Uçar Nazli, Deeney Jude T, Pickering R Taylor, Fan Ting-Yu, Loo Ralf, Mueller Peter M, Holick Michael F
Section of Endocrinology, Diabetes, Nutrition and Weight Management, Department of Medicine, Boston University Chobanian & Avedisian School of Medicine, Boston, MA, U.S.A.
Area of Preventive Medicine and Public Health, Department of Preventive Medicine and Public Health, Food Sciences, Toxicology and Legal Medicine, School of Pharmacy, University de Valencia, Valencia, Spain.
Anticancer Res. 2025 Jan;45(1):55-63. doi: 10.21873/anticanres.17392.
BACKGROUND/AIM: Obese individuals often exhibit vitamin D deficiency, potentially due to sequestration in fat cells. Little is known about how vitamin D enters adipocytes and associates with the intracellular lipid droplet.
Newly differentiated human and mouse (3T3-L1) adipocytes and primary mouse adipocytes were treated with vitamin D covalently linked to green fluorescent BODIPY (VitD-B) or Green BODIPY (GB) as control. Cells were exposed to 10-100 nM concentrations for various lengths of time (1-48 h). Fluorescence microscopy assessed vitamin D distribution.
VitD-B demonstrated stable incorporation into adipocytes without enzymatic cleavage, as HPLC showed no free vitamin D after 72 h. Fluorescence microscopy showed GB uptake was rapid and persisted for 48 h. VitD-B uptake was more gradual compared to GB in the human and 3T3-L1 adipocytes. Primary mouse adipocytes exhibited similar uptake patterns, with VitD-B appearing within 1 h and fluorescence intensity increasing 1.2-fold at 8 h and 5.7-fold at 24 h. GB exhibited rapid fluorescence uptake in these same cells, 29-fold higher than VitD-B at 1 h. At 24 h, some VitD-B treated cells exhibited greater fluorescence intensity around the surface of the lipid droplets, which was not observed in GB. Isolated lipid droplets exhibited rapid and immediate uptake of both VitD-B and GB, indicating a strong affinity for these lipid structures. The time-dependent accumulation of vitamin D in human adipocytes mirrored VitD-B uptake.
VitD-B is a reliable proxy for studying the dynamics of vitamin D uptake in adipocytes.
背景/目的：肥胖个体常表现出维生素D缺乏，这可能是由于维生素D被脂肪细胞隔离所致。关于维生素D如何进入脂肪细胞并与细胞内脂滴结合，目前所知甚少。
将新分化的人及小鼠（3T3-L1）脂肪细胞和原代小鼠脂肪细胞用与绿色荧光BODIPY共价连接的维生素D（VitD-B）或绿色BODIPY（GB）作为对照进行处理。细胞暴露于10 - 100 nM浓度下不同时长（1 - 48小时）。通过荧光显微镜评估维生素D的分布。
HPLC显示72小时后无游离维生素D，表明VitD-B在无酶解的情况下稳定掺入脂肪细胞。荧光显微镜显示GB摄取迅速且持续48小时。在人及3T3-L1脂肪细胞中，与GB相比，VitD-B的摄取更为缓慢。原代小鼠脂肪细胞呈现相似的摄取模式，VitD-B在1小时内出现，荧光强度在8小时时增加1.2倍，在24小时时增加5.7倍。GB在这些相同细胞中呈现快速荧光摄取，在1小时时比VitD-B高29倍。在24小时时，一些经VitD-B处理的细胞在脂滴表面周围呈现出更强的荧光强度，而在GB处理的细胞中未观察到这种现象。分离的脂滴对VitD-B和GB均呈现快速且即时的摄取，表明对这些脂质结构具有很强的亲和力。维生素D在人脂肪细胞中的时间依赖性积累反映了VitD-B的摄取情况。
VitD-B是研究脂肪细胞中维生素D摄取动态的可靠替代物。
