E3 Ubiquitin Ligase APC/CCdh1 Negatively Regulates FAH Protein Stability by Promoting Its Polyubiquitination

E3 ubiquitin ligase APC/CCdh1 regulates SLC35F2 protein turnover and inhibits cancer progression in HeLa cells

BACKGROUND

The solute carrier family 35 F2 (SLC35F2), belongs to membrane-bound carrier proteins that control various physiological functions and are activated in several cancers. However, the molecular mechanism regulating SLC35F2 protein turnover and its implication in cancer progression remains unexplored. Therefore, screening for E3 ligases that promote SLC35F2 protein degradation is essential during cancer progression.

METHODS

The immunoprecipitation and Duolink proximity ligation assays (PLA) were used to determine the interaction between APC/CCdh1 and SLC35F2 proteins. A CRISPR/Cas9-mediated knockdown and rescue experiment were used to validate the functional significance of APC/CCdh1 on SLC35F2 protein stabilization. The ubiquitination function of APC/CCdh1 on SLC35F2 protein was validated using in vitro ubiquitination assay and half-life analysis. The role of APC/CCdh1 regulating SLC35F2-mediated tumorigenesis was confirmed by in vitro oncogenic experiments in HeLa cells.

RESULTS

Based on the E3 ligase screen and in vitro biochemical experiments, we identified that APC/CCdh1 interacts with and reduces SLC35F2 protein level. APC/CCdh1 promotes SLC35F2 ubiquitination and decreases the half-life of SLC35F2 protein. On the other hand, the CRISPR/Cas9-mediated depletion of APC/CCdh1 increased SLC35F2 protein levels. The mRNA expression analysis revealed a negative correlation between APC/CCdh1 and SLC35F2 across a panel of cancer cell lines tested. Additionally, we demonstrated that depletion in APC/CCdh1 promotes SLC35F2-mediated cell proliferation, colony formation, migration, and invasion in HeLa cells.

CONCLUSION

Our study highlights that APC/CCdh1 is a critical regulator of SLC35F2 protein turnover and depletion of APC/CCdh1 promotes SLC35F2-mediated tumorigenesis. Thus, we envision that APC/CCdh1-SLC35F2 axis might be a therapeutic target in cancer.

PRSS37 deficiency leads to impaired energy metabolism in testis and sperm revealed by DIA-based quantitative proteomic analysis

Our previous studies have reported that a putative trypsin-like serine protease, PRSS37, is exclusively expressed in testicular germ cells during late spermatogenesis and essential for sperm migration from the uterus into the oviduct and sperm-egg recognition via mediating the interaction between PDILT and ADAM3. In the present study, the global proteome profiles of wild-type (wt) and Prss37^-/- mice in testis and sperm were compared employing data independent acquisition (DIA) technology. Overall, 2506 and 459 differentially expressed proteins (DEPs) were identified in Prss37-null testis and sperm, respectively, when compared to control groups. Bioinformatic analyses revealed that most of DEPs were related to energy metabolism. Of note, the DEPs associated with pathways for the catabolism such as glucose via glycolysis, fatty acids via β-oxidation, and amino acids via oxidative deamination were significantly down-regulated. Meanwhile, the DEPs involved in the tricarboxylic acid cycle (TCA cycle) and oxidative phosphorylation (OXPHOS) were remarkably decreased. The DIA data were further confirmed by a markedly reduction of intermediate metabolites (citrate and fumarate) in TCA cycle and terminal metabolite (ATP) in OXPHOS system after disruption of PRSS37. These outcomes not only provide a more comprehensive understanding of the male fertility of energy metabolism modulated by PRSS37 but also furnish a dynamic proteomic resource for further reproductive biology studies.

Dietary soy, pork and chicken proteins induce distinct nitrogen metabolism in rat liver

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Dietary amino acid composition affected nitrogen metabolism in rat liver.

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Amino acid metabolizing enzymes were downregulated by meat protein diets.

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Ribosome assembly and protein synthesis were regulated by diet by mTOR pathway.

Diets have been shown to alter metabolism and gene expression. However, few data are available about changes in gene expression in liver after intake of different meat protein diets. This work aimed to explore the long-term effects of protein source on liver metabolic enzymes. Rats were fed protein diets for 90 days to study whether intake of chicken and pork protein diets promoted gene expression involved in hepatic metabolism. Liver proteome profiles were measured by iTRAQ labeling and LC–ESI–MS/MS. Chicken protein diet induced higher level of serum amino acids in rats than soy protein. Amino acid metabolizing enzymes were downregulated by pork and chicken protein diets compared with soy protein diet. Intake of meat protein diets downregulated enzymes involved in protein synthesis, disulfide bond formation, signal peptide addition, transport, localization, degradation and glycosylation modification, but upregulated enzymes involved in prolyl cis–trans isomerization for protein synthesis. Protein diets from different sources affected the amino acid supply, and further influenced ribosome assembly and protein synthesis through mTOR signaling pathway.