Genetic Control of SP-B Gene Expression in the Lung

说明(申请人提供)：表面活性蛋白B(SP-B)是一种由79个氨基酸组成的多肽，由肺无纤毛细支气管上皮细胞(Clara细胞)和肺泡II型上皮细胞产生。SP-B肽储存在板层小体中，并与磷脂一起分泌到气道腔中，以促进表面活性磷脂在呼吸周期中的稳定和快速扩散。SP-B基因的零突变在新生儿和通过基因打靶产生的SP-B缺陷小鼠中会导致致命的呼吸窘迫。SP-B是新生儿出生后肺泡成熟和呼吸适应所必需的。这项工作的长期目标是确定在发育和成熟的肺中控制SP-B基因时空表达的顺式作用DNA元件和反式作用蛋白因子。最近几年的研究发现，维甲酸受体异二聚体(RAR/RXR)、甲状腺转录因子1(TTF-1)、核受体共激活因子(CBP/p300和p160共激活因子，包括SRC-1、TIF2和ACTR)以及信号转导和转录激活因子3(STAT3)通过增强子区(-500~-331bp)协同刺激HSP-B的转录。为了扩大研究范围，我们将1)鉴定参与RARpha和STAT3相互作用的功能结构域和氨基酸残基；2)鉴定HSP-B增强子区域(-500至-331bp)中决定HSP-B基因在细支气管上皮细胞中的时空表达的罕见的和TTF-1顺式作用位点；3)利用LacZ转基因小鼠鉴定决定HSP-B基因在肺泡II型上皮细胞中时空表达的顺式作用元件。这些研究和以前的发现将有助于更好地理解肺生物学中SP-B动态平衡的分子基础。了解这一点将有助于制定战略，以抗击先天性和获得性呼吸系统疾病，如肺气肿、呼吸窘迫综合征(RDS)和支气管肺发育不良(BPD)，这些疾病是早产儿死亡和发病的主要原因。

DESCRIPTION (provided by applicant): Surfactant protein B (SP-B) is a 79-amino acid peptide produced in pulmonary non-ciliated bronchiolar epithelial cells (Clara cells) and alveolar type II epithelial cells. The SP-B peptide is stored in lamellar bodies and secreted with phospholipids into the airway lumen to facilitate the stability and rapid spreading of surfactant phospholipids during respiratory cycles. Null mutations in the SP-B gene cause lethal respiratory distress in newborn infants and in SP-B deficient mice produced by gene targeting. SP-B is essential for postnatal alveolar maturation and respiratory adaptation in newborns. The long-term goals of this work are to identify cis-acting DNA elements and trans-acting protein factors that control SP-B gene temporal/spatial expression in developing and mature lungs. During the last several years of study, it has been identified that retinoic acid receptor heterodimer (RAR/RXR), thyroid transcription factor 1 (TTF-1), nuclear receptor co-activators (CBP/p300 and p160 co-activators, including SRC-1, TIF2 and ACTR) and signal transducers and activators of transcription 3 (STAT3) cooperatively stimulate hSP-B transcription through an enhancer region (-500 to -331 bp). To extend the study, we will 1): characterize functional domains and amino acid residues that are involved in the interaction between RARalpha and STAT3; 2) characterize RARE and TTF-1 cis-acting sites in the hSP-B enhancer region (-500 to -331 bp) that determine hSP-B gene temporal/spatial expression in bronchiolar epithelial cells using LacZ transgenic mice; 3) characterize cis-acting elements that determine hSP-B gene temporal/spatial expression in alveolar type II epithelial cells using LacZ transgenic mice. These studies along with previous findings will lead to a better understanding of molecular basis for SP-B homeostasis in lung biology. Knowing this will help to design strategies to combat congenital and acquired respiratory diseases such as emphysema, respiratory distress syndrome (RDS) and bronchopulmonary dysplasia (BPD), the leading causes of mortality and morbidity in preterm infants.