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Smooth Muscle Differentiation Is Essential for Airway Size, Tracheal Cartilage Segmentation, but Dispensable for
Randee E Young1, Mary-Kayt Jones2, Elizabeth A Hines2
1Department of Pediatrics, University of California-San Diego, La Jolla, CA 92093, USA; Laboratory of Genetics, Department of Medical Genetics, University of Wisconsin-Madison, Madison, WI 53706, USA.
Developmental Cell
|March 7, 2020
Summary
Airway smooth muscle is not essential for lung branching during development. However, it is crucial for tracheal architecture, airway growth, and supporting structures like cartilage and vasculature.
Area of Science:
- Developmental biology
- Pulmonology
- Cell biology
Background:
- Airway smooth muscle (ASM) is primarily known for its role in bronchoconstriction, implicated in asthma.
- Its specific function during lung development remains unclear and debated.
- A prevailing hypothesis suggests ASM drives lung branching via peristalsis.
Purpose of the Study:
- To investigate the in vivo role of ASM in lung development.
- To test the hypothesis that ASM-mediated peristalsis is essential for lung branching.
Main Methods:
- Inactivation of Myocardin to prevent ASM differentiation in vivo.
- Analysis of lung branching, tracheal cartilage, vasculature, and neural innervation in Myocardin mutants.
- Assessment of airway diameter and function.
Main Results:
- Myocardin mutants exhibited normal lung epithelial branching despite lacking ASM-induced peristalsis.
- Tracheal cartilage, vasculature, and neural innervation patterns were significantly disrupted in mutants.
- Mutant airways were narrower than controls, contradicting expectations of reduced constriction.
Conclusions:
- Airway smooth muscle is dispensable for lung epithelial branching during development.
- ASM plays an integral role in establishing tracheal architecture, promoting airway growth, and supporting vascular and neural development.
- The study refutes the model of ASM-driven branching via peristalsis in vivo.
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