Lipid raft interacting galectin 8 regulates primary ciliogenesis

Area of Science:

• Cell Biology
• Molecular Biology
• Biochemistry

Background:

• Primary cilia are crucial sensory organelles with tightly regulated length.
• Intraflagellar transport (IFT) trains deliver building materials like tubulin for cilia growth.
• The transition zone (TZ) acts as a barrier controlling protein entry into the cilium.

Purpose of the Study:

• To investigate the role of galectin 8 in regulating primary ciliogenesis.
• To elucidate the mechanism by which galectin 8 influences primary cilia length.
• To understand the interaction between galectin 8, lipid rafts, and the TZ barrier.

Main Methods:

• Investigated galectin 8's effect on primary cilia growth in polarized epithelia.
• Utilized lipid raft disruption (genetic knockout of Cav1, pharmacological inhibition).
• Analyzed protein localization and interactions using immunofluorescence and biochemical assays.

Main Results:

• Extracellular galectin 8 binds to the primary cilia base via lipid raft components (GD3 ganglioside, caveolin 1).
• Galectin 8 binding perturbs TZ barrier function, leading to rapid primary cilia elongation.
• Disruption of lipid rafts or Cav1 mimics galectin 8's effect, causing cilia elongation and protein redistribution.
• Galectin 8 interferes with caveolin 1 and TMEM231 interaction, impeding TZ barrier function.

Conclusions:

• Galectin 8 promotes primary cilia elongation by compromising the TZ barrier.
• This mechanism involves galectin 8's interaction with lipid rafts and key TZ components.
• The findings reveal a novel regulatory pathway for primary cilia length control.