Characterization of extracellular matrix proteoglycan transcripts expressed by vascular smooth muscle cells

Northern blot analysis using intraspecies and cross-species cDNA probes encoding a variety of proteoglycan (PG) core proteins was employed to examine in vitro and in vivo vascular smooth muscle cell (VSMC) extracellular matrix (ECM) PG gene expression. Similar studies were performed using a cDNA probe encoding the rat chondrosarcoma link protein. VSMCs maintained in vitro as well as in vivo expressed a 1.8 kb transcript homologous to a cDNA encoding the bovine bone small PGII. Densitometric analysis revealed an 11-fold increase in the in vivo level of this transcript when compared to an equivalent amount of RNA extracted from rat VSMCs maintained in vitro. Rat aorta medial tissue contained approximately a 10-fold higher level of the bovine bone PGII homologous transcript when compared to rat chondrosarcoma tissue. A 2.9 kb transcript homologous to a cDNA encoding the human bone small PGI (biglycan) was detected in poly(A)+ RNA isolated from rat VSMCs maintained in vitro as well as within rat thoracic aorta medial tissue. Densitometric analysis revealed a 0.55-fold increase in the in vitro level of the PGI transcript when compared to in vivo levels. Rat chondrosarcoma expressed approximately a 3-fold higher level of a human bone PGI homologous transcript when compared to rat aorta medial tissue. A 7.3 kb and an 8.4 kb transcript homologous to a cDNA encoding the rat chondrosarcoma large hyaluronic acid (HA) binding chondroitin-sulfate (CS) PG core protein was detected in poly(A)+ RNA extracted from rat VSMCs maintained in vitro.(ABSTRACT TRUNCATED AT 250 WORDS)