Department of Biomedical Sciences, Graduate School of Veterinary Medicine, Hokkaido University, Sapporo, Japan.
Department of Biomedical Sciences, Graduate School of Veterinary Medicine, Hokkaido University, Sapporo, Japan ; Department of Nutrition, Graduate School of Nursing and Nutrition, Tenshi College, Sapporo, Japan.
PLoS One. 2013 Dec 30;8(12):e84229. doi: 10.1371/journal.pone.0084229. eCollection 2013.
Chronic adrenergic activation leads to the emergence of beige adipocytes in some depots of white adipose tissue in mice. Despite their morphological similarities to brown adipocytes and their expression of uncoupling protein 1 (UCP1), a thermogenic protein exclusively expressed in brown adipocytes, the beige adipocytes have a gene expression pattern distinct from that of brown adipocytes. However, it is unclear whether the thermogenic function of beige adipocytes is different from that of classical brown adipocytes existing in brown adipose tissue. To examine the thermogenic ability of UCP1 expressed in beige and brown adipocytes, the adipocytes were isolated from the fat depots of C57BL/6J mice housed at 24°C (control group) or 10°C (cold-acclimated group) for 3 weeks. Morphological and gene expression analyses revealed that the adipocytes isolated from brown adipose tissue of both the control and cold-acclimated groups consisted mainly of brown adipocytes. These brown adipocytes contained large amounts of UCP1 and increased their oxygen consumption when stimulated with norepinephirine. Adipocytes isolated from the perigonadal white adipose tissues of both groups and the inguinal white adipose tissue of the control group were white adipocytes that showed no increase in oxygen consumption after norepinephrine stimulation. Adipocytes isolated from the inguinal white adipose tissue of the cold-acclimated group were a mixture of white and beige adipocytes, which expressed UCP1 and increased their oxygen consumption in response to norepinephrine. The UCP1 content and thermogenic ability of beige adipocytes estimated on the basis of their abundance in the cell mixture were similar to those of brown adipocytes. These results revealed that the inducible beige adipocytes have potent thermogenic ability comparable to classical brown adipocytes.
慢性肾上腺素能激活导致在白色脂肪组织的一些部位出现米色脂肪细胞。尽管它们在形态上与棕色脂肪细胞相似，并且表达解偶联蛋白 1（UCP1），这是一种专门在棕色脂肪细胞中表达的产热蛋白，但米色脂肪细胞的基因表达模式与棕色脂肪细胞不同。然而，尚不清楚米色脂肪细胞的产热功能是否与存在于棕色脂肪组织中的经典棕色脂肪细胞不同。为了检查 UCP1 在米色和棕色脂肪细胞中表达的产热能力，将脂肪细胞从 C57BL/6J 小鼠的脂肪组织中分离出来，这些小鼠分别在 24°C（对照组）或 10°C（冷适应组）下饲养 3 周。形态和基因表达分析表明，从对照组和冷适应组的棕色脂肪组织中分离出来的脂肪细胞主要由棕色脂肪细胞组成。这些棕色脂肪细胞含有大量的 UCP1，并在受到去甲肾上腺素刺激时增加其耗氧量。从两组的腹膜后白色脂肪组织和对照组的腹股沟白色脂肪组织中分离出的脂肪细胞是白色脂肪细胞，在去甲肾上腺素刺激后其耗氧量没有增加。从冷适应组的腹股沟白色脂肪组织中分离出的脂肪细胞是白色和米色脂肪细胞的混合物，它们在受到去甲肾上腺素刺激时表达 UCP1 并增加其耗氧量。根据细胞混合物中的丰度估计的米色脂肪细胞的 UCP1 含量和产热能力与棕色脂肪细胞相似。这些结果表明，诱导的米色脂肪细胞具有与经典棕色脂肪细胞相当的强大产热能力。
