Neuronal Primary Cilia Mediate Noggin Release to Enable Extracellular Signaling

Area of Science:

• Neuroscience
• Cell Biology
• Developmental Biology

Background:

• Primary cilia are sensory organelles responding to environmental stimuli.
• In the adult hippocampus, primary cilia regulate neurogenesis and function via signals like sonic hedgehog (Shh).
• Loss of primary cilia function leads to cognitive and behavioral deficits.

Purpose of the Study:

• To investigate the role of primary cilia in regulating noggin release in adult hippocampal granule cells.
• To explore the interplay between Shh signaling, neuronal activity, and noggin in the neurogenic niche.

Main Methods:

• Immunohistochemistry to determine noggin localization in primary cilia.
• In vitro and in vivo experiments to assess the impact of Shh, somatostatin (SST), and neuronal activation on noggin release.
• Analysis of BMP antagonism and neurogenesis regulation.

Main Results:

• Noggin is expressed by mature granule cells and localized near primary cilia.
• Primary cilia regulate noggin release through Shh and SST pathways.
• Granule cell activation modulates noggin dynamics, demonstrating synergy between Shh and noggin.

Conclusions:

• Primary cilia mediate extracellular signaling by regulating noggin release, expanding their known functions beyond sensory transduction.
• Neuronal activity positively regulates BMP antagonism within the hippocampal neurogenic niche.
• These findings offer insights into the connection between hippocampal activity, cognition, and ciliopathies.