Influence of sodium nitroprusside on expressions of FBXL5 and IRP2 in SH-SY5Y cells / 生理学报

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.

Mutations of FBXW7 in Adult T-Cell Acute Lymphocytic Leukemia / 中国实验血液学杂志

<p><b>BACKGROUD</b>F-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.</p><p><b>OBJECTIVE</b>To investigate the mutations of FBXW7 gene in adult T-cell acute lymphoblastic leukemia (T-ALL).</p><p><b>METHODS</b>Exon 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.</p><p><b>RESULTS</b>FBXW7 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).</p><p><b>CONCLUSION</b>FBXW7 mutations may play an important role in NOTCH1 mediated pathogenesis in T-ALL.</p>

Expression of FBXW7 in esophageal squamous cell carcinoma and its clinical significance / 中华肿瘤杂志

<p><b>OBJECTIVE</b>To 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.</p><p><b>METHODS</b>Ninety 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.</p><p><b>RESULTS</b>The 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).</p><p><b>CONCLUSIONS</b>The 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.</p>

Histone methyltransferases and demethylases: regulators in balancing osteogenic and adipogenic differentiation of mesenchymal stem cells / 国际口腔科学杂志·英文版

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.

Lack of association between three single nucleotide polymorphisms in the PARK9, PARK15, and BST1 genes and Parkinson's disease in the northern Han Chinese population / 中华医学杂志(英文版)

<p><b>BACKGROUND</b>Parkinson's disease (PD) is an autosomally inherited neurodegenerative disease in elderly people. The etiology of PD has long been thought to be associated with both genetic and environmental factors. To explore potential genetic risk factors for PD in the northern Han Chinese population, we investigated three single nucleotide polymorphisms (SNPs) (rs4538475, rs11107 and rs12564040) in the BST1, PARK15 and PARK9 genes.</p><p><b>METHODS</b>Genomic DNA from 215 PD patients and 212 matched controls was amplified in two independent PCR systems and subsequently genotyped by digestion with the endonuclease PstI. Genetic parameter and association studies were carried out with SPSS 13.0 and PLINK 1.07 software.</p><p><b>RESULTS</b>We could accurately detect all genotypes in the three loci with the PCR-RFLP or mismatched PCR-RFLP techniques. The observed heterozygosities of the rs4538475 and rs11107 loci in PD and control groups ranged from 0.460 - 0.481 and 0.410 - 0.441, in BST1, PARK15 respectively, while we detected no heterozygosity at the rs12564040 locus in PARK9. The similar distributions of genotypic frequency between both groups suggest that the three SNPs investigated in this study are unlikely to play roles as common risk factors or pathogenic mutations for PD in northern Han Chinese.</p><p><b>CONCLUSION</b>The SNPs investigated in the BST1, PARK15 and PARK9 genes associated with PD susceptibility are not associated with PD in the northern Han Chinese population.</p>

The Ubiquitin-Proteasome System and F-box Proteins in Pathogenic Fungi

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.

Identification and characterization of scirr1, a novel gene up-regulated after spinal cord injury

Spinal cord injury and regeneration involves transcriptional activity of many genes, of which many remain unknown. Using the rat spinal cord full- transection model, bioinformatics, cloning, expression assays, fusion proteins, and transfection techniques, we identified and characterized one such differentially expressed gene, termed scirr1 (spinal cord injury and/or regeneration related gene 1). Fourteen orthologs were found in 13 species from echinoderm to insect and human by Blast search of NCBI protein reference sequence database. However, no further information is available for these homologues. Using whole-mount in situ hybridization, mouse scirr1 mRNA was expressed temporally and spatially in accordance with the early development sequence of the central nervous system. In adult rat spinal cord, expression of scirr1 mRNA was localized to neurons of gray matter by in situ hybridization. Using immunohistochemistry, SCIRR1 protein was found to be up-regulated and expressed more highly in spinal cord neurons farther from the epicenter of injury. Although the precise function of SCIRR1 is unknown, its unique pattern of expression during CNS early development and up-regulation after spinal cord injury suggest that SCIRR1 should be involved in the succeeding injury and/or repair processes of the injured spinal cord. Also, the typical F-box and leucine-rich repeat (LRR) architecture of rat SCIRR1 indicated that it may play an important substrate recruiting role in the pleiotropic ubiquitin/proteasome pathway. All these make scirr1 a new interesting start to study the spinal cord injury and regeneration mechanism.

Studies on the relationship between D6S1581, a high frequency allele imbalance locus, and genetic susceptibility to nasopharyngeal carcinoma / 中华医学遗传学杂志

<p><b>OBJECTIVE</b>To 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.</p><p><b>METHODS</b>Genescan 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.</p><p><b>RESULTS</b>D6S1581 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).</p><p><b>CONCLUSION</b>These results suggest that D6S1581 is highly associated with NPC, and there may be one or more NPC associated genes near D6S1581, including FBXO30.</p>