement with immature cardiomyocyte signature. Biochemical, ultrastructural and metabolomics analyses confirmed downregulation of fatty acid and oxidative phosphorylation genes, deficits in fatty acid utilization, mitochondrial dysfunction, and significantly altered metabolic profiles in NAE1-deficient hearts or MLN4924-treated neonatal CMs. Mechanistically, we found that HIF1α, a transcription factor known to promote glycolysis and suppress oxidative metabolism, is a putative NEDD8 target. Inhibition of neddylation resulted in HIF1α accumulation and activation, which contributed to diminished fatty acid utilization. Taken together, we conclude that neddylation plays a crucial role in CM maturation and postnatal cardiac development through sustaining the glycolytic to oxidative metabolic switch in perinatal hearts.
Project description:Neddylation is a post-translational mechanism that adds a ubiquitin-like protein, namely neural precursor cell expressed developmentally down-regulated protein 8, to target proteins, with yet-unknown consequences. Here we show in mice that neddylation in liver is modulated by nutrient availability. Inhibition of neddylation in mouse liver (either pharmacologically or genetically) reduces gluconeogenic capacity and the hyperglycemic actions of counterregulatory hormones (glucagon, adrenaline and glucocorticoids). Further, people with obesity and type 2 diabetes (compared to people with obesity and normoglycemia) display elevated hepatic neddylation levels that correlate positively with fasting glucose levels. Mechanistically, we determined that fasting or caloric restriction of mice leads to neddylation of phosphoenolpyruvate carboxykinase 1 (PCK1) at three lysine residues—K278, K342 and K387. PCK1 is a key control point for gluconeogenesis regulation that can be post-translationally modified by acetylation and phosphorylation, but to date no modifications are known to affect its gluconeogenic capacity. Of note, we find that mutating the three PCK1 lysines that are neddylated reduces its gluconeogenic activity rate. Molecular dynamics simulations show that neddylation of PCK1 could re-position two loops surrounding the catalytic center into an open configuration, rendering the catalytic center more accessible. Our study reveals that neddylation of PCK1 provides a finely-tuned mechanism of controlling glucose metabolism by linking whole nutrient availability to metabolic homeostasis.
Project description:Neddylation is coupled with tumor-cell survival by its well-characterized substrates Cullins. However, how neddylation impacts the tumor immune microenvironment is not clear. SENP8 deconjugates NEDD8 from non-Cullin targets to maintain the dynamic and reversible neddylation equilibrium. CD47 treated SENP8+/+ and SENP8+/- BMDMs were detected to show impacted gene transcription.
Project description:The liver plays a protective role in myocardial infarction (MI). However, very little is known about the mechanisms. Here, we identify mineralocorticoid receptor (MR) as a pivotal nexus that conveys communications between the liver and the heart during MI. On one hand, hepatocyte MR deficiency and MR antagonist spironolactone both improve cardiac repair after MI through regulation on hepatic fibroblast growth factor 21 (FGF21), illustrating an MR/FGF21 axis that underlies the liver-to-heart protection against MI. On the other hand, an upstreaming acute interleukin-6 (IL6) / signal transducer and activator of transcription 3 (STAT3) pathway transmits the heart-to-liver signal to suppress MR expression after MI. Hepatocyte IL6 receptor (IL6R) deficiency and STAT3 deficiency both aggravate cardiac injury through their regulation on the MR/FGF21 axis. Therefore, we have unveiled an IL6/STAT3/MR/FGF21 signaling axis that mediates heart-liver crosstalk during MI. Targeting the signaling axis and the crosstalk may provide novel strategies to treat MI and heart failure.
Project description:Fumarylacetoacetate hydrolase (Fah), the last enzyme of the tyrosine degradation pathway, is specifically expressed in hepatocytes in the liver. Loss of Fah leads to liver failure in mice within 6-8 weeks. This can be prevented by blocking tyrosine degradation upstream of Fah with 2-(2-nitro-4-trifluoromethylbenzoyl)-1,3-cyclohexanedione (NTBC). Here, we investigate the impact of p21 on global gene expression in Fah deficiency. Keywords: treatment, genotype
Project description:Fumarylacetoacetate hydrolase (Fah), the last enzyme of the tyrosine degradation pathway, is specifically expressed in hepatocytes in the liver. Loss of Fah leads to liver failure in mice within 6-8 weeks. This can be prevented by blocking tyrosine degradation upstream of Fah with 2-(2-nitro-4-trifluoromethylbenzoyl)-1,3-cyclohexanedione (NTBC). Here, we investigate the impact of p21 on global gene expression in Fah deficiency. Experiment Overall Design: Livers from adult wildtype, Fah or Fah, p21 knockout mice were analyzed either after continuous treatment (ON) with NTBC or after NTBC withdrawal for 14 days (OFF).