B-cell receptor-associated protein 31 (Bap31) is a three trans-membrane protein of the endoplasmic reticulum (ER). Patients who have loss of function of Bap31 suffered from X-linked syndrome, such as motor and intellectual disabilities, dystonia, and sensorineural deafness. However, the underlying mechanism of Bap31 on X-linked syndrome remains unclear. Here, we found that a total of 21 proteins (9 up-regulated and 12 down-regulated proteins) related with X-linked syndrome were screened from shRNA-Bap31 transfected cells with the isobaric tags for relative and absolute quantification (iTRAQ) technique. One gene with the greatest change trend, monoamine oxidase A (MAOA), was identified. MAOA expression was up-regulated by Bap31 knockdown. However, Bap31 did not affect the ubiquitination degradation of MAOA protein. Of note, Bap31 selectively regulated the expression of cell division cycle associated 7-like (R1/RAM2/CDCA7L/JPO2, a transcriptional repressor of MAOA) and the binding activity of R1 with MAOA promoter, thereby affecting MAOA expression. This study demonstrates the molecular mechanisms of Bap31 in MAOA via R1 and supports the potential function of Bap31 on X-linked syndrome.

中文翻译：

---

B细胞受体相关蛋白31负调节R1单胺氧化酶A的表达。

B细胞受体相关蛋白31（Bap31）是内质网（ER）的三跨膜蛋白。Bap31功能丧失的患者患有X连锁综合症，例如运动和智力障碍，肌张力障碍和感觉神经性耳聋。但是，Bap31对X连锁综合征的潜在机制仍不清楚。在这里，我们发现从具有等压标记的shRNA-Bap31转染的细胞中筛选了总共21种与X连锁综合征相关的蛋白（9种上调和12种下调的蛋白），用于相对定量和绝对定量（iTRAQ）技术。鉴定出一种变化趋势最大的基因单胺氧化酶A（MAOA）。Bap31敲低可上调MAOA表达。但是，Bap31不会影响MAOA蛋白的泛素降解。值得注意的是 Bap31选择性调节与细胞分裂周期相关的7样（R1 / RAM2 / CDCA7L / JPO2，MAOA的转录阻遏物）的表达以及R1与MAOA启动子的结合活性，从而影响MAOA的表达。这项研究通过R1证明了MAOA中Bap31的分子机制，并支持Bap31在X连锁综合征上的潜在功能。