Cockayne syndrome: role of the innate immune response in neurodegeneration

描述(由申请人提供)：我们建议测试一个令人兴奋的新假说，关于一种称为Cockayne综合征(CS)的破坏性儿童神经发育早衰症的原因和分子机制。如果我们的假设是正确的，它将为这种目前无法治愈的疾病开辟新的治疗选择。长期以来，CS一直被认为是一种DNA修复疾病，因为所有5个导致CS的基因(CsA、CSB、XPB、XPD和XPG)都是转录偶联核苷酸切除修复(TC-NER)所必需的。然而，CS患者通常表现为髓鞘缺陷和脑钙化，类似于Aicardi-Gtières综合征(AGS)，AGS是一种儿童神经发育性脑白质营养不良，由先天抗病毒干扰素反应在没有病毒感染的情况下结构性激活引起。我们最近发现，CSB基因，导致所有已知的CS病例中，超过三分之二的病例含有一个iggyBac转座子(PGBD3)。因此，人类CSB基因座产生不是一个而是两个CSB相关蛋白：功能性CSB和将CSB的N末端结构域连接到C末端PGBD3转座酶结构域的CSB-PGBD3融合蛋白(Newman等人，2008年)。最令人惊讶的是，我们发现CSB-PGBD3融合蛋白在CSB缺失细胞中的表达可诱导强大的干扰素样先天免疫反应，而从正常细胞中缺失CSB也可诱导先天抗病毒反应(Bailey等人，2012)。我们的数据表明，融合蛋白可能与CS疾病有关，并可能为延缓或改善CS症状的干预提供一个切入点。我们提出了两个互补的目标来确定CS患者是否表现出类似的干扰素、抗病毒、炎症或自身免疫反应：(目标1)使用Affymetrix微阵列，我们将比较CS患者外周血单个核细胞(PBMC)中的mRNA表达，以及我们发表的稳定表达CSB-PGBD3融合蛋白的CSB零细胞的数据。微阵列将使我们能够检测干扰素、抗病毒或炎症基因的表达特征，即使这些基因在患者中受到SOCS1或相关调控途径的下调。(目的2)采用Luminex珠法和细胞报告素法，在蛋白水平检测CS患者血清和PBMC中干扰素、细胞因子和趋化因子的表达。我们还将使用显示9,000个人类蛋白质的Invitgen ProtoArrayV5.0蛋白质阵列来搜索CS血清自身抗体。我们的建议是高风险的，因为CS患者的CS细胞中的干扰素样反应可能会减弱；然而，回报可能会很高，因为干扰素或自身免疫反应的确认将证明使用免疫调节或抗炎生物制剂和药物治疗CS和相关疾病是合理的。

DESCRIPTION (provided by applicant): We propose to test an exciting new hypothesis regarding the causes and molecular mechanisms of a devastating childhood neurodevelopmental progeria known as Cockayne syndrome (CS). If our hypothesis is correct, it will open up new therapeutic options for this currently untreatable disease. CS has long been thought to be a disease of DNA repair because all 5 genes that can cause CS (CSA, CSB, XPB, XPD, and XPG) are essential for transcription-coupled nucleotide excision repair (TC-NER). Yet CS patients usually present with myelin defects and brain calcifications resembling those seen in Aicardi- Goutières syndrome (AGS), a childhood neurodevelopmental leukodystrophy caused by constitutive activation of an innate antiviral interferon response in the absence of viral infection. We recently discovered that the CSB gene, which causes over two thirds of all known cases of CS, contains a piggyBac transposon (PGBD3). As a result, the human CSB locus generates not one but two CSB-related proteins: functional CSB, and a CSB-PGBD3 fusion protein joining the N-terminal domain of CSB to a C-terminal PGBD3 transposase domain (Newman et al., 2008). Most surprisingly, we found that expression of the CSB-PGBD3 fusion protein in CSB-null cells induces a powerful interferon-like innate immune response, and that loss of CSB from normal cells also induces an innate antiviral response (Bailey et al., 2012). Our data suggest that the fusion protein may contribute to CS disease, and could provide an entry point for intervention to delay or ameliorate CS symptoms. We propose two complementary aims to determine whether CS patients display a similar interferon, antiviral, inflammatory, or autoimmune response: (Aim 1) Using Affymetrix microarrays, we will compare mRNA expression in peripheral blood mononuclear cells (PBMCs) of CS patients to our published data for CSB-null cells that stably express the CSB-PGBD3 fusion protein. Microarrays will enable us to detect an interferon, antiviral, or inflammatory gene expression signature, even if the genes are downregulated in patients by SOCS1 or related regulatory pathways. (Aim 2) Using Luminex bead-based assays and cell-based reporter assays, we will examine expression of interferons, cytokines, and chemokines at the protein level in CS serum and PBMCs. We will also use Invitrogen ProtoArray v5.0 protein arrays that display >9,000 human proteins to search for CS serum autoantibodies. Our proposal is high risk because the interferon-like response seen in CS cells may be muted in CS patients; however, the rewards could be high because confirmation of an interferon or autoimmune response would justify the use of immunomodulatory or anti-inflammatory biologicals and drugs for treating CS and related conditions.