Neurovascular functions of a small RNA Snord118-mediated ribosome biogenesis

项目摘要/摘要

PROJECT SUMMARY / ABSTRACT Dysfunction of neurovascular unit (NVU) contributes to diffuse white matter disorder associated with small- vessel disease (SVD), which affects approximately 50% of all dementia, including Alzheimer's disease and Alzheimer's disease-related dementias (AD/ADRD). Ribosomopathies are a group of human disorders caused by mutations in ribosomal proteins or ribosome biogenesis factors. How dysregulation of a universal ribosome biogenesis process leads to tissue-specific phenotypes remains poorly understood. The goal of this proposal is to develop two new genetic mouse models for SVD and use them to determine how NVU cell type(s) are selectively vulnerable to the disruption of a ubiquitous ribosome biogenesis process. We will focus on noncoding RNA Snord118, which encodes a ribosome biogenesis factor. Snord118 point mutations in humans lead to SVD named leukoencephalopathy with calcifications and cysts (LCC), which represents the first purely neurological disorder in ribosomopathies. We have assembled the following preliminary data: 1) generated two independent disease point mutation knock-in (KI) mouse models, which display patient-like motor and cognitive behavioral abnormalities; 2) identified pericyte loss, and microvascular and white matter injury in these Snord118 KI mouse brains, which reflects the vascular unit impairment without causing lethal hemorrhage; 3) developed a new crosslinking and sequencing based technology named PARIS to high throughput map RNA structures and RNA-RNA interactions at single molecule and genome-wide levels with base-pair resolution; 4) used PARIS and identified Snord118 targets in mouse brains at early developmental stage. Preliminary data led us to hypothesize that Snord118 mutation-mediated disruption of ribosome biogenesis selectively affects NVU cells via targeting rRNAs and non-rRNAs leading to LCC-like phenotypes. To test this hypothesis, two specific aims are proposed. Aim 1 will establish mouse models of LCC and identify how NVU cell(s) are selectively affected by Snord118 mutations. Aim 2 will use PARIS coupled with KI mice to identify Snord118 targets in vivo and determine Snord118 RNA structure-function relationships. Using our new KI mice and latest PARIS, this study will generate the first tractable mouse models that do not currently exist for Snord118 LCC, identify mechanisms of Snord118 action and LCC disease, uncover a previously unknown vulnerability of specific NVU cells to the disruption of a ubiquitous ribosome biogenesis process, therefore help to reconcile the neurological phenotype specificity of ribosomopathies with the global requirement of ribosome biogenesis in all cells.