Liver Kinase B1, a genetic risk factor for multiple sclerosis

在招募多发性硬化症患者进行外周血单核细胞研究的过程中，一个有5个兄弟姐妹的家庭被诊断为 经鉴定为多发性硬化。某些罕见肿瘤的共同发病导致了测序。 分析了抑癌基因STK11及其变异(小核苷酸多态，SNP)。 已确认身份。大量DNA样本的基因分型表明，这种SNP存在于更高的 高加索人和非裔美国人队列中多发性硬化症患者的水平。肝脏的STK11编码 激酶B1(LKB1)在细胞代谢和炎症反应中的调节作用 T细胞、神经胶质细胞和少突胶质细胞。由于LKB1在MS中的作用尚未被表征， 由于脑星形胶质细胞在维持能量平衡和限制 免疫反应，我们假设减少星形胶质细胞LKB1的表达或活性将 使EAE恶化。我们用LKB1基因从星形胶质细胞中敲除的小鼠(“CKO小鼠”)的研究结果证实 这一假设并确定了星形胶质细胞缺陷小鼠和细胞中改变的途径。 在这个项目中，我们将确定LKB1缺乏对星形胶质细胞代谢特性的影响 (线粒体功能，以及可按需提供给神经元的乳酸的产生)。我们 将测试从星形胶质细胞制备的培养液(条件培养液，CM)对小胶质细胞的影响 细胞，看看小胶质细胞的激活是否增加。我们将在幼稚的T细胞中加入星形胶质细胞CM，看看是否 CM将它们转化为破坏性的表型(Th1或Th17；产生有毒物质的细胞 在EAE和MS期间)。我们将测试CM对神经元的影响，看看星形胶质细胞是否产生 神经毒性物质；并将CM加入少突胶质细胞中，观察成熟度是否减少。 在我们的研究中，我们发现在星形细胞cko小鼠中增加最多的蛋白质之一是lipocalin 2。 (Lcn2)，一种参与其他疾病炎症反应的蛋白，并在 星形胶质细胞。然而，星形胶质细胞Lcn2在EAE中的作用还不是很清楚。我们将产生新的老鼠 星形胶质细胞Lcn2被击倒的地方，看看这是否可以减少EAE疾病。我们还发现在 星形胶质细胞LKB1 CKO小鼠，脊髓运动神经元发生广泛损伤 脐带，这可能导致MS患者的虚弱。造成损害的原因尚不清楚， 然而，免疫球蛋白在这些神经元中大量积累的研究结果表明 这些细胞增加了免疫球蛋白受体的表达。提出了测试这一点的实验。 最后，虽然我们的研究是使用条件基因敲除细胞中的LKB1，但我们不知道 STK11 SNP不会导致基因敲除，但会改变LKB1的水平，也有同样的效果。致信地址 为此，我们将使用一种新的方法从人外周血单核细胞中培养出小胶质细胞。 虽然小胶质细胞不同于星形胶质细胞，但我们将能够将小胶质细胞的反应与 正常的野生型STK11基因对那些具有STK11 SNP的人来说。 总体而言，这些研究将扩大我们对LKB1如何调节多发性硬化症和多发性硬化发展的了解 EAE，并确定对MS患者进行治疗干预的新靶点 LKB1的表达。

During the course of recruiting MS patients for a study of PBMCs, a family with 5 siblings diagnosed with MS was identified. The presence of a co-morbidity for certain rare tumors led to sequencing analysis of tumor suppressor gene STK11, and a variant (small nucleotide polymorphism, SNP) was identified. Genotyping of a large number of DNA samples showed that this SNP is present at higher levels in MS patients in both Caucasian and African American cohorts. STK11 codes for the Liver kinase B1 (LKB1) which has roles in regulation of cellular metabolism and inflammatory responses in Tcells, glial cells, and oligodendrocytes. Since the role of LKB1 in MS has not been characterized, and since brain astrocytes play an important role in maintaining energy balance and restricting immune responses, we hypothesized that reducing astrocyte LKB1 expression or activity would worsen EAE. Our findings using mice with LKB1 knocked out from astrocytes (“cKO mice”) confirmed this hypothesis and identified pathways that are altered in the astrocyte deficient mice and cells. In this project, we will determine how LKB1 deficiency in astrocyte effects their metabolic properties (mitochondrial function, and production of lactate which can be provided to neurons on demand). We will test the effects of the media prepared from the astrocytes (“Conditioned media”, CM) on microglial cells to see if microglial cell activation is increased. We will add astrocyte CM to naïve Tcells to see if the CM converts them into a damaging phenotype (Th1 or Th17; cells that produce toxic substances during EAE and MS). We will test effects of the CM on neurons, to see if the astrocytes produce neurotoxic substances; and add CM to oligodendrocytes to see if maturation is reduced. In our studies, we found that one of the proteins most increased in astrocyte cKO mice was lipocalin 2 (LCN2), a protein involved in inflammatory responses in other diseases, and highly expressed in astrocytes. However, roles for astrocyte LCN2 in EAE are not well known. We will generate new mice where astrocyte LCN2 is knocked down, to see if that reduces EAE disease. We also found that in astrocyte LKB1 cKO mice, there was extensive damage occurring to motor neurons in the spinal cord, which could contribute to weakness in MS patients. The cause of that damage is unknown, however findings that there is a large accumulation of immunoglobulins in those neurons suggests that these cells have increased expression of an IgG receptor. Experiments to test this are proposed. Finally, while our studies are using conditional knockout of LKB1 from cells, we do not know if the STK11 SNP, which does not cause knockout but alters LKB1 levels, has the same effect. To address this, we will use a novel method to generate microglial cells from human peripheral blood monocytes. Although microglia differ from astrocytes, we will be able to compare the responses of microglia with the normal, wildtype STK11 gene to those having the STK11 SNP. Overall, these studies will expand our knowledge of how LKB1 regulates the development of MS and EAE, and identify new targets for therapeutic interventions in MS patients who have deficiencies in LKB1 expression.