Etienne P, Parés-Herbuté N, Mani-Ponset L, Gabrion J, Rabesandratana H, Herbuté S, Monnier L
Department of Metabolism, Lapeyronie Hospital, Montpellier, France.
Differentiation. 1998 Aug;63(4):225-36. doi: 10.1111/j.1432-0436.1998.00225.x.
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.
糖尿病是动脉粥样硬化的主要危险因素。在动脉粥样硬化病变中，动脉平滑肌细胞（SMC）从收缩型转变为以活跃增殖为特征的合成型表型。当分离的动脉SMC在培养中生长时，体外也会发生类似的表型调节，其特征是细胞形态变化和肌动蛋白异构体表达的典型转变。在本研究中，我们研究了链脲佐菌素（STZ）诱导的糖尿病对培养的大鼠主动脉SMC分化状态和表型调节的影响。我们使用透射电子显微镜研究原代培养中STZ糖尿病和非糖尿病SMC的精细结构，并采用免疫学方法测定α-平滑肌肌动蛋白（α-SM）和非肌肉β-肌动蛋白（β-NM）异构体的比例。与培养的非糖尿病SMC相比，培养的STZ糖尿病SMC表现出较大的细胞质体积，富含粗面内质网。α-SM组织成应力纤维，分布不均匀且数量较少，相比之下，β-NM在STZ糖尿病SMC中比在非糖尿病SMC中更丰富。细胞荧光分析表明，新鲜的STZ糖尿病SMC中α-SM含量降低。此外，在培养的SMC对数生长期，α-SM的减少在STZ糖尿病SMC中比在非糖尿病SMC中更显著。肌动蛋白异构体的免疫印迹证实，即使在新鲜分离的细胞中，β-NM在STZ糖尿病SMC中的表达也比在非糖尿病SMC中更显著。结果表明，与非糖尿病大鼠的SMC相比，STZ糖尿病大鼠的SMC在原代培养中表现出更去分化的状态，并且经历更快速的表型调节。因此，糖尿病可能会诱导动脉SMC表型的变化，这可能与动脉粥样硬化过程的发生或进展有关。
