Department of Pathology and Applied Neurobiology, Graduate School of Medical Science, Kyoto Prefectural University of Medicine, 465 Kajii-cho, Kawaramachi Hirokoji, Kamigyo-ku, Kyoto 602-8566, Japan.
Mol Neurobiol. 2012 Apr;45(2):287-97. doi: 10.1007/s12035-012-8233-5. Epub 2012 Jan 19.
Duchenne muscular dystrophy (DMD) causes cognitive impairment in one third of the patients, although the underlying mechanisms remain to be elucidated. Recent studies showed that mutations in the distal part of the dystrophin gene correlate well with the cognitive impairment in DMD patients, which is attributed to Dp71. The study on the expression of the shortest isoform, Dp40, has not been possible due to the lack of an isoform specific antibody. Dp40 has the same promoter as that found in Dp71 and lacks the normal C-terminal end of Dp427. In the present study, we have raised polyclonal antibody against the N-terminal sequence common to short isoforms of dystrophin, including Dp40, and investigated the expression pattern of Dp40 in the mouse brain. Affinity chromatography with this antibody and the consecutive LC-MS/MS analysis on the interacting proteins revealed that Dp40 was abundantly expressed in synaptic vesicles and interacted with a group of presynaptic proteins, including syntaxin1A and SNAP25, which are involved in exocytosis of synaptic vesicles in neurons. We thus suggest that Dp40 may form a novel protein complex and play a crucial role in presynaptic function. Further studies on these aspects of Dp40 function might provide more insight into the molecular mechanisms of cognitive impairment found in patients with DMD.
杜氏肌营养不良症（DMD）导致三分之一的患者认知障碍，但其潜在机制仍有待阐明。最近的研究表明，抗肌萎缩蛋白基因远端部分的突变与 DMD 患者的认知障碍密切相关，这归因于 Dp71。由于缺乏同工型特异性抗体，最短同工型 Dp40 的表达研究尚未进行。Dp40 与在 Dp71 中发现的启动子相同，并且缺乏 Dp427 的正常 C 末端。在本研究中，我们针对包括 Dp40 在内的抗肌萎缩蛋白短同工型的 N 端序列，制备了多克隆抗体，并研究了 Dp40 在小鼠大脑中的表达模式。使用该抗体进行亲和层析，然后进行 LC-MS/MS 分析相互作用的蛋白质，结果表明 Dp40 在突触小泡中大量表达，并与一组突触前蛋白相互作用，包括突触融合蛋白 1A 和 SNAP25，它们参与神经元中突触小泡的胞吐作用。因此，我们认为 Dp40 可能形成一种新的蛋白质复合物，并在突触前功能中发挥关键作用。进一步研究 Dp40 功能的这些方面可能会深入了解 DMD 患者认知障碍的分子机制。
