Compromised N-Glycosylation Processing of Kv3.1b Correlates with Perturbed Motor Neuron Structure and Locomotor...

Area of Science:

• Neuroscience
• Molecular Biology
• Genetics

Background:

• Congenital disorders of glycosylation often lead to neurological issues.
• Kv3 voltage-gated K+ channels are vital for high-firing neurons, with specific sites (N220, N229) critical for activity.
• Aberrant N-glycosylation of Kv3 channels can disrupt neuronal function.

Purpose of the Study:

• To investigate the impact of altered N-glycosylation on Kv3.1b channel function.
• To examine neuron development, localization, and activity in response to N-glycosylation defects.
• To understand the role of Kv3.1b glycosylation in neuronal excitability and motor behavior.

Main Methods:

• Utilized wildtype AB zebrafish and CRISPR/Cas9 engineered neuroblastoma (NB) cells.
• Examined Kv3.1b channel glycosylation status (wildtype vs. N220Q mutation).
• Assessed neuronal morphology, axonal branching, and swimming activity in zebrafish larvae.
• Analyzed Kv3.1b localization and membrane particle dynamics in rat NB cells.
• Measured Kv3 channel opening and closing kinetics.

Main Results:

• Partially glycosylated Kv3.1b (N220Q) in zebrafish CaP motor neurons caused severe maldevelopment, including incomplete axonal branching and extension.
• Larvae expressing N220Q Kv3.1b exhibited impaired swimming behavior.
• Altered N-glycans (oligomannose) on Kv3.1b reduced its dispersal to neuronal outgrowths.
• Changes in glycosylation slowed Kv3 channel opening and closing rates, indicating altered intrinsic dynamics.

Conclusions:

• N-glycosylation processing of Kv3.1b is essential for normal neuronal development and axonal growth.
• Proper glycosylation of Kv3 channels regulates neuronal excitability and motor activity.
• Defects in Kv3.1b N-glycosylation contribute to neurological dysfunction observed in glycosylation disorders.