Tests for the statistical significance of protein sequence similarities in data-bank searches

Human-derived vascular smooth muscle cells produce angiotensin II by changing to the synthetic phenotype

We investigated whether vascular smooth muscle cells (VSMC)-derived from human produce angiotensin (Ang) II upon change from the contractile phenotype to the synthetic phenotype by incubation with fibronectin (FN). Expression of alpha-smooth muscle (SM) actin, apparent in the contractile phenotype, was decreased by FN. Expressions of matrix Gla and osteopontin, apparent in the synthetic phenotype, were increased by FN. Ang II measured by radioimmunoassay (RIA) was significantly increased in human VSMC by FN. Expression of mRNAs for Ang II-generating proteases cathepsin D, cathepsin G, ACE, and chymase was increased by FN. Expressions of cathepsin D and cathepsin G proteins were also increased by FN. Ang I-generating activity, which was inhibited by an aspartyl protease inhibitor pepstatin A, was readily detected in the conditioned medium from human VSMC. Antisense oligodeoxynucleotides (ODNs) that hybridize with cathepsin D and cathepsin G significantly inhibited FN-increased Ang II in conditioned medium and cell extracts. In VSMC conditioned medium, FN-induced elevation of Ang II was significantly inhibited by temocapril but not by chymostatin. Ang II type 1 receptor antagonist CV11974 completely, and antisense cathepsin D and cathepsin G ODNs partially inhibited the FN-stimulated growth of human VSMC. These results indicate that the change of homogeneous cultures of human VSMC from the contractile to the synthetic phenotype sequentially increases expression of proteases cathepsin D, cathepsin G, and ACE, production of Ang II and productions of growth factors, culminating in VSMC proliferation. These findings implicate a new mechanism for the pathogenesis of human vascular proliferative diseases.

Antisense oligodeoxynucleotide complementary to platelet-derived growth factor A-chain messenger RNA inhibits the arterial proliferation in spontaneously hypertensive rats without altering their blood pressures

OBJECTIVE

To evaluate the effects of the antisense oligodeoxynucleotide (ODN) to platelet-derived growth factor (PDGF) A-chain messenger RNA (mRNA) on the growth of cardiovascular organs in hypertension.

DESIGN

15-Mer antisense ODN complementary to the initiation codon region of rat PDGF-A chain mRNA and non-sense ODN of identical proportion but with a random order of bases relative to that of antisense ODN were synthesized with a DNA synthesizer.

METHODS

We examined the effects of the antisense ODN on the growth of vascular smooth muscle cells (VSMC) from spontaneously hypertensive rats (SHR) and Wistar-Kyoto rats, and on the expression of PDGF A-chain mRNA by reverse transcription and polymerase chain reaction and PDGF A-chain protein by Western blot analysis in vitro. We evaluated the distribution of 32P-labeled antisense ODN and examined the effects of the antisense ODN on the growth of cardiovascular organs in vivo.

RESULTS

The antisense ODN reduced the basal DNA synthesis of VSMC from SHR significantly, but did not do so in cells from Wistar-Kyoto rats. Mutations in the antisense ODN sequence reduced the ODN-induced inhibition of DNA synthesis. Addition of serum or transforming growth factor-beta 1 increased the DNA synthesis in the SHR-derived VSMC that was inhibited by the antisense ODN. The antisense ODN inhibited the production of PDGF A-chain protein, but not of the PDGF A-chain mRNA. The injection of 32P-antisense ODN in vivo led to a greater accumulation of radioactivity in the aorta than in other organs. Infusion of antisense ODN for 28 days did not alter the systolic blood pressure appreciably in rats of either strain. However, in SHR, it reduced markedly the elevated DNA content, [3H]-thymidine uptake, and incorporation of [3H]-thymidine into aortic DNA, and suppressed the production of aortic PDGF A-chain protein. These results indicated that the PDGF A-chain is involved in the exaggerated growth of VSMC from SHR by which inhibition of the translation of PDGF A-chain mRNA to the protein with antisense ODN occurs in vitro, and that antisense ODN to PDGF A-chain suppresses the exaggerated arterial proliferation in SHR without altering the high blood pressure in vivo.

CONCLUSION

These results imply that inhibition of the final responsible growth factor PDGF A-chain by antisense ODN can suppress the arterial proliferation in hypertension without altering the blood pressure, suggesting that the arterial proliferation in hypertension is independent of the high blood pressure in part, and that antisense therapy could be feasible for treating hypertension.