Gender-Specific Role of p202 in Lupus Susceptibility

描述(申请人提供)：系统性红斑狼疮(SLE)是一种主要影响育龄妇女的自身免疫性疾病。虽然性激素与这种疾病发展的性别偏见有关，但分子机制仍然很大程度上未知。阐明SLE易感基因的作用，其表达受性激素调节，对于了解疾病的发展非常重要。对B6.Nba2狼疮同基因小鼠的鉴定和功能分析表明，干扰素可激活的IFI202基因在SLE易感性中的作用是未知的。本研究的主要目的是了解IFI202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。P202蛋白(52 KDa)是一种可诱导的(受I型干扰素和白介素6诱导的)转录调节因子，具有抑制细胞周期进展和细胞凋亡的能力。根据我们的初步观察和其他观察，我们假设性别特定和遗传因素导致某些狼疮易感品系小鼠p202表达增加。此外，我们推测p202通过抑制促凋亡因子，如E2F和P53的转录活性，提高B细胞和T细胞的凋亡阈值，从而促进狼疮的易感性。目的#1：确定性别和遗传因素如何促进p202的表达增加。我们将比较年龄匹配的雄性和雌性小鼠(B6、NZB和B6.Nba2品系)、雄性和去卵巢雌性小鼠以及雌激素或安慰剂处理的去雄性和雌性小鼠中IFI202的mRNA和蛋白的表达。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Ifi202的转录；(Ii)E2介导的转录后机制，如Ifi202 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取决于性别、I型干扰素(α和β)水平或白细胞介素6。目的#2：探讨雄性和雌性小鼠脾细胞p202水平升高是否与E2F(E2F1和E2F2)转录活性抑制、E2F靶基因表达下调以及活化诱导的CD4+T细胞死亡缺陷有关。目的#3：阐明P202在脾细胞(雄性和雌性小鼠)中的高表达抑制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。意义：我们的研究将确定在狼疮小鼠模型中，免疫系统细胞中p202表达的性别特异性增加有助于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.