CSPG receptors and PTEN in CNS regeneration

描述（由申请人提供）：通过使用PI实验室开发的新颖，可全身递送的小抑制肽，我们的目标是确定细胞外抑制和神经元内在因子是否可以显著改善脊髓损伤（SCI）后的轴突再生和功能恢复。由于外部抑制环境和成熟神经元内在生长能力的降低，切断的中枢神经系统轴突无法再生。由胶质瘢痕产生的硫酸软骨素蛋白聚糖（CSPGs）强烈抑制轴突向损伤区域内外的延伸，是治疗脊髓损伤的主要分子靶点。最近，我们和其他实验室确定了LAR和PTP¿磷酸酶作为介导CSPG抑制的受体。删除其中任何一个都能刺激脊髓损伤后的轴突生长。最近对条件敲除小鼠的研究表明，PTEN严重限制了受损中枢神经系统轴突的内在再生能力。因此，抑制CSPG受体和PTEN有望促进中枢神经系统损伤后轴突的再生。我们设计了小肽来阻断这些抑制分子的功能，通过靶向它们的特定区域，并证明了我们的肽在体外和体内促进轴突生长的高功效。由于CSPGs和PTEN似乎通过不同的信号通路限制生长，抑制两者可能通过减少病变部位的环境抑制影响和增强成熟神经元的内在生长能力来协同促进轴突再生。我们假设CSPGs和PTEN是中枢神经系统神经元再生失败的关键因素，两者的联合抑制比单独抑制任何一种都能更好地促进轴突再生。我们建议解决以下3个具体目标：1)确定转基因缺失或肽阻断两种CSPG受体是否比单独抑制任一受体在体外和体内产生更好的轴突生长和功能恢复；2)在体外和体内，确定肽阻断PTEN对轴突生长和功能恢复的刺激程度是否与转基因PTEN缺失相似；3)对比单独阻断CSPG信号和PTEN是否能促进脊髓损伤后轴突再生和行为恢复。将多肽处理的结果与转基因小鼠实验的结果进行比较。我们的新策略是系统地单独或联合施用小化合物，可能有助于开发一种实用的治疗中枢神经系统损伤的方法。

DESCRIPTION (provided by applicant): By using novel, systemically deliverable, small inhibitory peptides developed in the PI's lab, we aim to determine whether targeting both extracellular inhibitory and neuron-intrinsic factors can markedly improve axon regeneration and functional recovery after spinal cord injury (SCI). Severed CNS axons fail to regenerate due to the extrinsic inhibitory environment and the reduced intrinsic growth capacity of mature neurons. Chondroitin sulfate proteoglycans (CSPGs) generated by glial scars strongly suppress axon extension into and beyond the lesion area and are the major molecular targets for treating SCI. Recently, we and other labs identified the LAR and PTP¿ phosphatases as receptors that mediate CSPG inhibition. Deleting either of them stimulated axon growth after SCI. Recent studies using conditional knockout mice suggested that PTEN critically restricts the intrinsic regenerative capacity of injured CNS axons. Thus, suppressing CSPG receptors and PTEN is promising for promoting axon regeneration after CNS injury. We have designed small peptides to block functions of these inhibitory molecules by targeting their specific domains and demonstrated the high efficacy of our peptides for promoting axon growth in vitro and in vivo. Since CSPGs and PTEN appear to limit growth by different signaling pathways, inhibition of both may act synergistically to promote axon regeneration by reducing environmental inhibitory influence at the lesion site and enhancing intrinsic growth capacity of mature neurons. We hypothesize that CSPGs and PTEN are critical contributors to regenerative failure of CNS neurons and that combined inhibition of both promotes axon regeneration better than inhibition of either one alone. We propose to address the following 3 Specific Aims: 1) determine whether transgenic deletion or peptide blockade of two CSPG receptors yields better axon growth in vitro and in vivo and functional recovery in adult mice with SCI than suppressing either receptor alone; 2) determine whether PTEN blockade with peptides stimulates similar degrees of axon growth and functional recovery as transgenic PTEN deletion in vitro and in vivo; 3) determine whether blocking both CSPG signaling and PTEN with peptides promotes greater axon regeneration and behavioral recovery after SCI than blocking either one alone. The results of peptide treatments will be compared with those of transgenic mouse experiments. Our novel strategy to administer small compounds systemically alone or in combination may facilitate development of a practical therapy for CNS injury.