PKC inhibition-mediated spinal cord regeneration

描述（由申请人提供）：已假设成年哺乳动物中枢神经系统（CMS）中受损轴突不能再生是由于成熟神经元内在再生能力降低和损伤部位局部抑制环境所致。成年CNS中的大多数抑制活性似乎来自两种CNS特异性神经胶质细胞类型，少突胶质细胞和星形胶质细胞。虽然硫酸软骨素蛋白聚糖（CSPG）已被牵连作为一个主要类别的抑制剂在星形胶质细胞衍生的胶质瘢痕，几个髓鞘相关的分子占主要的抑制活性的少突胶质细胞。我们最近的数据表明，蛋白激酶C（PKC）的传统亚型是介导髓鞘成分和CSPG抑制活性的途径中的关键信号成分。引人注目的是，通过独特的Vibraknife TM装置将PKC抑制剂Go6976鞘内输注到C3背侧半切部位，促进了跨越和超出损伤部位的上升背柱（DC）的强大轴突再生，从而导致功能性神经再支配。我们的数据还表明，PKC抑制可能对红核脊髓束的再生有影响。然而，这些再生的轴突是否能够到达它们原来的目标并形成突触连接，目前还不清楚。出乎意料的是，相同的PKC抑制剂在该模型中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，以调查是否不同的中枢神经系统的途径不同，在他们的要求再生和再生轴突的行为在受伤的成年中枢神经系统。在本申请中，我们将探索PKC抑制介导的轴突再生和C3背侧半切后功能恢复的作用和机制，具有以下三（3）个特定目的：目的1将确定PKC抑制引起的DC轴突再生后的解剖学再生、神经再支配、躯体定位组织和功能。目的2将确定在相同的损伤模型中，PKC抑制是否也诱导另一个下行通路的再生，以测试它是否对轴突再生具有广泛的影响。目的3将探索最大限度地再生和功能恢复后C3背侧半切的组合策略。具体而言，我们将联合收割机PKC抑制与三种有前途的策略相结合：1）增强受损神经元的内在再生能力，2）为神经营养因子再生轴突提供趋化性，3）去除沉积在胶质瘢痕内的CSPG。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，这些研究可以让我们了解PKC介导的轴突抑制不同的中枢神经系统通路的机制，并提供新的见解设计有效的治疗策略，以鼓励轴突再生不同类型的轴突在受伤的成年脊髓。

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.