Department of Anesthesiology and Pain Medicine, School of Medicine, Chosun University, 309 Pilmundaero, Dong-gu, Gwangju, 501-759, South Korea.
Department of Biochemistry, Chonbuk National University Medical School, Jeonju, Jeonbuk, Republic of Korea.
Cell Biol Toxicol. 2021 Apr;37(2):193-207. doi: 10.1007/s10565-020-09528-2. Epub 2020 May 11.
Sirtuin 6 (Sirt6) is important for maintaining kidney homeostasis and function. Cd exposure increases the risk of developing kidney diseases. However, the role of Sirt6 in kidney disease mechanisms is unclear. Here, we evaluated the role of Sirt6 in Cd-induced kidney toxicity. After Cd exposure, p62/sequestosome-1 (SQSTM1), an autophagy substrate, accumulated in mouse kidney mesangial cells in monomeric and polyubiquitinated (polyUb) forms. Sirt6 accumulated in response to Cd treatment at concentrations below the half-maximal inhibitory concentration and decreased after 12 h of treatment. Sirt6 and p62 co-localized in the nucleus and redistributed to the cytosol after Cd treatment. Sirt6 was mainly present in nuclei-rich membrane fractions. Sirt6 interacted with p62. Ub, and microtubule-associated protein light chain 3 (LC3). Knockdown of p62 promoted Sirt6 nuclear accumulation and inhibited apoptosis. Sirt6 overexpression altered levels of polyUb-p62 and apoptosis. At earlier times during Cd treatment, polyubiquitination of p62 and apoptosis were reduced. Cytoplasmic translocation of Sirt6 occurred later, with increased polyubiquitination of p62 and apoptosis. Bafilomycin 1 (BaF1) treatment promoted cytosolic Sirt6 accumulation, increasing cell death. Silencing autophagy related 5 (Atg5) increased nuclear Sirt6 levels, reduced polyUb-p62, and inhibited cell death, indicating that autophagy was necessary for Sirt6 redistribution. Cd resistance was associated with reduced polyUb-p62 and persistent Sirt6 expression. Cd treatment in mice for 4 weeks promoted p62, Sirt6, and LC3-II accumulation, inducing apoptosis in kidney tissues. Overall, our findings show that polyUb-p62 targeted Sirt6 to autophagosomes, playing a crucial role in Cd-induced cell death and kidney damage.
Sirtuin 6 (Sirt6) 对于维持肾脏内环境稳定和功能至关重要。Cd 暴露会增加患肾脏疾病的风险。然而，Sirt6 在肾脏疾病机制中的作用尚不清楚。在这里，我们评估了 Sirt6 在 Cd 诱导的肾脏毒性中的作用。在 Cd 暴露后，p62/自噬底物 sequestosome-1 (SQSTM1) 在小鼠肾系膜细胞中以单体和多聚泛素化 (polyUb) 形式积累。Sirt6 在低于半抑制浓度的 Cd 处理下积累，并在 12 小时后减少。Sirt6 与 Cd 处理后 p62 共定位在核内，并重新分布到细胞质中。Sirt6 主要存在于富含核的膜部分。Sirt6 与 p62、泛素和微管相关蛋白轻链 3 (LC3) 相互作用。p62 敲低促进 Sirt6 核积累并抑制细胞凋亡。Sirt6 过表达改变了多聚泛素化 p62 和细胞凋亡的水平。在 Cd 处理的早期，p62 的多泛素化和凋亡减少。Sirt6 的细胞质易位发生在后期，伴有 p62 的多泛素化和凋亡增加。Bafilomycin 1 (BaF1) 处理促进细胞质 Sirt6 积累，增加细胞死亡。沉默自噬相关 5 (Atg5) 增加核 Sirt6 水平，减少多聚泛素化 p62，并抑制细胞死亡，表明自噬是 Sirt6 重分布所必需的。Cd 耐药与减少的多聚泛素化 p62 和持续的 Sirt6 表达有关。在小鼠中进行 4 周的 Cd 处理促进了 p62、Sirt6 和 LC3-II 的积累，诱导肾脏组织中的细胞凋亡。总的来说，我们的研究结果表明，多聚泛素化 p62 将 Sirt6 靶向到自噬体，在 Cd 诱导的细胞死亡和肾脏损伤中发挥关键作用。
