SIAH1 ubiquitin ligase mediates ubiquitination and degradation of Akt3 in neural development

Neural crest cells and fetal alcohol spectrum disorders: Mechanisms and potential targets for prevention

Fetal alcohol spectrum disorders (FASD) are a group of preventable and nongenetic birth defects caused by prenatal alcohol exposure that can result in a range of cognitive, behavioral, emotional, and functioning deficits, as well as craniofacial dysmorphology and other congenital defects. During embryonic development, neural crest cells (NCCs) play a critical role in giving rise to many cell types in the developing embryos, including those in the peripheral nervous system and craniofacial structures. Ethanol exposure during this critical period can have detrimental effects on NCC induction, migration, differentiation, and survival, leading to a broad range of structural and functional abnormalities observed in individuals with FASD. This review article provides an overview of the current knowledge on the detrimental effects of ethanol on NCC induction, migration, differentiation, and survival. The article also examines the molecular mechanisms involved in ethanol-induced NCC dysfunction, such as oxidative stress, altered gene expression, apoptosis, epigenetic modifications, and other signaling pathways. Furthermore, the review highlights potential therapeutic strategies for preventing or mitigating the detrimental effects of ethanol on NCCs and reducing the risk of FASD. Overall, this article offers a comprehensive overview of the current understanding of the impact of ethanol on NCCs and its role in FASD, shedding light on potential avenues for future research and intervention.

SIAH1/CTR9 axis promotes the epithelial-mesenchymal transition of hepatocellular carcinoma

SIAH1 has been reported to participate in several human cancers, including hepatocellular carcinoma (HCC). However, the effect of SIAH1 on the epithelial-mesenchymal transition (EMT) has not been reported in HCC cells. Here, we discovered the inhibitory effect of SIAH1 on HCC cell migration and invasion, which was related with regulating EMT. Molecularly, a yeast two-hybrid experiment indicated that Cln Three Requiring 9 (CTR9) was a potential interacting protein of SIAH1, which was further verified by co-immunoprecipitation assays. Furthermore, SIAH1 inhibited the EMT of HCC cells through negatively regulating CTR9. Importantly, CTR9 was ubiquitinated and degraded by SIAH1 via the proteasome pathway in HCC cells. Additionally, it was showed that SIAH1 mainly mediated the K48-linked polyubiquitination on CTR9. Finally, the protein level of CTR9 was found to be inversely correlated with SIAH1 in human HCC tissues. Summed up all together, these findings reveal that SIAH1/CTR9 axis promotes the EMT of HCC cells and is a promising therapeutic target for HCC therapy.

Transcriptome-Wide lncRNA and mRNA Profiling of Spleens from Meishan Pigs at Different Development Stages

Simple Summary

Meishan pig is a local pig breed in China, which has higher immunity than commercial pig breeds for some diseases. The spleen has hematopoietic and immune response functions, making it a good organ model for studying immunity. We depicted the expression profiles of lncRNA-mRNA in the spleen of Meishan pigs at different developmental time points (7 d, 21 d, 35 d, 120 d and 180 d). In addition, we found that AKT3, CBL and PTK2B may be involved in immune regulation in Meishan pigs through a competing endogenous RNA network. This result provides valuable genomic resources for studying immune regulation in animals and finds potential molecular markers for pig disease resistance breeding.

Abstract

Meishan is a well-established local Chinese breed known for its high fecundity, strong immune response and high meat quality. However, the molecular mechanism of immune regulation during the development of Meishan pigs still remains unclear. Here, we performed the transcriptional sequencing of spleen tissues from Meishan pigs at different development stages. In total, 10,268 lncRNAs were identified, including 1254 novel lncRNAs and 9014 known lncRNAs. Time series analysis revealed that genes of the up-regulated module were enriched in pathways associated with transport, immunity, and histone acetylation modifications, while genes of the down-regulated module were enriched in DNA metabolic process and cell cycle. Weighted gene co-expression network analysis (WGCNA) showed the functional linkage between mRNAs and lncRNAs, indicating that lncRNAs are important regulatory elements of mRNAs. Notably, a lncRNA-miRNA-mRNA competing endogenous RNA (ceRNA) network that contained 3 mRNAs (AKT3, CBL and PTK2B), 17 lncRNAs and 67 miRNAs were screened out, which probably plays a critical role in immune regulation of Meishan pigs. Our findings not only revealed the transcriptome profile of spleen development, but also provide novel insights into the mechanism of lncRNA-miRNA-mRNA axis in the immune response in Meishan pigs.

Siah1 promotes the proliferation of NSCLC cells through ubiquitinating and stabilizing Notch1

Seven in absentia homolog 1 (Siah1) has been shown plays important roles in the pathogenesis and development of multiple cancers. However, the functions and mechanisms of Siah1 in non-small cell lung cancer (NSCLC) remain unclear. In our study, we found that knock down of Siah1 could inhibit the proliferation of NSCLC cells, while over-expression of Siah1 had the opposite effects. Molecularly, the bioinformatics analysis determined that notch receptor 1 (Notch1) might be the potential target of Siah1. Subsequently, we identified that Siah1 acted as an E3 ligase to promote the ubiquitination and stabilization of Notch1 through the proteasome pathway. Furthermore, the results showed that the Siah1 expression was directly correlated with CTR9 in human NSCLC tissues. Finally, Siah1 could promote Akt phosphorylation through regulating Notch1, thus promoting the proliferation of NSCLC cells. In conclusion, our study demonstrated that Siah1 acts as an oncogene, can ubiquitinate and stabilize Notch1 by proteasome pathway, which promotes Akt phosphorylation and ultimately leads to NSCLC cell proliferation.

Circ-CCNB1 Modulates Trophoblast Proliferation and Invasion in Spontaneous Abortion by Regulating miR-223/SIAH1 axis

CONTEXT

Spontaneous abortion (SA) is a common disorder in early pregnancy. Circular RNAs (circRNAs) have been reported to exert important regulatory effects on trophoblast function and embryo development.

OBJECTIVE

The aim of this study was to explore whether and how circRNAs regulate trophoblast function in SA during early pregnancy.

METHODS

Cell proliferation, 5-bromo-2-deoxyuridine (BrdU) staining, Transwell, immunofluorescence, Western blot, RNA pull-down, and dual luciferase reporter assays were performed to investigate the effect of circRNA cyclin B1 (circ-CCNB1) on trophoblast function in HTR-8/SVneo and JEG-3 cells.

RESULTS

An in vitro study demonstrated that upregulation of circ-CCNB1 significantly inhibited trophoblast proliferation and invasion compared with the controls using HTR-8/SVneo and JEG-3 cells, respectively. Moreover, miR-223 was downregulated in the villous tissues of patients with SA and was further predicted and shown to negatively interact with circ-CCNB1, which is involved in trophoblast proliferation and invasion. Using bioinformatics tools and subsequent RNA pull-down and dual luciferase assays, we found that miR-223 directly targets seven in absentia homolog-1 (SIAH1) and that upregulation of miR-223 decreased circ-CCNB1-induced SIAH1 expression levels in HTR-8/SVneo cells. Interestingly, upregulation of circ-CCNB1 suppressed trophoblast proliferation and invasion through inhibition of CCNB1 nuclear translocation induced by SIAH1. Downregulation of SIAH1 enhanced circ-CCNB1-suppressed CCNB1 nuclear protein expression in trophoblast cells.

CONCLUSION

Circ-CCNB1 served as a modulator of trophoblast proliferation and invasion by sponging miR-223, thus forming a regulatory network of circ-CCNB1/miR-223/SIAH1 in modulating CCNB1 nuclear translocation, which enabled us to elucidate the molecular mechanisms involved in normal embryo implantation or in SA.

SIAH1 reverses chemoresistance in epithelial ovarian cancer via ubiquitination of YBX-1

Chemoresistance is a severe outcome among patients with epithelial ovarian cancer (EOC) that leads to a poor prognosis. YBX-1 has been shown to cause treatment failure and cancer progression in EOC. However, strategies that directly target YBX-1 are not yet conceivable. Here, we identified that SIAH1 which was downregulated in chemoresistant EOC samples and cell lines functioned as novel E3 ligases to trigger degradation of YBX-1 at cytoplasm by RING finger domain. Mechanistic studies show that YBX-1 was ubiquitinated by SIAH1 at lys304 that lead to the instability of its target m5C-modified mRNAs, thus sensitized EOC cells to cDDP. Overexpression of SIAH1 enhanced the antitumor efficacy of cisplatin in vitro and in vivo, which were partially impaired by ectopic expression of YBX-1 or depletion of YBX-1 ubiquitination. In summary, our data identify the SIAH1/YBX-1 interaction as a therapeutic target for overcoming EOC chemoresistance.

Siah1 in cancer and nervous system diseases (Review)

The dysregulation of the ubiquitin‑proteasome system will result in the abnormal accumulation and dysfunction of proteins, thus leading to severe diseases. Seven in absentia homolog 1 (Siah1), an E3 ubiquitin ligase, has attracted wide attention due to its varied functions in physiological and pathological conditions, and the numerous newly discovered Siah1 substrates. In cancer and nervous system diseases, the functions of Siah1 as a promoter or a suppressor of diseases are related to the change in cellular microenvironment and subcellular localization. At the same time, complex upstream regulations make Siah1 different from other E3 ubiquitin ligases. Understanding the molecular mechanism of Siah1 will help the study of various signaling pathways and benefit the therapeutic strategy of human diseases (e.g., cancer and nervous system diseases). In the present review, the functions and regulations of Siah1 are described. Moreover, novel substrates of Siah1 discovered in recent studies will be highlighted in cancer and nervous system diseases, providing ideas for future research and clinical targeted therapies using Siah1.

De novo variants in SIAH1, encoding an E3 ubiquitin ligase, are associated with developmental delay, hypotonia and dysmorphic features

BACKGROUND

Ubiquitination has a central role in numerous biological processes, including cell development, stress responses and ageing. Perturbed ubiquitination has been implicated in human diseases ranging from cancer to neurodegenerative diseases. SIAH1 encodes a RING-type E3 ubiquitin ligase involved in protein ubiquitination. Among numerous other roles, SIAH1 regulates metabotropic glutamate receptor signalling and affects neural cell fate. Moreover, SIAH1 positively regulates Wnt signalling through ubiquitin-mediated degradation of Axin and accumulation of β-catenin.

METHODS

Trio exome sequencing followed by Sanger validation was undertaken in five individuals with syndromic developmental delay. Three-dimensional structural modelling was used to predict pathogenicity of affected residues. Wnt stimulatory activity was measured by luciferase reporter assays and Axin degradation assays in HEK293 cells transfected with wild-type and mutant SIAH1 expression plasmids.

RESULTS

We report five unrelated individuals with shared features of developmental delay, infantile hypotonia, dysmorphic features and laryngomalacia, in whom exome sequencing identified de novo monoallelic variants in SIAH1. In silico protein modelling suggested alteration of conserved functional sites. In vitro experiments demonstrated loss of Wnt stimulatory activity with the SIAH1 mutants, suggesting variant pathogenicity.

CONCLUSION

Our results lend support to SIAH1 as a candidate Mendelian disease gene for a recognisable syndrome, further strengthening the connection between SIAH1 and neurodevelopmental disorders. Furthermore, the results suggest that dysregulation of the Wnt/β-catenin pathway may be involved in the pathogenesis.

Mechanistic advances in axon pathfinding

The development of a functional nervous system entails establishing connectivity between appropriate synaptic partners. During axonal pathfinding, the developing axon navigates through the extracellular environment, extending toward postsynaptic targets. In the early 1900s, Ramon y Cajal suggested that the growth cone, a specialized, dynamic, and cytoskeletal-rich structure at the tip of the extending axon, is guided by chemical cues in the extracellular environment. A century of work supports this hypothesis and introduced myriad guidance cues and receptors that promote a variety of growth cone behaviors including extension, pause, collapse, retraction, turning, and branching. Here, we highlight research from the last two years regarding pathways implicated in axon pathfinding.