Inhibition of UBA52 induces autophagy via EMC6 to suppress hepatocellular carcinoma tumorigenesis and progression

Ubiquitin A-52 residue ribosomal protein fusion product 1 (UBA52) has a role in the occurrence and development of tumours. However, the mechanism by which UBA52 regulates hepatocellular carcinoma (HCC) tumorigenesis and progression remains poorly understood. By using the Cell Counting Kit (CCK-8), colony formation, wound healing and Transwell assays, we assessed the effects of UBA52 knockdown and overexpression on the proliferation and migration of HCC cells in vitro. By establishing subcutaneous and metastatic tumour models in nude mice, we evaluated the effects of UBA52 on HCC cell proliferation and migration in vivo. Through bioinformatic analysis of data from the Gene Expression Profiling Interactive Analysis (GEPIA) and The Cancer Genome Atlas (TCGA) databases, we discovered that UBA52 is associated with autophagy. In addition, we discovered that HCC tissues with high UBA52 expression had a poor prognosis in patients. Moreover, knockdown of UBA52 reduced HCC cell growth and metastasis both in vitro and in vivo. Mechanistically, knockdown of UBA52 induced autophagy through EMC6 in HCC cells. These findings suggest that UBA52 promoted the proliferation and migration of HCC cells through autophagy regulation via EMC6 and imply that UBA52 may be a viable novel treatment target for HCC patients.

Hydralazine represses Fpn ubiquitination to rescue injured neurons via competitive binding to UBA52

A major impedance to neuronal regeneration after peripheral nerve injury (PNI) is the activation of various programmed cell death mechanisms in the dorsal root ganglion. Ferroptosis is a form of programmed cell death distinguished by imbalance in iron and thiol metabolism, leading to lethal lipid peroxidation. However, the molecular mechanisms of ferroptosis in the context of PNI and nerve regeneration remain unclear. Ferroportin (Fpn), the only known mammalian nonheme iron export protein, plays a pivotal part in inhibiting ferroptosis by maintaining intracellular iron homeostasis. Here, we explored in vitro and in vivo the involvement of Fpn in neuronal ferroptosis. We first delineated that reactive oxygen species at the injury site induces neuronal ferroptosis by increasing intracellular iron via accelerated UBA52-driven ubiquitination and degradation of Fpn, and stimulation of lipid peroxidation. Early administration of the potent arterial vasodilator, hydralazine (HYD), decreases the ubiquitination of Fpn after PNI by binding to UBA52, leading to suppression of neuronal cell death and significant acceleration of axon regeneration and motor function recovery. HYD targeting of ferroptosis is a promising strategy for clinical management of PNI.

Omics Analyses in a Neural Stem Cell Model of Familial Parkinson's Disease

Parkinson's disease (PD) is the second most common neurodegenerative disorder, affecting millions of people worldwide. Despite considerable efforts, the underlying pathological mechanisms remain elusive, and yet, no treatment has been developed to efficiently reverse or modify disease progression. Thus, new experimental models are required to provide insights into the pathology of PD. Small-molecule neural precursor cells (smNPCs) are ideal for the study of neurodegenerative disorders due to their neural identity and stem cell properties. Cytoplasmic aggregates of α-synuclein (αSyn) are considered a hallmark of PD and a point mutation in the gene encoding p.A53T is responsible for a familial PD form with earlier and robust symptom onset. In order to study the cellular pathology of PD, we genetically modified smNPCs to inducibly overexpress EYFP-SNCA A53T. This cellular model was biochemically characterized, while dysregulated biological pathways and key regulators of PD pathology were identified by computational analyses. Our study indicates three novel genes, UBA52, PIP5K1A, and RPS2, which may mediate PD cellular pathology.

Circular RNA expression profile in blood according to ischemic stroke etiology

Background

The discovery of novel biomarkers of stroke etiology would be most helpful in management of acute ischemic stroke patients. Recently, circular RNAs (circRNAs) have been proposed as candidate biomarkers of neurological conditions due to its high stability. circRNAs function as sponges, sequestering miRNAs and are involved in most relevant biological functions. Our aim was to identify differentially expressed circRNAs in acute ischemic stroke patients according to stroke etiology.

Methods

A comprehensive expression profile of blood circRNAs was conducted by Arraystar Human circRNA arrays (13,617 probes) on a discovery cohort of 30 stroke patients with different stroke etiologies by TOAST classification. Real-time quantitative PCR (RT-qPCR) was used to validate array results in a cohort of 50 stroke patients. Functional in silico analysis was performed to identify potential interactions with microRNAs (miRNAs) and pathways underlying deregulated circRNAs.

Results

A set of 60 circRNAs were found to be upregulated in atherotrombotic versus cardioembolic strokes (fold-change > = 1.5 and p-value ≤ 0.05). Differential expression of hsa_circRNA_102488, originated from UBA52 gene, was replicated in the validation cohort. RNA-binding proteins (RBPs) sites of hsa_circRNA_102488 clustered around AGO2 and FUS proteins. Further functional analysis revealed interactions between deregulated circRNAs and a set of miRNAs involved in stroke-related pathways, such as fatty acid biogenesis or lysine degradation.

Conclusion

Different stroke subtypes show specific profiles of circRNAs expression. circRNAs may serve as a new source of biomarkers of stroke etiology in acute ischemic stroke patients.

Degradation of CCNB1 mediated by APC11 through UBA52 ubiquitination promotes cell cycle progression and proliferation of non-small cell lung cancer cells

OBJECTIVE

Mechanism by which CCNB1 regulates the cell cycle progression and its prognostic function in non-squamous non-small cell lung cancer (NSCLC) are necessary to be further elucidated.

METHODS

Data retrieved from gene expression omnibus (GEO) and cancer genome atlas (TCGA) combined with clinical data were used. Survival analysis was conducted in public datasets. Proteomics and co-immunoprecipation assays were designed to unravel proteins with interaction with CCNB1. Short hairpin RNA and small interfering RNA as well as overexpressing genes of interest were used.

RESULTS

CCNB1 was not implicated in apoptosis, migration and invasion of NSCLC cells. After either knockdown or overexpression of CCNB1, the occurrence of cell cycle arrest in G2/M phase, fewer cloning formation and diminished dimension of xenograft tumors were observed. CCNB1 expression level was clinically associated with several clinicopathological parameters including gender, smoking, T stage and N stage. Survival analysis showed that the higher level of CCNB1, the more dismal outcome in overall survival as well as in disease-free survival. Mechanistically, we confirmed that the role of CCNB1 on cell cycle and cloning formation was dependent on UBA52, which was able to promote degradation of CCNB1; nevertheless, this consequence relied on APC11. Knockdown of APC11 led to cell cycle arrest in G2/M and less cloning formation even in the presence of overexpressed UBA52. Following upregulation of APC11, the protein of CCNB1 degraded with resultant cell cycle progression and more cloning formation.

CONCLUSION

Degradation of CCNB1 by APC11 via UBA52 ubiquitylation was critical in cell cycle progression and proliferation of NSCLC cell lines.

LUCAT1 promotes colorectal cancer tumorigenesis by targeting the ribosomal protein L40-MDM2-p53 pathway through binding with UBA52

Colorectal cancer (CRC) is the third most commonly diagnosed cancer in both men and women in the USA. However, the underlying molecular mechanisms that drive CRC tumorigenesis are still not clear. Several studies have reported that long noncoding RNAs (lncRNAs) have important roles in tumor development. Here, we undertook a transcriptome microarray analysis in 6 pairs of CRC tissues and their corresponding adjacent normal tissues. A total of 1705 differentially expressed lncRNAs were detected in CRC tissues at stages I/II and III/IV (fold change greater than or equal to 2 or less than or equal to 0.5). Among them, we found that the lncRNA lung cancer-associated transcript 1 (LUCAT1) was upregulated in CRC tissues and was closely associated with poor overall survival of CRC patients, through analysis of clinical data and The Cancer Genome Atlas. Functional studies indicated that LUCAT1 promoted CRC cell proliferation, apoptosis, migration, and invasion in vitro and in vivo. Furthermore, knockdown of LUCAT1 rendered CRC cells hypersensitive to oxaliplatin treatment. Mechanistically, bioinformatic analysis indicated that low expression of LUCAT1 was associated with the p53 signaling pathway. Chromatin isolation by RNA purification followed by mass spectrometry and RNA immunoprecipitation revealed that LUCAT1 bound with UBA52, which encodes ubiquitin and 60S ribosomal protein L40 (RPL40). We found that RPL40 functions in the ribosomal protein-MDM2-p53 pathway to regulate p53 expression. Taken together, our findings indicate that suppression of LUCAT1 induces CRC cell cycle arrest and apoptosis by binding UBA52 and activating the RPL40-MDM2-p53 pathway. These results implicate LUCAT1 as a potential prognostic biomarker and therapeutic target for CRC.

Host Interaction Analysis of PA-N155 and PA-N182 in Chicken Cells Reveals an Essential Role of UBA52 for Replication of H5N1 Avian Influenza Virus

PA-N155 and PA-N182 proteins were translated from the 11th and 13th start codon AUG of the RNA polymerase acidic protein (PA) mRNA of H5N1 influenza A virus (IAV), which plays an important role in viral replication. Little is known about the interactions between PA-N155 and PA-N182 and the host proteins. This study investigated the interaction landscape of PA-N155 and PA-N182 of H5N1 IAV in chicken cells while their interacting complexes were captured by immunoprecipitation and analyzed by mass spectrometry. A total of 491 (PA-N155) and 302 (PA-N182) interacting proteins were identified. Gene ontology and pathway enrichment analyses showed that proteins of the two interactomes were enriched in RNA processing, viral processing and protein transport, and proteins related to signaling pathways of proteasome, ribosome, and aminoacy1-tRNA biosynthesis were significantly enriched, suggesting their potential roles in H5N1 IAV infection. Comparative analysis of the interactome of PA, PA-N155, and PA-N182 identified UBA52 as a conserved host factor that interacted with all three viral proteins. UBA52 is a fusion protein consisting of ubiquitin at the N terminus and ribosomal protein L40 at the C terminus. Knockdown of UBA52 significantly decreased the titer of H5N1 IAV in chicken cells and was accompanied with attenuated production of proinflammatory cytokines. Our analyses of the influenza–host protein interactomes identified UBA52 as a PA interaction protein for virus replication.