Compartment-specific small non-coding RNA changes and nucleolar defects in human mesial temporal lobe epilepsy.

Area of Science:

• Neuroscience
• Molecular Biology
• Epilepsy Research

Background:

• Mesial temporal lobe epilepsy (mTLE) is a severe neurological disorder with poorly understood causes.
• Non-coding RNA expression changes in the brain are linked to mTLE, but sub-cellular compartment alterations are unclear.

Purpose of the Study:

• To investigate nuclear and cytoplasmic microRNA (miRNA) expression in the hippocampus of mTLE patients.
• To identify sub-cellular RNA changes and their role in mTLE pathogenesis.
• To examine nucleolar structure and function in mTLE.

Main Methods:

• Small RNA sequencing (RNA-seq) of hippocampal sub-cellular fractions from mTLE patients and controls.
• Analysis of miRNA and isomiR expression, focusing on nuclear localization.
• Investigation of nucleolar protein localization, size, shape, and snoRNA levels.

Main Results:

• Differential expression of miRNAs and isomiRs, with several showing enriched nuclear presence in mTLE.
• miR-92b accumulation in the nucleolus and association with snoRNAs in mTLE.
• Evidence of nucleolar stress in human mTLE, including altered morphology and protein mislocalization.
• Nucleolar defects observed in a rat epilepsy model prior to seizure onset.

Conclusions:

• Nucleolar dysfunction is a novel factor in mTLE pathogenesis.
• Altered sub-cellular RNA profiles, particularly in the nucleus and nucleolus, contribute to epilepsy.
• Findings provide a basis for understanding RNA's role in mTLE and potential therapeutic targets.