Smooth Muscle Mechanisms in Dynamic Airway Properties

描述（由申请人提供）：呼吸期间气道伸展和振荡期间发生的气道平滑肌（ASM）的机械刺激对于维持正常低水平的气道反应性至关重要。此外，通过体内持续呼气末正压（CPAP）或体外ASM长期负荷气道可降低气道反应性并改变ASM表型，这表明CPAP可作为哮喘的潜在治疗方法。病理生理条件还诱导呼吸期间施加在气道上的机械力以及气道组织结构和细胞外基质组成的改变。这些环境变化调节ASM的表型及其对生理刺激的反应，但机械力和细胞外环境对ASM性质的影响的机制尚不清楚。粘附体提供细胞与其基质环境之间的机械耦合，并且它们还使细胞能够感知和响应其周围环境的变化。ASM的收缩刺激触发了结构和信号蛋白向粘附体复合物的募集，并且粘附体信号复合物组分对于ASM对刺激的正常生理反应至关重要。然而，催化粘附体组装响应ASM刺激和调节组分蛋白的组织和激活的分子机制尚不清楚。拟议的研究将探索一种新的分子假说的装配和激活的粘附体蛋白在ASM的收缩和炎症刺激。这些过程是ASM信号转导过程的基本组成部分，并为ASM整合其对体液和环境刺激的生理反应提供了机制。拟开展的研究将采用ASM组织和新鲜分离的分化ASM细胞，以实现三个特定目的：1）确定RhoA和NM肌球蛋白II在调节粘附体信号复合物组装和激活、细胞骨架动力学和ASM收缩性中的作用。2)确定收缩刺激如何调节整合素粘附体复合物蛋白的激活。3)确定RhoA、NM肌球蛋白II和粘附体蛋白激活在调节ASM对炎症和体液刺激的反应中的作用，以及机械力和细胞外基质蛋白对其的调节。这些研究将提供新的见解ASM中的信号转导的分子机制，可能是广泛相关的其他细胞和组织，并了解如何机械力相互作用与药物和激素调节ASM组织的生理反应是重要的。他们将提供一个基础，设计新的治疗方法，包括机械方式以及药物治疗气道疾病的治疗。

DESCRIPTION (provided by applicant): The mechanical stimulation of airway smooth muscle (ASM) that occurs during stretch and oscillation of the airways during breathing is critical for maintaining a normal low level of airway reactivity. Furthermore, chronic loading of the airways by continuous positive end expiratory pressure (CPAP) in vivo or prolonged loading of ASM in vitro reduces airway responsiveness and alters ASM phenotype, suggesting that CPAP may act as a potential therapy for asthma. Pathophysiologic conditions also induce alterations in mechanical forces imposed on the airways during breathing and in airway tissue structure and extracellular matrix composition. These environmental changes modulate ASM phenotype and its responses to physiologic stimuli, but the mechanisms for the effects of mechanical forces and the extracellular environment on the properties of ASM are not understood.The adhesion junctions that connect cells within tissues to the extracellular matrix are composed of large multiprotein complexes termed "adhesomes". Adhesomes provide mechanical coupling between cells and their matrix environment, and they also enable cells to sense and respond to changes in their surrounding milieu. The contractile stimulation of ASM triggers the recruitment of structural and signaling proteins to adhesome complexes, and adhesome signaling complex components are critical for the normal physiologic responses of ASM to stimulation. However, the molecular mechanisms that catalyze adhesome assembly in response to ASM stimulation and regulate the organization and activation of component proteins are not known. The proposed studies will explore a novel molecular hypothesis for the assembly and activation of adhesome proteins in ASM in response to contractile and inflammatory stimuli. These processes are fundamental components of the signal transduction process in ASM, and provide a mechanism for ASM to integrate its physiologic responses to humoral and environmental stimuli. The proposed studies will employ ASM tissues and freshly dissociated differentiated ASM cells to address three Specific Aims: 1) Determine the roles of RhoA and NM myosin II in regulating the assembly and activation of adhesome signaling complexes, cytoskeletal dynamics and ASM contractility. 2) Determine how contractile stimulation regulates the activation of integrin adhesome complex proteins. 3) Determine the roles of RhoA, NM myosin II and adhesome protein activation in regulating the responses of ASM to inflammatory and humoral stimuli and their modulation by mechanical forces and extracellular matrix proteins. These studies will provide new insights into the molecular mechanisms of signal transduction in ASM that are likely to be broadly relevant to other cells and tissues, and are important for understanding how mechanical forces interact with drugs and hormones to regulate the physiologic responses in ASM tissues. They will provide a basis for designing new therapeutic approaches involving mechanical modalities as well as pharmacologic therapy for the treatment of airways disease.