期刊
ARCHIVES OF BIOCHEMISTRY AND BIOPHYSICS
卷 508, 期 1, 页码 87-92出版社
ELSEVIER SCIENCE INC
DOI: 10.1016/j.abb.2011.01.015
关键词
Lipogenesis; Fatty acid synthesis; Mammary gland; Milk fat globules; Mass spectrometry; Mammalian target of rapamycin
资金
- Ministry of Education, Culture, Sports, Science and Technology of Japan
- Grants-in-Aid for Scientific Research [21580412] Funding Source: KAKEN
The mammary epithelium produces numerous lipid droplets during lactation and secretes them in plasma membrane-enclosed vesicles known as milk fat globules. The biogenesis of such fat globules is considered to provide a model for clarifying the mechanisms of lipogenesis in mammals. In the present study, we identified acetyl coenzyme A carboxylase, ATP citrate lyase, and fatty acid synthase in mouse milk. Fractionation of milk showed that these three enzymes were located predominantly in milk fat globules. The three enzymes were resistant to trypsin digestion without Triton X-100, indicating that they were not located on the outer surface of the globules and thus associated with the precursors of the globules before secretion. When a low dose of rapamycin, an inhibitor of the mammalian target of rapamycin (mTOR), was injected into lactating mice, the levels of the three enzymes in milk were decreased within 3 h after injection. Since the protein levels of the three enzymes in tissues were not obviously altered by this short-term treatment, known transcriptional control by mTOR signaling was unlikely to account for this decrease in their levels in milk. Our findings suggest a new, putatively mTOR-dependent localization of the three enzymes for de novo lipogenesis. (C) 2011 Elsevier Inc. All rights reserved.
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