Department of Molecular Biology, Princeton University, Princeton, NJ 08544, USA.
Department of Cell Physiology and Metabolism, Centre Médical Universitaire, 1 Rue Michel-Servet, CMU, 1211 Geneva 4, Switzerland.
Cells. 2020 Mar 8;9(3):655. doi: 10.3390/cells9030655.
Diabetic nephropathy, a devastating consequence of diabetes mellitus, is characterized by the accumulation of extracellular matrix (ECM) that disrupts the kidney's filtration apparatus. Elevated glucose levels increase the deposition of a fibronectin (FN) matrix by mesangial cells, the primary matrix-producing cells of the kidney, and also increase acetyl-CoA leading to higher levels of lysine acetylation. Here, we investigated the connection between acetylation and the ECM and show that treatment of mesangial cells with deacetylase inhibitors increases both acetylation and FN matrix assembly compared to untreated cells. The matrix effects were linked to lysine 794 (K794) in the β1 integrin cytoplasmic domain based on studies of cells expressing acetylated (K794Q) and non-acetylated (K794R) mimetics. β1(K794Q) cells assembled significantly more FN matrix than wildtype β1 cells, while the non-acetylated β1(K794R) form was inactive. We show that mutation of K794 affects FN assembly by stimulating integrin-FN binding activity and cell contractility. Wildtype and β1(K794Q) cells but not β1(K794R) cells further increased their FN matrix when stimulated with deacetylase inhibitors indicating that increased acetylation on other proteins is required for maximum FN assembly. Thus, lysine acetylation provides a mechanism for glucose-induced fibrosis by up-regulation of FN matrix assembly.
糖尿病肾病是糖尿病的一种严重后果，其特征是细胞外基质（ECM）的积累，破坏了肾脏的过滤装置。高血糖水平会增加肾小球系膜细胞（肾脏的主要基质产生细胞）中纤维连接蛋白（FN）基质的沉积，并增加乙酰辅酶 A，导致赖氨酸乙酰化水平升高。在这里，我们研究了乙酰化和 ECM 之间的联系，并表明与未处理的细胞相比，用去乙酰化酶抑制剂处理系膜细胞会增加乙酰化和 FN 基质组装。基于表达乙酰化（K794Q）和非乙酰化（K794R）模拟物的细胞的研究，发现这种基质效应与 β1 整合素胞质结构域中的赖氨酸 794（K794）有关。β1（K794Q）细胞组装的 FN 基质明显多于野生型 β1 细胞，而非乙酰化的 β1（K794R）形式则没有活性。我们表明，突变 K794 通过刺激整合素-FN 结合活性和细胞收缩性来影响 FN 组装。野生型和 β1（K794Q）细胞但不是 β1（K794R）细胞在受到去乙酰化酶抑制剂刺激时进一步增加了它们的 FN 基质，表明需要其他蛋白质的增加乙酰化以达到最大的 FN 组装。因此，赖氨酸乙酰化通过上调 FN 基质组装提供了一种葡萄糖诱导纤维化的机制。
