The ciliary GTPase Arl13b regulates cell migration and cell cycle progression

Area of Science:

• Cell Biology
• Developmental Biology
• Biophysics

Background:

• ARL13B protein localizes to primary cilia, essential for sensing extracellular cues.
• A defective ARL13B hennin (HNN) variant is linked to Joubert Syndrome, a ciliopathy.
• Joubert Syndrome is associated with impaired sensing of extracellular chemical gradients.

Purpose of the Study:

• To investigate if impaired detection of extracellular voltage gradients contributes to the HNN phenotype.
• To elucidate the cellular mechanisms underlying ARL13B dysfunction in Joubert Syndrome.

Main Methods:

• In vitro analysis of wild-type (WT) and HNN fibroblast migration in response to electric fields.
• Cell cycle analysis of WT and HNN cells.
• Assessment of intracellular signaling pathways (phospho-ERK1/2, Suppressor of Fused) and tubulin detyrosination.

Main Results:

• Extracellular electric fields stimulated WT cell migration but not HNN cell migration speed.
• HNN cells exhibited slower proliferation and arrested at the G2/M phase.
• HNN cells showed reduced phospho-ERK1/2 signaling, elevated Suppressor of Fused, and increased tubulin stabilization.

Conclusions:

• ARL13B dysfunction leads to cell stagnation via impaired growth factor signaling and electric gradient detection.
• ARL13B plays a significant role in cell proliferation, potentially understated in current literature.
• Deficits in sensing extracellular electrical cues may contribute to Joubert Syndrome pathogenesis.