Tamaroglio T A, Lo C S
Department of Physiology, Uniformed Services University of the Health Sciences, Bethesda, Maryland 20814.
Exp Cell Res. 1994 Dec;215(2):338-46. doi: 10.1006/excr.1994.1350.
We examined the regulation of fibronectin (FN) levels by insulin-like growth factor-I (IGF-I) in rat thoracic aortic smooth muscle cell (SMC) and glomerular mesangial cell cultures. IGF-I enhances FN levels in the culture media of the SMC and in the cell samples of the mesangial cells. It shows no effect on FN levels in the cell samples of the SMC and in the culture media of the mesangial cells. Modulation of IGF-I-induced FN levels by insulin was also examined. Insulin enhances FN levels in the culture media of the SMC but not in the cell samples. Insulin did not induce an increase in FN levels in either the mesangial cell samples or the culture media. No additive effect of FN levels was observed when the SMC were treated with insulin and IGF-I together. The effect of IGF-I on FN mRNA levels was assessed. IGF-I enhances SMC and FN mRNA levels, implying that acquisition of additional FN mRNA units accounts for the increase in FN levels. The effects of actinomycin D and cycloheximide on IGF-I-induced FN mRNA levels were also examined. Inhibition of the IGF-I-induced FN mRNA levels by actinomycin D and an increase of FN mRNA levels by cycloheximide suggest that IGF-I regulates FN mRNA synthesis at the transcriptional level.
我们研究了胰岛素样生长因子-I（IGF-I）对大鼠胸主动脉平滑肌细胞（SMC）和肾小球系膜细胞培养物中纤连蛋白（FN）水平的调节作用。IGF-I可提高SMC培养基和系膜细胞样本中的FN水平。它对SMC样本和系膜细胞培养基中的FN水平没有影响。我们还研究了胰岛素对IGF-I诱导的FN水平的调节作用。胰岛素可提高SMC培养基中的FN水平，但对SMC样本中的FN水平没有影响。胰岛素在系膜细胞样本或培养基中均未诱导FN水平升高。当SMC同时用胰岛素和IGF-I处理时，未观察到FN水平的叠加效应。评估了IGF-I对FN mRNA水平的影响。IGF-I可提高SMC和FN mRNA水平，这意味着额外的FN mRNA单位的获得是FN水平升高的原因。还研究了放线菌素D和环己酰亚胺对IGF-I诱导的FN mRNA水平的影响。放线菌素D抑制IGF-I诱导的FN mRNA水平，而环己酰亚胺提高FN mRNA水平，这表明IGF-I在转录水平上调节FN mRNA的合成。
