Brady L J, Brady P S
Department of Food Science and Nutrition, University of Minnesota, St. Paul 55108.
Diabetes. 1989 Jan;38(1):65-9. doi: 10.2337/diab.38.1.65.
The long-term regulation of hepatic mitochondrial carnitine palmitoyltransferase (CPT) was studied in control, insulin-treated, and untreated spontaneously diabetic BB Wistar rats. The activity of CPT was elevated approximately twofold in the untreated diabetic rats. This corresponded to an approximately equivalent elevation in the immunoreactive CPT activity. mRNACPT was assayed by reticulocyte lysate translation and by dot blot to a CPT oligonucleotide probe. The level of mRNACPT was approximately proportional to the observed CPT activity. A cDNA probe to CPT was developed, and transcriptional activity for CPT was assessed in isolated hepatic nuclei. Again, transcription of CPT mRNA was approximately proportional to the observed activity. We therefore conclude that at least part of the long-term regulation of hepatic CPT in spontaneously diabetic BB Wistar rats is the product of increased de novo synthesis of CPT protein brought about by regulation at the transcriptional level. Additional control of the amount of CPT may be via the regulation of RNA processing and turnover and enzyme insertion into the mitochondrial membrane.
在对照、胰岛素治疗以及未治疗的自发性糖尿病BB Wistar大鼠中，研究了肝脏线粒体肉碱棕榈酰转移酶（CPT）的长期调节。在未治疗的糖尿病大鼠中，CPT的活性升高了约两倍。这与免疫反应性CPT活性的近似等效升高相对应。通过网织红细胞裂解物翻译以及与CPT寡核苷酸探针的斑点印迹法来检测CPT mRNA。CPT mRNA的水平与观察到的CPT活性大致成比例。开发了一种针对CPT的cDNA探针，并在分离的肝细胞核中评估了CPT的转录活性。同样，CPT mRNA的转录与观察到的活性大致成比例。因此，我们得出结论，在自发性糖尿病BB Wistar大鼠中，肝脏CPT的长期调节至少部分是转录水平调节导致CPT蛋白从头合成增加的产物。CPT量的额外控制可能通过RNA加工和周转的调节以及酶插入线粒体膜来实现。
