Department of Biochemistry and Molecular Biology, Faculty of Science and Technology, University of the Basque Country, P.O. Box 644, 48980 Bilbao, Spain.
Respiratory Department, Cruces University Hospital, 48903 Barakaldo (Bizkaia), Spain.
Int J Mol Sci. 2021 Feb 1;22(3):1452. doi: 10.3390/ijms22031452.
Phosphatidic acid (PA) is a bioactive phospholipid capable of regulating key biological functions, including neutrophil respiratory burst, chemotaxis, or cell growth and differentiation. However, the mechanisms whereby PA exerts these actions are not completely understood. In this work, we show that PA stimulates myoblast proliferation, as determined by measuring the incorporation of [H]thymidine into DNA and by staining the cells with crystal violet. PA induced the rapid phosphorylation of Akt and ERK1/2, and pretreatment of the cells with specific small interferin RNA (siRNA) to silence the genes encoding these kinases, or with selective pharmacologic inhibitors, blocked PA-stimulated myoblast proliferation. The mitogenic effects of PA were abolished by the preincubation of the myoblasts with pertussis toxin, a Gi protein inhibitor, suggesting the implication of Gi protein-coupled receptors in this action. Although some of the effects of PA have been associated with its possible conversion to lysoPA (LPA), treatment of the myoblasts with PA for up to 60 min did not produce any significant amount of LPA in these cells. Of interest, pharmacological blockade of the LPA receptors 1 and 2, or specific siRNA to silence the genes encoding these receptors, abolished PA-stimulated myoblast proliferation. Moreover, PA was able to compete with LPA for binding to LPA receptors, suggesting that PA can act as a ligand of LPA receptors. It can be concluded that PA stimulates myoblast proliferation through interaction with LPA1 and LPA2 receptors and the subsequent activation of the PI3K/Akt and MEK/ERK1-2 pathways, independently of LPA formation.
磷脂酸 (PA) 是一种具有生物活性的磷脂，能够调节关键的生物学功能，包括中性粒细胞呼吸爆发、趋化性或细胞生长和分化。然而，PA 发挥这些作用的机制尚不完全清楚。在这项工作中，我们表明 PA 可刺激成肌细胞增殖，这可通过测量 [H]胸腺嘧啶核苷掺入 DNA 以及用结晶紫染色细胞来确定。PA 可诱导 Akt 和 ERK1/2 的快速磷酸化，并且用特异性小干扰 RNA (siRNA) 预处理细胞以沉默编码这些激酶的基因，或用选择性药理学抑制剂阻断 PA 刺激的成肌细胞增殖。Gi 蛋白抑制剂百日咳毒素预孵育可消除 PA 的有丝分裂效应，表明 Gi 蛋白偶联受体在此作用中起作用。尽管 PA 的一些作用与它可能转化为溶血磷脂酸 (LPA) 有关，但将成肌细胞与 PA 孵育长达 60 分钟不会在这些细胞中产生任何大量的 LPA。有趣的是，LPA 受体 1 和 2 的药理学阻断或沉默这些受体编码基因的特异性 siRNA 可消除 PA 刺激的成肌细胞增殖。此外，PA 能够与 LPA 竞争与 LPA 受体结合，表明 PA 可以作为 LPA 受体的配体。可以得出结论，PA 通过与 LPA1 和 LPA2 受体相互作用并随后激活 PI3K/Akt 和 MEK/ERK1-2 途径刺激成肌细胞增殖，而与 LPA 的形成无关。
