RSG1 is required for cilia-dependent neural tube closure

Area of Science:

• Cell Biology
• Developmental Biology
• Genetics

Background:

• Cilia are essential for embryonic development, regulating signaling pathways like Sonic hedgehog.
• Proper neural tube formation relies on cilia function.
• Neural tube defects (NTDs) can arise from disruptions in these developmental processes.

Purpose of the Study:

• To investigate the genetic basis of neural tube defects and disrupted cilia formation.
• To characterize a novel mouse mutant line (L3P) with developmental abnormalities.
• To identify the specific gene and mutation responsible for the observed phenotypes.

Main Methods:

• Utilized forward genetic screens to generate and analyze mutant mouse lines.
• Mapped a point mutation within the L3P line to the Rsg1 gene.
• Investigated protein localization of the mutant RSG1 and other ciliary proteins.

Main Results:

• The L3P mutant line exhibits NTDs and disrupted Sonic hedgehog signaling, affecting cilia initiation.
• A point mutation in Rsg1, encoding a GTPase-like protein, was identified within the GTP-binding pocket and G1 domain.
• Mutant RSG1 and other ciliary proteins correctly localize to the basal body, indicating normal basal body maturation.

Conclusions:

• RSG1 GTPase activity is not essential for basal body maturation but is required for subsequent steps in axonemal elongation.
• This finding provides insight into the molecular mechanisms regulating cilia assembly and function during embryonic development.
• The identified Rsg1 mutation offers a valuable tool for studying Sonic hedgehog signaling and ciliopathies.