Delimont Duane, Dufek Brianna M, Meehan Daniel T, Zallocchi Marisa, Gratton Michael Anne, Phillips Grady, Cosgrove Dominic
Department of Genetics, Boys Town National Research Hospital, Omaha, Nebraska, United States of America.
Department of Otolaryngology, Saint Louis University, Saint Louis, Missouri, United States of America.
PLoS One. 2014 Jun 10;9(6):e99083. doi: 10.1371/journal.pone.0099083. eCollection 2014.
It has been known for some time that laminins containing α1 and α2 chains, which are normally restricted to the mesangial matrix, accumulate in the glomerular basement membranes (GBM) of Alport mice, dogs, and humans. We show that laminins containing the α2 chain, but not those containing the α1 chain activates focal adhesion kinase (FAK) on glomerular podocytes in vitro and in vivo. CD151-null mice, which have weakened podocyte adhesion to the GBM rendering these mice more susceptible to biomechanical strain in the glomerulus, also show progressive accumulation of α2 laminins in the GBM, and podocyte FAK activation. Analysis of glomerular mRNA from both models demonstrates significant induction of MMP-9, MMP-10, MMP-12, MMPs linked to GBM destruction in Alport disease models, as well as the pro-inflammatory cytokine IL-6. SiRNA knockdown of FAK in cultured podocytes significantly reduced expression of MMP-9, MMP-10 and IL-6, but not MMP-12. Treatment of Alport mice with TAE226, a small molecule inhibitor of FAK activation, ameliorated fibrosis and glomerulosclerosis, significantly reduced proteinuria and blood urea nitrogen levels, and partially restored GBM ultrastructure. Glomerular expression of MMP-9, MMP-10 and MMP-12 mRNAs was significantly reduced in TAE226 treated animals. Collectively, this work identifies laminin α2-mediated FAK activation in podocytes as an important early event in Alport glomerular pathogenesis and suggests that FAK inhibitors, if safe formulations can be developed, might be employed as a novel therapeutic approach for treating Alport renal disease in its early stages.
一段时间以来已知，含有α1和α2链的层粘连蛋白通常局限于系膜基质，但在阿尔波特综合征小鼠、犬类和人类的肾小球基底膜（GBM）中会蓄积。我们发现，含有α2链的层粘连蛋白而非含有α1链的层粘连蛋白，在体外和体内均可激活肾小球足细胞上的粘着斑激酶（FAK）。CD151基因敲除小鼠的足细胞与GBM的粘附减弱，使其更容易受到肾小球内生物力学应变的影响，这些小鼠的GBM中也出现α2层粘连蛋白的渐进性蓄积以及足细胞FAK激活。对这两种模型的肾小球mRNA分析表明，与阿尔波特综合征疾病模型中GBM破坏相关的基质金属蛋白酶（MMP）-9、MMP-10、MMP-12以及促炎细胞因子白细胞介素（IL）-6均有显著诱导。在培养的足细胞中通过小干扰RNA（siRNA）敲低FAK可显著降低MMP-9、MMP-10和IL-6的表达，但对MMP-12无影响。用TAE226（一种FAK激活的小分子抑制剂）治疗阿尔波特综合征小鼠可改善纤维化和肾小球硬化，显著降低蛋白尿和血尿素氮水平，并部分恢复GBM超微结构。在TAE226治疗的动物中，MMP-9、MMP-10和MMP-12 mRNA的肾小球表达显著降低。总的来说，这项研究确定足细胞中层粘连蛋白α2介导的FAK激活是阿尔波特综合征肾小球发病机制中的一个重要早期事件，并表明如果能开发出安全的制剂，FAK抑制剂可能作为一种新的治疗方法用于阿尔波特肾病的早期治疗。
