PDF(Pubmed)
Abstract：
Leucine-rich glioma-inactivated protein 1 (LGI1), a secretory protein in the brain, plays a critical role in myelination; dysfunction of this protein leads to hypomyelination and white matter abnormalities (WMAs). Here, we hypothesized that LGI1 may regulate myelination through binding to an unidentified receptor on the membrane of oligodendrocytes (OLs). To search for this hypothetic receptor, we analyzed LGI1 binding proteins through LGI1-3 × FLAG affinity chromatography with mouse brain lysates followed by mass spectrometry. An OL-specific membrane protein, the oligodendrocytic myelin paranodal and inner loop protein (OPALIN), was identified. Conditional knockout (cKO) of OPALIN in the OL lineage caused hypomyelination and WMAs, phenocopying LGI1 deficiency in mice. Biochemical analysis revealed the downregulation of Sox10 and Olig2, transcription factors critical for OL differentiation, further confirming the impaired OL maturation in Opalin cKO mice. Moreover, virus-mediated re-expression of OPALIN successfully restored myelination in Opalin cKO mice. In contrast, re-expression of LGI1-unbound OPALIN_K23A/D26A failed to reverse the hypomyelination phenotype. In conclusion, our study demonstrated that OPALIN on the OL membrane serves as an LGI1 receptor, highlighting the importance of the LGI1/OPALIN complex in orchestrating OL differentiation and myelination.
摘要：
富含亮氨酸的神经胶质瘤灭活蛋白1（LGI1），大脑中的一种分泌蛋白质，在髓鞘形成中起关键作用;该蛋白的功能障碍导致髓鞘减少和白质异常（WMA）。这里,我们假设LGI1可能通过与少突胶质细胞(OLs)膜上一种未识别的受体结合来调节髓鞘形成.为了寻找这个假设受体，我们通过LGI1-3×FLAG亲和层析和小鼠脑裂解物，然后通过质谱分析LGI1结合蛋白。一种OL特异性膜蛋白，少突胶质髓鞘旁和内环蛋白（OPALIN），已确定。OPALIN在OL谱系中的条件性敲除(cKO)引起的髓鞘减少和WMA,小鼠LGI1缺乏症的表型表现。生化分析显示Sox10和Olig2的下调，这些转录因子对OL分化至关重要，进一步证实了乳品素cKO小鼠的OL成熟受损。此外，病毒介导的OPALIN再表达成功恢复了OpalincKO小鼠的髓鞘形成。相比之下,LGI1未结合的OPALIN_K23A/D26A的再表达未能逆转髓鞘减少表型。总之,我们的研究表明，在OL膜上的OPALIN作为LGI1受体，强调LGI1/OPALIN复合物在协调OL分化和髓鞘形成中的重要性。
