Ciliary Hedgehog signaling patterns the digestive system to generate mechanical forces driving elongation

• Published in: Nature communications Vol. 12; no. 1; p. 7186
• Main Authors: Yang, Ying, Paivinen, Pekka, Xie, Chang, Krup, Alexis Leigh, Makela, Tomi P., Mostov, Keith E., Reiter, Jeremy F.
• Format: Journal Article
• Language: English
• Published: London Nature Publishing Group UK 10.12.2021; Nature Publishing Group; Nature Portfolio
• Subjects: 14/19; 38/1; 631/136; 631/80; Ablation; Animals; Cell culture; Cell Proliferation; Cilia; Cilia - metabolism; Digestive system; Digestive tract; Elongation; Esophagus; Gastrointestinal Tract; Hedgehog protein; Hedgehog Proteins - genetics; Hedgehog Proteins - metabolism; Humanities and Social Sciences; Intestine; Mesenchyme; Mesoderm - metabolism; Mice; multidisciplinary; Muscle, Smooth - metabolism; Muscles; Myocytes, Smooth Muscle - metabolism; Organs; Patterning; Protein Serine-Threonine Kinases - metabolism; Residual stress; Science; Science (multidisciplinary); Signal Transduction - physiology; Signaling; Smooth muscle; Yes-associated protein
• ISSN: 2041-1723; 2041-1723
• DOI: 10.1038/s41467-021-27319-z

How tubular organs elongate is poorly understood. We found that attenuated ciliary Hedgehog signaling in the gut wall impaired patterning of the circumferential smooth muscle and inhibited proliferation and elongation of developing intestine and esophagus. Similarly, ablation of gut-wall smooth muscle cells reduced lengthening. Disruption of ciliary Hedgehog signaling or removal of smooth muscle reduced residual stress within the gut wall and decreased activity of the mechanotransductive effector YAP. Removing YAP in the mesenchyme also reduced proliferation and elongation, but without affecting smooth muscle formation, suggesting that YAP interprets the smooth muscle-generated force to promote longitudinal growth. Additionally, we developed an intestinal culture system that recapitulates the requirements for cilia and mechanical forces in elongation. Pharmacologically activating YAP in this system restored elongation of cilia-deficient intestines. Thus, our results reveal that ciliary Hedgehog signaling patterns the circumferential smooth muscle to generate radial mechanical forces that activate YAP and elongate the gut. The mechanisms underlying tubular organ elongation remain poorly understood. Here, the authors show that primary cilia interpret Hedgehog signals to pattern the developing gut and that smooth muscle in the gut wall generates mechanical forces that direct longitudinal growth.