Sequences of exon 6 and the adjacent intron boundaries of the rat platelet-derived growth factor A-chain gene: implications for alternative splicing

Adenovirus-mediated transfer of ribozyme targeting platelet-derived growth factor A-chain mRNA inhibits growth of vascular smooth muscle cells from spontaneously hypertensive rats

Platelet-derived growth factor (PDGF) is a potent stimulator of growth of vascular smooth muscle cells (VSMCs). VSMCs from spontaneously hypertensive rats (SHRs) show exaggerated growth and increasingly express PDGF A-chain messenger RNA (mRNA). To examine adenovirus-mediated transfer of a ribozyme targeting the PDGF A-chain mRNA as a possible gene therapy for vascular proliferative diseases, a recombinant adenovirus vector encoding a ribozyme that targets rat PDGF A-chain mRNA (Ad. ribozyme) was designed and synthesized and its effect on the growth of VSMCs from SHRs was investigated. This vector dose-dependently inhibited DNA synthesis in VMSCs from SHRs, whereas an adenovirus vector encoding the Escherichia coli LacZ gene (Ad. LacZ) did not affect DNA synthesis. Ad. ribozyme significantly suppressed proliferation of VSMCs from SHRs in a dose-dependent manner. Ad. LacZ had no effect. Ad. ribozyme significantly inhibited expression of PDGF A-chain mRNA and PDGF-AA protein in VSMCs from SHRs. Ad. LacZ had no effect. These results demonstrated that adenovirus-mediated transfer of a ribozyme targeting the PDGF A-chain mRNA effectively and specifically inhibited the growth of VSMCs from SHRs with suppression of PDGF A-chain mRNA and PDGF-AA protein expression. Adenovirus-mediated transfer of ribozyme targeting PDGF A-chain mRNA may be a feasible gene therapy for vascular proliferative diseases.

Hammerhead ribozyme targeting human platelet-derived growth factor A-chain mRNA inhibited the proliferation of human vascular smooth muscle cells

Platelet-derived growth factor (PDGF) A-chain contributes to the pathogenesis of cardiovascular proliferative diseases, such as hypertensive vascular disease, atherosclerosis, and re-stenosis of an artery after angioplasty. To develop a ribozyme against human PDGF A-chain mRNA as a gene therapy for human arterial proliferative diseases, we designed and synthesized a 38-base hammerhead ribozyme to cleave human PDGF A-chain mRNA at the GUC sequence at nucleotide 591. In the presence of MgCl(2), synthetic hammerhead ribozyme to human PDGF A-chain mRNA cleaved the synthetic target RNA to two RNA fragments at a predicted size. Doses of 0.01-1.0 microM hammerhead ribozyme to human PDGF A-chain mRNA significantly inhibited angiotensin II (Ang II) and transforming growth factor (TGF)-beta(1)-induced DNA synthesis in vascular smooth muscle cells (VSMC) from human in a dose-dependent manner. One micromolor of hammerhead ribozyme to human PDGF A-chain mRNA significantly inhibited Ang II-induced PDGF A-chain mRNA and PDGF-AA protein expressions in VSMC from humans. These results indicate that the designed hammerhead ribozyme to human PDGF A-chain mRNA effectively inhibited growth of human VSMC by cleaving the PDGF A-chain mRNA and inhibiting the PDGF-AA protein expression in human VSMC. This suggests that the designed hammerhead ribozyme to PDGF A-chain mRNA is a feasible gene therapy for treating arterial proliferative diseases.

Inhibition of vascular smooth muscle cell proliferation by DNA-RNA chimeric hammerhead ribozyme targeting to rat platelet-derived growth factor A-chain mRNA

BACKGROUND

Spontaneously hypertensive rats (SHR)-derived vascular smooth muscle cells (VSMC) show exaggerated growth and increasingly express platelet-derived growth factor (PDGF) A-chain mRNA compared to VSMC from normotensive Wistar-Kyoto (WKY) rats.

OBJECTIVE

To investigate the effects of designed DNA-RNA chimeric hammerhead ribozyme to rat PDGF A-chain on exaggerated growth of VSMC from SHR.

DESIGN AND METHODS

We designed and synthesized a 38-base DNA-RNA chimeric hammerhead ribozyme with two phosphorothioate linkages at the 3' terminal to cleave rat PDGF A-chain mRNA at the GUC sequence at nucleotide 921. We confirmed the cleavage activity of designed ribozyme by in vitro cleavage reaction and by lipofectin-mediated transfection of ribozyme into VSMC.

RESULTS

Doses of 0.1 and 1 micromol/l DNA-RNA chimeric ribozyme dose-dependently inhibited basal DNA synthesis in VSMC from SHR. A dose of 1 micromol/l DNA-RNA chimeric ribozyme time-dependently inhibited basal DNA synthesis in VSMC from SHR. However, the same doses of all-RNA ribozyme had no effects on DNA synthesis in VSMC from SHR. Fluorescein isothiocyanate-labeled DNA-RNA chimeric ribozyme was recognized in cytosol at 30 min, and in nucleus at 60 min after lipofectin transfection. A dose of 1 micromol/l DNA-RNA chimeric ribozyme significantly inhibited expressions of both PDGF A-chain mRNA and PDGF-AA protein in VSMC from SHR, but not from WKY rats.

CONCLUSION

These results indicated that the designed DNA-RNA chimeric ribozyme to PDGF A-chain mRNA effectively and specifically inhibited the exaggerated growth of VSMC from SHR at low concentrations, which were mediated by the reduction of PDGF A-chain mRNA and PDGF-AA protein expressions.

Effect of methylene methylimino linkage of antisense oligonucleotide to the platelet-derived growth factor A-chain on growth of vascular smooth muscle cells from spontaneously hypertensive rats

Spontaneously hypertensive rats (SHR)-derived vascular smooth muscle cells show exaggerated growth and increased expression of platelet-derived growth factor (PDGF) A-chain mRNA. We examined the effect of methylene methylimino linkage of antisense oligodeoxynucleotide, a novel modification of antisense oligodeoxynucleotide designed to increase nuclease resistance, to PDGF A-chain on the exaggerated growth of vascular smooth muscle cells from SHR. Methylene methylimino-linked oligodeoxynucleotide provided complete resistance against S1 nuclease. Methylene methylimino linkage of antisense oligodeoxynucleotide to PDGF A-chain resulted in a rapid inhibition of basal DNA synthesis of vascular smooth muscle cells from SHR. This inhibition was much greater than that produced by phosphorothioate linkage of antisense oligodeoxynucleotide to PDGF A-chain. The methylene methylimino linkage of antisense oligodeoxynucleotide to PDGF A-chain may prove useful in the treatment of arterial proliferative diseases including hypertension.