The COP9 signalosome subunit 3 is necessary for early embryo survival by way of a stable protein deposit in mouse oocytes.

Investigations of genes required in early mammalian development are complicated by protein deposits of maternal products, which continue to operate after the gene locus has been disrupted. This leads to delayed phenotypic manifestations and underestimation of the number of genes known to be needed during the embryonic phase of cellular totipotency. Here we expose a critical role of the gene Cops3 by showing that it protects genome integrity during the 2-cell stage of mouse development, in contrast to the previous functional assignment at postimplantation. This new role is mediated by a substantial deposit of protein (94th percentile of the proteome), divided between an exceptionally stable cortical rim, which is prevalent in oocytes, and an ancillary deposit in the embryonic nuclei. Since protein abundance and stability defeat prospects of DNA- or RNA-based gene inactivation in oocytes, we harnessed a classical method next to an emerging method for protein inactivation: antigen masking (for functional inhibition) versus TRIM21-mediated proteasomal degradation, also known as 'Trim away' (for physical removal). Both resulted in 2-cell embryo lethality, unlike the embryos receiving anti-green fluorescent protein. Comparisons between COPS3 protein-targeted and non-targeted embryos revealed large-scale transcriptome differences, which were most evident for genes associated with biological functions critical for RNA metabolism and for the preservation of genome integrity. The gene expression abnormalities associated with COPS3 inactivation were confirmed in situ by the occurrence of DNA endoreduplication and DNA strand breaks in 2-cell embryos. These results recruit Cops3 to the small family of genes that are necessary for early embryo survival. Overall, assigning genes with roles in embryogenesis may be less safe than assumed, if the protein products of these genes accumulate in oocytes: the inactivation of a gene at the protein level can expose an earlier phenotype than that identified by genetic techniques such as conventional gene silencing.

PDIA6 promotes pancreatic cancer progression and immune escape through CSN5-mediated deubiquitination of ß-catenin and PD-L1.

Protein Disulfide Isomerase Family A Member 6 (PDIA6) is an endoplasmic reticulum protein that is capable of catalyzing protein folding and disulfide bond formation. Abnormally elevated expression of PDIA6 has been reported to predict poor outcomes in various cancers. Herein, gain-of- and loss-of-function experiments were performed to investigate how PDIA6 participated in the carcinogenesis of pancreatic cancer (PC). By analyzing the protein expression of PDIA6 in 28 paired PC and para carcinoma specimens, we first found that PDIA6 expression was higher in PC samples. Both the overall survival and disease-free survival rates of PC patients with higher PDIA6 expression were poorer than those with lower PDIA6 (n = 178). Furthermore, knockdown of PDIA6 impaired the malignancies of PC cells - suppressed cell proliferation, invasion, migration, cisplatin resistance, and xenografted tumor growth. PDIA6-silenced PC cells were more sensitive to cytotoxic natural killer (NK) cells. Overexpression of PDIA6 had opposite effects on PC cells. Interestingly, COP9 signalosome subunit 5 (CSN5), a regulator of E3 ubiquitin ligases known to promote deubiquitination of its downstream targets, was demonstrated to interact with PDIA6, and its expression was increased in PC cells overexpressing PDIA6. Additionally, PDIA6 overexpression promoted deubiquitination of ß-catenin and PD-L1 and subsequently upregulated their expression in PC cells. These alterations were partly reversed by CSN5 shRNA. Collectively, the above results demonstrate that PDIA6 contributes to PC progression, which may be associated with CSN5-regulated deubiquitination of ß-catenin and PD-L1. Our findings suggest PDIA6 as a potential target for the treatment of PC.

Knockdown of COPS3 inhibits the progress of prostate cancer through reducing phosphorylated p38 MAPK expression and impairs the epithelial-mesenchymal transition process.

BACKGROUND: The amplification of gene COPS3 is closely related to the development of osteosarcoma and hepatocellular carcinoma. However, the effects of COPS3 on prostate cancer (PCa) are poorly understood. METHODS: In this study, the protein expression of COPS3 in PCa tissues, adjacent normal tissues, and bone metastasis tissues of PCa was analyzed by immunohistochemistry. Furthermore, cell proliferation, colony formation, migration, and invasion assay were performed in 22rv1 and PC-3 cells after knocking down COPS3 by small interfering RNAs. Furthermore, we performed western blot analysis to explore the potential mechanisms underlying it. RESULTS: This study found that the overall survival of the COPS3 high-expression group was significantly shorter than the low-expression group. This study discovered that the protein expression of COPS3 in PCa tissues was higher than that in the matched nontumor prostate tissues. In addition, tissues from bone metastasis of PCa had a high percentage of overexpressing COPS3. After knockdown of the COPS3 gene in 22rv1 and PC3 cells, two classic human PCa cell lines which had a high level of COPS3, the abilities of migration, invasion, and proliferation were inhibited. Finally, protein levels of phosphorylated P38 mitogen-activated protein kinase (MAPK) and N-cadherin were significantly decreased after knocking down the expression of COPS3, and the protein levels of E-cadherin were significantly increased. CONCLUSIONS: In conclusion, COPS3 may be closely related to the progress of PCa. Knockdown of COPS3 inhibited the progress of PCa through reducing the levels of phosphorylated P38 MAPK and impaired the epithelial-mesenchymal transition process.