BACKGROUND The limited options to treat obesity and its complications result from an incomplete understanding of the underlying molecular mechanisms regulating white adipose tissue development, including adipocyte hypertrophy (increase in size) and hyperplasia (increase in number through adipogenesis). We recently demonstrated that lack of the adaptor protein Nck1 in mice is associated with reduced adiposity and impaired adipocyte differentiation. In agreement, Nck1 depletion in 3 T3-L1 cells also attenuates adipocyte differentiation by enhancing PDGFRα activation and signaling. This is accompanied by higher expression of PDGF-A, a specific PDGFRα ligand, that may contribute to enhanced activation of PDGFRα signaling in the absence of Nck1 in white adipose tissue. However, whether Nck1 deficiency also impairs adipogenic differentiation in bone marrow still remains to be determined. METHODS To address this point, Nck1-deficient derived bone marrow mesenchymal stem/stromal cells (BM-MSCs) and C3H10T1/2 mesenchymal stem cells were differentiated into adipocytes in vitro. Genes and proteins expression in these cellular models were determined using qPCR and western blotting respectively. Pharmacological approaches were used to assess a role for Nrf2 in mediating Nck1 deficiency effect on mesenchymal stem cells adipocyte differentiation. RESULTS Nck1 deficiency in both BM-MSCs and C3H10T1/2 results in impaired adipocyte differentiation, accompanied by increased activation of the transcription factor Nrf2, as shown by increased mRNA levels of Nrf2 target genes, including PDGF-A. Using pharmacological activator and inhibitor of Nrf2, we further provide evidence that Nrf2 is an important player in PDGFRα signaling that mediates expression of PDGF-A and impaired adipogenesis in Nck1-deficient BM-MSCs and C3H10T1/2 cells. CONCLUSION This study demonstrates that Nck1 deficiency in mesenchymal stem cells impairs adipogenesis through activation of the PDGFRα-Nrf2 anti-adipogenic signaling pathway. Video Abstract.

中文翻译：

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PDGFRα-Nrf2途径的激活介导缺乏Nck1的骨髓间充质干细胞中受损的脂肪细胞分化。

背景技术治疗肥胖症及其并发症的选择有限，是由于对调节白色脂肪组织发育的潜在分子机制的不完全了解，这些机制包括脂肪细胞肥大（大小增加）和增生（通过脂肪形成增加数目）。我们最近证明，在小鼠体内缺乏衔接蛋白Nck1与脂肪减少和脂肪细胞分化受损有关。一致地，在3个T3-L1细胞中的Nck1消耗也通过增强PDGFRα激活和信号传导而减弱了脂肪细胞的分化。这伴随着PDGF-A（一种特定的PDGFRα配体）的更高表达，在白色脂肪组织中缺少Nck1的情况下，可能有助于增强PDGFRα信号的激活。然而，Nck1缺乏症是否也损害骨髓中的脂肪形成分化仍有待确定。方法为了解决这一问题，将Nck1缺陷型骨髓间充质干/基质细胞（BM-MSC）和C3H10T1 / 2间充质干细胞体外分化为脂肪细胞。这些细胞模型中的基因和蛋白质表达分别使用qPCR和Western blotting确定。使用药理学方法评估Nrf2在介导Nck1缺乏对间充质干细胞脂肪细胞分化的作用中的作用。结果BM-MSC和C3H10T1 / 2中Nck1的缺乏都会导致脂肪细胞分化受损，并伴随转录因子Nrf2的活化增加，这由Nrf2靶基因（包括PDGF-A）的mRNA水平升高所证明。使用Nrf2的药理激活剂和抑制剂，我们进一步提供证据表明Nrf2是PDGFRα信号的重要参与者，该信号介导PDGF-A的表达和Nck1缺失的BM-MSC和C3H10T1 / 2细胞的脂肪形成受损。结论这项研究表明，间质干细胞中Nck1的缺乏通过激活PDGFRα-Nrf2抗脂肪形成信号通路而损害脂肪形成。录像摘要。