Role of the CCAAT-Binding Protein NFY in SCA17 Pathogenesis

Spinocerebellar ataxia 17 (SCA17) is caused by expansion of the polyglutamine (polyQ) tract in human TATA-box binding protein (TBP) that is ubiquitously expressed in both central nervous system and peripheral tissues. The spectrum of SCA17 clinical presentation is broad. The precise pathogenic mechanism in SCA17 remains unclear. Previously proteomics study using a cellular model of SCA17 has revealed reduced expression of heat shock 70 kDa protein 5 (HSPA5) and heat shock 70 kDa protein 8 (HSPA8), suggesting that impaired protein folding may contribute to the cell dysfunction of SCA17 (Lee et al., 2009). In lymphoblastoid cells, HSPA5 and HSPA8 expression levels in cells with mutant TBP were also significantly lower than that of the control cells (Chen et al., 2010). As nuclear transcription factor Y (NFY) has been reported to regulate HSPA5 transcription, we focused on if NFY activity and HSPA5 expression in SCA17 cells are altered. Here, we show that TBP interacts with NFY subunit A (NFYA) in HEK-293 cells and NFYA incorporated into mutant TBP aggregates. In both HEK-293 and SH-SY5Y cells expressing TBP/Q61∼79, the level of soluble NFYA was significantly reduced. In vitro binding assay revealed that the interaction between TBP and NFYA is direct. HSPA5 luciferase reporter assay and endogenous HSPA5 expression analysis in NFYA cDNA and siRNA transfection cells further clarified the important role of NFYA in regulating HSPA5 transcription. In SCA17 cells, HSPA5 promoter activity was activated as a compensatory response before aggregate formation. NFYA dysfunction was indicated in SCA17 cells as HSPA5 promoter activity reduced along with TBP aggregate formation. Because essential roles of HSPA5 in protection from neuronal apoptosis have been shown in a mouse model, NFYA could be a target of mutant TBP in SCA17

The 3′ Splice Site of Influenza A Segment 7 mRNA Can Exist in Two Conformations: A Pseudoknot and a Hairpin

The 3′ splice site of influenza A segment 7 is used to produce mRNA for the M2 ion-channel protein, which is critical to the formation of viable influenza virions. Native gel analysis, enzymatic/chemical structure probing, and oligonucleotide binding studies of a 63 nt fragment, containing the 3′ splice site, key residues of an SF2/ASF splicing factor binding site, and a polypyrimidine tract, provide evidence for an equilibrium between pseudoknot and hairpin structures. This equilibrium is sensitive to multivalent cations, and can be forced towards the pseudoknot by addition of 5 mM cobalt hexammine. In the two conformations, the splice site and other functional elements exist in very different structural environments. In particular, the splice site is sequestered in the middle of a double helix in the pseudoknot conformation, while in the hairpin it resides in a two-by-two nucleotide internal loop. The results suggest that segment 7 mRNA splicing can be controlled by a conformational switch that exposes or hides the splice site

Overexpression of ST3Gal-I promotes migration and invasion of HCCLM3 in vitro and poor prognosis in human hepatocellular carcinoma

Han Wu,1,* Xue-Liang Shi,1,* Hai-Jian Zhang,2 Qing-Jie Song,1 Xiao-Bing Yang,1 Wei-Dong Hu,1 Guang-Lin Mei,1 Xi Chen,1 Qin-Sheng Mao,1 Zhong Chen1 1Department of General Surgery, The Affiliated Hospital of Nantong University, 2Research Center of Clinical Medicine, The Affiliated Hospital of Nantong University, Nantong, People’s Republic of China *These authors contributed equally to this work Purpose: Excessive ST3Gal-I levels predict a poor outcome for patients with several types of tumors. This study aims to investigate the role of ST3Gal-I in determining the invasive and metastatic potential of human hepatocellular carcinoma (HCC) and clinical prognosis for patients with HCC.Methods: We compared the expression of ST3Gal-I in various HCC cell lines and in 20 pairs of tumor and peritumor tissue samples using Western blot analysis. Changes in the degree of invasiveness and migration were determined before and after small interfering RNA-induced knockdown of ST3Gal-I using a Transwell matrigel invasion assay and scratch wound assay. The correlation between ST3Gal-I expression and prognosis was determined in a large HCC patient cohort (n=273).Results: ST3Gal-I expression was higher in metastatic HCCLM3 cells and tumor tissue compared with normal adjacent tissue. Following the ST3Gal-I knockdown, the invasiveness and migration of HCCLM3 cells were markedly reduced. ST3Gal-I expression in HCC correlated closely with tumor thrombus (P<0.001), tumor size (>5.0 cm, P=0.032), tumor node metastasis stages II–III (P=0.002), and Barcelona Clinic Liver Cancer stages B–C (P<0.001). Cox regression analysis demonstrated that ST3Gal-I is an independent predictor of prognosis in patients with HCC, and related to disease-free survival (hazard ratio =1.464, P=0.037) and overall survival (hazard ratio =1.662, P=0.012).Conclusion: ST3Gal-I might contribute to the invasiveness and metastatic nature of HCC and, thus, could be an independent predictor of recurrence and a suitable pharmaceutical target in patients with HCC. Keywords: ST3Gal-I, hepatocellular carcinoma, sialyltransferase, prognosis, tumor progressio

A Novel Web Video Event Mining Framework with the Integration of Correlation and Co-Occurrence Information

The massive web videos prompt an imperative demand on efficiently grasping the major events. However, the distinct characteristics of web videos, such as the limited number of features, the noisy text information, and the unavoidable error in near-duplicate keyframes (NDKs) detection, make web video event mining a challenging task. In this paper, we propose a novel four-stage framework to improve the performance of web video event mining. Data preprocessing is the first stage. Multiple Correspondence Analysis (MCA) is then applied to explore the correlation between terms and classes, targeting for bridging the gap between NDKs and high-level semantic concepts. Next, co-occurrence information is used to detect the similarity between NDKs and classes using the NDK-within-video information. Finally, both of them are integrated for web video event mining through negative NDK pruning and positive NDK enhancement. Moreover, both NDKs and terms with relatively low frequencies are treated as useful information in our experiments. Experimental results on large-scale web videos from YouTube demonstrate that the proposed framework outperforms several existing mining methods and obtains good results for web video event mining