Gender-Specific Role of p202 in Lupus Susceptibility

描述（由申请人提供）：系统性红斑狼疮（SLE）是一种自身免疫性疾病，主要影响育龄妇女。虽然性激素与这种疾病的性别偏见有关，但分子机制在很大程度上仍然未知。阐明SLE易感基因的作用，其表达受性激素的调节，对了解疾病的发展是重要的。对B6.Nba2狼疮易感同类小鼠的特征和功能分析揭示了干扰素（IFN）激活的Ifi 202基因在SLE易感性中的先前未知作用。这些研究的主要目的是了解Ifi 202基因在某些狼疮易感小鼠品系中的性别特异性表达增加，并确定编码的磷蛋白p202在狼疮易感性发展中的作用。蛋白质p202（52-kDa）是一种诱导型（可被I型IFN和白介素-6诱导）转录调节剂，具有抑制细胞周期进展和凋亡的能力。根据我们的初步和其他观察，我们假设，性别特异性和遗传因素有助于增加p202的表达在某些狼疮易感小鼠品系。此外，我们推测p202通过抑制促凋亡因子（如E2 F和p53）的转录活性，增加B和T细胞凋亡的阈值，从而促进狼疮易感性。目的#1：确定性别特异性和遗传因素如何促进p202表达增加。我们将比较年龄匹配的雄性和雌性小鼠（B6、NZB和B6.Nba2小鼠品系）、雄性和卵巢切除的雌性小鼠以及雌激素或安慰剂治疗的睾丸切除的雄性和雌性小鼠之间Ifi 202 mRNA和蛋白质的表达。此外，我们将确定（i）雌激素（E2）水平如何通过雌激素受体激活Ifi 202的转录;（ii）E2介导的转录后机制，如Ifi 202 mRNA和蛋白质稳定，是否有助于上调p202;以及（iii）p202的核质分布及其磷酸化是否依赖于性别、I型干扰素水平（α和β）或白细胞介素-6。目标二：研究脾细胞（来自雄性和雌性小鼠）中p202水平升高是否与E2 F（E2 F1和E2 F2）转录活性抑制、E2 F靶基因表达下调以及CD 4 + T细胞活化诱导细胞死亡缺陷相关。目标3：阐明脾细胞（来自雄性和雌性小鼠）中p202表达增加抑制p53介导的基因转录激活和抑制以及p53介导的细胞凋亡的分子机制。重要性：我们的研究将确定免疫系统细胞中p202的性别特异性表达增加有助于狼疮小鼠模型中狼疮易感性的分子机制。

DESCRIPTION (provided by applicant): Systemic lupus erythematosus (SLE) is an autoimmune disease that predominantly affects women of childbearing age. Although sex hormones have been implicated in gender bias of the development of this disease, molecular mechanisms remain largely unknown. Elucidation of the role of SLE susceptibility genes, expression of which is regulated by sex hormones, is important to understand the development of the disease. Characterization of the B6.Nba2 lupus prone congenic mice and functional analysis has revealed a previously unknown role for the interferon (IFN)-activatable Ifi202 gene in SLE susceptibility. The major objectives of the proposed studies are to understand the gender-specific increased expression of Ifi202 gene in certain lupus prone strains of mice and to define the role of the encoded phosphoprotein, p202, in the development of lupus susceptibility. The protein p202 (52-kDa) is an inducible (inducible by type-I IFN and interleukin-6) transcriptional modulator with demonstrated ability to inhibit cell cycle progression and apoptosis. Based on our preliminary and other observations, we hypothesize that gender-specific and genetic factors contribute to increased expression of p202 in certain lupus-prone strains of mice. Moreover, we postulate that p202 contributes to lupus susceptibility by increasing the threshold for apoptosis in B and T cells by inhibiting the transcriptional activity of proapoptotic factors, such as E2F and p53. Aim #1: To determine how gender-specific and genetic factors contribute to increased expression of p202. We will compare expression of Ifi202 mRNA and protein between age-matched male and female mice (B6, NZB, and B6.Nba2 strains of mice), male and ovariectomized female mice, and estrogen or placebo treated orchiectomized male and female mice. Additionally, we will determine (i) how estrogen (E2) levels through estrogen receptor activate the transcription of the Ifi202; (ii) whether E2-mediated posttranscriptional mechanisms, such as Ifi202 mRNA and protein stabilization, contribute to up-regulation of p202; and (iii) whether nucleocytoplasmic distribution of p202 and its phosphorylation depend on the gender, levels of type-I interferons (alpha and beta), or interleukin-6. Aim #2: To investigate whether increased levels of p202 in splenocytes (from male and female mice) correlate with inhibition of the transcriptional activity of E2Fs (E2F1 and E2F2), down-regulation of the expression of the E2F target genes, and defects in activation-induced cell death of CD4+ T cells. Aim #3: To elucidate the molecular mechanisms by which increased expression of p202 in splenocytes (from male and female mice) inhibits p53-mediated transcriptional activation and repression of genes, and p53-mediated apoptosis. Significance: Our studies will identify molecular mechanisms by which gender-specific increased expression of p202 in cells of the immune system contributes to lupus susceptibility in a mouse model of lupus.