Abstract：
Dystrophin Dp71 is the major product of the Duchenne muscular dystrophy (DMD) gene in the brain, and its loss in DMD patients and mouse models leads to cognitive impairments. Dp71 is expressed as a range of proteins generated by alternative splicing of exons 71 to 74 and 78, classified in the main Dp71d and Dp71f groups that contain specific C-terminal ends. However, it is unknown whether each isoform has a specific role in distinct cell types, brain regions, and/or stages of brain development. In the present study, we characterized the expression of Dp71 isoforms during fetal (E10.5, E15.5) and postnatal (P1, P7, P14, P21 and P60) mouse and rat brain development. We finely quantified the expression of several Dp71 transcripts by RT-PCR and cloning assays in samples from whole-brain and distinct brain structures. The following Dp71 transcripts were detected: Dp71d, Dp71d∆71, Dp71d∆74, Dp71d∆71,74, Dp71d∆71-74, Dp71f, Dp71f∆71, Dp71f∆74, Dp71f∆71,74, and Dp71fΔ71-74. We found that the Dp71f isoform is the main transcript expressed at E10.5 (> 80%), while its expression is then progressively reduced and replaced by the expression of isoforms of the Dp71d group from E15.5 to postnatal and adult ages. This major finding was confirmed by third-generation nanopore sequencing. In addition, we found that the level of expression of specific Dp71 isoforms varies as a function of postnatal stages and brain structure. Our results suggest that Dp71 isoforms have different and complementary roles during embryonic and postnatal brain development, likely taking part in a variety of maturation processes in distinct cell types.
摘要：
肌营养不良蛋白Dp71是大脑中Duchenne型肌营养不良症（DMD）基因的主要产物，其在DMD患者和小鼠模型中的丢失导致认知障碍。Dp71表达为通过外显子71至74和78的可变剪接产生的一系列蛋白质，分类在含有特定C末端的主要Dp71d和Dp71f组中。然而,尚不清楚每种同工型是否在不同的细胞类型中具有特定的作用，大脑区域,和/或大脑发育阶段。在本研究中,我们表征了胎儿（E10.5，E15.5）和出生后（P1，P7，P14，P21和P60）小鼠和大鼠脑发育过程中Dp71亚型的表达。我们通过RT-PCR和克隆测定法在来自全脑和不同脑结构的样品中精细定量了几种Dp71转录本的表达。检测到以下Dp71转录本：Dp71d，Dp71dΔ71,Dp71dΔ74,Dp71dΔ71,74,Dp71dΔ71-74,Dp71f,Dp71fΔ71、Dp71fΔ74、Dp71fΔ71,74和Dp71fΔ71-74。我们发现Dp71f同种型是在E10.5表达的主要转录本（>80％），从E15.5到出生后和成年年龄，其表达逐渐减少，并被Dp71d组的同种型表达所取代。第三代纳米孔测序证实了这一主要发现。此外,我们发现特定Dp71亚型的表达水平随出生后阶段和大脑结构而变化。我们的结果表明，Dp71同工型在胚胎和出生后脑发育过程中具有不同和互补的作用。可能参与不同细胞类型的各种成熟过程。
