Modifier Genes of SP-C Induced ILD

SP-C诱导ILD的修饰基因

• 批准号: 6889793
• 负责人: Daniel R Prows
• 金额: $ 19.17万
• 依托单位: CINCINNATI CHILDRENS HOSP MED CTR
• 依托单位国家: 美国
• 财政年份: 2004
• 资助国家: 美国
• 起止时间: 2004-07-01 至 2009-06-30
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/6889793
• 关键词: gene expression; gene mutation; genetically modified animals; interstitial lung diseases; laboratory mouse; microarray technology; polymerase chain reaction; pulmonary surfactants; respiratory epithelium; western blottings

Interstitial lung diseases (ILDs) are chronic, progressive lung diseases with many potential causes; however, most etiologies are unknown. Patients with these disorders are often clinically indistinguishable, presenting with advancing ILD that is associated with exercise limitation, tachypnea, and shortness of breath. Pathologically, the various forms of ILD are all associated with alveolar inflammation, pulmonary interstitial infiltration with connective tissue matrix and leukocytes, progressive loss of alveolar structure, and pulmonary fibrosis. Despite well-recognized histological and clinical manifestations, the molecular mechanisms involved in ILD pathogenesis have been elusive. Many known familial genetic disorders have an ILD component, including pulmonary alveolar proteinosis, Gaucher disease, Hermansky-Pudlak syndrome, Neimann-Pick disease, neurofibromatosis, and tuberous sclerosis. Susceptibility to ILDs beyond those for known disorders, however, is believed to have only a minor familial component. Recently, human ILD was associated with an autosomal dominant mutation in the surfactant protein-C (SP-C) gene. This resulted in a functional loss of Type II cell specific SP-C protein in the epithelium, causing alveolar cell injury and predisposing to various forms of ILD. These findings extended earlier studies that associated SP-C gene mutations and protein deficiency in family members diagnosed with familial ILD. An intriguing, but troublesome attribute of familial ILD is the high variability in histopathologic patterns seen among affected individuals, strongly implicating modifier genes in ILD severity. Additional evidence for modifier genes of ILD stems from knockout mice. When SP-C was gene-targeted in FVB/N mice, only subtle changes in lung mechanics and histology were noted. To the contrary, 129S6/SvEvTac (129/Sv) SP-C null mice developed severe and progressive pulmonary disease with many histological features consistent with ILD; thus, SP-C deficiency in the 129/Sv strain represents a mouse model of ILD. The central hypothesis of the proposed research is that ILD severity in a SP-C null state is modified by one or more genes, which can be delineated using genetic and molecular analyses of the FVB/N-129/Sv mouse model. Identification of modifier genes affecting ILD severity will be accomplished using 4 Specific Aims: 1) determine the likely mode of inheritance for each intermediate ILD phenotype and estimate the minimum number of loci affecting the disparate lung responses in the SP-C null mouse model (segregation analysis); 2) identify chromosomal regions linked to phenotype differences in a large backcross cohort generated from the two SP-C null strains (QTL analysis); 3) identify candidate and positional candidate modifier genes associated with strain differences in SP-C null mice (microarray analysis); and 4) assess positional candidate ILD modifier genes in the SP-C null mouse model (functional analysis). Gene identification should yield valuable information needed to further assess therapeutic strategies and genetic variations affecting susceptibility and outcome of surfactant-associated lung diseases.

间质性肺部疾病（ILD）是慢性进行性肺部疾病，具有许多潜在的原因。但是，大多数病因是未知的。患有这些疾病的患者通常在临床上是无法区分的，并且具有与运动限制，呼吸呼吸和呼吸急促有关的ILD。从病理上讲，各种形式的ILD都与肺泡炎症，结缔组织基质和白细胞的肺间隙浸润，肺泡结构的进行性丧失以及肺纤维化有关。尽管良好认可的组织学和临床表现，但涉及ILD发病机理的分子机制仍然难以捉摸。许多已知的家族性遗传疾病具有ILD成分，包括肺肺泡蛋白质病，Gaucher病，Hermansky-Pudlak综合征，Neimann-Pick疾病，神经纤维瘤病和结节性硬化症。然而，人们认为对ILD的敏感性仅具有较小的家族性成分。最近，人类ILD与常染色体显性突变有关 表面活性剂蛋白-C（SP-C）基因。这导致上皮中II型细胞特异性SP-C蛋白的功能丧失，从而导致肺泡细胞损伤并易于体外。这些发现扩展了早期的研究，该研究将SP-C基因突变和被诊断为家族性ILD的家庭成员中的蛋白质缺乏症相关联。家族性ILD的一个有趣但麻烦的属性是受影响个体中观察到的组织病理学模式的高度差异，强烈暗示了修饰基因在ILD严重性中。 ILD修饰基因的其他证据来自基因敲除小鼠。当在FVB/N小鼠中对SP-C进行基因靶向时，只有微妙的变化 注意到肺力学和组织学。相反，129S6/SVEVTAC（129/SV）SP-C NULL小鼠出现了严重和进行性肺部疾病，许多组织学特征与ILD一致。因此，129/SV菌株中的SP-C缺乏代表ILD的小鼠模型。拟议研究的中心假设是，SP-C无效状态的ILD严重程度通过一个或多个基因修饰，可以使用FVB/N-N-129/SV小鼠模型的遗传和分子分析来划定该基因。鉴定影响ILD严重程度的修饰符基因将使用4个特定目的来完成：1）确定每个中间ILD表型的遗传模式，并估算影响不同的基因座的最小数量 SP-C NULL小鼠模型中的肺反应（分离分析）； 2）确定与两种SP-C NULL菌株产生的大反向交叉队列中表型差异相关的染色体区域（QTL分析）； 3）确定候选和位置候选修饰符基因与SP-C无小鼠中的应变差异相关的基因（微阵列分析）； 4）评估SP-C NULL小鼠模型中的位置候选ILD修饰基因（功能分析）。基因识别应产生所需的有价值的信息，以进一步评估影响表面活性剂相关肺部疾病的易感性和结果的遗传变异。