Triglyceride synthesis in hepatocytes isolated from rats fed a low-protein diet is enhanced independently of upregulation of insulin signaling
| Autor: | Shinichiro Takahashi, Yusuke Taguchi, Reiko Tokita, Shiro Minami, Hisanori Kato, Yuka Toyoshima |
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| Rok vydání: | 2017 |
| Předmět: |
Male
0301 basic medicine medicine.medical_specialty medicine.medical_treatment Biophysics 030209 endocrinology & metabolism Biochemistry 03 medical and health sciences chemistry.chemical_compound 0302 clinical medicine Downregulation and upregulation Low-protein diet Internal medicine Diet Protein-Restricted medicine Animals Insulin Rats Wistar Molecular Biology Cells Cultured Triglycerides Fatty acid synthesis biology Lipogenesis Fatty liver Cell Biology medicine.disease Rats Pyruvate carboxylase Fatty Liver Insulin receptor Fatty acid synthase 030104 developmental biology Endocrinology chemistry Hepatocytes biology.protein Signal Transduction |
| Zdroj: | Biochemical and Biophysical Research Communications. 490:800-805 |
| ISSN: | 0006-291X |
| DOI: | 10.1016/j.bbrc.2017.06.120 |
| Popis: | It is known that protein malnutrition develops fatty liver in rats. However, the mechanisms by which protein malnutrition enhances lipid accumulation in the liver are not fully understood. Our previous studies have demonstrated that protein malnutrition upregulates insulin signaling with an increase in TG levels in rat livers. Here, we examined whether the upregulated insulin signaling contributes to an enhancement of TG accumulation under protein malnutrition. As it is difficult to analyze insulin-induced hepatic TG synthesis in vivo, the isolated hepatocytes derived from rats fed a low-protein diet were used. The hepatocytes were isolated from rats fed a 15% casein diet (15C) as a control diet or a 5% casein diet (5C) as a low-protein diet and then treated with insulin. As shown in vivo, insulin signaling was upregulated in isolated hepatocytes from 5C-fed rats (5C hepatocytes). However, the insulin-induced increase in the mRNA levels of lipogenic enzymes, including acetyl-CoA carboxylase 1 (ACC1) and fatty acid synthase (FAS), was similar in both groups. The amounts of TG synthesized from both glucose and palmitate, as well as ACC1 and FAS protein levels, were increased at the basal state in 5C hepatocytes, but were not further increased by insulin. These results indicate that TG synthesis via both de novo fatty acid synthesis and esterification is enhanced in 5C hepatocytes, which is independent of the upregulation of insulin signaling. |
| Databáze: | OpenAIRE |
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