Chronic Disease Research Institute, The Children's Hospital, National Clinical Research Center for Child Health, School of Public Health, School of Medicine, Zhejiang University, Hangzhou, Zhejiang, China; Department of Nutrition and Food Hygiene, School of Public Health, School of Medicine, Zhejiang University, Hangzhou, Zhejiang, China; School of Basic Medical Sciences, Zhejiang University, Hangzhou, Zhejiang, China.
Chronic Disease Research Institute, The Children's Hospital, National Clinical Research Center for Child Health, School of Public Health, School of Medicine, Zhejiang University, Hangzhou, Zhejiang, China; Department of Nutrition and Food Hygiene, School of Public Health, School of Medicine, Zhejiang University, Hangzhou, Zhejiang, China.
Clin Nutr. 2021 Apr;40(4):2025-2034. doi: 10.1016/j.clnu.2020.09.023. Epub 2020 Sep 19.
BACKGROUND & AIMS: Our previous study found that platelet counts were positively associated with body fat percentage in human. In the present study, we conducted a reverse translational study to explore the role of platelets in modulating pre-adipocyte proliferation in mice.
Mouse pre-adipocyte cell line (3T3-L1) and human pre-adipocytes harvested from female subcutaneous fat were used. Pre-adipocytes were co-cultured with platelets or platelet releasate, which were isolated from mice or humans. The cell viability and proliferative ability of the pre-adipocytes were examined by MTT and flow cytometry assays. Western blotting analysis was used to determine the phosphorylation levels of proteins in the mTOR pathway.
The number of platelets in the adipose tissues from obese mice was significantly higher than that from lean mice. Platelets and collagen-activated platelet releasate stimulated the proliferation of human pre-adipocytes and 3T3-L1 cells in vitro. Besides, platelets from obese mice were more potent in stimulating pre-adipocyte proliferation than those from lean control mice. Mechanistically, platelets enhanced pre-adipocyte proliferation through the acceleration of cell cycle progression from G0/G1 to S phase cell cycle progression. At the molecular level, platelets promoted pre-adipocyte proliferation through mTOR pathway-mediated upregulation of cyclin D1 expression.
In conclusion, platelets and platelet releasate play an important role in the proliferation of pre-adipocytes. Our study may provide new clues and the molecular mechanism of the causal pathways between platelets and body fat to explain the finding we observed in population study.
我们之前的研究发现，血小板计数与人体脂肪百分比呈正相关。在本研究中，我们进行了一项反向转化研究，以探索血小板在调节小鼠前体脂肪细胞增殖中的作用。
使用小鼠前体脂肪细胞系（3T3-L1）和从女性皮下脂肪中分离出的人前体脂肪细胞。将前体脂肪细胞与血小板或血小板释放物共培养，这些血小板或血小板释放物分别从小鼠或人类中分离得到。通过 MTT 和流式细胞术检测前体脂肪细胞的细胞活力和增殖能力。Western blot 分析用于确定 mTOR 通路中蛋白质的磷酸化水平。
肥胖小鼠脂肪组织中的血小板数量明显高于瘦小鼠。血小板和胶原激活的血小板释放物刺激人前体脂肪细胞和 3T3-L1 细胞在体外增殖。此外，肥胖小鼠的血小板比瘦对照组小鼠的血小板更能刺激前体脂肪细胞增殖。从机制上讲，血小板通过加速细胞周期从 G0/G1 期到 S 期的进展来促进前体脂肪细胞的增殖。在分子水平上，血小板通过 mTOR 通路介导的 cyclin D1 表达上调促进前体脂肪细胞增殖。
总之，血小板和血小板释放物在前体脂肪细胞的增殖中发挥重要作用。我们的研究可能为人群研究中观察到的血小板与体脂之间因果关系的新线索和分子机制提供解释。
