Function of muscle lim protein (MLP) in neuroprotection and axon regeneration

肌肉 lim 蛋白 (MLP) 在神经保护和轴突再生中的作用

• 批准号: 278526477
• 负责人: Professor Dr. Dietmar Fischer
• 金额: --
• 依托单位: Zentrum für Pharmakologie
• 依托单位国家: 德国
• 项目类别: Research Grants
• 财政年份: 2015
• 资助国家: 德国
• 起止时间: 2014-12-31 至 2022-12-31
• 项目状态: 已结题
• 来源: https://gepris.dfg.de/gepris/projekt/278526477?language=en
• 关键词: Function; muscle; lim; protein; MLP

As typical CNS neurons, retinal ganglion cells (RGCs) do not normally regenerate axons in the injured optic nerve and instead undergo apoptosis. However, inflammatory stimulation (IS) in the inner eye, induced by lens injury, is strongly neuroprotective and transforms RGCs into an active regenerative state, enabling them to regrow axons into the injured optic nerve. Based on a microarray study we identified genes differentially expressed in regenerating (induced by IS) vs. solely axotomized and naïve RGCs, one of which was muscle LIM protein (MLP). MLP has been postulated to be muscle-specific (skeletal muscle, but mainly heart) and involved in myogenesis without any known expression in the adult mammalian CNS. Using Western blot analysis and immunohistochemistry, we found profound induction of MLP protein in the cytosol (including nuclei) and axonal growth cones of mature RGCs upon optic nerve injury. Expression was further enhanced when RGCs entered a regenerative state after additional IS. Moreover, we detected MLP in a subpopulation of dorsal root ganglion (DRG) neurons upon sciatic nerve injury. Inhibition of MLP expression by short hairpin RNA (shRNA) compromised neurite growth of cultured RGCs and preliminary data demonstrate that overexpression of MLP further pro-motes IS-induced axon regeneration in the crushed optic nerve. In this proposed research project, we will (i) investigate the role of MLP in neuroprotection of axotomized RGCs, optic nerve as well as spinal cord regeneration, (ii) we will identify the underlying molecular mechanisms by testing the hypothesis that nuclear MLP might regulate gene expression after axon injury and (iii) by identification of functional relevant neuronal interaction partners and downstream signaling cascades of MLP. These experiments will identify the molecular mechanisms underlying the yet unknown role of MLP in CNS axon regeneration and might open novel approaches for CNS repair.

作为典型的中枢神经系统神经元，视网膜神经节细胞（RGC）通常不会在受损的视神经中强烈再生轴突，而是会发生细胞凋亡。然而，晶状体损伤引起的内眼炎症刺激（IS）具有神经保护作用，并将 RGC 转化为神经细胞。活跃的再生状态，使它们能够将轴突重新生长到受损的视神经中。基于微阵列研究，我们确定了在再生（由 IS 诱导）与单独再生中差异表达的基因。轴突和幼稚 RGC，其中一种是肌肉 LIM 蛋白 (MLP)，被认为是肌肉特异性的（骨骼肌，但主要是心脏），并参与肌生成，但在成年哺乳动物中枢神经系统中没有任何已知的表达。通过分析和免疫组织化学，我们发现在视神经损伤时，成熟RGC的细胞质（包括细胞核）和轴突生长锥中MLP蛋白的表达进一步增强。此外，我们在坐骨神经损伤后的背根神经节 (DRG) 神经元亚群中检测到 MLP，因为短发夹 RNA (shRNA) 抑制了培养的 RGC 的神经突生长。证明 MLP 的过度表达进一步促进 IS 诱导的视神经轴突再生。在这个拟议的研究项目中，我们将 (i) 研究 MLP 在损伤中的作用。轴突 RGC、视神经以及脊髓再生的神经保护，(ii) 我们将通过测试核 MLP 可能在轴突损伤后调节基因表达的假设来确定潜在的分子机制，以及 (iii) 通过识别功能相关的神经相互作用伙伴这些实验将确定 MLP 在中枢神经系统轴突再生中的未知作用的分子机制，并可能为中枢神经系统修复开辟新的方法。