Suppression of Nonsense Mutations in the Dystrophin Gene by a Suppressor tRNA Gene

Nonsense mutations in the dystrophin gene are the cause of Duchenne muscular dystrophy (DMD) in 10–15% of patients. In such an event, one approach to gene therapy for DMD is the use of suppressor tRNAs to overcome the premature termination of translation of the mutant mRNA. We have carried out cotransfection of the HeLa cell culture with constructs containing a suptRNA gene (pcDNA3suptRNA) and a marker LacZ gene (pNTLacZhis) using their polymer VSST-525 complexes. It was found that the number of cells producing -galactosidase depends inversely on the dose of the suptRNA gene. A single in vivo injection of the construct providing for expression of the suptRNAochre gene into mdx mouse muscle resulted in the production of dystrophin in 2.5% of fibers. This suggests that suppressor tRNAs are applicable in gene therapy for hereditary diseases caused by nonsense mutations.     

Optimization of transfection properties of DNA-lysine dendrimer complexes

We studied the possibility of optimizing the DNA transfection properties of carriers based on lysine dendrimers of the third and the fifth generation, including those containing a chloroacetyl or a lipophilic palmitoyl moiety at C-end. The use of lysosome-destroying antibiotic chloroquine and an amphipathic polycationic nonadecapeptide JTS-1 was found to enhance the DNA transfecting properties of the lysine dendrimers. The triple complex including DNA, a lysine dendrimer of the third generation modified with lipophylic moieties of palmitic acid at its C-end, and JTS-1 was shown to be comparable in its transfecting activity to a complex containing Escort, a commercial cationic liposome carrier.     

Influence of Electroporation Conditions on Transfection of Muscle Fibers in Vivo

This study is a survey of in vivo experiments on transfection of laboratory mouse muscle fibers by electoporation using an original device generating electric impulses. Transfection efficiency proved to depend on DNA dose and the number of electric impulses. It can be increased significantly by electroporation at varying pulse burst polarity. At both direct electrode application to muscles and electroporation through the skin, the muscle fiber transfection was more efficient under electroporation conditions much milder than those usually reported. The use of electroporation method for gene therapy of Duchenne muscular dystrophy is discussed.     

Lysine dendrimers as vectors for delivering genetic constructs to eukaryotic cells

Asymmetrical lysine dendrimers are promising as vectors for delivering gene expression constructs into mammalian cells. The condensing, protective, and transfection properties were studied for pentaspherical lysine dendrimer D5 and its analog D5C10, modified with capric acid residues at the outer sphere; in addition, the transfection activity was assayed for complexes DNA-dendrimer-endosomolytic peptide JTS-1. Fatty acid residues incorporated in lysine dendrimers proved to improve their ability to bind DNA, to protect DNA from nuclease degradation, and to ensure its transfer into the nucleus. Peptide JTS-1 introduced in DNA-dendrimer complexes significantly increased their transfection activity. The potentiating effect of JTS-1 was especially high with the DNA-D5C10 complex. An excess of JTS-1 changed the structure of the complexes and reduced their transfection activity. It was assumed that dendrimers D5 and D5C10 are promising vectors for delivering DNA to eukaryotic cells and provide a basis for constructing more refined nonvirus module carriers.     

Suppression of nonsense mutations in the Dystrophin gene by a suppressor tRNA gene

Nonsense mutations in the dystrophin gene are the cause of Duchenne muscular dystrophy (DMD) in 10-15% of patients. In such an event, one approach to gene therapy for DMD is the use of suppressor tRNAs to overcome the premature termination of translation of the mutant mRNA. We have carried out cotransfection of the HeLa cell culture with constructs containing a suptRNA gene (pcDNA3suptRNA) and a marker LacZ gene (pNTLacZhis) using their polymer VSST-525 complexes. It was found that the number of cells producing beta-galactosidase depends inversely on the dose of the suptRNA gene. A single in vivo injection of the construct providing for expression of the suptRNAochre gene into mdx mouse muscle resulted in the production of dystrophin in 2.5% of fibers. This suggests that suppressor tRNAs are applicable in gene therapy for hereditary diseases caused by nonsense mutations.     

Lysine Dendrimers and Their Starburst Polymer Derivatives: Possible Application for DNA Compaction and in vitro Delivery of Genetic Constructs

We attempted to find some compounds for the effective delivery of gene constructs into cells and obtained two trispherical dendrimers on the basis of lysine, (Lys)₈-(,-Lys)₄-(,-Lys)₂-(,-Lys)-Ala-NH₂ (D1) and ((Lys)₈-(,-Lys)₄-(,-Lys)₂-,-Lys)-Ala-[Lys(Plm)]₂-Ala-NH₂ (D2), as well as the starburst polymeric derivatives of D1, (pVIm) ₈ -D1 and (pLys) _n -D1, containing poly(N-vinylimidazole) and polylysine chains single-point bound to the dendrimer amino groups. The conditions of dendrimer–plasmid DNA complex formation were studied. The intracellular localization of these complexes and the expression of gene constructs delivered with their help were analyzed in transfection experiments on the HeLa cell cultures of human epithelial carcinoma and on mouse C2C12 myoblasts. It was found that the chemical structure of dendrimer D1 and its derivatives significantly affected the structure and properties of complex.     

Dendrimers based lysine and their "starburst" polymeric derivatives: prospects of use in compacting DNA and in vitro delivery of genetic constructs

We attempted to find some compounds for the effective delivery of gene constructs into cells and obtained two trispherical dendrimers on the basis of lysine, (Lys)8-(alpha, epsilon-Lys)4-(alpha, epsilon-Lys)2-(alpha, epsilon-Lys)-Ala-NH2 (D1) and (Lys)8-(alpha, epsilon-Lys)4-(alpha, epsilon-Lys)2-(alpha, epsilon-Lys)-Ala-[Lys(Plm)]2-Ala-NH2 (D2), as well as the starburst polymeric derivatives of D1, (pVIm)8-D1 and (pLys)n-D1, containing poly(N-vinylimidazole) and polylysine chains bound at a single point to the dendrimer amino groups. The conditions of dendrimer-plasmid DNA complex formation were studied. The intracellular localization of these complexes and the expression of gene constructs delivered with their help were analyzed in transfection experiments on the HeLa cell cultures of human epithelial carcinoma and on C2C12 mouse myoblasts. It was found that the chemical structure of dendrimer D1 and its derivatives significantly affected the structure and properties of complex. The English version of the paper: Russian Journal of Bioorganic Chemistry, 2004, vol. 30, no. 1; see also http://www.maik.ru.     

Dependence of the efficacy of transfecting muscle fibers in vivo on electroporation conditions

This study is a survey of in vivo experiments on transfection of laboratory mouse muscle fibers by electroporation using an original device generating electric impulses. Transfection efficiency proved to depend on DNA dose and the number of electric impulses. It can be increased significantly by electroporation at varying pulse burst polarity. At both direct electrode application to muscles and electroporation through the skin, the muscle fiber transfection was more efficient under electroporation conditions much milder than those usually reported. The use of electroporation method for gene therapy of Duchenne muscular dystrophy is discussed.     

Optimization of transfection properties of DNA-lysine dendrimer complexes

We studied the possibility of optimizing the DNA transfection properties of carriers based on lysine dendrimers of the third and the fifth generation, including those containing a chloroacetyl or a lipophilic palmitoyl moiety at the C-end. The use of the lysosome-destroying antibiotic chloroquine and the amphipathic polycationic nonadecapeptide JTS-1 was found to enhance the DNA-transfecting properties of the lysine dendrimers. A triple complex including DNA, a lysine dendrimer of the third generation modified with lipophilic moieties of palmitic acid at its C-end, and JTS-1 was shown to be comparable in its transfecting activity to a complex containing Escort, a commercial cationic liposome carrier.__________Translated from Bioorganicheskaya Khimiya, Vol. 31, No. 2, 2005, pp. 167–174.Original Russian Text Copyright © 2005 by Vlasov, Lesina, Korolkov, Guryanov, Bayanova, Baranov, Kiselev, Baranov.