PTHrP NLS与C末端促进小鼠脊髓损伤后髓鞘再生的作用及机制研究

Our previous studies have shown that the deficiency of the nuclear localization sequence (NLS) and C terminus of parathyroid hormone related peptide (PTHrP) mice (i.e., PTHrP KI mice) exhibit the decrese of proliferation and differentiation , increase of apoptosis of oligodendrocyte progenitor cells (OPCs), resulting in the deficiency of myelinogenesis. Meanwhile, the oxidative stress and DNA damage is increased in OPCs from the PTHrP KI mice, but the mechanism of which is still not clear. To identify whether the deficiency of PTHrP NLS and C terminus may inhibit the proliferation and differentiation, and increase the apoptosis of OPCs by increase the oxidative stress and DNA damage to the OPCs via activation of ATM and ATR signal pathways and inhibition of PIK3/AKT/mTOR signal pathway, we design this study as following: firstly, PTHrP KI mice will be used to identify whether the deficiency of PTHrP NLS and C teriminus will suppress the development of OPCs through the activation of oxidative stress and DNA damage response (DDR) pathway. Secondly, PTHrP87-139 peptide will be constructed and used to treat the injuried spinal cord in adult mice to verify whether PTHrP87-139 peptide can promote the axonal remyelination after spinal cord injury (SCI) via decrease the oxidative stress and DDR. This study will be helpful to further reveal the role of PTHrP NLS and C terminus in the regulation of OPCs development and will provide the experimental evidence to develop the PTHrP 87-139 peptide as a drug to promote axonal remyelination after SCI.

我们前期研究发现甲状旁腺素相关肽（PTHrP）核定位（NLS）与C末端缺失小鼠（即PTHrP KI小鼠）少突胶质前体细胞（OPCs）增殖分化降低，凋亡增加，髓鞘发育障碍；且OPCs氧化应激反应增强，DNA损伤加剧，但具体机制不清。为明确PTHrP NLS与C末端缺失是否可通过增强氧化应激，加剧DNA损伤，进而激活ATM、ATR通路, 抑制PI3K/AKT/mTOR通路，从而抑制OPCs增殖分化、促进其凋亡，首先，我们利用PTHrP KI小鼠，结合体内外实验，研究PTHrP NLS与C末端缺失对OPCs的影响是否由氧化应激与DNA损伤反应所介导；然后，运用PTHrP87-139蛋白处理脊髓损伤小鼠，观察其能否通过减轻OPCs的氧化应激与DNA损伤反应而促进髓鞘的功能性再生。本研究有望阐明PTHrP NLS与C末端调控OPCs发育的机制，并为促进脊髓损伤修复提供新的治疗靶标。

我们前期研究发现甲状旁腺素相关肽（PTHrP）核定位（NLS）与C末端缺失小鼠（即PTHrP KI小鼠）少突胶质前体细胞（OPCs）增殖分化降低，凋亡增加，髓鞘发育障碍；且OPCs氧化应激反应增强，DNA损伤加剧，但具体机制不清。为明确PTHrP NLS与C末端缺失是否可通过增强氧化应激，加剧DNA损伤，从而抑制OPCs增殖分化、促进其凋亡，首先，我们利用PTHrP KI小鼠，结合体内外实验，研究PTHrP NLS与C末端缺失对OPCs的影响是否由氧化应激与DNA损伤反应所介导；然后，运用PTHrP87-139蛋白处理脊髓损伤小鼠，观察其能否通过减轻OPCs的氧化应激与DNA损伤反应而促进髓鞘的功能性再生。结果显示1）PTHrP NLS与C末端缺失可通过加剧氧化应激及DNA损伤反应导致少突胶质细胞发育异常。2）芯片分析结果显示NONMMUT064530是PTHrP核定位序列与C末端促进脊髓发育的重要靶向lncRNA。3）抗氧化剂PQQ处理可通过抑制氧化应激及DNA损伤而部分纠正PTHrP KI小鼠少突胶质细胞发育的异常。4)初步提示PTHrP87-139片段可促进脊髓损伤后的功能恢复。.本研究结果提示PTHrP NLS和C末端可增加脊髓的抗氧化应激能力，减少DNA损伤，促进脊髓损伤后髓鞘再生。可为将PTHrP NLS和C末端（87-139片段）开发为新的治疗脊髓损伤的靶标提供初步的实验依据。