Lysophosphatidylcholine (LPC) may accumulate in the heart to cause fibrotic events, which is mediated through fibroblast activation and collagen accumulation. Here, we evaluated the mechanisms underlying LPC-mediated collagen induction via mitochondrial events in human cardiac fibroblasts (HCFs), coupling application of the pharmacologic cyclooxygenase-2 (COX-2) inhibitor, celecoxib, and genetic mutations in FOXO1 on the fibrosis pathway. In HCFs, LPC caused prostaglandin E₂ (PGE₂)/PGE₂ receptor 4 (EP₄)-dependent collagen induction via activation of transcriptional activity of forkhead box protein O1 (FoxO1) on COX-2 gene expression. These responses were mediated through LPC-induced generation of mitochondrial reactive oxygen species (mitoROS), as confirmed by ex vivo studies, which indicated that LPC increased COX-2 expression and oxidative stress. LPC-induced mitoROS mediated the activation of protein kinase C (PKC)α, which interacted with and phosphorylated dynamin-related protein 1 (Drp1) at Ser⁶¹⁶, thereby increasing Drp1-mediated mitochondrial fission and mitochondrial depolarization. Furthermore, inhibition of PKCα and Drp1 reduced FoxO1-mediated phosphorylation at Ser²⁵⁶ and nuclear accumulation, which suppressed COX-2/PGE₂ expression and collagen production. Moreover, pretreatment with celecoxib or COX-2 siRNA suppressed WT FoxO1; mutated Ser²⁵⁶-to-Asp²⁵⁶ FoxO1-enhanced collagen induction, which was reversed by addition of PGE₂ Our results demonstrate that LPC-induced generation of mitoROS regulates PKCα-mediated Drp1-dependent mitochondrial fission and COX-2 expression via a PKCα/Drp1/FoxO1 cascade, leading to PGE₂/EP₄-mediated collagen induction. These findings provide new insights about the role of LPC in the pathway of fibrotic injury in HCFs.

中文翻译：

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溶血磷脂酰胆碱诱导的线粒体裂变有助于人心脏成纤维细胞产生胶原蛋白。


溶血磷脂酰胆碱 (LPC) 可能在心脏中积聚，导致纤维化事件，这是通过成纤维细胞活化和胶原蛋白积聚介导的。在这里，我们评估了通过人心脏成纤维细胞 (HCF) 中的线粒体事件、药理环加氧酶-2 (COX-2) 抑制剂塞来昔布和FOXO1基因突变在纤维化途径中的耦合应用，LPC 介导的胶原蛋白诱导的机制。在 HCF 中，LPC 通过激活叉头盒蛋白 O1 (FoxO1) 对 COX-2 基因表达的转录活性，引起前列腺素 E ₂ (PGE ₂ )/PGE ₂受体 4 (EP ₄ ) 依赖性胶原诱导。这些反应是通过 LPC 诱导产生线粒体活性氧 (mitoROS) 介导的，体外研究证实，LPC 增加了 COX-2 表达和氧化应激。 LPC 诱导的 mitoROS 介导蛋白激酶 C (PKC)α 的激活，该蛋白激酶 C (PKC)α 与动力相关蛋白 1 (Drp1) 在 Ser ⁶¹⁶处相互作用并被磷酸化，从而增加 Drp1 介导的线粒体裂变和线粒体去极化。此外，抑制 PKCα 和 Drp1 可减少 FoxO1 介导的 Ser ²⁵⁶磷酸化和核积累，从而抑制 COX-2/PGE ₂表达和胶原蛋白产生。 此外，塞来昔布或 COX-2 siRNA 预处理可抑制 WT FoxO1； Ser ²⁵⁶突变为 Asp ²⁵⁶ FoxO1 增强了胶原诱导，通过添加 PGE ₂可逆转我们的结果表明，LPC 诱导的 mitoROS 生成通过 PKCα/ 调节 PKCα 介导的 Drp1 依赖性线粒体裂变和 COX-2 表达Drp1/FoxO1 级联，导致 PGE ₂ /EP ₄介导的胶原蛋白诱导。这些发现为 LPC 在 HCF 纤维化损伤途径中的作用提供了新的见解。