Levchenko Svitlana M, Dobrucki Jurek W
Department of Cell Biophysics, Faculty of Biochemistry, Biophysics and Biotechnology, Jagiellonian University, Kraków, Poland.
FASEB J. 2025 Sep 15;39(17):e71010. doi: 10.1096/fj.202501727R.
The density of mammalian cells is determined primarily by the protein content. Local concentration of proteins in a cell is tightly controlled and varies between the cytoplasm, nucleoplasm, and nucleoli. We demonstrate that repair foci that are formed in response to DNA breaks are much more densely packed with proteins than the surrounding nucleoplasm. Using fluorescence lifetime imaging (FLIM), we demonstrated that the local concentration of all proteins (i.e., the residing and recruited ones) in double- and single-strand DNA repair foci can be even 2.2 times higher than that in the surrounding nucleoplasm, which brings them close to the achievable maximum concentration. The highest protein density is found in the center of a repair focus and gradually decreases with distance from the DNA lesion. We hypothesize that a microenvironment characterized by such a high protein concentration may facilitate the formation of protein condensates, resulting in the stabilization of repair complexes.
哺乳动物细胞的密度主要由蛋白质含量决定。细胞内蛋白质的局部浓度受到严格控制，在细胞质、核质和核仁之间存在差异。我们证明，响应DNA断裂而形成的修复灶比周围的核质含有更多密集堆积的蛋白质。使用荧光寿命成像（FLIM），我们证明双链和单链DNA修复灶中所有蛋白质（即驻留和募集的蛋白质）的局部浓度甚至可比周围核质高2.2倍，这使其接近可达到的最大浓度。在修复灶的中心发现最高的蛋白质密度，并随着与DNA损伤距离的增加而逐渐降低。我们推测，以如此高蛋白质浓度为特征的微环境可能有助于蛋白质凝聚物的形成，从而导致修复复合物的稳定。
