Differentiation of adipose progenitor cells into mature adipocytes entails a dramatic reorganization of the cellular architecture to accommodate lipid storage into cytoplasmic lipid droplets. Lipid droplets occupy most of the adipocyte volume, compressing the nucleus beneath the plasma membrane. How this cellular remodeling affects sub-nuclear structure, including size and number of nucleoli, remains unclear. We describe the morphological remodeling of the nucleus and the nucleolus during in vitro adipogenic differentiation of primary human adipose stem cells. We find that cell cycle arrest elicits a remodeling of nucleolar structure which correlates with a decrease in protein synthesis. Strikingly, triggering cytoskeletal rearrangements mimics the nucleolar remodeling observed during adipogenesis. Our results point to nucleolar remodeling as an active, mechano-regulated mechanism during adipogenic differentiation and demonstrate a key role of the actin cytoskeleton in defining nuclear and nucleolar architecture in differentiating human adipose stem cells.

脂肪祖细胞分化为成熟脂肪细胞需要细胞结构的显着重组，以将脂质储存适应细胞质脂滴。脂滴占据了脂肪细胞的大部分体积，将细胞核压缩在质膜下方。这种细胞重塑如何影响亚核结构，包括核仁的大小和数量，目前尚不清楚。我们描述了原代人脂肪干细胞体外成脂分化过程中细胞核和核仁的形态重塑。我们发现细胞周期停滞引起核仁结构的重塑，这与蛋白质合成的减少相关。引人注目的是，触发细胞骨架重排模仿了脂肪生成过程中观察到的核仁重塑。我们的结果表明核仁重塑是脂肪形成分化过程中一种活跃的机械调节机制，并证明了肌动蛋白细胞骨架在定义人类脂肪干细胞分化过程中的核和核仁结构中的关键作用。