Department of Life Science, Dongguk University-Seoul, Biomedi Campus, 32 Dongguk-ro, Ilsandong-gu, Goyang, Gyeonggi-do, 10326, Republic of Korea.
Sci Rep. 2023 Sep 29;13(1):16384. doi: 10.1038/s41598-023-43737-z.
Bone marrow-derived human mesenchymal stem cells (hMSCs) can differentiate into various lineages, such as chondrocytes, adipocytes, osteoblasts, and neuronal lineages. It has been shown that the high-efficiency DNA-repair capacity of hMSCs is decreased during their differentiation. However, the underlying its mechanism during adipogenesis and osteogenesis is unknown. Herein, we investigated how alkyl-damage repair is modulated during adipogenic and osteogenic differentiation, especially focusing on the base excision repair (BER) pathway. Response to an alkylation agent was assessed via quantification of the double-strand break (DSB) foci and activities of BER-related enzymes during differentiation in hMSCs. Adipocytes showed high resistance against methyl methanesulfonate (MMS)-induced alkyl damage, whereas osteoblasts were more sensitive than hMSCs. During the differentiation, activities, and protein levels of uracil-DNA glycosylase were found to be regulated. In addition, ligation-related proteins, such as X-ray repair cross-complementing protein 1 (XRCC1) and DNA polymerase β, were upregulated in adipocytes, whereas their levels and recruitment declined during osteogenesis. These modulations of BER enzyme activity during differentiation influenced DNA repair efficiency and the accumulation of DSBs as repair intermediates in the nucleus. Taken together, we suggest that BER enzymatic activity is regulated in adipogenic and osteogenic differentiation and these alterations in the BER pathway led to different responses to alkyl damage from those in hMSCs.
骨髓来源的人骨髓间充质干细胞（hMSCs）可分化为多种细胞谱系，如软骨细胞、脂肪细胞、成骨细胞和神经元谱系。已表明 hMSCs 在分化过程中其高效的 DNA 修复能力降低。然而，其在脂肪生成和成骨过程中的潜在机制尚不清楚。在此，我们研究了烷基损伤修复在脂肪生成和成骨分化过程中是如何被调节的，尤其是集中研究碱基切除修复（BER）途径。通过定量分析 hMSCs 分化过程中双链断裂（DSB）焦点和 BER 相关酶的活性来评估烷基化剂的反应。脂肪细胞对甲磺酸甲酯（MMS）诱导的烷基损伤表现出高抗性，而与 hMSCs 相比，成骨细胞更为敏感。在分化过程中，尿嘧啶-DNA 糖基化酶的活性和蛋白水平被发现受到调节。此外，在脂肪细胞中，连接相关蛋白，如 X 射线修复交叉互补蛋白 1（XRCC1）和 DNA 聚合酶 β，其水平和募集在成骨过程中下降。这些 BER 酶活性在分化过程中的调节影响了 DNA 修复效率和细胞核中 DSB 作为修复中间体的积累。总之，我们认为 BER 酶活性在脂肪生成和成骨分化中受到调节，BER 途径的这些改变导致对烷基损伤的反应与 hMSCs 不同。
