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

The ubiquitin-proteasome system is one of the major protein turnover mechanisms that plays important roles in the regulation of a variety of cellular functions. It is composed of E1 (ubiquitin-activating enzyme), E2 (ubiquitin-conjugating enzyme), and E3 ubiquitin ligases that transfer ubiquitin to the substrates that are subjected to degradation in the 26S proteasome. The Skp1, Cullin, F-box protein (SCF) E3 ligases are the largest E3 gene family, in which the F-box protein is the key component to determine substrate specificity. Although the SCF E3 ligase and its F-box proteins have been extensively studied in the model yeast Saccharomyces cerevisiae, only limited studies have been reported on the role of F-box proteins in other fungi. Recently, a number of studies revealed that F-box proteins are required for fungal pathogenicity. In this communication, we review the current understanding of F-box proteins in pathogenic fungi.
Cryptococcus neoformans ; F-Box Proteins ; Fungi ; Humans ; Ligases ; Proteasome Endopeptidase Complex ; Saccharomyces cerevisiae ; Substrate Specificity ; Ubiquitin ; Ubiquitin-Protein Ligases ; Yeasts

Aged ; Cognition Disorders ; genetics ; F-Box Proteins ; genetics ; HSP40 Heat-Shock Proteins ; genetics ; Humans ; Male ; Monocytes ; metabolism ; Parkinson Disease ; genetics ; alpha-Synuclein ; genetics

Animals ; Carcinogenesis ; Cell Cycle Proteins ; genetics ; metabolism ; Cyclin E ; metabolism ; F-Box Proteins ; genetics ; metabolism ; F-Box-WD Repeat-Containing Protein 7 ; Gene Silencing ; Genes, Tumor Suppressor ; Humans ; Mutation ; Myeloid Cell Leukemia Sequence 1 Protein ; metabolism ; Neoplasms ; genetics ; metabolism ; pathology ; Proto-Oncogene Proteins c-myc ; metabolism ; Receptors, Notch ; metabolism ; Signal Transduction ; TOR Serine-Threonine Kinases ; metabolism ; Ubiquitin-Protein Ligases ; genetics ; metabolism

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

OBJECTIVETo study muscle atrophy F-box (MAFbx) and muscle ring finger 1 (MuRF1) mRNA expression and its relationship with muscular contraction following free muscle transfer.

METHODSThe gracilis muscle was orthotopic transferred in adult rat to establish the animal model. The muscle at the unoperated side was used as control. The expression of MAFbx and MuRF1 mRNA, the muscle contraction and muscle function were measured by real-time PCR and multiple function physiological device. The relationship among the expression of MAFbx and MuRF1 mRNA, the muscle contraction and muscle function was analyzed.

RESULTSAfter muscle free transfer, muscle wet weight reservation, the maximum contraction and tetanus strength reduce first and increased later, but still lower than those at control side. The expression of MAFbx and MuRF1 mRNA reached peak level 3 - 4 weeks after muscle transfer which was 7.1 and 4.1 times as that at control side. It decreased later, but still higher than that at control side, showing a significant difference between them (P< 0. 05).

CONCLUSIONSPersistent over-expression of MAFbx and MuRF1 mRNA after muscle transfer has a close relationship with muscle atrophy and muscle dysfunction. MAFbx and MuRF1 can be used as markers for early muscle atrophy, and also as potential target for drug treatment of muscle atrophy.

Animals ; Female ; Muscle Contraction ; Muscle Proteins ; genetics ; Muscle, Skeletal ; pathology ; Muscular Atrophy ; genetics ; metabolism ; pathology ; RING Finger Domains ; RNA, Messenger ; genetics ; Rats ; Rats, Sprague-Dawley ; SKP Cullin F-Box Protein Ligases ; genetics ; Tripartite Motif Proteins ; Ubiquitin-Protein Ligases ; genetics

OBJECTIVETo investigate the relationship of nasopharyngeal carcinoma (NPC) with the high frequency allele imbalance locus D6S1581, and the NPC associated gene FBXO30 which is located near D6S1581.

METHODSGenescan was used to genotype D6S1581 of 12 NPC pedigrees, 85 sporadic NPC patients and 181 normal volunteers. Then parametric/nonparametric linkage analysis and association analysis were performed.

RESULTSD6S1581 was linked with NPC, a Lod score of 2.611436 (P=0.00245) was obtained, and a significant difference in allele frequency was observed between familial NPC and control (P<0.005).

CONCLUSIONThese results suggest that D6S1581 is highly associated with NPC, and there may be one or more NPC associated genes near D6S1581, including FBXO30.

Adult ; Aged ; Aged, 80 and over ; Alleles ; China ; F-Box Proteins ; genetics ; Female ; Gene Frequency ; Genetic Linkage ; Genetic Predisposition to Disease ; genetics ; Humans ; Male ; Microsatellite Repeats ; genetics ; Middle Aged ; Nasopharyngeal Neoplasms ; genetics ; Pedigree

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

OBJECTIVETo explore the interaction between SerpinB5 and MAFbx in gastric cancer cell and to identify the interaction sites.

METHODSThe interaction between SerpinB5 and MAFbx was screened and validated by yeast two-hybrid screening and co-immunoprecipitation. The expression of MAFbx was analyzed after SerpinB5 expression being modified by RNA interference and pGBKT7-SerpinB5 transfection. The impact of SerpinB5 on the expression of MAFbx was studied in gastric cancer cell line SUN-16. A model of MAFbx was constructed by homology modeling. The related residues for interaction were analyzed by Autodock4.0.

RESULTSThe interaction between SerpinB5 and MAFbx was validated. The expression of MAFbx changed along with SerpinB5 expression. Amino acids including PRO261, ASN361, and LYS362 were key residue in the interaction of SerpinB5 and MAFbx.

CONCLUSIONSerpinB5 interacts with MAFbx in gastric cancer cell. Amino acids including PRO261, ASN361, and LYS362 are potential binding sites.

Cell Line, Tumor ; Humans ; Immunoprecipitation ; Muscle Proteins ; genetics ; metabolism ; RNA Interference ; SKP Cullin F-Box Protein Ligases ; genetics ; metabolism ; Serpins ; genetics ; metabolism ; Stomach Neoplasms ; genetics ; metabolism ; Two-Hybrid System Techniques

OBJECTIVETo investigate the protective effect of Atrogin-1 gene silencing via RNA interference technique on a model of muscle cell malnutrition.

METHODSSequences of five target Atrogin-1 siRNA and the control were selected and synthesized and cloned to vector pBS-hU6-I and then to vector FG12. The length and rightness of the sequences were confirmed. The recombinant FG12 vectors were cotransfected along with pRSVREV, pMDLg/pRRE and pHCMV-G into 293T cells to package lentivirus particles, with which C2C12 cells were infected. The infected C2C12 cells were cultured and differentiated to form myotubes before TNF-alpha was added to induce malnutrition. Expressed products of Atrogin-1 of myotubes were identified by real time PCR and Western blot methods. Myotubes were observed and photographed directly in culture plate without fixation.

RESULTSThe length and sequences of inserted DNA were right. Compared with the RNA interferencing group, significant atrophy and upregulated expression of Atrogin-1 of myotubes treated by TNF-alpha was found in the control group.

CONCLUSIONAtrogin-1 gene silencing could be used to inhibit malnutrition of muscle cells caused by TNF-alpha. Atrogin-1 could be an ideal target in the treatment of cancer cachexia.

Animals ; Cell Differentiation ; Cell Proliferation ; Cells, Cultured ; Gene Silencing ; Genetic Vectors ; Lentivirus ; genetics ; Mice ; Muscle Cells ; cytology ; drug effects ; metabolism ; Muscle Proteins ; genetics ; RNA, Small Interfering ; genetics ; SKP Cullin F-Box Protein Ligases ; genetics ; Transfection ; Tumor Necrosis Factor-alpha ; pharmacology