RU Neural Regeneration, Max-Planck Institute of Experimental Medicine, Goettingen, Germany.
J Neurosci Res. 2010 Feb 15;88(3):572-88. doi: 10.1002/jnr.22235.
Signaling of growth factors may depend on the recruitment of their receptors to specialized microdomains. Previous reports on PC12 cells indicated an interaction of raft-organized caveolin and TrkA signaling. Because porcine oligodendrocytes (OLs) respond to nerve growth factor (NGF), we were interested to know whether caveolin also plays a role in oligodendroglial NGF/TrkA signaling. OLs expressed caveolin at the plasma membrane but also intracellularly. This was partially organized in the classically Omega-shaped invaginations, which may represent caveolae. We could show that caveolin and TrkA colocalize by using a discontinuous sucrose gradient (Song et al. [1996] J. Biol. Chem. 271:9690-9697), MACS technology, and immunoprecipitation. However, differential extraction of caveolin and TrkA with Triton X-100 at 4 degrees C indicated that caveolin and TrkA are probably not exclusively present in detergent-resistant, caveolin-containing rafts (CCRs). NGF treatment of OLs up-regulated the expression of caveolin-1 (cav-1) and stimulated tyrosine-14 phosphorylation of cav-1. Furthermore, OLs were transfected with cav-1-specific small interfering RNA (siRNA). A knockdown of cav-1 resulted in a reduced activation of downstream components of the NGF signaling cascade, such as p21Ras and mitogen-activated protein kinase (MAPK) after NGF exposure of OLs. Subsequently, increased oligodendroglial process formation via NGF was impaired. The present study indicates that CCRs/caveolin could play a modulating role during oligodendroglial differentiation and regeneration.
生长因子的信号可能依赖于其受体向专门的微域募集。先前关于 PC12 细胞的报告表明，筏状组织的 caveolin 和 TrkA 信号之间存在相互作用。由于猪少突胶质细胞 (OL) 对神经生长因子 (NGF) 有反应，我们想知道 caveolin 是否也在少突胶质细胞 NGF/TrkA 信号中发挥作用。OL 在质膜上表达 caveolin，但也在细胞内表达。这部分组织呈经典的 Ω 形内陷，可能代表 caveolae。我们可以通过使用不连续蔗糖梯度 (Song 等人，[1996] J. Biol. Chem. 271:9690-9697)、MACS 技术和免疫沉淀来显示 caveolin 和 TrkA 共定位。然而，用 Triton X-100 在 4°C 对 caveolin 和 TrkA 进行差异提取表明，caveolin 和 TrkA 可能不是仅存在于去污剂抗性、含 caveolin 的筏 (CCR) 中。NGF 处理 OL 上调了 caveolin-1 (cav-1) 的表达并刺激了 cav-1 的酪氨酸-14 磷酸化。此外，OL 被 cav-1 特异性小干扰 RNA (siRNA) 转染。cav-1 的敲低导致 NGF 暴露于 OL 后 NGF 信号级联的下游成分如 p21Ras 和丝裂原活化蛋白激酶 (MAPK) 的激活减少。随后，通过 NGF 增加少突胶质细胞突起的形成受到损害。本研究表明，CCR/caveolin 在少突胶质细胞分化和再生过程中可能发挥调节作用。
