Glutamine provides carbon and nitrogen to support the proliferation of cancer cells. However, the precise reason why cancer cells are particularly dependent on glutamine remains unclear. In this study, we report that glutamine modulates the tumor suppressor F-box and WD repeat domain-containing 7 (FBW7) to promote cancer cell proliferation and survival. Specifically, lysine 604 (K604) in the sixth of the 7 substrate-recruiting WD repeats of FBW7 undergoes glutaminylation (Gln-K604) by glutaminyl tRNA synthetase. Gln-K604 inhibits SCFFBW7-mediated degradation of c-Myc and Mcl-1, enhances glutamine utilization, and stimulates nucleotide and DNA biosynthesis through the activation of c-Myc. Additionally, Gln-K604 promotes resistance to apoptosis by activating Mcl-1. In contrast, SIRT1 deglutaminylates Gln-K604, thereby reversing its effects. Cancer cells lacking Gln-K604 exhibit overexpression of c-Myc and Mcl-1 and display resistance to chemotherapy-induced apoptosis. Silencing both c-MYC and MCL-1 in these cells sensitizes them to chemotherapy. These findings indicate that the glutamine-mediated signal via Gln-K604 is a key driver of cancer progression and suggest potential strategies for targeted cancer therapies based on varying Gln-K604 status.
Glutamine/metabolism* ; Myeloid Cell Leukemia Sequence 1 Protein/genetics* ; Humans ; Proto-Oncogene Proteins c-myc/genetics* ; Cell Proliferation ; Signal Transduction ; Neoplasms/pathology* ; F-Box-WD Repeat-Containing Protein 7/genetics* ; Cell Survival ; Cell Line, Tumor ; Apoptosis

The plant F-box protein more axillary growth 2 (MAX2) is a key factor in the signal transduction of strigolactones (SLs) and karrinkins (KARs). As the main component of the SKP1-CUL1-FBX (SCF) complex ubiquitin ligase E3, MAX2 is responsible for specifically recognizing the target proteins, suppressor of MAX2 1/SMAX1-like proteins (SMAX1/SMXLs), which would be degraded after ubiquitination. It can thereby regulate plant morphogenesis and stress responses. There exist homologous genes of MAX2 in the important grain and oil crop soybean (Glycine max). However, its role in plant defense responses has not been investigated yet. Here, GmMAX2b, a homologous gene of MAX2, was successfully cloned from stressed soybean. Bioinformatics analysis revealed that there were two MAX2 homologous genes, GmMAX2a and GmMAX2b, with a similarity of 96.2% in soybean. Their F-box regions were highly conserved. The sequence alignment and cluster analysis of plant MAX2 homologous proteins basically reflected the evolutionary relationship of plants and also suggested that soybean MAX2 might be a multifunctional protein. Expression analysis showed that plant pathogen infection and salicylic acid treatment induced the expression of GmMAX2b in soybean, which is consistent with that of MAX2 in Arabidopsis. Ectopic expression of GmMAX2b compensated for the susceptibility of Arabidopsis max2-2 mutant to pathogen, indicating that GmMAX2b positively regulated plant disease resistance. In addition, yeast two hybrid technology was used to explore the potential target proteins of GmMAX2b. The results showed that GmMAX2b interacted with SMXL6 and weakly interacted with SMXL2. In summary, GmMAX2b is a positive regulator in plant defense responses, and its expression is induced by pathogen infection and salicylic acid treatment. GmMAX2b might exert its effect through interaction with SMXL6 and SMXL2. This study expands the theoretical exploration of soybean disease resistant F-box and provides a scientific basis for future soybean disease resistant breeding.
Glycine max/metabolism* ; Disease Resistance/genetics* ; Plant Diseases/immunology* ; Plant Proteins/genetics* ; Cloning, Molecular ; Gene Expression Regulation, Plant ; F-Box Proteins/genetics* ; Arabidopsis/genetics* ; Phylogeny

OBJECTIVE: To investigate the therapeutic effects of massage on denervated skeletal muscle atrophy in rats and its mechanism. METHODS: Forty-eight male SD rats were randomly divided into model group (n=24) and massage group (n=24). Gastrocnemius muscle atrophy model was established by transecting the right tibial nerve of rat. On the second day after operation, the gastrocnemius muscle of the rats in the massage group was given manual intervention and the model group was not intervened. Six rats were sacrificed at the four time points of 0 d, 7 d, 14 d and 21 d. The gastrocnemius of the rats were obtained and measured the wet mass ratio after weighing. Cross-sectional area and diameter of the muscle fiber were measured after HE staining. The relative expressions of miR-23a, Akt, MuRF1 and MAFbx mRNA were tested with qPCR. RESULTS: Compared with 0 d, the wet weight ratio, cross-sectional area and diameter of gastrocnemius muscle showed a progressive decline in the model group and massage group. The wet weight ratio, cross-sectional area and diameter of gastrocnemius muscle in the massage group were higher than those in the model group on 7 d, 14 d and 21 d (P＜0.05, P＜0.01). Compared with 0 d, the expressions of MuRF1, MAFbx and Akt mRNA were increased first and then were decreased in the model group and massage group. The expression of MuRF1 mRNA in massage group was lower than that in model group on 7 d and 21 d (P＜0.05, P＜0.01). The expression of MAFbx mRNA in massage group was lower than that in model group on 7 d, 14 d and 21 d (P＜0.01, P＜0.05, P＜0.01). The expression of Akt mRNA in massage group was higher than that in model group on 7 d, 14 d and 21 d (P＜0.05, P＜0.01). Compared with 0 d, the expression of miR-23a mRNA was increased in the model group and massage group on 21 d, and the expression of miR-23a mRNA in massage group was higher than that in model group (P＜ 0.05). CONCLUSION Massage can delay the atrophy of denervated skeletal muscle. The mechanism may be related to up-regulation of the expression of miR-23a and Akt mRNA, down-regulation of the expressions of MuRF1 and MAFbx mRNA, inhibition of protein degradation rate, and reduction of skeletal muscle protein degradation.
Animals ; Male ; Massage ; MicroRNAs ; metabolism ; Muscle Fibers, Skeletal ; Muscle Proteins ; metabolism ; Muscle, Skeletal ; physiopathology ; Muscular Atrophy ; therapy ; Proto-Oncogene Proteins c-akt ; metabolism ; Rats ; Rats, Sprague-Dawley ; SKP Cullin F-Box Protein Ligases ; metabolism ; Tripartite Motif Proteins ; metabolism ; Ubiquitin-Protein Ligases ; metabolism

Wnt signaling has emerged as a major regulator of tissue development by governing the self-renewal and maintenance of stem cells in most tissue types. As a key upstream regulator of the Wnt pathway, the transmembrane E3 ligase ZNRF3 has recently been established to play a role in negative regulation of Wnt signaling by targeting Frizzled (FZD) receptor for ubiquitination and degradation. However, the upstream regulation of ZNRF3, in particular the turnover of ZNRF3, is still unclear. Here we report that ZNRF3 is accumulated in the presence of proteasome inhibitor treatment independent of its E3-ubiquitin ligase activity. Furthermore, the Cullin 1-specific SCF complex containing β-TRCP has been identified to directly interact with and ubiquitinate ZNRF3 thereby regulating its protein stability. Similar with the degradation of β-catenin by β-TRCP, ZNRF3 is ubiquitinated by β-TRCP in both CKI-phosphorylation- and degron-dependent manners. Thus, our findings not only identify a novel substrate for β-TRCP oncogenic regulation, but also highlight the dual regulation of Wnt signaling by β-TRCP in a context-dependent manner where β-TRCP negatively regulates Wnt signaling by targeting β-catenin, and positively regulates Wnt signaling by targeting ZNRF3.
Cells, Cultured ; Humans ; Proteolysis ; Ubiquitin-Protein Ligases ; metabolism ; Ubiquitination ; beta-Transducin Repeat-Containing Proteins ; metabolism

Iron accumulation in the brain is associated with the pathogenesis of Parkinson's disease (PD). Misexpression of some iron transport and storage proteins is related to iron dyshomeostasis. Iron regulatory proteins (IRPs) including IRP1 and IRP2 are cytosolic proteins that play important roles in maintaining cellular iron homeostasis. F-box and leucine-rich repeat protein 5 (FBXL5) is involved in the regulation of iron metabolism by degrading IRP2 through the ubiquitin-proteasome system. Nitric oxide (NO) enhances the binding activity of IRP1, but its effect on IRP2 is ambiguous. Therefore, in the present study, we aim to determine whether sodium nitroprusside (SNP), a NO donor, regulates FBXL5 and IRP2 expression in cultured SH-SY5Y cells. MTT assay revealed that treatment of SNP attenuated the cell viability in a dose-dependent manner. Flow cytometry test showed that 100 and 300 μmol/L SNP administration significantly reduced the mitochondrial membrane potential by 45% and 60%, respectively. Moreover, Western blotting analysis demonstrated that 300 μmol/L SNP significantly increased FBXL5 expression by about 39%, whereas the expression of IRP2 was decreased by 46%, correspondingly. These findings provide evidence that SNP could induce mitochondrial dysfunction, enhance FBXL5 expression and decrease IRP2 expression in SH-SY5Y cells.
Cell Line ; Cell Survival ; F-Box Proteins ; metabolism ; Homeostasis ; Humans ; Iron Regulatory Protein 2 ; metabolism ; Nitric Oxide ; metabolism ; Nitroprusside ; pharmacology ; Proteasome Endopeptidase Complex ; Ubiquitin ; metabolism ; Ubiquitin-Protein Ligase Complexes ; metabolism

OBJECTIVEThis study was to investigate the mRNA expression of T-bet, GATA-3, ROR γt and Foxp3 mRNA in peripheral blood of patients with chronic lymphocytic leukemia (CLL) in different stages and explore their potential role in the pathogenesis and clinical diagnosis.

METHODSA total of 46 newly diagnosed and untreated patients with CLL was chosen as patient group, including 16 patients in the stage of Binet A, 15 in the stage of Binet B, and 15 in the stage of Binet C; 20 healthy persons were selected as controls. The quantitative fluorescence PCR was adopted to detect the mRNA expression of T-bet, GATA-3, RORγt and Foxp3 in peripheral blood mononuclear cell (PBMNC).

RESULTS(1) The expression of T-bet mRNA in patient group was lower than that in normal controls (P < 0.05), while the mRNA expression of GATA-3 mRNA, ROR γt, Foxp3 in CLL patients group were higher than that in normal controls (P < 0.05), and the ratio of T-bet/GATA-3 and RORγt/Foxp3 in CLL in patient group were lower than that in normal controls(P < 0.05); (2) The later the stage, the higher the mRNA expression of GATA-3 and Foxp3. The mRNA expression of GATA-3 in stage Binet B and stage Binet C of CLL patients were higher than that in stage Binet A (P < 0.05),and the mRNA expression of Foxp3 in stage Binet C was higher than that in stage of Binet A and Binet B (P < 0.05); the later the stage, the lower the ratio of T-bet/GATA-3 and RORγt/Foxp3. The ratio of T-bet/GATA-3 in stage of Binet A CLL patients was higher than that in stage Binet C (P < 0.05) and the ratio of RORγt/Foxp3 in stage of Binet A and stage of Binet B were higher than that in stage Binet C (P < 0.05).

CONCLUSIONThis study found in the level of transcription factors in CLL patients that with the process of disease, the balance shifts from Th1/Th2 and Th17/Treg to Th17 and Treg, and Treg cell may play a critical immunosuppressive role in the development of CLL.

Forkhead Transcription Factors ; GATA3 Transcription Factor ; Humans ; Leukemia, Lymphocytic, Chronic, B-Cell ; Nuclear Receptor Subfamily 1, Group F, Member 3 ; RNA, Messenger ; T-Box Domain Proteins ; T-Lymphocytes, Regulatory ; Th17 Cells

Mesenchymal stem cells (MSCs) are characterized by their self-renewing capacity and differentiation potential into multiple tissues. Thus, management of the differentiation capacities of MSCs is important for MSC-based regenerative medicine, such as craniofacial bone regeneration, and in new treatments for metabolic bone diseases, such as osteoporosis. In recent years, histone modification has been a growing topic in the field of MSC lineage specification, in which the Su(var)3-9, enhancer-of-zeste, trithorax (SET) domain-containing family and the Jumonji C (JmjC) domain-containing family represent the major histone lysine methyltransferases (KMTs) and histone lysine demethylases (KDMs), respectively. In this review, we summarize the current understanding of the epigenetic mechanisms by which SET domain-containing KMTs and JmjC domain-containing KDMs balance the osteogenic and adipogenic differentiation of MSCs.
Adipogenesis ; genetics ; physiology ; Cell Differentiation ; genetics ; physiology ; Cell Lineage ; genetics ; Epigenesis, Genetic ; genetics ; F-Box Proteins ; genetics ; physiology ; Histone Demethylases ; genetics ; physiology ; Histone-Lysine N-Methyltransferase ; genetics ; physiology ; Humans ; Jumonji Domain-Containing Histone Demethylases ; genetics ; physiology ; Mesenchymal Stromal Cells ; enzymology ; physiology ; Methyltransferases ; genetics ; physiology ; Osteogenesis ; genetics ; physiology

OBJECTIVETo evaluate the expression of FBXW7 in esophageal squamous cell carcinoma (ESCC) and to explore the correlation of FBXW7 expression with clinicopathologic features and prognosis of ESCC.

METHODSNinety cases of ESCC and twenty cases of tumor-adjacent normal tissues and forty intraepithelial neoplasia tissues were detected by immunohistochemistry methods. The expression of FBXW7 in 40 surgical ESCC tissues and tumor-adjacent normal tissues was detected by Western blotting and RT-PCR. The relationship between the expression of FBXW7, clinicopathological characteristics and prognosis was analyzed.

RESULTSThe positive rate of FBXW7 protein was significantly lower in the ESCC and high-grade intraepithelial neoplasia tissues than in the tumor-adjacent normal tissues and low grade intraepithelial neoplasia tissues (40.0% and 33.3% vs. 85.0% and 77.3%, χ² = 21.923, P < 0.001). The FBXW7 protein was down-regulated in ESCC tissues (P < 0.05), whereas the FBXW7 mRNA was down-regulated in ESCC tissues compared with that in the paracancerous tissues. The expression of FBXW7 was significantly correlated with TNM stage, degree of differentiation, invasion depth and lymph node metastasis (χ² =9.643, 14.908, 16.294, 10.222, respectively, P = 0.002, 0.001, 0.000, 0.001). In the ninety patients, the 5-year survival rates of cases with positive and negative expression of FBXW7 protein was 67.6% and 39.3%, respectively (χ² =6.699, P = 0.01).

CONCLUSIONSThe results of this study demonstrate that FBXW7 expression is significantly declined in ESCC and high grade intraepithelial neoplasia tissues, and is closely correlated with poor prognosis of this disease. FBXW7 as a tumor suppressor gene may play an important role in the carcinogenesis, development and metastasis of ESCC. These results suggest that FBXW7 may become a valuable marker for the severity and prognosis in ESCC.

Biomarkers, Tumor ; metabolism ; Blotting, Western ; Carcinoma, Squamous Cell ; diagnosis ; metabolism ; Cell Cycle Proteins ; genetics ; Down-Regulation ; Esophageal Neoplasms ; diagnosis ; metabolism ; F-Box Proteins ; genetics ; F-Box-WD Repeat-Containing Protein 7 ; Humans ; Immunohistochemistry ; Lymphatic Metastasis ; Neoplasm Staging ; Prognosis ; RNA, Messenger ; Survival Rate ; Ubiquitin-Protein Ligases ; genetics

BACKGROUDF-Box and WD40 domain containing protein 7 gene (FBXW7) is part of the E3 ubiquitin ligase complex that controls the turnover of various proteins including NOTCH1, c-MYC and Cyclin E.

OBJECTIVETo investigate the mutations of FBXW7 gene in adult T-cell acute lymphoblastic leukemia (T-ALL).

METHODSExon 5-12 of FBXW7 were amplified, cloned and sequenced in 54 adult T-ALL patients; the frequency, position and types of FBXW7 mutation were analyzed; the co-existing of mutations with NOTCH1 and their relevant prognostic significance were explored as well.

RESULTSFBXW7 mutations were identified in 11.1% of adult T-ALL patients. A total of 4 types of point mutations (R465H, R465L, R479P and R505C) and 1 deletion/insertion mutation were observed, and all of them located in WD40 domain of FBXW7. In addition, co-existing mutations with NOTCH1 were identified in 83.3% of patients with FBXW7 mutation. Notably, the co-existed NOTCH1 mutations, including 3 point mutations (L1574P, L1596H and L1600P) and 2 deletion/insertion mutations located in HD domain. Furthermore, patients with FBXW7 mutation only had significantly longer overall survival compared with those without mutation (P=0.049).

CONCLUSIONFBXW7 mutations may play an important role in NOTCH1 mediated pathogenesis in T-ALL.

Adult ; Cell Cycle Proteins ; Exons ; F-Box Proteins ; F-Box-WD Repeat-Containing Protein 7 ; Genes, myc ; Humans ; Mutation ; Precursor T-Cell Lymphoblastic Leukemia-Lymphoma ; Prognosis ; Ubiquitin-Protein Ligases

An F-box protein, beta-TrCP recognizes substrate proteins and destabilizes them through ubiquitin-dependent proteolysis. It regulates the stability of diverse proteins and functions as either a tumor suppressor or an oncogene. Although the regulation by beta-TrCP has been widely studied, the regulation of beta-TrCP itself is not well understood yet. In this study, we found that the level of beta-TrCP1 is downregulated by various protein kinase inhibitors in triple-negative breast cancer (TNBC) cells. A PI3K/mTOR inhibitor PI-103 reduced the level of beta-TrCP1 in a wide range of TNBC cells in a proteasome-dependent manner. Concomitantly, the levels of c-Myc and cyclin E were also downregulated by PI-103. PI-103 reduced the phosphorylation of beta-TrCP1 prior to its degradation. In addition, knockdown of beta-TrCP1 inhibited the proliferation of TNBC cells. We further identified that pharmacological inhibition of mTORC2 was sufficient to reduce the beta-TrCP1 and c-Myc levels. These results suggest that mTORC2 regulates the stability of beta-TrCP1 in TNBC cells and targeting beta-TrCP1 is a potential approach to treat human TNBC.
Cell Line, Tumor ; Cell Proliferation ; Cell Survival/drug effects ; Cyclin E/genetics/metabolism ; Dose-Response Relationship, Drug ; Female ; Furans/pharmacology ; Gene Knockdown Techniques ; Humans ; Models, Biological ; Multiprotein Complexes/antagonists & inhibitors ; Phosphatidylinositol 3-Kinases/*antagonists & inhibitors ; Phosphorylation/drug effects ; Protein Kinase Inhibitors/*pharmacology ; Proteolysis/drug effects ; Proto-Oncogene Proteins c-myc/genetics/metabolism ; Pyridines/pharmacology ; Pyrimidines/pharmacology ; TOR Serine-Threonine Kinases/*antagonists & inhibitors ; Triple Negative Breast Neoplasms/genetics/*metabolism ; beta-Transducin Repeat-Containing Proteins/genetics/*metabolism