The N-Terminal Domain of Vimentin Alters Bladder Permeability

MicroRNA-497 upregulation inhibits cell invasion and metastasis in T24 and BIU-87 bladder cancer cells

Previous studies have reported the crucial role of microRNAs (miRNAs) in the biology and tumorigenesis of various types of cancer, including bladder cancer. The present study aimed to investigate the importance of miRNA (miR)‑497 on the pathogenesis of bladder cancer. A total of 50 patients diagnosed with bladder cancer were enrolled in the current study. The expression levels of miR‑497 in the cancerous and the adjacent noncancerous tissues were detected using reverse transcription‑quantitative polymerase chain reaction. The association between miR‑497 expression and various parameters, including age, tumor‑node‑metastasis (TNM) stage and pathological classification was determined. An miR‑497‑overexpressing vector was transfected into the T24 and BIU‑87 bladder cancer cell lines in order to determine the effect of miR‑497 expression on cell migration and invasion using Transwell assays. Additionally, the cell migration and invasion‑associated protein expression levels were also analyzed using western blotting. The findings of the present study revealed that miR‑497 was expressed at low levels in the cancer bladder tissue compared with the adjacent noncancerous tissue, and its expression was associated with the pathological classification, TNM stage and metastasis. Additionally, miR‑497 overexpression significantly reduced the number of migrated and invasive T24 and BIU‑87 cells. The mRNA and protein expression levels of E‑cadherin were increased, whereas levels of vimentin and α‑smooth muscle actin were reduced following miR‑497 overexpression. The present study revealed that miR‑497 overexpression may be a suppressor of the metastasis of bladder cancer, and may have an important role in the diagnosis of bladder cancer.

Interaction in vitro of type III intermediate filament proteins with higher order structures of single-stranded DNA, particularly with G-quadruplex DNA

Cytoplasmic intermediate filament (cIF) proteins interact strongly with single-stranded (ss) DNAs and RNAs, particularly with G-rich sequences. To test the hypothesis that this interaction depends on special nucleotide sequences and, possibly, higher order structures of ssDNA, a random mixture of mouse genomic ssDNA fragments generated by a novel "whole ssDNA genome PCR" technique via RNA intermediates was subjected to three rounds of affinity binding to in vitro reconstituted vimentin IFs at physiological ionic strength with intermediate PCR amplification of the bound ssDNA segments. Nucleotide sequence and computer folding analysis of the vimentin-selected fragments revealed an enrichment in microsatellites, predominantly of the (GT)n type, telomere DNA, and C/T-rich sequences, most of which, however, were incapable of folding into stable stem-loop structures. Because G-rich sequences were underrepresented in the vimentin-bound fraction, it had to be assumed that such sequences require intramolecular folding or lateral assembly into multistrand structures to be able to stably interact with vimentin, but that this requirement was inadequately fulfilled under the conditions of the selection experiment. For that reason, the few vimentin-selected G-rich ssDNA fragments and a number of telomere models were analyzed for their capacity to form inter- and intramolecular Gquadruplexes (G4 DNAs) under optimized conditions and to interact as such with vimentin and its type III relatives, glial fibrillary acidic protein, and desmin. Band shift assays indeed demonstrated differential binding of the cIF proteins to parallel four-stranded G4 DNAs and, with lower affinity, to bimolecular G'2 and unimolecular G'4 DNA configurations, whereby the transition regions from four- to single-strandedness played an additional role in the binding reaction. In this respect, the binding activity of cIF proteins was comparable with that toward other noncanonical DNA structures, like ds/ss DNA forks, triplex DNA, four-way junction DNA and Z-DNA, which also involve configurational transitions in their interaction with the filament proteins. Association of the cIF proteins with the corresponding nonfolded G-rich ssDNAs was negligible. Considering the almost universal involvement of ssDNA regions and G-quadruplexes in nuclear processes, including DNA transcription and recombination as well as telomere maintenance and dynamics, it is plausible to presume that cIF proteins as complementary constituents of the nuclear matrix participate in the cell- and tissue-specific regulation of these processes.