Maturation of Normal & Sensitized Airway Contractility

正常成熟度

• 批准号: 7105911
• 负责人: THOMAS Miles MURPHY
• 金额: $ 34.96万
• 依托单位: DUKE UNIVERSITY
• 依托单位国家: 美国
• 财政年份: 2006
• 资助国家: 美国
• 起止时间: 2006-04-01 至 2010-02-28
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/7105911
• 关键词: age difference; asthma; biomechanics; calcium flux; calmodulin; cell surface receptors; cytoskeleton; disease /disorder onset; enzyme activity; gene induction /repression; genetic regulation; guinea pigs; inflammation; inositol phosphates; juvenile animal; mature animal; muscle contraction; myosin light chain kinase; ovalbumin; phosphoprotein phosphatase; phosphorylation; posttranscriptional RNA processing; protein isoforms; small interfering RNA; smooth muscle; trachea; vimentin

DESCRIPTION (provided by applicant): Asthma prevalence is greater during childhood and early airway insults may affect the expression of asthma in adults. Airway reactivity in several species increases from minimal during fetal life and birth to a substantial level in a few days to weeks. We have discovered key and parallel roles for the phosphorylation of myosin light chain (MLC20) by myosin light chain kinase (MLCK) and the reduced mechanical opposition to shortening in the normally augmented shortening of airway smooth muscle (ASM) in 3 week old juvenile guinea pigs and immune-augmented shortening in adults following neonatal sensitization. Maximal force generation is unchanged with maturation and following sensitization. Based on our results: ASM shortening declines from juveniles to adulthood while the internal resistance to shortening Rsi and the passive stiffness of the muscle increase. MLCK levels and the phosphorylation of MLC20 decline in parallel. In preliminary experiments neonatal sensitization increases ASM shortening and MLCK content and decreases the Rsi of adult ASM only. In this application, these findings are integrated into a novel hypothetical mechanism that reflects a new paradigm for augmented smooth muscle shortening in normal non-neonatal juveniles and in adults previously sensitized as neonates. This paradigm suggests that changes in the cytoskeleton matrix to facilitate shortening are of similar importance to those factors that facilitate the phosphorylation of myosin light chain. It also suggests that airway hyperresponsiveness may have its origins (and thus the need for intervention) early in life. The specific aims are: 1. To determine whether or not increased MLCK content plays a key regulatory role in the increased ASM shortening in normal juvenile trachealis and adults sensitized as newborns. To determine whether or not the increased content of the fast isoforms SM1B and SM2B of myosin heavy chain increases ASM shortening. 2. To determine the genetic and protein regulation of MLCK expression with development and following neonatal sensitization. 3. To determine whether the increased shortening in normal juvenile trachealis and in adults sensitized as newborns is associated with passive mechanical properties that reduce the internal resistance to shortening. To determine whether the content/phosphorylation of the intermediate filaments desmin and vimentin plays a role in the internal resistance to shortening of airway smooth muscle.

描述（由申请人提供）：儿童时期哮喘患病率较高，早期气道损伤可能会影响成人哮喘的表现。一些物种的气道反应性在几天到几周内从胎儿生命和出生期间的最低水平增加到相当高的水平。我们发现了肌球蛋白轻链激酶 (MLCK) 磷酸化肌球蛋白轻链 (MLC20) 的关键和平行作用，以及在 3 周龄幼年几内亚正常增强的气道平滑肌 (ASM) 缩短过程中减少机械阻力的作用猪和新生儿致敏后成人的免疫增强缩短。最大力的产生随着成熟和随后的敏化而改变。根据我们的结果：从青少年到成年，ASM 缩短量下降，而缩短 Rsi 的内部阻力和肌肉的被动刚度增加。 MLCK 水平和 MLC20 磷酸化同时下降。在初步实验中，新生儿致敏增加了 ASM 缩短和 MLCK 含量，并仅降低了成人 ASM 的 Rsi。在本申请中，这些发现被整合到一种新的假设机制中，该机制反映了正常非新生儿青少年和先前作为新生儿致敏的成年人中增强平滑肌缩短的新范例。这一范式表明，细胞骨架基质中促进缩短的变化与促进肌球蛋白轻链磷酸化的因素具有相似的重要性。它还表明气道高反应性可能起源于生命早期（因此需要干预）。具体目标是： 1. 确定 MLCK 含量增加是否在正常幼年气管和新生儿致敏成人 ASM 缩短增加中发挥关键调节作用。确定肌球蛋白重链快速异构体 SM1B 和 SM2B 含量的增加是否会增加 ASM 缩短。 2. 确定发育和新生儿致敏后 MLCK 表达的遗传和蛋白质调节。 3. 确定正常幼年气管和新生儿时敏感的成人气管缩短的增加是否与减少缩短的内部阻力的被动机械特性有关。确定中间丝结蛋白和波形蛋白的含量/磷酸化是否在气道平滑肌缩短的内阻力中发挥作用。