BMP7抑制少突胶质细胞凋亡及在脊髓损伤中的神经保护作用

Bone morphogentic protein 7 (BMP7）is a multifunctional growth factor that belongs to the transforming growth factor-β (TGF-β) superfamily and plays an important role in the neural development. Our previous studies found that BMP7 protects oligodendrocytes from apoptosis induced by hydrogen peroxide. The results suggest that BMP7 may function as a neural protection factor via inhibition of oligodendrocytes apoptosis after spinal cord injury. Therefore, the aim of this study is to further identify whether the BMP7 will be a new neural protection target on oligodendrocytes after spinal cord injury, and in vitro and in vivo studies will be used in this study. Firstly, we will culture the oligodendrocytes, investigate the apoptotic effect of various apoptosis inducing factors on the oligodendrocytes with the treatment of exogenous BMP7 or with the inhibition of internal BMP7 by infection of BMP7 shRNA lentiviral particles, and further investigate the contribution of PI3K/AKt and IKK/NF-κB signal pathway on the neural protection of BMP7 on oligodendrocytes. Secondly, we will inject BMP7 or BMP7 shRNA into the contusive injured spinal cord on rats, and observe the changes of electrophysiology, behavior tests, and histology at different time points. This study will explore the role of apoptotic inhibition of BMP7 to the oligodendrocytes after spinal cord injury and is benefit to its clinical application study.

骨形态发生蛋白7（BMP7）属转化生长因子-β超家族成员，在神经发育中起重要作用。课题组前期工作发现：BMP7可明显抑制过氧化氢诱导的少突胶质细胞凋亡。提示BMP7可能通过抑制少突胶质细胞凋亡而在创伤性脊髓损伤中产生神经保护作用。为进一步证实BMP7作为脊髓损伤中神经保护新靶点，本研究培养少突胶质细胞，观察外源性BMP7及BMP7 shRNA慢病毒抑制BMP7对不同的凋亡刺激因子所致的少突胶质细胞凋亡的作用；观察PI3K/AKt和IKK/NF-κB信号通路在BMP7的少突胶质细胞保护中的作用；在此基础上，将外源性BMP7及BMP7 shRNA慢病毒注入钝性损伤的大鼠脊髓，检测不同组别不同时间点动物电生理学、行为学及组织学改变。本研究将阐明BMP7抑制少突胶质细胞凋亡的作用及机制，为临床创伤性脊髓损伤的治疗奠定基础。

脊髓损伤（SCI）一直是科学研究的热点，因为它是一种没有有效治疗措施的严重疾病。最近，研究人员的重点从增强神经再生转向保护少突胶质细胞（OLs）以及髓鞘。骨形态发生蛋白7（BMP7）作为一种多功能细胞因子，在体内对神经系统具有保护作用。但是，SCI后BMP7对OLs的影响仍然未知。因此，我们探讨了BMP7对SCI后脱髓鞘的影响。我们发现了SCI后大鼠中BMP7水平随脱髓鞘的进展而降低。在此基础上我们将BMP7腺相关病毒（AAV-BMP7）局部注射到脊髓中来上调BMP7。 qPCR，蛋白质印迹和免疫组化分析的结果表明，BMP7过表达可以部分逆转CNPase的丢失。透射电镜（TEM）成像用于分析髓鞘的超微结构和厚度，并显示BMP7有助于维持髓鞘的正常结构。 AAV-BMP7组的BBB评分较高表明BMP7可以促进功能恢复。此外，双标记的免疫荧光表明BMP7诱导的OLs中的p-Smad1 / 5/9和p-STAT3可能在BMP7的保护中起作用。总的来说，我们的结果证实BMP7对SCI后的脱髓鞘具有保护作用，并且促进了功能恢复，是脊髓损伤后的潜在治疗靶点。