Unexpected deposition of brown fat in mammary gland during postnatal development
Unexpected deposition of brown fat in mammary gland during postnatal development
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DOI：
10.1210/me.2001-0337
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发表时间：
2002-11-01
影响因子：
--
通讯作者：
Pollard, JW
中科院分区：
文献类型：
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作者：
Gouon-Evans, V;Pollard, JW
乳腺脂肪组织是胎儿和成年小鼠乳腺导管形态发生的关键。脂肪细胞分为蓄能型白色脂肪细胞和耗能型棕色脂肪细胞两种。乳腺中脂肪细胞的确切类型从未被研究过，但一直被认为只是白色脂肪。在这项研究中，我们发现出生后乳腺中存在白色和棕色脂肪细胞。组织学和电镜检查的棕色脂肪组织（BAT）的数量与解偶联蛋白1的转录水平相关，解偶联蛋白1是一种仅在BAT中表达的线粒体载体。解偶联蛋白1 mrna在青春期前最高，青春期后减少，最终在成年乳腺中无法检测到。对BAT缺失小鼠模型的分析表明，在出生后早期发育过程中，乳腺BAT的缺失可诱导上皮分化。肺泡结构沿着所有导管形成，由于它们产生β -酪蛋白而具有功能。然而，乳腺移植实验表明，系统性的影响是上皮分化的原因。我们的数据表明，BAT在青春期前导管生长过程中系统性地负向调节乳腺上皮细胞的分化。
Mammary fat tissue is crucial for mammary ductal morphogenesis in both fetal and adult mice. There are two kinds of adipocytes, the energy-storing white and the energy-dissipating brown adipocyte. The precise identity of the types of adipocyte in the mammary gland has never been investigated but was always assumed to be only white fat. In this study, we show that both white and brown adipocytes are present in the postnatal mammary gland. The amount of brown adipose tissue (BAT) examined by histology and electron microscopy correlates with the transcript levels of uncoupling protein 1, which is a mitochondrial carrier expressed exclusively in BAT. Uncoupling protein 1 mRNAs are the highest during prepuberty, decrease upon puberty, and are finally undetectable in the adult mammary gland. The analysis of a BAT-depleted mouse model showed that depletion of mammary BAT in early postnatal development induces epithelial differentiation. Alveolar structures were formed along all ducts and were functional since they produced beta-casein. However, mammary transplantation experiments indicated that a systemic effect was responsible for epithelium differentiation. Our data suggest that BAT negatively regulates the differentiation of mammary epithelial cells in a systemic manner during prepubertal ductal outgrowth.