Mechanisms of Airway Smooth Muscle Hypertrophy

描述（由申请方提供）：哮喘患者存在由于肥大或增生引起的气道平滑肌质量增加。虽然调节细胞增殖的生物化学途径已被充分研究，但对调节气道平滑肌蛋白质合成、细胞大小或收缩器蛋白质积累的生物化学途径知之甚少。来自细胞培养模型和哮喘患者的最新数据表明，气道平滑肌收缩蛋白的表达可能以转录后方式调节。在这个修订后的申请中，我们提出气道平滑肌肥大需要激活特定的翻译控制途径。为了测试这一点，我们将研究1）肥大的细胞培养模型，其中用转化生长因子（TGF）-β处理原代人支气管平滑肌细胞; 2）两种哮喘小鼠模型;和3）来自人哮喘患者的活检样品。我们提出三个具体目标：具体目标1。确定收缩器转录和翻译在人气道平滑肌肥大发展中的作用。我们假设：1）TGF β通过增加基因转录和翻译效率促进气道平滑肌肥大;和2）鼠气道重塑的部分特征在于平滑肌肥大。具体目标2。检测帽依赖性蛋白质合成对人气道平滑肌肥大的贡献。我们假设：1）4 E-BP磷酸化，其增加eIF 4 E用于eIF 4F复合物形成的可用性，是TGF β诱导的气道平滑肌肥大所需的; 2）MAP激酶信号整合激酶（MNK）-1的eIF 4 E磷酸化是气道平滑肌肥大所需的;和3）气道重塑的部分特征在于气道平滑肌4 E-BP和eIF 4 E的磷酸化增加。具体目标3。检测帽非依赖性蛋白质合成对人气道平滑肌肥大的贡献。我们假设：1）p70核糖体S6激酶（S6激酶）对于气道平滑肌肥大来说既不是必需的，也不是充分的; 2）GSK 3 β磷酸化和失活对于气道平滑肌肥大来说是必需的且足够的;和3）气道重塑的部分特征是气道平滑肌GSK 3 β磷酸化的增加。了解哮喘气道重塑的生化机制将有助于改善哮喘的治疗。

DESCRIPTION (provided by applicant): Increased airway smooth muscle mass, due either to hypertrophy or hyperplasia, is present in patients with asthma. While the biochemical pathways regulating cell proliferation have been well studied, little is known about the biochemical pathways regulating airway smooth muscle protein synthesis, cell size or the accumulation of contractile apparatus proteins. Recent data from cell culture models and patients with asthma suggest that airway smooth muscle contractile protein expression may be regulated in a post- transcriptional manner. In this revised application, we propose that airway smooth muscle hypertrophy requires the activation of specific translational control pathways. To test this, we will study 1) a cell culture model of hypertrophy in which primary human bronchial smooth muscle cells are treated with transforming growth factor (TGF)-beta; 2) two mouse models of asthma; and 3) biopsy samples from human asthmatics. We propose three Specific Aims: Specific Aim 1. Determine the contributions of contractile apparatus transcription and translation in the development of human airway smooth muscle hypertrophy. We hypothesize that: 1) TGFbeta promotes airway smooth muscle hypertrophy by increasing both gene transcription and translational efficiency; and 2) murine airway remodeling is characterized in part by smooth muscle hypertrophy. Specific Aim 2. Examine the contribution of cap-dependent protein synthesis to human airway smooth muscle hypertrophy. We hypothesize that: 1) 4E-BP phosphorylation, which increases the availability of elF4E for elF4F complex formation, is required for TGFbeta-induced airway smooth muscle hypertrophy; 2) elF4E phosphorylation by MAP kinase signal integrating kinase (MNK)-1 is required for airway smooth muscle hypertrophy; and 3) airway remodeling is characterized in part by increased phosphorylation of airway smooth muscle 4E-BP and elF4E. Specific Aim 3. Examine the contribution of cap-independent protein synthesis to human airway smooth muscle hypertrophy. We hypothesize that: 1) p70 ribosomal S6 kinase (S6 kinase) is neither required nor sufficient for airway smooth muscle hypertrophy; 2) GSK3beta phosphorylation and inactivation is required and sufficient for airway smooth muscle hypertrophy; and 3) airway remodeling is characterized in part by increased phosphorylation of airway smooth muscle GSK3beta. Understanding biochemical mechanisms of airway remodeling in asthma will lead to improvements in the treatment of this disease.