DISTINCT RAT AORTIC SMOOTH-MUSCLE CELLS DIFFER IN VERSICAN PG-M EXPRESSION/

Smooth muscle cells (SMCs) with distinct phenotypes are present in blo od vessels, and distinct culture types appear when SMCs are maintained in vitro. For example, cultured SMCs from rat adult media grow as bip olar cells, which differ in gene expression from the predominantly cob blestone-shaped SMCs from rat pup aortas and rat neointimas that we ca ll pi SMCs. Since proteoglycans art present at different concentration s in the normal intima and media and are elevated in atherosclerotic p laque, we sought to determine whether pi and adult medial SMC types sy nthesize different or unique proteoglycans that are characteristic of each phenotype. [S-35]sulfate-labeled proteoglycans were purified by i on-exchange chromatography. An adult medial SMC line synthesized a lar ge proteoglycan (0.2 K-av on Sepharose CL-2B) that was not delectable in a pi SMC line. Digestion of this proteoglycan with chondroitin ABC lyase revealed three core glycoproteins of 330, 370, and 450 kD. By We stern blot analysis, the two smallest of these reacted with two antibo dies to the human fibroblast proteoglycan versican. RNAs hybridizing t o versican probes were found only in adult medial-type SMCs, including an adult medial type clone from pup aortal by Northern blot analysis. Both SMC types synthesize RNAs that hybridize to probes for other pro teoglycans, such as perlecan, biglycan, and decorin. We conclude that rat ii SMC cultures, unlike monkey, human, and rat adult medial SMC cu ltures, express little or no versican. This difference in expression m ay be responsible for the different morphologies and growth properties of the two cell types.