A circular RNA produced by LRBA promotes cirrhotic mouse liver regeneration through facilitating the ubiquitination degradation of p27.

BACKGROUND AND AIMS: Accumulating circular RNAs (circRNAs) play important roles in tissue repair and organ regeneration. However, the biological effects of circRNAs on liver regeneration remain largely unknown. This study aims to systematically elucidate the functions and mechanisms of circRNAs derived from lipopolysaccharide-responsive beige-like anchor protein (LRBA) in regulating liver regeneration. METHODS: CircRNAs derived from mouse LRBA gene were identified using CircBase. In vivo and in vitro experiments were conducted to confirm the effects of circLRBA on liver regeneration. RNA pull-down and RNA immunoprecipitation assays were used to investigate the underlying mechanisms. Clinical samples and cirrhotic mouse models were used to evaluate the clinical significance and transitional value of circLRBA. RESULTS: Eight circRNAs derived from LRBA were registered in CircBase. The circRNA mmu_circ_0018031 (circLRBA) was significantly upregulated in the liver tissues after 2/3 partial hepatectomy (PHx). Adeno-associated virus serotype 8 (AAV8)-mediated knockdown of circLRBA markedly inhibited mouse liver regeneration after 2/3 PHx. In vitro experiments confirmed that circLRBA exerted its growth-promoting function mainly through liver parenchymal cells. Mechanistically, circLRBA acted as a scaffold for the interaction between E3 ubiquitin-protein ligase ring finger protein 123 and p27, facilitating the ubiquitination degradation of p27. Clinically, circLRBA was lowly expressed in cirrhotic liver tissues and negatively correlated with perioperative levels of total bilirubin. Furthermore, overexpression of circLRBA enhanced cirrhotic mouse liver regeneration after 2/3 PHx. CONCLUSIONS: We conclude that circLRBA is a novel growth promoter in liver regeneration and a potential therapeutic target related to deficiency of cirrhotic liver regeneration.

RNF123 Mediates Ubiquitination and Degradation of SOCS1 To Regulate Type I Interferon Production during Duck Tembusu Virus Infection.

Many RING domain E3 ubiquitin ligases play critical roles in fine-tuning the innate immune response, yet little is known about their regulatory role in flavivirus-induced innate immunity. In previous studies, we found that the suppressor of cytokine signaling 1 (SOCS1) protein mainly undergoes lysine 48 (K48)-linked ubiquitination. However, the E3 ubiquitin ligase that promotes the K48-linked ubiquitination of SOCS1 is unknown. In the present study, we found that RING finger protein 123 (RNF123) binds to the SH2 domain of SOCS1 through its RING domain and facilitates the K48-linked ubiquitination of the K114 and K137 residues of SOCS1. Further studies found that RNF123 promoted the proteasomal degradation of SOCS1 and promoted Toll-like receptor 3 (TLR3)- and interferon (IFN) regulatory factor 7 (IRF7)-mediated type I IFN production during duck Tembusu virus (DTMUV) infection through SOCS1, ultimately inhibiting DTMUV replication. Overall, these findings demonstrate a novel mechanism by which RNF123 regulates type I IFN signaling during DTMUV infection by targeting SOCS1 degradation. IMPORTANCE In recent years, posttranslational modification (PTM) has gradually become a research hot spot in the field of innate immunity regulation, and ubiquitination is one of the critical PTMs. DTMUV has seriously endangered the development of the waterfowl industry in Southeast Asian countries since its outbreak in 2009. Previous studies have shown that SOCS1 is modified by K48-linked ubiquitination during DTMUV infection, but E3 ubiquitin ligase catalyzing the ubiquitination of SOCS1 has not been reported. Here, we identify for the first time that RNF123 acts as an E3 ubiquitin ligase that regulates TLR3- and IRF7-induced type I IFN signaling during DTMUV infection by targeting the K48-linked ubiquitination of the K114 and K137 residues of SOCS1 and the proteasomal degradation of SOCS1.

E3 ubiquitin ligase RNF123-deficient mice exhibit reduced parasitemia and mortality in rodent malaria (Plasmodium yoelii 17XL) infection.

Increased levels of several human ubiquitin ligases, including ring finger protein 123 (RNF123), in red blood cells with Plasmodium falciparum infection, have been reported. RNF123 is an E3 ubiquitin ligase that is highly expressed in erythroid cells. However, the function of the RNF123 gene and the relationship between the RNF123 gene and malarial parasite has not been clarified in vivo. In this study, we generated RNF123-deficient mice using the CRISPR/Cas9 system, and analyzed malaria susceptibility and erythrocyte morphology. The levels of parasitemia 5 days post-infection and mortality 21 days post-infection with the lethal type of rodent malaria (Plasmodium yoelii 17XL) in RNF123-deficient mice was significantly lower than that in wild-type mice. In contrast, red blood cell morphology in RNF123-deficient mice was almost normal. These results suggest that erythrocytic RNF123 plays a role in susceptibility to rodent malaria infection, but does not play a role in erythrocyte morphology.

Insights into potential targeted nonsurgical therapies for the treatment of moyamoya disease.

Since its initial description in 1957 as an idiopathic disease, moyamoya disease has proved challenging to treat. Although the basic pathophysiology of this disease involves narrowing of the terminal carotid artery with compensatory angiogenesis, the molecular and cellular mechanisms underlying these changes are far more complex. In this article, the authors review the literature on the molecular and cellular pathophysiology of moyamoya disease with an emphasis on potential therapeutic targets.

Cyclin G2 upregulation impairs migration, invasion, and network formation through RNF123/Dvl2/JNK signaling in the trophoblast cell line HTR8/SVneo, a possible role in preeclampsia.

Disruption of extravillous trophoblast (EVT) migration and invasion is considered to be responsible for pathological placentation in preeclampsia (PE). Cyclin G2 (CCNG2) is an atypical cyclin that inhibits cell cycle progression. However, its biological function and underlying molecular mechanism in PE are poorly understood. In this study, clinical data demonstrated that CCNG2 was significantly upregulated in PE placenta and associated with invasive EVT dysfunction. Additionally, Ccng2 knockout led to an attenuation of PE-like symptoms in the PE mouse model produced via treatment with NG-nitro-L-arginine methyl ester (L-NAME). In vitro, CCNG2 inhibited the migration, invasion, and endothelial-like network formation of human trophoblast cell line HTR8/SVneo. Mechanically, CCNG2 suppressed JNK-dependent Wnt/PCP signaling and its downstream indicators including epithelial-to-mesenchymal transition (EMT) markers and matrix metalloproteinases (MMPs) via promoting the polyubiquitination degradation of dishevelled 2 (Dvl2) protein in HTR8/SVneo cells. We also discovered that the E3 ligase Ring finger protein 123 (RNF123), as a novel CCNG2 target among HTR8/SVneo cells, interacted with Dvl2 and participated in CCNG2-induced polyubiquitination degradation of Dvl2. Moreover, we verified that the treatment of HTR8/SVneo cells with RNF123-specific siRNA improved polyubiquitination-induced degradation of Dvl2 and the activity of Wnt/PCP-JNK signaling mediated by CCNG2. Taken together, our results reveal that the CCNG2/RNF123/Dvl2/JNK axis may be involved in the pathogenesis and progression of PE through trophoblastic cell function modulation, thus probably providing us with new therapeutic strategies for PE treatment.

RNF123 has an E3 ligase-independent function in RIG-I-like receptor-mediated antiviral signaling.

Retinoic acid-inducible gene I (RIG-I) and melanoma differentiation-associated gene 5 (MDA5) are cytoplasmic sensors crucial for recognizing different species of viral RNAs, which triggers the production of type I interferons (IFNs) and inflammatory cytokines. Here, we identify RING finger protein 123 (RNF123) as a negative regulator of RIG-I and MDA5. Overexpression of RNF123 inhibits IFN-ß production triggered by Sendai virus (SeV) and encephalomyocarditis picornavirus (EMCV). Knockdown or knockout of endogenous RNF123 potentiates IFN-ß production triggered by SeV and EMCV, but not by the sensor of DNA viruses cGAS RNF123 associates with RIG-I and MDA5 in both endogenous and exogenous cases in a viral infection-inducible manner. The SPRY and coiled-coil, but not the RING, domains of RNF123 are required for the inhibitory function. RNF123 interacts with the N-terminal CARD domains of RIG-I/MDA5 and competes with the downstream adaptor VISA/MAVS/IPS-1/Cardif for RIG-I/MDA5 CARD binding. These findings suggest that RNF123 functions as a novel inhibitor of innate antiviral signaling mediated by RIG-I and MDA5, a function that does not depend on its E3 ligase activity.

Correlative gene expression pattern linking RNF123 to cellular stress-senescence genes in patients with depressive disorder: implication of DRD1 in the cerebral cortex.

BACKGROUND: The expression level of the RNF1213 gene in blood cells has been identified as a disease risk marker, more than ten years before the diagnosis of depression (Glahn et al., 2012). To explore the status of this gene in the acute depressive state we have quantified the expression of RNF123 in the blood leukocytes (N=17), dorsolateral prefrontal and cingulate cortex (N=24) of patients with diagnosed depression and of matched controls. We have measured the expression of the DRD1 gene as a "neuronal probe". We have also quantified the mRNA of six genes previously identified as markers of the biopsychological stress associated with major depression: FOS, DUSP1, OGG1, STMN1, p16(INK4a) and TERT. METHODS: The steady state of mRNA has been quantified by the real-time quantitative PCR technique. RESULTS: RNF123 was overexpressed by 45% in the cingulate cortex of patients with psychotic depression. There were distinct co-expression patterns of RNF123 and stress-related genes in the blood cells and brain cortex of patients, demonstrating a transcriptional regulatory shift. In both the prefrontal and cingulate cortex of these patients a strong correlation interlinked STMN1, TERT and DRD1 pointing to a role of these genes in dopamine signaling. LIMITATIONS: The two groups of patients were clinically heterogeneous. All the patients had received antidepressant treatment, details of which were not available. CONCLUSION: We did not identify RNF123 as a clinically relevant, peripheral state marker of depression, but our study probably lacked statistical power to detect small effect size. It is likely to be involved in distinct pleiotropic molecular pathways at peripheral (blood) and central (brain) level.