Zebrafish Tsc1 reveals functional interactions between the cilium and the TOR pathway

Area of Science:

• Cell Biology
• Developmental Biology
• Genetics

Background:

• Cilia are crucial for preventing kidney cysts and establishing body asymmetry.
• Cilia act as sensory organelles for signaling pathways like hedgehog and Wnt.
• Kidney cyst formation in tuberous sclerosis complex (TSC) prompts investigation into cilia's role in the TSC-TOR pathway.

Purpose of the Study:

• To investigate the role of the cilium in the TSC-TOR pathway using zebrafish.
• To understand the interaction between Tuberous Sclerosis Complex 1 (TSC1) and ciliary function.
• To explore how Tsc1a affects kidney cyst formation and cilium length.

Main Methods:

• Zebrafish model used for genetic studies.
• Morpholino knockdown of tsc1a to observe ciliary and developmental phenotypes.
• Analysis of TOR pathway activation in ciliary mutants and tsc1a knockdown.
• Treatment of ciliary mutants with the TOR inhibitor rapamycin.

Main Results:

• Knockdown of tsc1a in zebrafish caused kidney cysts and left-right asymmetry defects.
• Tsc1a localized to the Golgi and interacted with ciliary genes.
• TOR pathway was aberrantly activated in ciliary mutants, similar to tsc1a knockdown.
• Rapamycin treatment blocked kidney cyst formation in ciliary mutants.
• Tsc1a knockdown resulted in elongated cilia.

Conclusions:

• A signaling network exists between cilia and the TOR pathway.
• Ciliary signals influence the TOR pathway, and Tsc1a regulates cilium length.
• These findings link cilia dysfunction and TSC to kidney cyst development.