Mechanistic Study of the Dual Role of Nucleolar Protein Pno40 in Synaptic Gene Transcription Regulation and Cns Immune Surveillance at Choroid Plexus: Implication for Neurodegenerative Diseases

Brain aging is found associated with chronic inflammation, which along with synaptic dysfunction are viewed to occur early in the progression of neurodegenerative disease and to modulate both brain pathology and behavior. As age is the principal risk factor for neurodegenerative disorders such as Alzheimers disease (AD) and until now there is no specific cut-off recognized for the definitive prognosis of AD, it is imperative to further understand the cellular and molecular events that underlie the aging of the organism and prompt for intervention strategy for disease progression. Based on this notion we are intrigued to characterize the role of pNO40, a nucleolus protein with a zinc finger motif involved in DNA/RNA binding, in brain aging because pNO40-depleted mouse developed accelerating aging phenotype in cortical neurons and at choroid plexus (CP) of brain ventricle upon senescence associated gal (SA-gal ) staining, a biomarker for aging. Reduced pNO40 expression downregulates synaptic gene expression and elicits CP helper Th-2 response with elevated Arginase 1 expression, a reflection of the situation in the circulation during aging. The CP aging phenotype in pNO40 mutant brain particularly attracts our attention since recent studies clearly indicate that the CP is able to modulate the cognitive function through its gateway mechanism to regulate changes in the neuroinflammatory response and brain immune surveillance. In this proposal, we are attempting to establish an integrated, functional genomic-based system that will aid us in exploring two of the major questions regarding pNO40 in neurodegenerative diseases related to brain aging: (1) the mechanism of pNO40-mediated gene expression regulation in synapse and CP structure/function integrity, and (2) patho-physiological significance of such transcription role in CNS homeostasis in terms of diminished pNO40 expression-induced aged phenotype. To characterize the role that pNO40 plays in transcriptional regulation, we aim to systematically pinpoint pNO40 targets in the defined cells (primary cultured neurons) and tissue (CP) by first, RNA immunoprecipitation (RIP) combined with RNA- Seq (RIP-Seq) to capture at the transcriptome-wide level RNAs bound by pNO40 and second, ChIP-Seq technique to determine the localization of transcriptional regulator binding within mammalian genomes (Aim 1). Detailed molecular mechanism underlying pNO40-targeted gene expression will also be assessed by delineating promoter-associated activity (Aim 2). In particular, we will address how pNO40 effects on CP barrier function and influences CNS homeostasis with transwell filter system. Finally to faithfully comprehend the biological and functional significance of pNO40 and its associated transcription factors and targeted genes in synapse and CP structure/function integrity, we will employ compound mice obtained by cross pNO40 mutant mice with 3x-Tg-AD mice, model mice harboring triple transgenes of familiar AD, to evaluate the impact of pNO40 expression level on the neuropathological phenotype (Aim 3). By answering these questions we can not only elucidate the transcription regulation via pNO40 in a context-specific manner but also get a whole picture of the biological significance of dual role of pNO40 in both immunomodulation and synaptic regulation of CNS homeostasis, with hope to elucidate its relevance to etiology and early diagnosis of neurodegenerative diseases.

Project ID:PC10901-0061
External Project ID:MOST107-2320-B182-038-MY3