Targeting Protein Neddylation to Inactivate Cullin-RING Ligases by Gossypol: A Lucky Hit or a New Start?

Ubiquitination plays an important role during the formation of chicken primordial germ cells

As an important posttranslational modification, ubiquitination plays an important role in regulating protein homeostasis in eukaryotic cells. In our previous studies, both the transcriptome and proteome suggested that ubiquitination is involved in the formation of chicken primordial germ cells (PGCs). Here, affinity enrichment combined with liquid chromatography-tandem mass spectrometry (MS/MS) was used to analyze the ubiquitome during the differentiation from embryonic stem cells to PGCs, and we identify that 724 lysine ubiquitinated sites were up-regulated in 558 proteins and 138 lysine ubiquitinated sites were down-regulated in 109 proteins. Furthermore, GO and KEGG enrichment analysis showed that ubiquitination regulates key proteins to participate in the progression of key events related to PGC formation and the transduction of key signals such as Wnt, MAPK, and insulin signals, followed by the detailed explanation of the specific regulatory mechanism of ubiquitination through the combined proteome and ubiquitome analysis. Moreover, both the activation and inhibition of neddylation were detrimental to the maintenance of the biological characteristics of PGCs, which also verified the importance of ubiquitination. In conclusion, this study provides a global view of the ubiquitome during the formation of PGCs by label-free quantitative ubiquitomics, which lays a theoretical foundation for the formation mechanism and specific application of chicken PGCs.

A small molecule inhibitor of the UBE2F-CRL5 axis induces apoptosis and radiosensitization in lung cancer

Protein neddylation is catalyzed by a neddylation activating enzyme (NAE, E1), an E2 conjugating enzyme, and an E3 ligase. In various types of human cancers, the neddylation pathway is abnormally activated. Our previous study validated that the neddylation E2 UBE2F is a promising therapeutic target in lung cancer. Although the NAE inhibitor MLN4924/pevonedistat is currently under clinical investigation as an anti-cancer agent, there are no small molecules available that selectively target UBE2F. Here, we report, for the first time, the discovery, via structure-based virtual screen and chemical optimization, of such a small molecule, designated as HA-9104. HA-9104 binds to UBE2F, reduces its protein levels, and consequently inhibits cullin-5 neddylation. Blockage of cullin-5 neddylation inactivates cullin-RING ligase-5 (CRL5) activity, leading to accumulation of the CRL5 substrate, NOXA, to induce apoptosis. Moreover, HA-9104 appears to form the DNA adduct via its 7-azaindole group to induce DNA damage and G2/M arrest. Biologically, HA-9104 effectively suppresses the growth and survival of lung cancer cells and confers radiosensitization in both in vitro cell culture and in vivo xenograft tumor models. In summary, we discovered a small molecule, designated HA-9104, that targets the UBE2F-CRL5 axis with anti-cancer activity alone or in combination with radiation.

Natural products are an important source for proteasome regulating agents

BACKGROUND

Natural medicines have a long history in the prevention and treatment of various diseases in East Asian region, especially in China. Modern research has proved that the pharmacological effects of numerous natural medicines involve the participation of ubiquitin proteasome system (UPS). UPS can degrade the unwanted and damaged proteins widely distributed in the nucleus and cytoplasm of various eukaryotes.

PURPOSE

The objective of the present study was to review and discuss the regulatory effects of natural products and extracts on proteasome components, which may help to find new proteasome regulators for drug development and clinical applications.

METHODS

The related information was compiled using the major scientific databases, such as CNKI, Elsevier, ScienceDirect, PubMed, SpringerLink, Wiley Online, and GeenMedical. The keywords "natural product" and "proteasome" were applied to extract the literature. Nature derived extracts, compounds and their derivatives involved in proteasome regulation were included, and the publications related to synthetic proteasome agents were excluded.

RESULTS

The pharmacological effects of more than 80 natural products and extracts derived from phytomedicines related to the proteasome regulation were reviewed. These natural products were classified according to their chemical properties. We also summarized some laws of action of natural products as proteasome regulators in the treatment of diseases, and listed the action characteristics of the typical natural products.

CONCLUSION

Natural products derived from nature can induce the degradation of damaged proteins through UPS or act as regulators to directly regulate the activity of proteasome. But few proteasome modulators are applied clinically. Summary of known rules for proteasome modulators will contribute to discover, modify and synthesize more proteasome modulators for clinical applications.

Identification of uterine leiomyosarcoma-associated hub genes and immune cell infiltration pattern using weighted co-expression network analysis and CIBERSORT algorithm

BACKGROUND

While large-scale genomic analyses symbolize a precious attempt to decipher the molecular foundation of uterine leiomyosarcoma (ULMS), bioinformatics results associated with the occurrence of ULMS based totally on WGCNA and CIBERSORT have not yet been reported. This study aimed to screen the hub genes and the immune cell infiltration pattern in ULMS by bioinformatics methods.

METHODS

Firstly, the GSE67463 dataset, including 25 ULMS tissues and 29 normal myometrium (NL) tissues, was downloaded from the public database. The differentially expressed genes (DEGs) were screened by the 'limma' package and hub modules were identified by weighted gene co-expression network analysis (WGCNA). Subsequently, gene function annotations were performed to investigate the biological role of the genes from the intersection of two groups (hub module and DEGs). The above genes were calculated in the protein-protein interaction (PPI) network to select the hub genes further. The hub genes were validated using external data (GSE764 and GSE68295). In addition, the differential immune cell infiltration between UL and ULMS tissues was investigated using the CIBERSORT algorithm. Finally, we used western blot to preliminarily detect the hub genes in cell lines.

RESULTS

WGCNA analysis revealed a green-yellow module possessed the highest correlation with ULMS, including 1063 genes. A total of 172 DEGs were selected by thresholds set in the 'limma' package. The above two groups of genes were intersected to obtain 72 genes for functional annotation analysis. Interestingly, it indicated that 72 genes were mainly involved in immune processes and the Neddylation pathway. We found a higher infiltration of five types of cells (memory B cells, M0-type macrophages, mast cells activated, M1-type macrophages, and T cells follicular helper) in ULMS tissues than NL tissues, while the infiltration of two types of cells (NK cells activated and mast cells resting) was lower than in NL tissues. In addition, a total of five genes (KDR, CCL21, SELP, DPT, and DCN) were identified as the hub genes. Internal and external validation demonstrated that the five genes were over-expressed in NL tissues compared with USML tissues. Finally, the correlation analysis results indicate that NK cells activated and mast cells activated positively correlated with the hub genes. However, M1-type macrophages had a negative correlation with the hub genes. Moreover, only the DCN may be associated with the Neddylation pathway.

CONCLUSION

A series of evidence confirm that the five hub genes and the infiltration of seven types of immune cells are related to USML occurrence. These hub genes may affect the occurrence of USML through immune-related and Neddylation pathways, providing molecular evidence for the treatment of USML in the future.