Rojas Valentina, Carrasco-Gallardo Carlos, Tenorio Lidia, Olesen Margrethe A, Tapia Victor, Carrasco Manuel, Araos Patricio, Quintanilla Rodrigo A, Ruiz Lina M
Institute of Biomedical Sciences, Faculty of Health Sciences, Universidad Autónoma de Chile, Santiago, Chile.
Escuela Especial Magdalena Ávalos Cruz, ASPAUT, San Miguel, Santiago, Chile.
Autism Res. 2025 May;18(5):933-953. doi: 10.1002/aur.3277. Epub 2024 Nov 29.
Autism spectrum disorder (ASD) is a neurodevelopmental condition often associated with mitochondrial dysfunction, including increased mitochondrial DNA (mtDNA) copy number and impaired energy production. This study investigates the role of the mitochondrial replisome-specifically, the genes TFAM, TWNK, POLG, and TOP1MT-in mtDNA replication and its potential contribution to ASD pathophysiology. We analyzed samples from the oral mucosa of children with ASD and typically developing (TD) controls, assessing mtDNA copy number, gene expression, and protein levels. Our findings revealed a significant increase in mtDNA copy number in the oral mucosa of ASD children, along with partially deleted mtDNA molecules. However, there were no significant changes in the expression of TFAM, TWNK, POLG, or MT-TL1 genes between ASD and TD samples. Additionally, TFAM protein levels, including monomeric, dimeric, and trimeric forms, did not differ significantly. We also observed increased oxidative stress and inflammatory markers in the oral mucosa of ASD children, suggesting that mitochondrial alterations may be linked to inflammation and oxidative damage in ASD. To further investigate the functional impact of TFAM, we overexpressed it in human HEK293 cells and cortical neurons (CN1.4). TFAM overexpression led to increased mtDNA copy number, cell proliferation, and ATP production in HEK293 cells, but did not significantly alter mitochondrial gene expression, protein oxidation, or mtDNA integrity. In CN1.4 neurons, TFAM overexpression increased mitochondrial membrane potential and length, indicating potential changes in mitochondrial dynamics. Overall, our study suggests that while mtDNA alterations are present in ASD, they are not directly driven by changes in mitochondrial replisome gene expression. These findings highlight the complexity of mitochondrial dysfunction in ASD and suggest the need for further investigation into the underlying molecular mechanisms.
自闭症谱系障碍（ASD）是一种神经发育疾病，常与线粒体功能障碍相关，包括线粒体DNA（mtDNA）拷贝数增加和能量产生受损。本研究调查线粒体复制体的作用，具体而言，即TFAM、TWNK、POLG和TOP1MT基因在mtDNA复制中的作用及其对ASD病理生理学的潜在贡献。我们分析了ASD儿童和发育正常（TD）对照儿童口腔黏膜的样本，评估了mtDNA拷贝数、基因表达和蛋白质水平。我们的研究结果显示，ASD儿童口腔黏膜中的mtDNA拷贝数显著增加，同时存在部分缺失的mtDNA分子。然而，ASD样本和TD样本之间TFAM、TWNK、POLG或MT-TL1基因的表达没有显著变化。此外，TFAM蛋白水平，包括单体、二聚体和三聚体形式，也没有显著差异。我们还观察到ASD儿童口腔黏膜中的氧化应激和炎症标志物增加，这表明线粒体改变可能与ASD中的炎症和氧化损伤有关。为了进一步研究TFAM的功能影响，我们在人HEK293细胞和皮质神经元（CN1.4）中过表达了它。TFAM过表达导致HEK293细胞中的mtDNA拷贝数、细胞增殖和ATP产生增加，但没有显著改变线粒体基因表达、蛋白质氧化或mtDNA完整性。在CN1.4神经元中，TFAM过表达增加了线粒体膜电位和长度，表明线粒体动力学可能发生了变化。总体而言，我们的研究表明，虽然ASD中存在mtDNA改变，但它们并非直接由线粒体复制体基因表达的变化驱动。这些发现凸显了ASD中线粒体功能障碍的复杂性，并表明需要进一步研究其潜在的分子机制。
