Two phosphate modifications were introduced into the DNA backbone using the Staudinger reaction between the 3’,5’-dinucleoside β-cyanoethyl phosphite triester formed during DNA synthesis and sulfonyl azides, 4-(azidosulfonyl)-N,N,N-trimethylbutan-1-aminium iodide (N+ azide) or p-toluenesulfonyl (tosyl or Ts) azide, to provide either a zwitterionic phosphoramidate with N+ modification or a negatively charged phosphoramidate for Ts modification in the DNA sequence. The incorporation of these N+ and Ts modifications led to the formation of thermally stable parallel DNA triplexes, regardless of the number of modifications incorporated into the oligodeoxynucleotides (ONs). For both N+ and Ts-modified ONs, the antiparallel duplexes formed with complementary RNA were more stable than those formed with complementary DNA (except for ONs with modification in the middle of the sequence). Additionally, the incorporation of N+ modifications led to the formation of duplexes with a thermal stability that was less dependent on the ionic strength than native DNA duplexes. The thermodynamic analysis of the melting curves revealed that it is the reduction in unfavourable entropy, despite the decrease in favourable enthalpy, which is responsible for the stabilisation of duplexes with N+ modification. N+ONs also demonstrated greater resistance to nuclease digestion by snake venom phosphodiesterase I than the corresponding Ts-ONs. Cell uptake studies showed that Ts-ONs can enter the nucleus of mouse fibroblast NIH3T3 cells without any transfection reagent, whereas, N+ONs remain concentrated in vesicles within the cytoplasm. These results indicate that both N+ and Ts-modified ONs are promising for various in vivo applications.
Purpose: To investigate global protein expression profiles in the trabecular meshwork (TM) of normal and glucocorticoid-induced ocular hypertensive rat eyes by proteomic analysis, which has not yet been conducted to date. Materials and Methods: A rat ocular hypertension model was produced by topical application of dexamethasone (DEX) for 4 weeks. Age-matched untreated rats served as controls. Intraocular pressure (IOP) was monitored by an electronic tonometer. TM protein expression profiling and protein identification was carried out by a two-dimensional fluorescence differential gel electrophoresis (2-D DIGE) system and matrix-assisted laser desorption/ionization time-of-flight (MALDI-TOF) mass spectrometry, respectively. Results: In DEX-treated rats, average IOP was elevated significantly, as compared with controls. By the DEX treatment, 14 TM protein spots were up- or downregulated consistently in 2-D DIGE analyses. Proteins exhibiting more than 2-fold statistically significant change were identified by MALDI-TOF mass spectrometry. αA-Crystallin and βA3-crystallin were upregulated, while the C-propeptides of type I collagen were downregulated. Conclusion: Relatively short-term glucocorticoid application induced alteration in the expression of a number of proteins, including downregulation of type I collagen C-propeptides. This could reflect impaired collagen turnover in the TM of glucocorticoid-treated eyes.
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