ubtor Mutation Causes Motor Hyperactivity by Activating mTOR Signaling in Zebrafish

Area of Science:

• Neuroscience
• Molecular Biology
• Genetics

Background:

• Mechanistic target of rapamycin (mTOR) signaling is crucial for cellular functions.
• Dysregulation of mTOR signaling, often due to loss of negative regulators, is implicated in epileptic encephalopathy.
• The role of UBTOR (also known as KIAA1024/MINAR1), a known negative regulator of mTOR, in neurological disorders was previously unexplored.

Purpose of the Study:

• To investigate the role of UBTOR in neurological diseases, specifically focusing on its potential involvement in epilepsy.
• To determine if UBTOR disruption affects mTOR signaling and leads to epilepsy-like behaviors in a zebrafish model.

Main Methods:

• Utilized a zebrafish model to study the effects of ubtor gene disruption.
• Assessed embryonic and larval motor activity, spinal interneuron activity, and mTOR signaling pathways.
• Administered pentylenetetrazol to evaluate seizure sensitivity in mutant zebrafish.
• Investigated the therapeutic potential of rapamycin, an mTORC1 inhibitor, in rescuing observed phenotypes.

Main Results:

• Disruption of ubtor in zebrafish resulted in increased spontaneous embryonic movement and elevated neuronal activity in spinal interneurons.
• Mutant zebrafish exhibited hyperactivation of mTOR signaling and increased sensitivity to pentylenetetrazol, indicating epilepsy-like behaviors.
• Treatment with rapamycin successfully rescued the motor hyperactivity, increased neuronal activity, and epilepsy-like phenotypes in ubtor mutant zebrafish.

Conclusions:

• UBTOR functions as a critical regulator of neuronal activity and motor behavior.
• Loss of UBTOR leads to mTOR hyperactivation, contributing to epilepsy-like phenotypes.
• Targeting mTORC1 signaling with inhibitors like rapamycin may offer a therapeutic strategy for UBTOR-associated neurological disorders.