Mantuano Elisabetta, Inoue Gen, Li Xiaoqing, Takahashi Kazuhisa, Gaultier Alban, Gonias Steven L, Campana W Marie
Department of Anesthesiology and Pathology, University of California, San Diego, La Jolla, California 92093-0629, USA.
J Neurosci. 2008 Nov 5;28(45):11571-82. doi: 10.1523/JNEUROSCI.3053-08.2008.
Low-density lipoprotein receptor-related protein (LRP-1) is an endocytic receptor for diverse proteins, including matrix metalloproteinase-9 (MMP-9), and a cell-signaling receptor. In the peripheral nervous system (PNS), LRP-1 is robustly expressed by Schwann cells only after injury. Herein, we demonstrate that MMP-9 activates extracellular-signal-regulated kinase (ERK1/2) and Akt in Schwann cells in culture. MMP-9 also promotes Schwann cell migration. These activities require LRP-1. MMP-9-induced cell signaling and migration were blocked by inhibiting MMP-9-binding to LRP-1 with receptor-associated protein (RAP) or by LRP-1 gene silencing. The effects of MMP-9 on Schwann cell migration also were inhibited by blocking the cell-signaling response. An antibody targeting the hemopexin domain of MMP-9, which mediates the interaction with LRP-1, blocked MMP-9-induced cell signaling and migration. Furthermore, a novel glutathione-S-transferase fusion protein (MMP-9-PEX), which includes only the hemopexin domain of MMP-9, replicated the activities of intact MMP-9, activating Schwann cell signaling and migration by an LRP-1-dependent pathway. Constitutively active MEK1 promoted Schwann cell migration; in these cells, MMP-9-PEX had no further effect, indicating that ERK1/2 activation is sufficient to explain the effects of MMP-9-PEX on Schwann cell migration. Injection of MMP-9-PEX into sciatic nerves, 24 h after crush injury, robustly increased phosphorylation of ERK1/2 and Akt. This response was inhibited by RAP. MMP-9-PEX failed to activate cell signaling in uninjured nerves, consistent with the observation that Schwann cells express LRP-1 at significant levels only after nerve injury. These results establish LRP-1 as a cell-signaling receptor for MMP-9, which may be significant in regulating Schwann cell migration and physiology in PNS injury.
低密度脂蛋白受体相关蛋白（LRP - 1）是多种蛋白质的内吞受体，包括基质金属蛋白酶 - 9（MMP - 9），也是一种细胞信号受体。在周围神经系统（PNS）中，LRP - 1仅在损伤后由施万细胞强烈表达。在此，我们证明MMP - 9在培养的施万细胞中激活细胞外信号调节激酶（ERK1/2）和Akt。MMP - 9还促进施万细胞迁移。这些活性需要LRP - 1。通过用受体相关蛋白（RAP）抑制MMP - 9与LRP - 1的结合或通过LRP - 1基因沉默，可阻断MMP - 9诱导的细胞信号传导和迁移。阻断细胞信号反应也可抑制MMP - 9对施万细胞迁移的影响。一种靶向MMP - 9血色素结合蛋白结构域的抗体，该结构域介导与LRP - 1的相互作用，可阻断MMP - 9诱导的细胞信号传导和迁移。此外，一种新型谷胱甘肽 - S - 转移酶融合蛋白（MMP - 9 - PEX），其仅包含MMP - 9的血色素结合蛋白结构域，复制了完整MMP - 9的活性，通过依赖LRP - 1的途径激活施万细胞信号传导和迁移。组成型活性MEK1促进施万细胞迁移；在这些细胞中，MMP - 9 - PEX没有进一步作用，表明ERK1/2激活足以解释MMP - 9 - PEX对施万细胞迁移的影响。在挤压伤后24小时将MMP - 9 - PEX注射到坐骨神经中，可强烈增加ERK1/2和Akt的磷酸化。这种反应被RAP抑制。MMP - �- PEX未能在未损伤的神经中激活细胞信号传导，这与施万细胞仅在神经损伤后才大量表达LRP - 1的观察结果一致。这些结果确立了LRP - 1作为MMP - 9的细胞信号受体，这可能在调节PNS损伤中施万细胞迁移和生理功能方面具有重要意义。
