Advances in peptidyl Asx-specific ligases for the application of cyclic peptides / 药学学报

Asparaginyl endopeptidases (AEPs) in plants belong to the family of cysteine protease that undergo self-activation in the form of zymogen in acidic vacuole and play important physiological roles in maturation of seed storage proteins, protein degradation, programmed cell death and host defense. Bioprocessing enzymes (peptidyl Asx-specific ligases, PALs) that promote the maturation of cyclotides have recently been isolated and identified from several cyclotide-rich plants. PALs derived from AEPs can site-specifically catalyze the formation of asparagine or aspartate peptide bonds. Due to the advantages of relatively traceless peptide bonds and broad substrate spectrum and high catalytic efficiency, they have been playing important roles in the cyclization and modification of peptides and proteins, and are powerful tools for improving the stability of peptide drugs. This review describes the physiological functions of AEPs in plants and summarizes the discoveries, structural characteristics, catalytic mechanism and protein engineering of PALs, as well as the limitation of their applications and future trends. In addition, the applications of PALs in cyclotides biosynthesis and the development of macrocyclic peptides are highlighted, with the aim of providing a new idea for the biocatalytic synthesis of cyclic peptides.

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.

The Ubiquitin Ligase SMURF1 Catalyzes the Polyubiquitination of ADAR1 / 中国生物化学与分子生物学报

It is known that SMAD specific E3 ubiquitin protein ligase 1 (SMURF1) mediates autophagy through its E3 ubiquitin ligase activity, but the ubiquitinated substrates of SMURF1 need to be further explored. In this paper, the interacting proteins of SMURF1 in THP-1 cells were captured and identified by co-immunoprecipitation (Co-IP) combined with mass spectrometry. It was found that SMURF1 could physically bind to 222 proteins in THP-1 cells, and Adenosine deaminase acting on RNA 1 (ADAR1) had a higher peptide binding score. SMURF1 overexpression vectors were constructed and transfected into HEK-293T cells, then Co-IP and Western blotting assays verified the interaction between exogenous SMURF1 and endogenous ADAR1. qRT-PCR and Western blotting assays were carried out after transfecting SMURF1 overexpression vectors in HEK-293T cells, which identified that overexpression of SMURF1 attenuated the protein levels of ADAR1 (P<0. 05). However, there was no significant difference in the mRNA level of ADAR1. HEK-293T cells with normal and overexpressing SMURF1 were treated with cycloheximide (CHX), respectively, and Western blotting assays showed a shortened half-life of ADAR1 after overexpression of SMURF1 (P < 0. 05). Furthermore, overexpression of SMURF1 increased the polyubiquitination level of ADAR1 as detected by Co-IP and Western blot (P<0. 05). After the proteasome inhibitor (MG132) treatment, the Western blotting assay was performed to demonstrate that the negative regulatory effect of SMURF1 on ADAR1 was weakened after the proteasome degradation pathway was attenuated (P<0. 05). This study shows that SMURF1 interacts with ADAR1, catalyzes the polyubiquitination of ADAR1 and mediates its degradation through the proteasome pathway, which provides a theoretical basis for exploring the various biological functions of SMURF1 by affecting the stability of ADAR1.

The reversal effect of albiflorin on multidrug resistance of human ovarian cancer and its mechanism / 中国药理学通报

Aim To study the reversal effect of albiflorin(AL)on multidrug resistance of human ovarian cancer and the potential mechanism. Methods The drug resistance reversal effect of AL on SKOV3/DDP cells was detected by CCK-8 kit,and the effect of AL on P-glycoprotein(P-gp)function was detected by flow cytometry. The effects of AL on MYC,WWP1 and ABCB1 in SKOV3/DDP cells were detected by RT-qPCR and Western blot. The MYC-knockdown SKOV3/DDP cell line was constructed by RNA interference technology,and its drug resistance,P-gp function and related gene and protein expression changes were investigated. Results AL had a drug resistance reversal effect on SKOV3/DDP cells and a concentration-dependent inhibitory effect on P-gp function. The inhibitory effects of AL 25,50 and 100 μmol·L-1 on ABCB1/P-gp,MYC and WWP1 were gradually enhanced. The inhibitory effect of MYCi975,a MYC inhibitor,on ABCB1/P-gp,MYC and WWP1 was stronger than or equivalent to that of AL 100 μmol·L-1 group. After knockdown of MYC in SKOV3/DDP cells,cell drug resistance,P-gp function,and related gene and protein expression were inhibited. Conclusions The drug resistance reversal effect of AL on SKOV3/DDP cells may be related to the inhibition of P-gp function and the expression of ABCB1/P-gp,MYC and WWP1,which provides an experiment base for the development of AL as a drug resistance reversal agent for the clinical treatment of ovarian cancer.

Function, mechanism and drug discovery of ubiquitin and ubiquitin-like modification with multiomics profiling for cancer therapy

Ubiquitin (Ub) and ubiquitin-like (Ubl) pathways are critical post-translational modifications that determine whether functional proteins are degraded or activated/inactivated. To date, >600 associated enzymes have been reported that comprise a hierarchical task network (e.g., E1-E2-E3 cascade enzymatic reaction and deubiquitination) to modulate substrates, including enormous oncoproteins and tumor-suppressive proteins. Several strategies, such as classical biochemical approaches, multiomics, and clinical sample analysis, were combined to elucidate the functional relations between these enzymes and tumors. In this regard, the fundamental advances and follow-on drug discoveries have been crucial in providing vital information concerning contemporary translational efforts to tailor individualized treatment by targeting Ub and Ubl pathways. Correspondingly, emphasizing the current progress of Ub-related pathways as therapeutic targets in cancer is deemed essential. In the present review, we summarize and discuss the functions, clinical significance, and regulatory mechanisms of Ub and Ubl pathways in tumorigenesis as well as the current progress of small-molecular drug discovery. In particular, multiomics analyses were integrated to delineate the complexity of Ub and Ubl modifications for cancer therapy. The present review will provide a focused and up-to-date overview for the researchers to pursue further studies regarding the Ub and Ubl pathways targeted anticancer strategies.

The F-box-only protein 44 regulates pregnane X receptor protein level by ubiquitination and degradation

Pregnane X receptor (PXR) is a ligand-activated nuclear receptor that transcriptionally upregulates drug-metabolizing enzymes [e.g., cytochrome P450 3A4 (CYP3A4)] and transporters. Although the regulation of PXR target genes is well-characterized, less is known about the regulation of PXR protein level. By screening an RNAi library, we identified the F-box-only protein 44 (FBXO44) as a novel E3 ligase for PXR. PXR abundance increases upon knockdown of FBXO44, and, inversely, decreases upon overexpression of FBXO44. Further analysis revealed that FBXO44 interacts with PXR, leading to its ubiquitination and proteasomal degradation, and we determined that the F-box associated domain of FBXO44 and the ligand binding domain of PXR are required for the functional interaction. In summary, FBXO44 regulates PXR protein abundance, which has downstream consequences for CYP3A4 levels and drug-drug interactions. The results of this study provide new insight into the molecular mechanisms that regulate PXR protein level and activity and suggest the importance of considering how modulating E3 ubiquitin ligase activities will affect PXR-mediated drug metabolism.

The role of E3 ubiquitin ligases in bone homeostasis and related diseases

The ubiquitin-proteasome system (UPS) dedicates to degrade intracellular proteins to modulate demic homeostasis and functions of organisms. These enzymatic cascades mark and modifies target proteins diversly through covalently binding ubiquitin molecules. In the UPS, E3 ubiquitin ligases are the crucial constituents by the advantage of recognizing and presenting proteins to proteasomes for proteolysis. As the major regulators of protein homeostasis, E3 ligases are indispensable to proper cell manners in diverse systems, and they are well described in physiological bone growth and bone metabolism. Pathologically, classic bone-related diseases such as metabolic bone diseases, arthritis, bone neoplasms and bone metastasis of the tumor, etc., were also depicted in a UPS-dependent manner. Therefore, skeletal system is versatilely regulated by UPS and it is worthy to summarize the underlying mechanism. Furthermore, based on the current status of treatment, normal or pathological osteogenesis and tumorigenesis elaborated in this review highlight the clinical significance of UPS research. As a strategy possibly remedies the limitations of UPS treatment, emerging PROTAC was described comprehensively to illustrate its potential in clinical application. Altogether, the purpose of this review aims to provide more evidence for exploiting novel therapeutic strategies based on UPS for bone associated diseases.

Effects of contusion and exhaustive exercise on murf1 and mafbx in the skeletal muscle of rats / Efectos de la contusión y del ejercicio exhaustivo sobre murf1 y mafbx en el músculo esquelético de ratas / Efeitos do trauma contuso e do exercício exaustivo no em murf1 e mafbx no músculo esquelético de ratos

ABSTRACT Objective To study the effects of contusion and exhaustive exercise on the expression of degradation-related factors MuRF1 and MAFbx in the skeletal muscle of rats and describe the repair mechanism of skeletal muscle injury. Methods Forty-two male SD rats were randomly divided into 7 groups. The rats in each group were killed at different time points (0h, 24h, 48h) after exhaustive exercise (E0, E24, E48) and contusion (D0, D24, D48), respectively, and in the resting state in control group (C). The right gastrocnemius muscles were resected and divided into two parts, one for the mRNAs of MuRF1 and MAFbx by real-time PCR, and the other for protein measurement by Western blotting. Results Compared with the control group, the MuRF1 mRNA and protein expression of the skeletal muscle in the E0 group was markedly increased (P <0.05) and followed by a downward trend in E24 the E48 groups. On the other hand, MuRF1 mRNA expression of the skeletal muscle in the D24 group was significantly upregulated (P <0.01), then decreased in the D48 group (P <0.01). Meanwhile, compared with the C group, MAFbx mRNA gene expression continued to be upregulated in D24 and D48 (P <0.05), but decreased in E24 and E48 (p<0.01). On the other hand, the NF-κB protein contents of the skeletal muscle in the D0, D24, and D48 groups, as well as in the E48 group, were markedly downregulated (P <0.05), and the one in E48 was also remarkably downregulated (P <0.05). Conclusion NF-κB may negatively regulate the process of protein degradation by the NF-κB / MuRF1 signal pathway. Level of evidence III; Therapeutic studies investigating the results of treatment.

RESUMEN Objetivo Estudiar los efectos de la contusión y del ejercicio exhaustivo sobre la expresión de los factores relacionados con la degradación MuRF1 y MAFbx en el músculo esquelético de ratas y describir el mecanismo de reparación de la lesión muscular esquelética. Métodos Cuarenta y dos ratas macho SD fueron divididas aleatoriamente en 7 grupos. Las ratas de cada grupo fueron sacrificadas en diferentes momentos (0h, 24h, 48h) después del ejercicio exhaustivo (E0, E24, E48) y de la contusión (D0, D24, D48), respectivamente, y en estado de reposo en el grupo de control (C). Se resecaron los músculos gastrocnemios derechos y se dividieron en dos partes, una para los ARNm de MuRF1 y MAFbx mediante PCR en tiempo real y la otra para la medición de proteínas mediante Western blot. Resultados En comparación con el grupo control, el ARNm de MuRF1 y la expresión proteica del músculo esquelético en el grupo E0 se incrementó notablemente (P <0,05) y fueron seguidos por una tendencia a la baja en los grupos E24 y E48. Por otra parte, la expresión del ARNm de MuRF1 del músculo esquelético en el grupo D24 fue significativamente regulada al alza (P <0,01), y luego disminuyó en el grupo D48 (P <0,01). Mientras tanto, en comparación con el grupo C, la expresión génica del ARNm de MAFbx permaneció regulada al alza en D24 y D48 (P <0,05), pero disminuyó en E24 y E48 (p<0,01). Por otro lado, el contenido de proteína NF-κB del músculo esquelético en los grupos D0, D24 y D48, así como en el grupo E48, se vio notablemente regulado a la baja (P <0,05), y el del grupo E48 también se vio notablemente regulado a la baja (P <0,05). Conclusión NF-κB puede regular negativamente el proceso de degradación de la proteína a través de la vía NF-κB / MuRF1. Nivel de evidencia III; Estudios terapéuticos que investigan los resultados del tratamiento.

RESUMO Objetivo Estudar os efeitos do trauma contuso e do exercício exaustivo na expressão dos fatores relacionados à degradação MuRF1 e MAFbx no músculo esquelético de ratos e descrever o mecanismo de reparo da lesão muscular esquelética. Métodos Quarenta e dois ratos SD machos foram divididos aleatoriamente em 7 grupos. Os ratos de cada grupo foram mortos em diferentes momentos (0h, 24h, 48h) após exercício exaustivo (E0, E24, E48) e trauma contuso (D0, D24, D48), respectivamente, e no estado de repouso no grupo controle (C). Os músculos gastrocnêmios direitos foram ressecados e divididos em duas partes, uma para os mRNAs de MuRF1 e MAFbx por PCR em tempo real e outra para a medição de proteínas a partir do Western blot. Resultados Em comparação com o grupo controle, o mRNA de MuRF1 e a expressão proteica do músculo esquelético no grupo E0 foram acentuadamente aumentados (P <0,05) e seguidos por uma tendência descendente nos grupos E24 e E48. Por outro lado, a expressão do mRNA de MuRF1 do músculo esquelético no grupo D24 foi significativamente regulada para cima (P <0,01), depois diminuiu no grupo D48 (P <0,01). Enquanto isso, em comparação com o grupo C, a expressão gênica do mRNA de MAFbx continuou regulada para cima em D24 e D48 (P <0,05), mas diminuiu em E24 e E48 (p<0,01). Por outro lado, os teores de proteína NF-κB do músculo esquelético nos grupos D0, D24 e D48, bem como no grupo E48, foram marcadamente regulados para baixo (P <0,05), e o do grupo E48 também foi notavelmente regulado para baixo (P <0,05). Conclusão NF-κB pode regular negativamente o processo de degradação da proteína pela via NF-κB / MuRF1. Nível de evidência III; Estudos terapêuticos que investigam os resultados do tratamento.

TRIB3 promotes pulmonary fibrosis through inhibiting SLUG degradation by physically interacting with MDM2

Pulmonary fibrosis (PF) is the pathological structure of incurable fibroproliferative lung diseases that are attributed to the repeated lung injury-caused failure of lung alveolar regeneration (LAR). Here, we report that repetitive lung damage results in a progressive accumulation of the transcriptional repressor SLUG in alveolar epithelial type II cells (AEC2s). The abnormal increased SLUG inhibits AEC2s from self-renewal and differentiation into alveolar epithelial type I cells (AEC1s). We found that the elevated SLUG represses the expression of the phosphate transporter SLC34A2 in AEC2s, which reduces intracellular phosphate and represses the phosphorylation of JNK and P38 MAPK, two critical kinases supporting LAR, leading to LAR failure. TRIB3, a stress sensor, interacts with the E3 ligase MDM2 to suppress SLUG degradation in AEC2s by impeding MDM2-catalyzed SLUG ubiquitination. Targeting SLUG degradation by disturbing the TRIB3/MDM2 interaction using a new synthetic staple peptide restores LAR capacity and exhibits potent therapeutic efficacy against experimental PF. Our study reveals a mechanism of the TRIB3-MDM2-SLUG-SLC34A2 axis causing the LAR failure in PF, which confers a potential strategy for treating patients with fibroproliferative lung diseases.

Mutación heterocigota, autosómica recesiva del gen RARS2 en una paciente colombiana de padres no consanguíneos / Autosomal recessive heterocygote mutation of the RARS2 gene in a colombian patient with non- consanguineous parents

Las nuevas metodologías de secuenciación masiva han permitido caracterizar e identificar variantes genéticas asociadas a diferentes patologías. En este trabajo se presenta el caso de una paciente con una mutación del gen RARS2 que codifica la enzima arginino-ARNt ligasa para la codificación de proteínas. Esta alteración genética se manifiesta en hipoplasia pontocerebelosa tipo 6, con una prevalencia de <1/1 000 0000, caracterizada por un cerebelo y un puente de menor tamaño asociados a un retraso grave en el neurodesarrollo. El análisis de caso permite un mejor conocimiento de enfermedades de origen genético, específicamente, de aquellas con patrones de herencia autosómicos recesivos de padres no consanguíneos. Su estudio sobre todo en lo relacionado con el ámbito familiar y socioeconómico, y su base genética, ayuda a una mejor calidad de vida de los pacientes y su familia.

The latest method of next-generation sequencing has allowed the characterization and identification of genetic variants associated to diverse pathologies. In this article, we present the case of female patient with a mutation of the RARS2 gene that encodes the enzyme for arginyl tRNA synthetase for coding of proteins. This genetic alteration manifests in pontocerebellar hypoplasia type 6, with a prevalence of <1/1,000,0000, characterized by a cerebellum and pons that are smaller in size and are associated with severe neurodevelopmental delay. The analysis of the case of this patient provides better knowledge of diseases of genetic origin; specifically, regarding genetic diseases of autosomal recessive patterns of inheritance from non-consanguineous parents. The impact of these studies; specially within the family, social, economic and genetic aspects helps provide a better quality of life for these patients and their family.

Puerarin Inhibits the Proliferation,Invasion,and Migration of Non-small Cell Lung Cancer Cells through Regulating miR-490/Denticleless E3 Ubiquitin Protein Ligase / 中国医学科学院学报

Objective To explore the mechanism of puerarin inhibiting the proliferation,invasion,and migration of non-small cell lung cancer cells. Methods A549 cells were cultured and treated with different concentrations of puerarin.The inhibition rate (IR) on cell proliferation was detected by CCK-8,and qRT-PCR was performed to detect the mRNA levels of miR-490 and denticleless E3 ubiquitin protein ligase(DTL).Double luciferase reporter assay was employed to identify the targets of miR-490 and DTL based on the establishment of NC mimic group,miR-490 mimic group,NC inhibitor group,and miR-490 inhibitor group.The cells treated by 20 μmol/L puerarin were classified into six groups:DMSO,puerarin,puerarin+NC inhibitor,puerarin+miR-490 inhibitor,puerarin+miR-490 inhibitor+Si-NC,and puerarin+miR-490 inhibitor+Si-DTL.Transwell was used to detect cell migration and invasion.Western blotting was performed to detect the protein levels of epithelial-mesenchymal transition-related markers E-cadherin,N-cadherin,and Vimentin. Results With the increase in puerarin concentration,the IR gradually elevated (F=105.375,P<0.001),miR-490 expression gradually increased (F=32.919,P<0.001),and DTL expression gradually decreased (F=116.120,P<0.001).Compared with NC mimic group,miR-490 mimic group had decreased luciferase activity (t=7.762,P=0.016),raised miR-490 mRNA level (t=13.319,P<0.001),and declined DTL mRNA level (t=7.415,P=0.002).Compared with those in NC inhibitor group,miR-490 demonstrated decreased mRNA level (t=9.523,P=0.001) and DTL presented increased mRNA level (t=11.305,P<0.001) in miR-490 inhibitor group.Western blotting showed that the protein level of DTL was higher in NC mimic group (t=7.953,P=0.001) than in miR-490 mimic group and higher in miR-490 inhibitor group than in NC inhibitor group (t=10.552,P<0.001).Compared with DMSO group,puerarin group showed up-regulated mRNA level of miR-490 (t=10.255,P=0.001) while down-regulated mRNA level of DTL (t=6.682,P=0.003).Compared with those in puerarin+NC inhibitor group,the mRNA level of miR-490 declined (t=10.995,P<0.001) while that of DTL raised (t=12.478,P<0.001) in puerarin+miR-490 inhibitor group.The mRNA level of miR-490 had no significant difference between puerarin+miR-490 inhibitor+Si-NC group and puerarin+miR-490 inhibitor+Si-DTL group (t=1.081,P=0.341),and that of DTL was lower in the latter group (t=14.321,P<0.001).The protein level of DTL was higher in puerarin+miR-490 inhibitor group than in puerarin+NC inhibitor group (t=11.423,P<0.001),and lower in puerarin+miR-490 inhibitor+Si-DTL group than in puerarin+miR-490 inhibitor+Si-NC group (t=12.080,P<0.001).Compared with DMSO group,puerarin group showed inhibited cell proliferation (F=129.27,P<0.001).The activity of cell proliferation was higher in puerarin+miR-490 inhibitor group than in puerarin+NC inhibitor group (F=75.12,P<0.001),and higher in puerarin+miR-490 inhibitor+Si-NC group than in puerarin+miR-490 inhibitor+Si-DTL group (F=52.59,P<0.001).Compared with DMSO group,puerarin group had suppressed cell migration (t=8.963,P=0.001).The cell migration ability was higher in puerarin+miR-490 inhibitor group than in puerarin+NC inhibitor group (t=12.117,P<0.001) and higher in puerarin+miR-490 inhibitor+Si-NC group than in puerarin+miR-490 inhibitor+Si-DTL group (t=12.934,P<0.001).Puerarin group showed weakened cell invasion ability compared with DMSO group (t=4.710,P=0.009).The cell invasion ability was higher in puerarin+miR-490 inhibitor group than in puerarin+NC inhibitor group (t=13.264,P<0.001) and lower in puerarin+miR-490 inhibitor+Si-DTL group than in puerarin+miR-490 inhibitor+Si-NC group (t=13.476,P<0.001).Compared with DMSO group,puerarin group showed up-regulated protein level of E-cadherin (t=7.137,P=0.002) while down-regulated protein levels of N-cadherin (t=8.828,P=0.001) and vimentin (t=6.594,P=0.003).Compared with those in puerarin+NC inhibitor group,the protein level of E-cadherin (t=12.376,P<0.001) decreased while those of N-cadherin (t=13.436,P<0.001) and vimentin (t=11.467,P<0.001) increased in puerarin+miR-490 inhibitor group.Compared with puerarin+miR-490 inhibitor+Si-NC group,puerarin+miR-490 inhibitor+Si-DTL group up-regulated the protein level of E-cadherin (t=13.081,P<0.001) while down-regulated the protein levels of N-cadherin (t=10.835,P<0.001) and vimentin (t=11.862,P<0.001). Conclusion Puerarin could inhibit the proliferation,invasion,and migration of non-small cell lung cancer cells by up-regulating miR-490 and down-regulating DTL.

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.

The mechanisms of type 2 diabetic skeletal muscle atrophy and the effects of commonly used hypoglycemic drugs: a review / 药学学报

Type 2 diabetes is a hypermetabolic disease characterized with disorders of glucose/lipid metabolism, absolute or relative lack of insulin, and can induce skeletal muscle atrophy. Hyperglycemia, hyperlipidemia, insulin resistance, and abnormal release of inflammatory factors can lead to abnormal signal transduction in skeletal muscle, thus make protein synthesis and degradation imbalance and eventually causing muscle atrophy. Under normal conditions, insulin-like growth factor 1 (IGF-1)/insulin can activate phosphoinositide 3-kinase (PI3K)/protein kinase B (AKT). AKT not only increases protein synthesis through mammalian target protein of rapamycin (mTOR), but also phosphorylates forkhead box O (FoxO) transcription factor and then inhibits the transcription of several ubiquitin ligases (such as MAFbx/atrogin-1 and MuRF1), or autophagy related genes. The weakened IGF-1/PI3K/AKT pathway in type 2 diabetes is an important factor leading to skeletal muscle atrophy. Studies have shown that the commonly used anti-type 2 diabetic drugs have different effects in regulating the synthesis and degradation of skeletal muscle protein. Studies reported that drugs with effect of anti-diabetic muscle atrophy include thiazolidinediones, glucagon-like peptide analogs, glucose-sodium cotransporter 2 inhibitors, etc.; drugs that are still in controversial or even promote skeletal muscle atrophy include metformin, and some sulfonylurea or non-sulfonylurea insulin secretagogues. This article overviewed and analyzed the currently commonly used drugs for type 2 diabetes and summarized the related mechanisms, with the aim to provide references for the rational applications of drugs for type 2 diabetes.

Recombinant Expression and Purification of F-box and Leucine-rich Repeat Protein 5 (FBXL5) using a Prokaryotic Expression System

Background@#The F-box and Leucine-rich Repeat Protein 5 (FBXL5), a member of the E3 ligases, is considered to be the central iron sensor in mammals. The cryo-EM structure of FBXL5 in complex with IRP2 and SKP1 was reported by Wang et.al. in 2020. Surprisingly, a 2Fe-2S cluster seemed to be responsible for the iron-sensing capability of FBXL5. @*Objectives@#To further explore the mechanism of its regulation, it is important to study the interaction of FBXL5 with other proteins under regulated conditions so we attempted to express FBXL5 in the hopes of studying its interaction with IRPs in vitro. @*Methodology@#Plasmids were constructed to express FBXL5 in Escherichia coli expression hosts. Purification of an MBP-fused FBXL5 and GST-fused FBXL5 were performed using affinity chromatography. Peptide Mass Fingerprinting, Circular Dichroism spectroscopy, and SEC-MALS were employed to analyze the purified MBP-FBXL5. GST-FBXL5 was also used in a pull-down assay with Iron Regulatory Protein 1 (IRP1). @*Results@#We are successful in expressing and partially purifying full-length FBXL5 using E. coli with the aid of a protein tag, the maltose binding protein (MBP) tag. However, cleavage of the protein tag resulted in decreased stability of FBXL5 as shown in SEC-MALS data. CD spectroscopy showed consistent secondary structure of FBXL5. A preliminary pull-down assay of GST-FBXL5 with IRP1 showed that IRP1 displayed interaction with the recombinant GST-FBXL5. @*Conclusion@#FBXL5, a 78-kDa mammalian protein was overexpressed in a prokaryotic expression system made stable by a fusion protein. The interaction of GST-FBXL5 with IRP1 also shows that it is possible to study their interaction in vitro.

ARIH2 Inhibits the Linear Ubiquitination Ligase Activity of LUBAC / 中国生物化学与分子生物学报

Linear ubiquitination plays an important role in tumor and the immune system. Linear ubiq- uitin chain assembly complex ( LUBAC) is the only known ubiquitin ligase that can catalyze the synthesis of linear ubiquitin chains. We found that ubiquitin ligase ariadne homolog 2 ( ARIH2) was a new interacting protein of LUBAC, and ARIH2 inhibited the level of linear ubiquitination of substrates by LUBAC. We further demonstrated that ARIH2 interacted with HOIP by Co-IP experiment, and that HOIP interacted with ARIH2 through the ZF-NZF ( zinc finger-Npl4-Zinc finger) domain by GST pull-down experiments. Moreover, we showed that LUBAC could not modify ARIH2 by linear ubiquitination; On the contrary, ARIH2 inhibited the linear ubiquitination level of LUBAC substrates. The mechanism may be that ARIH2 affects the ubiquitination level of SHANK-associated RH domain interacting protein ( SHARP- IN ), thereby affecting the enzyme activity of LUBAC, which leads to the weakening of the linear ubiquit- ination level of LUBAC to the substrate.

The Role of NEDD4-1 in Tumorigenesis of the Digestive System / 中国生物化学与分子生物学报

Neural precursor cell Expressed‚Developmentally Down-regulated protein 4 (NEDD4-1‚ also known as NEDD4 in some papers) is a tumor-related protein that has attracted much attention in recent years. It belongs to the E3 HECT (homologous to E6 associated protein C terminus) ubiquitin ligase‚ which could ubiquitinate various proteins that are subsequently degraded in lysosomes or proteasomes‚ or mediate their nuclear-cytoplasmic translocation‚ or indirectly affect various signaling pathways of different malignant tumors. With the deepening of a large number of tumor-related experiments‚ it has been found that NEDD4-1 can affect the biological behavior of tumors by regulating cell cycle‚ invasion and metastasis of cancer cells‚ antagonize drug resistance and many other pathways. In digestive system tumors‚ NEDD4-1 mainly promotes the proliferation‚ invasion and migration of hepatocellular carcinoma through multiple pathways such as PTEN/ PI3K/ Akt‚ TGF-β‚ Hippo and LDLRAD4. In pancreatic cancer‚ NEDD4-1 acted as an oncogene in the PI3K/ Akt signaling pathway‚ but acted as a tumor suppressor gene in the Myc-Sirt2 signaling circuit. In gastric and colorectal cancer‚ the NEDD4-1-related signaling pathways are different from other digestive system tumors. NEDD4-1 promotes gastric cancer progression and metastasis (via the EGFR signaling pathway) and inhibits colorectal cancer tumor growth (via the Wnt signaling pathway) independently of the PTEN/ PI3K/ Akt pathway. NEDD4-1 has become a hot research direction for therapeutic purposes. In this paper‚ we summarize the functions‚ signaling pathways and potential inhibitors of NEDD4-1 in different digestive system tumors‚ and discuss the relationship between NEDD4-1 and different signaling pathways‚ aiming to provide important reference data for cancer therapy.

Signaling pathways involved in inhibition of macrophage phagocytosis by TcpC of uropathogenic Escherichia coli / 中华微生物学和免疫学杂志

Objective:To investigate the signaling pathway of inhibiting macrophage phagocytosis of TIR domain-containing protein encoded by Escherichia coli (TcpC) N-terminal ubiquitin ligase active fragments of uropathogenic Escherichia coli. Methods:Bioinformatics software was used to analyze the amino acid sequences and the function of TcpC N-terminal ubiquitin ligase active fragments as well as the functional sites. PCR was performed to amplify tcpc-330, tcpc-450 and tcpc-510 genes and a prokaryotic expression system was constructed to express the target proteins. The recombinant proteins rTcpC-N110, rTcpC-N150 and rTcpC-N170 were purified by Ni-NTA affinity chromatography. LPS in the recombinant proteins was removed by Detoxi-gel chromatography. The expression of MyD88 at protein and mRNA levels in macrophages incubated with rTcpC-N110, rTcpC-N150, rTcpC-N170 or rTcpC-TIR was detected by Western blot and qRT-PCR. The activation of NF-κB signal pathway and the levels of proinflammatory factors in macrophages incubated with the above TcpC protein fragments were measured by Western blot and ELISA, respectively. Results:Cys12, Trp104 and Trp106 in the N-terminal fragment of TcpC were crucial amino acids in maintaining its ubiquitin ligase activity. The target recombinant proteins rTcpC-N110, rTcpC-N150 and rTcpC-N170 were successfully expressed and purified. After Detoxi-gel chromatography, rTcpC-N110, rTcpC-N150 and rTcpC-N170 extracts were undetectable for LPS. TcpC ubiquitin ligase fragments inhibited the expression of MyD88 at protein level, but not affect its expression at mRNA level in macrophages. LPS-induced phosphorylation of NF-κB signaling pathway-related proteins p50 and p65 was significantly inhibited in macrophages treated with TcpC ubiquitin ligase fragments. Moreover, LPS-induced production of pro-inflammatory factors was also significantly inhibited.Conclusions:The recombinant proteins rTcpC-N110, rTcpC-N150 and rTcpC-N170 could inhibit the expression of MyD88 at protein level and suppress the activation of NF-κB signaling pathway, suggesting that they were closely related to the inhibition of innate immune activity of macrophages.

The expression of the recombinant human phenylalanine-tRNA ligase beta subunit gene in hepatocellular carcinoma and its prognostic value / 中华老年医学杂志

Objective:To analyze the expression of the recombinant human phenylalanine-tRNA ligase beta subunit(FARSB)gene in hepatocellular carcinoma(HCC)and explore its association with clinicopathologic characteristics and prognosis.Methods:Data sets of hepatocellular carcinoma and paracancerous tissues were downloaded from the Cancer Genome Atlas(TCGA), and the data were analyzed using the R and Perl programming languages.Cox regression and the Kaplan-Meier method were used to analyze the relationship between clinicopathological characteristics and overall survival.Gene set enrichment analysis(GSEA)was used to predict the signal pathways involved in the regulation of FARSB.qPCR and Western blot were used to verify the expression level of FARSB in hepatocellular carcinoma and adjacent tissues.Results:FARSB was highly expressed in HCC and the prognosis of HCC patients with high FARSB expression was poor.The clinical stage, T stage, M stage and FARSB were significantly correlated with overall survival, while only high FARSB expression was an independent prognostic factor in HCC patients.Conclusions:High expression of FARSB indicates a poor prognosis in HCC patients and FARSB can be used as a marker for poor prognosis in HCC.

Speckle type POZ adaptor protein (SPOP) and its role in cancer / La proteína adaptadora Speckle-type POZ (SPOP) y su papel en cáncer

Abstract Proteasomal degradation is an essential regulatory mechanism for cellular homeostasis maintenance. The speckle-type POZ adaptor protein (SPOP) is part of the ubiquitin ligase E3 cullin-3 RING-box1 complex, responsible for the ubiquitination and proteasomal degradation of biomolecules involved in cell cycle control, proliferation, response to DNA damage, epigenetic control, and hormone signaling, among others. Changes in SPOP have been associated with the development of different types of cancer, since it can act as a tumor suppressor mainly in prostate, breast, colorectal, lung cancer and liver cancer, due to point mutations and/or reduced expression, or as an oncogene in kidney cancer by protein overexpression. In endometrial cancer it has a dual role, since it can act as a tumor suppressor or as an oncogene. SPOP is a potential prognostic biomarker and a promising therapeutic target.

Resumen La degradación proteosómica es un mecanismo de regulación esencial para el mantenimiento de la homeostasis celular. La proteína adaptadora Speckle-type POZ (SPOP) hace parte del complejo ubiquitin ligasa E3 cullin-3 RING-box1, encargado de la ubiquitinación y degradación proteosomal de biomoléculas involucradas en el control del ciclo celular, proliferación, respuesta al daño de ADN, control epigenético, señalización hormonal, entre otros. Las alteraciones en SPOP han sido asociadas al desarrollo de diferentes tipos de cáncer, ya que puede actuar como supresor tumoral principalmente en cáncer de próstata, mama, colorrectal y pulmón, debido a mutaciones puntuales y/o expresión reducida o como oncogén en cáncer riñón por sobreexpresión de la proteína. En cáncer endometrial tiene un rol dual, ya que puede actuar como supresor tumoral o como oncogén. SPOP es considerado como un potencial biomarcador pronóstico y un objetivo terapéutico prometedor.

IARS2 regulates proliferation, migration, and angiogenesis of human umbilical vein endothelial cells

SUMMARY OBJECTIVE: In this study, we aimed at investigating the role of isoleucyl-tRNA synthetase in the growth, migration, and angiogenesis of human umbilical vein endothelial cells and the underlying molecular mechanism. METHODS: To assess the role of isoleucyl-tRNA synthetase, we silenced isoleucyl-tRNA synthetase in human umbilical vein endothelial cells using lentiviral 2 specific short hairpin RNAs (short hairpin RNAs 1 and 2) and examined silencing efficiency using real time quantitative polymerase chain reaction and western blot analyses. Short hairpin RNAs 1-isoleucyl-tRNA synthetase had greater knockdown efficiency, it was used in the entire downstream analysis. Short hairpin RNAs 1- isoleucyl-tRNA synthetase silencing effects on cell proliferation, cell colony generation, cell migration, as well as angiogenesis were assessed using cell counting kit-8, colony development, cell migration, and angiogenesis tube formation assays, respectively. RESULTS: Compared to the control group, anti-isoleucyl-tRNA synthetase short hairpin RNAs significantly silenced isoleucyl-tRNA synthetase expression in human umbilical vein endothelial cells, and suppressed their proliferation, migration, and angiogenic capacity. To characterize the underlying mechanism, western blot analyses showed that isoleucyl-tRNA synthetase knockdown suppressed phosphorylation of extracellular-regulated kinase ½ and protein-serine- threonine kinase, as well as expression of vascular endothelial growth factor, GSK-3β, and β-catenin. CONCLUSIONS: We have shown, for the first time, the critical role of isoleucyl-tRNA synthetase in human umbilical vein endothelial cells. Our data show that isoleucyl-tRNA synthetase knockdown suppresses human umbilical vein endothelial cell proliferation, migration, and angiogenesis. We have also shown that isoleucyl-tRNA synthetase knockdown suppresses phosphorylation of extracellular-regulated kinase ½ and protein-serine- threonine kinase, as well as expression of vascular endothelial growth factor, GSK-3β, and β-catenin. Together, these data highlight isoleucyl-tRNA synthetase as a potential antitumor anti-angiogenic target.