Scientists at St. Jude Children’s Research Hospital have identified a precise way the Sonic Hedgehog (SHH) pathway is regulated during embryonic development—one that helps explain how organs form with correct timing and intensity. The work focuses on Smoothened, a key SHH signal relay protein inside cells, and shows that its activity is boosted by a lipid-derived molecule rather than simply turned on or off.
The lipid arachidonic acid was found to enhance Smoothened signaling by binding to a newly discovered regulatory site on the receptor. This interaction changes Smoothened’s behavior in an allosteric manner, effectively increasing the strength of the response once SHH is present. In other words, the pathway’s output is “tuned” rather than switched, adding a layer of control suited to complex tissue development.
To test functional impact, researchers disrupted this arachidonic-acid–Smoothened mechanism and observed reduced Smoothened activation. The result was impaired cardiopulmonary development, indicating that the lipid-driven enhancement is especially important for forming the heart and lungs. The study suggests that SHH must not only be present, but also properly amplified in specific tissue contexts.
A striking aspect of the findings is tissue specificity. Despite SHH’s well-established role in the developing nervous system, breaking this regulatory interaction did not produce detectable effects on neural development. This implies that different tissues may use distinct molecular strategies to achieve the SHH signaling levels they require.
“This provides a better framework for thinking about how we might selectively regulate this pathway in disease settings,” said corresponding author Stacey Ogden, PhD. Since abnormal Smoothened activity is also linked to cancers, understanding the receptor’s regulation could inform future approaches that modulate SHH without broadly disturbing other tissues.
The study builds on earlier St. Jude work identifying the lipid enzyme cPLA2α as a regulator of SHH signaling. Because cPLA2α produces arachidonic acid, the new results connect enzyme activity to a mechanistic understanding of how Smoothened is functionally controlled during development.
Researchers describe the model as a context-specific enhancer of SHH signaling. Activated Smoothened appears to amplify its normal signaling output when arachidonic acid is bound, creating an additional “gain control” mechanism that matters most in cardiopulmonary tissues.
By revealing functional consequences of receptor allostery in vivo, the findings provide new avenues for studying SHH regulation across developmental settings. The next challenge, according to the team, is to understand why some tissues depend on this particular lipid mechanism and what other signals may regulate Smoothened elsewhere.
The findings are published in Nature Communications.
Subject of Research: Cells
Article Title: Receptor allostery promotes context-specific Sonic Hedgehog signaling during embryonic development
News Publication Date: 27-Jul-2026
Web References: https://www.nature.com/articles/s41467-026-75918-5
References: Nature Communications (article link above)
Image Credits: Courtesy of St. Jude Children’s Research Hospital
Keywords: Sonic Hedgehog pathway, Smoothened, arachidonic acid, receptor allostery, cPLA2α, embryonic development, cardiopulmonary development, neural tissue specificity
