Phenotype modulation in primary cultures of aortic smooth muscle cells from streptozotocin-diabetic rats.
Diabetes mellitus is a major risk factor for atherosclerosis. In atherosclerotic lesions, arterial smooth muscle cells (SMC) change from a contractile to a synthetic phenotype characterized by active proliferation. A similar phenotype modulation occurs in vitro when isolated arterial SMC are grown in culture and is characterized by both changes in cell morphology and a typical switch in actin isoform expression. In this study, we examined the influence of streptozotocin (STZ)-induced diabetes on the differentiation state and the phenotype modulation of cultured rat aortic SMC. We used transmission electron microscopy to study the fine structure of STZ-diabetic and non-diabetic SMC in primary culture and immunological methods for the determination of the proportions of alpha-smooth muscle actin (alpha-SM) and nonmuscle beta-actin (beta-NM) isoforms. Cultured STZ-diabetic SMC exhibited a large cytoplasmic volume, rich in rough endoplasmic reticulum, when compared with cultured non-diabetic SMC. alpha-SM, organized in stress fibers, was less homogeneously and abundantly distributed and by contrast, beta-NM was more abundant in STZ-diabetic than in non-diabetic SMC. Cytofluorimetric analyses demonstrated that the alpha-SM content was reduced in freshly STZ-diabetic SMC. Furthermore, during logarithmic growth of cultured SMC, the decrease of alpha-SM was more important in STZ-diabetic than in non-diabetic SMC. Immunoblotting of actin isoforms confirmed that expression of beta-NM was more important in STZ-diabetic than in non-diabetic SMC even in freshly isolated cells. The results suggest that SMC from STZ-diabetic rats express a more dedifferentiated state and undergo a more rapid phenotypic modulation in primary cultures than SMC from non-diabetic rats. Therefore, diabetes could induce changes in the phenotype of arterial SMC which might be associated with the onset or progression of the atherogenic process.
Etienne
P
P
Department of Metabolism, Lapeyronie Hospital, Montpellier, France.
Parés-Herbuté
N
N
Mani-Ponset
L
L
Gabrion
J
J
Rabesandratana
H
H
Herbuté
S
S
Monnier
L
L
D000199:Actins / Q000032:analysis / Q000096:biosynthesis; D000818:Animals; D001013:Aorta, Thoracic / Q000166:cytology / Q000473:pathology* / Q000648:ultrastructure; D002454:Cell Differentiation; D002455:Cell Division; D002478:Cells, Cultured; D003921:Diabetes Mellitus, Experimental / Q000473:pathology*; D005434:Flow Cytometry; D007700:Kinetics; D008297:Male; D009131:Muscle, Smooth, Vascular / Q000166:cytology / Q000473:pathology* / Q000648:ultrastructure; D010641:Phenotype; D051381:Rats; D017208:Rats, Wistar; D012016:Reference Values; D013997:Time Factors
D000199:Actins