Research progress in the role of E3 ubiquitin ligases in viral infection / 中华微生物学和免疫学杂志

Ubiquitination modifications are a kind of post-translational modifications of proteins widely found in eukaryotes and involved in a variety of biological activities. E3 ubiquitin ligases are an important component of the ubiquitin system, with the function of specific recognition of substrate proteins and mediation of different types of ubiquitination modifications. They can regulate the function and life time of substrate proteins. Recent studies have shown that E3 ubiquitin ligases are widely involved in the regulation of the host innate immune response and can directly or indirectly influence viral infection. Moreover, viruses are able to encode or hijack E3 ubiquitin ligases in their long-term evolution, allowing them to play an important role in viral infection and replication cycle. This paper reviewed the progress in the mechanisms of E3 ubiquitin ligases in innate immune responses and viral infection in recent years.

Effect of Gandou Decoction on Mitophagy in Toxic Milk （TX） Mouse Model of Wilson Disease Based on Pink1/Parkin Pathway / 中国实验方剂学杂志

ObjectiveTo investigate the effects of Gandou decoction （GDD） on the mitophagy of hippocampal neurons in toxic milk （TX） mouse model of Wilson disease and explore the protective mechanism of GDD against neuron injury through the PTEN induced kinase 1 （Pink1） /E3 ubiquitin ligase （Parkin） pathway. MethodSixty mice were randomly divided into a blank group， a model group， a penicillamine group （0.09 g·kg-1）， and low- （5.5 g·kg-1）， medium- （11 g·kg-1）， and high-dose （22 g·kg-1） GDD groups， and treated correspondingly by gavage for 8 weeks. Morris water maze， traction test， and pole test were used for the evaluation of animal behaviors. Hematoxylin-eosin （HE） staining and transmission electron microscopy were used to observe cell apoptosis， ultrastructure， autophagy， and mitochondrial structure. The levels of superoxide dismutase （SOD）， reactive oxygen species （ROS）， and malondialdehyde （MDA） were detected by enzyme-linked immunosorbent assay （ELISA）. Real-time fluorescence-based quantitative polymerase chain reaction （Real-time PCR） was used to detect the mRNA expression of Pink1， Parkin， autophagy-associated protein Beclin-1， microtubule-associated protein 1 light chain 3Ⅱ （LC3Ⅱ）， and p62. Western blot was conducted to detect the protein expression of Pink1， Parkin， Beclin-1， LC3Ⅱ/Ⅰ， and p62. ResultCompared with the blank group， the model group showed prolonged escape latency， decreased times of platform crossing， lower score in the traction test， and longer pole climbing time （P<0.01）. Compared with the model group， the medium- and high-dose GDD groups and the penicillamine group showed shortened escape latencies， increased times of platform crossing， higher scores in the traction test， and shortened pole climbing time （P<0.01）. Compared with the blank group， the model group displayed severely damaged neurons and increased autophagosomes. Compared with the model group， the medium- and high-dose GDD groups and the penicillamine group showed improved neuron damage and reduced autophagosomes. The levels of ROS and MDA were higher and SOD was lower in the model group than those in the blank group （P<0.01）， while the levels of the above indicators were reversed by GDD intervention as compared with the model group （P<0.01）. Compared with the blank group， the model group exhibited up-regulated mRNA and protein expression of Pink1， Parkin， LC3Ⅱ， and Beclin-1 and down-regulated p62 （P<0.05）. Compared with the model group， the medium- and high-dose GDD groups showed reduced mRNA and protein expression of Pink1， Parkin， LC3Ⅱ， and Beclin-1 and increased p62 （P<0.05， P<0.01）. ConclusionGDD can significantly inhibit the excessive mitophagy in neurons of TX mice and protect neurons from damage. The mechanism may be related to the regulation of the Pink1/Parkin pathway.

mTOR-targeted cancer therapy: great target but disappointing clinical outcomes, why? / 医学前沿

The mammalian target of rapamycin (mTOR) critically regulates several essential biological functions, such as cell growth, metabolism, survival, and immune response by forming two important complexes, namely, mTOR complex 1 (mTORC1) and complex 2 (mTORC2). mTOR signaling is often dysregulated in cancers and has been considered an attractive cancer therapeutic target. Great efforts have been made to develop efficacious mTOR inhibitors, particularly mTOR kinase inhibitors, which suppress mTORC1 and mTORC2; however, major success has not been achieved. With the strong scientific rationale, the intriguing question is why cancers are insensitive or not responsive to mTOR-targeted cancer therapy in clinics. Beyond early findings on induced activation of PI3K/Akt, MEK/ERK, and Mnk/eIF4E survival signaling pathways that compromise the efficacy of rapalog-based cancer therapy, recent findings on the essential role of GSK3 in mediating cancer cell response to mTOR inhibitors and mTORC1 inhibition-induced upregulation of PD-L1 in cancer cells may provide some explanations. These new findings may also offer us the opportunity to rationally utilize mTOR inhibitors in cancer therapy. Further elucidation of the biology of complicated mTOR networks may bring us the hope to develop effective therapeutic strategies with mTOR inhibitors against cancer.

Degradation of proteins by PROTACs and other strategies

Blocking the biological functions of scaffold proteins and aggregated proteins is a challenging goal. PROTAC proteolysis-targeting chimaera (PROTAC) technology may be the solution, considering its ability to selectively degrade target proteins. Recent progress in the PROTAC strategy include identification of the structure of the first ternary eutectic complex, extra-terminal domain-4-PROTAC-Von-Hippel-Lindau (BRD4-PROTAC-VHL), and PROTAC ARV-110 has entered clinical trials for the treatment of prostate cancer in 2019. These discoveries strongly proved the value of the PROTAC strategy. In this perspective, we summarized recent meaningful research of PROTAC, including the types of degradation proteins, preliminary biological data in vitro and in vivo, and new E3 ubiquitin ligases. Importantly, the molecular design, optimization strategy and clinical application of candidate molecules are highlighted in detail. Future perspectives for development of advanced PROTAC in medical fields have also been discussed systematically.

Mechanism of Effect of Ubiquitination Modification Mediated by E3 Ubiquitin Ligase in Inflammatory Bowel Disease / 胃肠病学

Ubiquitination is the important type of post-translational modification of proteins, and its main effects include protein degradation and functional regulation. Studies have shown that abnormal ubiquitination is involved in the development and progress of inflammatory bowel disease (IBD), which makes some ubiquitinases and their antibodies having the potential to be important markers for clinical diagnosis and evaluation of severity of Crohn's disease (CD). This article reviewed the research on mechanism of effect of ubiquitination modification mediated by E3 ubiquitin ligase in IBD.

Progress in research on the novel cancer therapeutic target Cdc20 / 药学学报

The anaphase promoting complex (APC) regulates cell cycle progression by forming two functionally distinct E3 ubiquitin ligase complexes, APCCdc20 activated by cell division cycle protein 20 (Cdc20) and APCCdh1 activated by Cdc20 homologue 1 (Cdh1), respectively. Cdc20 and Cdh1 have different functions in the occurrence and development of the tumor. Cdc20 is a cancer promoter while Cdh1 suppresses tumorigenesis. Emerging evidence has begun to reveal that Cdc20 has positive functions in tumorigenesis, the overexpression of Cdc20 has been observed in many cancers. Currently, Cdc20 inhibitors, mostly non-specific inhibitors except apcin, not only block the combination between Cdc20 and APC, also block the combination between Cdh1 and APC, which leads to a poor selectivity. In this paper, the Cdc20 role in the development and process of cancers and its inhibitors are reviewed.

Role of RNF87 in predicting the prognosis of human hepatocellular carcinoma patients / 中国现代普通外科进展

Objective:To investigate the level and prognostic significance of RNF87 in human hepatocellular carcinoma.Methods:Detected the expression of RNF87 in 98 HCC tissues by immunohistochemistry and Western Blot.According to the clinical data of the patients,we analyzed the relationship between RNF87 level and the prognosis of the HCC patients.Results:The level of RNF87 in HCC tissues is down-regulated,compared with the adjacent tissues.And the expression of RNF87 was significantly related to the prognosis of HCC patients.Besides,the lower level of RNF87 was also obviously related with microvascular invasion.Conclusions:The down-regulated level of RNF87 may be one of the risk factors of human hepatocellular carcinoma progression;RNF87 maybe one of potential tumor suppressors;the level of RNF87 can be used as an indicator to predict the prognosis of HCC patients.

Loss of Ovarian Function Results in Increased Loss of Skeletal Muscle in Arthritic Rats / Perda da função ovariana resulta em perda de músculo esquelético aumentada em ratos artríticos

Objective We studied the effects of loss of ovarian function (ovariectomy) onmuscle mass of gastrocnemius and themRNA levels of IGF-1, atrogin-1, MuRF-1, andmyostatin in an experimental model of rheumatoid arthritis in rats. Methods We randomly allocated 24 female Wistar rats (9 weeks, 195.3±17.4 grams) into four groups: control (CT-Sham; n = 6); rheumatoid arthritis (RA; n = 6); ovariectomy without rheumatoid arthritis (OV; n = 6); ovariectomy with rheumatoid arthritis (RAOV; n = 6). We performed the ovariectomy (OV and RAOV) or Sham (CTSham or RA) procedures at the same time, fifteen days before the rheumatoid arthritis induction. The RA and RAOV groups were immunized and then were injected with Met- BSA in the tibiotarsal joint. After 15 days of intra-articular injections the animals were euthanized. We evaluated the external manifestations of rheumatoid arthritis (perimeter joint) as well as animal weight, and food intake throughout the study. We also analyzed the cross-sectional areas (CSA) of gastrocnemius muscle fibers in 200 fibers (H&E method). In the gastrocnemius muscle, we analyzed mRNA expression by quantitative real time PCR followed by the Livak method (ΔΔCT). Results The rheumatoid arthritis induced reduction in CSA of gastrocnemius muscle fibers. The RAOV group showed a lower CSA of gastrocnemius muscle fibers compared to RA and CT-Sham groups. Skeletal muscle IGF-1 mRNA increased in arthritics and ovariectomized rats. The increased IGF-1 mRNA was higher in OV groups than in the RA and RAOV groups. Antrogin-1 mRNA also increased in the gastrocnemius muscle of arthritic and ovariectomized rats. However, the increased atrogin-1 mRNA was higher in RAOV groups than in the RA and OV groups. Gastrocnemius muscle MuRF-1 mRNA increased in the OVand RAOVgroups, but not in the RA and Shamgroups. However, the RAOV group showed higher MuRF-1 mRNA than the OV group. The myostatin gene expression was similar in all groups. Conclusion Loss of ovarian function results in increased loss of skeletal musclerelated ubiquitin ligases atrogin-1 and MuRF-1 in arthritic rats.

Objetivo Foram estudados os efeitos da perda da função ovariana (ovariectomia) sobre músculo esquelético e os níveis de RNAm de IGF-1, atrogina-1, MuRF-1, e de miostatina em modelo experimental de artrite reumatóide em ratos. Métodos 24 ratos Wistar (9 semanas, 195,3±17,4 gramas) foram distribuídos aleatoriamente em quatro grupos: controle (CT-Sham, n = 6); artrite reumatóide (RA, n = 6); ovariectomia sem artrite reumatóide (OV; n = 6); ovariectomia com artrite reumatóide (RAOV; n = 6). Os procedimentos da ovariectomia (OV e RAOV) ou simulação da ovariectomia (CT-Shamou RA) foramrealizados aomesmo tempo, quinze dias antes da indução da artrite reumatóide. Os grupos RA e RAOV foramimunizados e, em seguida, foram injetados com Met-BSA na articulação tibiotársica. Após 15 dias das injeções intra-articulares, os animais foram eutanasiados. Foram avaliadas as manifestações externas da artrite reumatóide (perimetria articular), bem como o peso dos animais e a ingestão de alimentos ao longo do estudo. Além disso, as áreas de secção transversa (CSA) do músculo gastrocnêmio foram analisadas em 200 fibras (método H & E). No músculo gastrocnêmio, a expressão de RNAm foi analisada por PCR quantitativo em tempo real, seguido pelo método Livak (ΔΔCT). Resultados A artrite reumatoide reduziu a CSA das fibras do músculo gastrocnêmio. O grupo RAOV mostrou uma CSA menor nas fibras do músculo gastrocnêmio em comparação com os grupos RA e CT-Sham. O RNAm do IGF-1 do músculo esquelético aumentou nos ratos artríticos e ovariectomizados. O RNAm do IGF-1 foi maior nos grupos OV do que nos grupos RA e RAOV. A expressão de antrogina-1 também aumentou no músculo gastrocnêmio dos ratos artríticos e ovariectomizados. No entanto, o aumento do RNAm da atrogina-1 foi maior no grupo RAOV do que nos grupos RA e OV. O RNAm da MuRF-1 aumentou nos grupos OV e RAOV, mas não nos grupos RA e CT-Sham. Porém, o grupo RAOV apresentou maior expressão gênica de MuRF-1 do que o grupo OV. A expressão do gene da miostatina foi semelhante em todos os grupos. Conclusão A perda de função ovariana resulta em perda de músculo esquelético associado às ubiquitina-ligases atrogina-1 e MuRF-1 em ratos artríticos.

The Role of E3 Ubiquitin Ligase Smurfs in BMP and TGF-bata Signaling in Bone Cells / 生物化学与生物物理进展

The ubiquitin-proteasome system is composed by multiple enzymes which are ubiquitously expressed in mammalian cells and plays an essential role in a variety of biological processes. As key members of the protein degradation enzymatic system, the function of E3 ubiquitin ligases has been extensively investigated. BMP and TGF-? are critical molecules that regulate proliferation, differentiation and apoptosis of osteoblasts and chondrocytes through different signaling pathways. Resent findings indicate that the ubiquitin-proteasome system functions as a key regulator in bone cells and the E3 ligase mediates the proteolytic degradation of critical molecules in BMP and TGF-? signaling pathways. Recent progress on studies of HECT domain E3 ligase, Smurf, in osteoblasts and chondrocytes were summarized. The regulatory role of Smurf1 and Smurf2 in BMP and TGF-? signaling and osteoblast and chondrocyte function has been reviewed.