Expression of matrix Gla protein and osteonectin mRNA by human aortic smooth muscle cells.
BACKGROUND
Recent data indicate that matrix proteins such as matrix Gla protein (MGP) and osteonectin (ON) influence not only mineralization of vasculature but smooth muscle cell (SMC) differentiation.


METHODS
We examined whether MGP and ON are expressed by human aortic SMCs in vivo using Northern blotting, in situ hybridization and immunohistochemistry.


RESULTS
MGP and ON mRNAs were strongly expressed in the aorta without atherosclerosis from newborn and four young subjects up to 10 years old. In the aorta from 15 adult cases, MGP and ON mRNAs were decreased as atherosclerosis developed. We determined cell type and distribution of the MGP- and ON mRNA-expressing cells by in situ hybridization and immunohistochemistry. In the aorta obtained from newborn and young subjects, SMCs in the media and thin intima expressed MGP mRNA and, to a lesser extent, ON mRNA. In the adult aorta with fibrous thickening, MGP mRNA was expressed by intimal SMCs and subpopulation of medial SMCs. Osteonectin mRNA was expressed mainly by intimal SMCs and few medial SMCs. Double immunohistochemical staining revealed that both MGP- and ON protein-expressing cells were positive for anti-alpha-smooth muscle actin antibody, aortic SMCs.


CONCLUSIONS
These results suggested that MGP and ON expression by aortic SMCs might be regulated by the degree of atherosclerosis and SMC differentiation in human aorta.
Hao
Hiroyuki
H
Department of Pathology, National Cardiovascular Center, Suita, Osaka, Japan. hiroyuki@hsp.ncvc.go.jp
Hirota
Seiichi
S
Ishibashi-Ueda
Hatsue
H
Kushiro
Toshio
T
Kanmatsuse
Katsuo
K
Yutani
Chikao
C
D000328:Adult; D000367:Age Factors; D000368:Aged; D001011:Aorta / Q000166:cytology / Q000378:metabolism* / Q000473:pathology; D001161:Arteriosclerosis / Q000378:metabolism* / Q000473:pathology; D015415:Biomarkers / Q000032:analysis; D015152:Blotting, Northern; D002135:Calcium-Binding Proteins / Q000096:biosynthesis*; D002454:Cell Differentiation / Q000502:physiology; D002648:Child; D002675:Child, Preschool; D015536:Down-Regulation; D016326:Extracellular Matrix Proteins / Q000096:biosynthesis*; D005260:Female; D015870:Gene Expression; D006801:Humans; D007150:Immunohistochemistry; D017403:In Situ Hybridization; D007223:Infant; D007231:Infant, Newborn; D008297:Male; D008875:Middle Aged; D009131:Muscle, Smooth, Vascular / Q000166:cytology / Q000378:metabolism* / Q000473:pathology; D032389:Myocytes, Smooth Muscle / Q000166:cytology / Q000378:metabolism; D015676:Osteonectin / Q000096:biosynthesis*; D012333:RNA, Messenger; D000097568:Matrix Gla Protein
D015415:Biomarkers; D002135:Calcium-Binding Proteins; D016326:Extracellular Matrix Proteins; D015676:Osteonectin; D012333:RNA, Messenger; D000097568:Matrix Gla Protein