Kuipers Hedwich F, Yoon Jane, van Horssen Jack, Han May H, Bollyky Paul L, Palmer Theo D, Steinman Lawrence
Department of Neurology and Neurological Sciences, Stanford University School of Medicine, Stanford, CA 94305;
Department of Neurology and Neurological Sciences, Stanford University School of Medicine, Stanford, CA 94305.
Proc Natl Acad Sci U S A. 2017 Feb 28;114(9):E1745-E1754. doi: 10.1073/pnas.1621314114. Epub 2017 Feb 14.
The small heat shock protein αB-crystallin (CRYAB) has been implicated in multiple sclerosis (MS) pathogenesis. Earlier studies have indicated that CRYAB inhibits inflammation and attenuates clinical disease when administered in the experimental autoimmune encephalomyelitis model of MS. In this study, we evaluated the role of CRYAB in primary demyelinating events. Using the cuprizone model of demyelination, a noninflammatory model that allows the analysis of glial responses in MS, we show that endogenous CRYAB expression is associated with increased severity of demyelination. Moreover, we demonstrate a strong correlation between the expression of CRYAB and the extent of reactive astrogliosis in demyelinating areas and in in vitro assays. In addition, we reveal that CRYAB is differentially phosphorylated in astrocytes in active demyelinating MS lesions, as well as in cuprizone-induced lesions, and that this phosphorylation is required for the reactive astrocyte response associated with demyelination. Furthermore, taking a proteomics approach to identify proteins that are bound by the phosphorylated forms of CRYAB in primary cultured astrocytes, we show that there is clear differential binding of protein targets due to the specific phosphorylation of CRYAB. Subsequent Ingenuity Pathway Analysis of these targets reveals implications for intracellular pathways and biological processes that could be affected by these modifications. Together, these findings demonstrate that astrocytes play a pivotal role in demyelination, making them a potential target for therapeutic intervention, and that phosphorylation of CRYAB is a key factor supporting the pathogenic response of astrocytes to oligodendrocyte injury.
小分子热休克蛋白αB-晶状体蛋白（CRYAB）与多发性硬化症（MS）的发病机制有关。早期研究表明，在MS的实验性自身免疫性脑脊髓炎模型中给予CRYAB可抑制炎症并减轻临床疾病。在本研究中，我们评估了CRYAB在原发性脱髓鞘事件中的作用。使用脱髓鞘的铜螯合剂模型（一种允许分析MS中胶质细胞反应的非炎症模型），我们发现内源性CRYAB表达与脱髓鞘严重程度增加有关。此外，我们在脱髓鞘区域和体外试验中证明了CRYAB表达与反应性星形胶质细胞增生程度之间存在强相关性。此外，我们发现CRYAB在活动性脱髓鞘MS病变以及铜螯合剂诱导的病变中的星形胶质细胞中存在差异磷酸化，并且这种磷酸化是与脱髓鞘相关的反应性星形胶质细胞反应所必需的。此外，采用蛋白质组学方法鉴定原代培养星形胶质细胞中与CRYAB磷酸化形式结合的蛋白质，我们发现由于CRYAB的特异性磷酸化，蛋白质靶标存在明显的差异结合。随后对这些靶标的 Ingenuity 通路分析揭示了可能受这些修饰影响的细胞内通路和生物学过程。总之，这些发现表明星形胶质细胞在脱髓鞘中起关键作用，使其成为治疗干预的潜在靶点，并且CRYAB的磷酸化是支持星形胶质细胞对少突胶质细胞损伤的致病反应的关键因素。
