Lactate leads to the imbalance of mitochondria homeostasis, which then promotes vascular calcification. PARP1 can upregulate osteogenic genes and accelerate vascular calcification. However, the relationship among lactate, PARP1, and mitochondrial homeostasis is unclear. The present study aimed to explore the new molecular mechanism of lactate to promote VSMC calcification by evaluating PARP1 as a breakthrough molecule. A coculture model of VECs and VSMCs was established, and the model revealed that the glycolysis ability and lactate production of VECs were significantly enhanced after incubation in DOM. Osteogenic marker expression, calcium deposition, and apoptosis in VSMCs were decreased after lactate dehydrogenase A knockdown in VECs. Mechanistically, exogenous lactate increased the overall level of PARP and PARylation in VSMCs. PARP1 knockdown inhibited Drp1-mediated mitochondrial fission and partially restored PINK1/Parkin-mediated mitophagy, thereby reducing mitochondrial oxidative stress. Moreover, lactate induced the translocation of PARP1 from the nucleus to the mitochondria, which then combined with POLG and inhibited POLG-mediated mitochondrial DNA synthesis. This process led to the downregulation of mitochondria-encoded genes, disturbance of mitochondrial respiration, and inhibition of oxidative phosphorylation. The knockdown of PARP1 could partially reverse the damage of mitochondrial gene expression and function caused by lactate. Furthermore, UCP2 was upregulated by the PARP1/POLG signal, and UCP2 knockdown inhibited Drp1-mediated mitochondrial fission and partially recovered PINK1/Parkin-mediated mitophagy. Finally, UCP2 knockdown in VSMCs alleviated DOM-caused VSMC calcification in the coculture model. The study results thus suggest that upregulated PARP1 is involved in the mechanism through which lactate accelerates VSMC calcification partly via POLG/UCP2-caused unbalanced mitochondrial homeostasis.

乳酸导致线粒体稳态失衡，进而促进血管钙化。PARP1可以上调成骨基因并加速血管钙化。然而，乳酸、PARP1 和线粒体稳态之间的关系尚不清楚。本研究旨在通过评价PARP1作为突破性分子，探讨乳酸促进VSMC钙化的新分子机制。建立了VECs和VSMCs的共培养模型，该模型显示，在DOM中孵育后，VECs的糖酵解能力和乳酸产量显着增强。VEC 中乳酸脱氢酶 A 敲低后，VSMC 中的成骨标志物表达、钙沉积和细胞凋亡均减少。从机制上讲，外源性乳酸增加了 VSMC 中 PARP 和 PARylation 的总体水平。PARP1 敲低抑制了 Drp1 介导的线粒体裂变，部分恢复了 PINK1/Parkin 介导的线粒体自噬，从而减少了线粒体氧化应激。此外，乳酸诱导PARP1从细胞核易位至线粒体，然后与POLG结合并抑制POLG介导的线粒体DNA合成。这一过程导致线粒体编码基因的下调、线粒体呼吸的紊乱以及氧化磷酸化的抑制。PARP1的敲低可以部分逆转乳酸引起的线粒体基因表达和功能的损伤。此外，UCP2 被 PARP1/POLG 信号上调，UCP2 敲低抑制了 Drp1 介导的线粒体裂变，并部分恢复了 PINK1/Parkin 介导的线粒体自噬。最后，VSMC 中的 UCP2 敲除减轻了共培养模型中 DOM 引起的 VSMC 钙化。因此，研究结果表明，上调的 PARP1 参与了乳酸加速 VSMC 钙化的机制，部分是通过 POLG/UCP2 引起的线粒体稳态失衡。