Heterogeneity of 2′-O-methylation in Ribosome and its role in Synaptic Translation

Abstract

Epitranscriptomic modifications serve as key regulators of several RNA functions. 2’-O-Methylation (2’-O-Me) on ribosomal RNA (rRNA) is emerging as a crucial post-transcriptional modification that modulates ribosome biogenesis, activity and translation efficiency. In neurons, localised protein synthesis at synapses is essential for synaptic plasticity and the stability of neural circuits. This study investigates the heterogeneity of 2’-O-Me of ribosomes from synaptic compartments, eventually aiming to understand its role in regulating neuronal translation. We employed biochemical approaches like RTL-P (Reverse Transcription at Low dNTP concentration followed by qPCR) in total brain homogenate and isolated Synaptosomes to assess compartment-specific variations in certain rRNA 2’-O-Me sites and demonstrate how these modifications can contribute to spatial ribosome heterogeneity in neurons. Additionally, we examined the altered rRNA 2’-O-Me on specific sites in Alzheimer’s disease (AD), an aspect of neurodegeneration that is less explored. These insights prompted us to investigate 2’-O-Me-associated proteins, particularly Fragile X Mental Retardation Protein (FMRP). Notably, our work uncovers a reduction of FMRP levels during the early stages of AD, which coincides with impaired dendritic protein synthesis. These findings suggest a plausible mechanistic link between FMRP loss and translational dysfunction in AD. Overall, our study highlights the potential role of ribosome heterogeneity in regulating translation in neurons and indicates a link between ribosomal modifications, FMRP and synaptic pathology in AD.