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）：儿童哮喘患病率较高，早期气道损伤可能影响成人哮喘的表达。一些物种的气道反应性从胎儿和出生时的最低水平增加到几天到几周内的大量水平。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3周龄幼年豚鼠气道平滑肌（ASM）正常增强缩短和新生儿致敏后成人免疫增强缩短的机械反对缩短。最大发力随成熟和致敏后不变。根据我们的研究结果：从青少年到成年，ASM缩短率下降，而缩短Rsi的内阻和肌肉被动僵硬度增加。MLCK水平和MLC20磷酸化水平平行下降。在初步实验中，新生儿致敏只增加了ASM缩短和MLCK含量，降低了成人ASM的Rsi。在这项应用中，这些发现被整合到一个新的假设机制中，该机制反映了正常的非新生儿少年和以前在新生儿时敏感的成人中增强平滑肌缩短的新范式。这种模式表明，促进缩短的细胞骨架基质的变化与促进肌球蛋白轻链磷酸化的那些因素具有相似的重要性。它还表明，气道高反应性可能在生命早期就有其起源（因此需要干预）。具体目标是：1。确定MLCK含量的增加是否在正常少年气管和新生儿致敏成人气道中ASM缩短增加中起关键调节作用。测定肌球蛋白重链快速同工异构体SM1B和SM2B含量的增加是否增加了ASM缩短。2. 目的：探讨MLCK基因和蛋白在发育及新生儿致敏过程中的表达调控。3. 确定正常青少年气管和新生儿致敏成人气管缩短的增加是否与被动力学特性有关，从而降低了气管缩短的内部阻力。目的：确定中间纤维聚乳酸蛋白和波形蛋白的含量/磷酸化是否在气道平滑肌缩短内阻中起作用。