PKC inhibition-mediated spinal cord regeneration

描述（由申请人提供）：假设成年哺乳动物中枢神经系统（CMS）受损轴突无法再生是由于成熟神经元内在再生能力下降和损伤部位的局部抑制环境造成的。似乎成人中枢神经系统的大部分抑制活性来自两种中枢神经系统特异性胶质细胞类型，少突胶质细胞和星形胶质细胞。虽然硫酸软骨素蛋白聚糖（CSPGs）被认为是星形胶质细胞来源的胶质瘢痕的主要抑制剂，但几种髓磷脂相关分子对少突胶质细胞的主要抑制活性起作用。我们最近的数据表明，蛋白激酶C （PKC）的传统同工型是介导髓磷脂成分和CSPGs抑制活性的途径中的关键信号成分。引人注目的是，鞘内输注PKC抑制剂Go6976，通过独特的VibraknifeTM装置，在C3背侧半切部位，促进了横跨和超越病变部位的上行背柱（DC）的强大轴突再生，从而导致功能性神经再生。我们的数据还表明，PKC抑制可能对rubbrospinal tract （RST）的再生有影响。然而，尚不清楚这些再生轴突是否能够到达其原始目标并形成突触连接。出乎意料的是，在该模型中，相同的PKC抑制剂并没有促进皮质脊髓束（CST）的再生。这些结果为我们提供了一个独特的机会来研究不同的中枢神经系统通路对再生的需求是否不同，以及再生轴突在受伤的成人中枢神经系统中的行为如何。在本应用中，我们将探讨PKC抑制介导的C3背半球切除后轴突再生和功能恢复的作用和机制，具体目的如下：目的1将确定PKC抑制诱导的DC轴突再生后的解剖再生、神经再生、躯体组织和功能。Aim 2将确定PKC抑制是否也诱导另一下行通路RST的再生，在相同的病变模型中，以测试它是否对轴突再生有广泛的影响。目的3将探讨C3背半球切除术后最大限度地再生和功能恢复的组合策略。具体来说，我们将把PKC抑制与三种有前景的策略结合起来：1)增强损伤神经元的内在再生能力，2)为神经营养物质再生轴突提供趋化性，以及3)去除沉积在胶质疤痕内的CSPGs。我们将研究联合策略是否会导致体外抑制底物上更强的神经突生长和体内更大的轴突再生和功能恢复。总的来说，这些研究可能使我们了解pkc介导的不同中枢神经系统通路轴突抑制的机制，并为设计有效的治疗策略提供新的见解，以促进受伤成人脊髓不同类型轴突的轴突再生。

DESCRIPTION (provided by applicant): Inability of lesioned axons in the adult mammalian central nervous system (CMS) to regenerate has been hypothesized to result from both a decrease in intrinsic regenerative capacity of mature neurons and a local inhibitory environment at the site of injury. It appears that the majority of inhibitory activities in the adult CNS are derived from two CNS-specific glial cell types, the oligodendrocyte and astrocyte. While chondroitin sulfate proteoglycans (CSPGs) have been implicated as a major class of inhibitors in astrocyte-derived glial scar, several myelin-associated molecules account for the major inhibitory activities of the oligodendrocytes. Our recent data demonstrated that conventional isoforms of protein kinase C (PKC) are key signaling components in the pathways that mediate the inhibitory activities of both myelin components and CSPGs. Strikingly, intrathecal infusion of a PKC inhibitor, Go6976, into the site of C3 dorsal hemisection, made by a unique VibraknifeTM device, promoted robust axonal regeneration of the ascending dorsal column (DC) across and beyond the lesion site which led to functional reinnervation. Our data also indicates that PKC inhibition may have an effect on regeneration of the rubrospinal tract (RST). It remains unclear, however, whether these regenerating axons are able to reach their original targets and form synaptic connections. Unexpectedly, the same PKC inhibitor did not promote the regeneration of the corticospinal tract (CST) in this model. These results provide us with a unique opportunity to investigate whether different CNS pathways differ in their requirements for regeneration and how regenerating axons behave in the injured adult CNS. In this application, we will explore the role and mechanism of PKC inhibition-mediated axonal regeneration and functional recovery after the C3 dorsal hemisection with the following three (3) Specific Aims: Aim 1 will determine anatomical regeneration, reinnervation, somatotopic organization and function following DC axonal regeneration elicited by PKC inhibition. Aim 2 will determine whether PKC inhibition also induces regeneration of another descending pathway, the RST, in the same lesion model to test whether it has a broad effect on axonal regeneration. Aim 3 will explore combinatorial strategies to maximize regeneration and functional recovery after C3 dorsal hemisection. Specifically, we will combine the PKC inhibition with three promising strategies to: 1) enhance injured neuron's intrinsic regenerative capacity, 2) provide chemotropism for regenerating axons with neurotrophins, and 3) remove CSPGs deposited within the glial scar. We will examine whether the combination strategies will result in stronger neurite outgrowth on inhibitory substrates in vitro and greater axonal regeneration and functional recovery in vivo. Collectively, these studies may allow us to understand mechanisms underlying PKC-mediated axonal inhibition of different CNS pathways and provide new insights into designing effective therapeutic strategies to encourage axonal regeneration of different types of axons in the injured adult spinal cord.