Soulet Caroline, Josa-Castro Jordi, Moriel-Carretero María
Centre de Recherche en Biologie cellulaire de Montpellier (CRBM), Université de Montpellier, Centre National de la Recherche Scientifique, Montpellier, France.
Institut de Génétique Moléculaire de Montpellier (IGMM), Université de Montpellier, Centre National de la Recherche Scientifique, Montpellier, France.
Biol Cell. 2025 Jan;117(1):e2400141. doi: 10.1111/boc.202400141.
One widespread technique to assess in relative terms the amount of broken DNA present in the genome of individual cells consists of immobilizing the cell's nucleus under an agarose pad (called the nucleoid) and subjecting the whole genome to electrophoresis to force broken DNA molecules out of it. Since the migrating broken DNA molecules create a tail behind the nucleoid, this technique is named the comet assay. While performing comet assays regularly, we systematically observed circular regions devoid of DNA within the nucleoid region. We characterize here that these correspond to clusters of neutral (apolar) lipids, since they could be labeled with neutral lipid-dying molecules, increased when cells were fed with oleic acid, and were irresponsive to the electrophoretic field. Of relevance, de-lipidation assays, either in vivo, or in vitro using acetone, show that these neutral lipids (NL) within the nucleoid limit the ability of broken DNA molecules to migrate into the comet tail. From a technical point of view, we show that de-lipidation permits a wider range for the detection of broken DNA molecules. Biologically, we put forward the notion that NL in contact with DNA may locally exert regulatory functions within the cell's nucleus.
一种相对评估单个细胞基因组中破碎DNA含量的广泛技术，是将细胞核固定在琼脂糖垫（称为类核）下，对整个基因组进行电泳，以使破碎的DNA分子从中排出。由于迁移的破碎DNA分子在类核后面形成一条尾巴，这种技术被称为彗星试验。在定期进行彗星试验时，我们系统地观察到类核区域内存在无DNA的圆形区域。我们在此表征，这些区域对应于中性（非极性）脂质簇，因为它们可以用中性脂质染色分子标记，在细胞用油酸喂养时增加，并且对电泳场无反应。相关的是，体内或体外使用丙酮的脱脂试验表明，类核内的这些中性脂质（NL）限制了破碎DNA分子迁移到彗星尾中的能力。从技术角度来看，我们表明脱脂允许更广泛地检测破碎的DNA分子。从生物学角度来看，我们提出与DNA接触的NL可能在细胞核内局部发挥调节功能的观点。
