Collagen synthesis by cultured rabbit aortic smooth-muscle cells. Alteration with phenotype

Abstract

Enzymically isolated rabbit aortic smooth-muscle cells (SMC) in the first few days of primary culture express a 'contractile phenotype', but with time these cells modulate to a 'synthetic phenotype'. Synthetic-state SMC are able to proliferate, and, provided that they undergo fewer than 5 cumulative population doublings, return to the contractile phenotype after reaching confluency [Campbell, Kocher, Skalli, Gabbiani & Campbell (1989) Arteriosclerosis 9, 633-643]. The present study has determined the synthesis of collagen, at the protein and mRNA levels, by cultured SMC as they undergo a change in phenotypic state. The results show that, upon modulating to the synthetic phenotype, SMC synthesized 25-30 times more collagen than did contractile cells. At the same time, non-collagen-protein synthesis increased only 5-6-fold, indicating a specific stimulation of collagen synthesis. Steady-state mRNA levels are also elevated, with alpha 2(I) and alpha 1(III) mRNA levels 30 times and 20 times higher respectively, probably reflecting increased transcriptional activity. Phenotypic modulation was also associated with an alteration in the relative proportions of type I and III collagens synthesized, contractile SMC synthesizing 78.1 +/- 3.6% (mean +/- S.D.) type I collagen and 17.5 +/- 4.7% type III collagen, and synthetic cells synthesizing 90.3 +/- 2.0% type I collagen and 5.8% +/- 1.8% type III collagen. Enrichment of type I collagen was similarly noted at the mRNA level. On return to the contractile state, at confluency, collagen production and the percentage of type I collagen decreased. This further illustrates the close association between the phenotypic state of SMC and their collagen-biosynthetic phenotype.

Non Insulin Dependent Diabetes in Sand Rat (Psammomys obesus) and Production of Collagen in Cultured Aortic Smooth Muscle Cells. Influence of Insulin

“…[33] Our qualitative and quantitative study on the phenotypic expression of collagen has shown that cultured SMCs of the normal and diabetic Psammomys obesus synthesise more type I than type III collagen, in accord with the results of Layman et al [34] [36] have shown that SMC produced essentially collagen I and III. Ang et al [37] have observed an activation of mRNA coding 1 (I) and czl (III) chains of procollagen in rabbit synthetic SMCs. Compared with control, the diabetic state induced a large increase in type I and type III collagen biosynthesis and secretion. In addition, comparatively to collagen III, collagen I appeared more important in the medium (x10.8 vs x9.3) than in the cells (x13.6 vs x11.6).…”

Treatment with Vitamin K2 Combined with Bisphosphonates Synergistically Inhibits Calcification in Cultured Smooth Muscle Cells

“…For example, it has been revealed that fibronectin and collagen promote arterial calcification 32) and that elastin, or laminin, inhibits such calcification 33,34) . We have previously reported that elastic fiber-related proteins, TE, fibrillin-1, and Lysyl oxidase, are suppressed by the induction of vascular calcification in cultured BASMCs 12) and the addition of recombinant tropoelastin significantly inhibits arterial calcification via 67 kDa elastin-binding protein (EBP) 15) .…”

Retroviral Overexpression of Decorin Differentially Affects the Response of Arterial Smooth Muscle Cells to Growth Factors

“…The transient nature of the decorin effect on cell cycle-regulatory proteins may be due instead to the neutralization of decorin by binding to other matrix components, such as fibronectin and collagen, 25,62 because these ECM components are produced in large amounts in ASMCs. [63][64][65] Alternatively, the deposition of ECM molecules, such as fibronectin and collagen, may influence the proliferative response of ASMCs to growth factors 47,66 and override the effects of decorin on cell proliferation. For example, Koyama et al 47 demonstrated that ASMCs grown on fibrillar collagen had increased levels of cyclin-dependent kinase inhibitors and a decreased growth response to PDGF compared with cells cultured on monomeric collagen.…”