Department of Experimental Medical Science, Lund University , Lund, Sweden.
Adipocyte. 2020 Dec;9(1):636-648. doi: 10.1080/21623945.2020.1838684.
Adipose tissue plays a major role in regulating whole-body energy metabolism. While the biochemical processes regulating storage and release of excess energy are well known, the temporal organization of these events is much less defined. In this study, we have characterized the presence of small surface-associated lipid droplets, distinct from the central droplet, in primary human adipocytes. Based on microscopy analyses, we illustrate the distribution of mitochondria, endoplasmic reticulum and lysosomes in the vicinity of these specialized lipid droplets. Ultrastructure analysis confirmed the presence of small droplets in intact adipose tissue. Further, CIDEC, known to bind and regulate lipid droplet expansion, clearly localized at these lipid droplets. Neither acute or prolonged stimulation with insulin or isoprenaline, or pharmacologic intervention to suppress lipid flux, affected the presence of these lipid droplets. Still, phosphorylated perilipin and hormone-sensitive lipase accumulated at these droplets following adrenergic stimuli, which supports metabolic activity at these locations. Altogether, we propose these lipid droplet clusters represent an intermediate site involved in lipid transport in primary adipocytes.
脂肪组织在调节全身能量代谢方面起着重要作用。虽然调节多余能量储存和释放的生化过程众所周知,但这些事件的时间组织却知之甚少。在这项研究中,我们已经描述了在原代人脂肪细胞中存在的与中央液滴不同的小表面相关的脂质滴。基于显微镜分析,我们说明了线粒体、内质网和溶酶体在这些特殊脂质滴附近的分布。超微结构分析证实了完整脂肪组织中小滴的存在。此外,已知与脂质滴扩张结合并调节其扩张的 CIDEC 明显定位于这些脂质滴上。无论是急性或长期用胰岛素或异丙肾上腺素刺激,还是用药物抑制脂质流动来进行干预,都不会影响这些脂质滴的存在。尽管如此,在肾上腺素刺激后,磷酸化的 perilipin 和激素敏感脂肪酶会在这些小滴中积累,这支持了这些部位的代谢活性。总之,我们提出这些脂质滴簇代表原代脂肪细胞中参与脂质转运的中间部位。