The Translational Landscape of Reactive Astrocytes Reveals the Impact of eIF2B-mediated Dysregulation in VWM Disease

Abstract

A devastating genetic recessive neurodegenerative disorder, Vanishing White Matter Disease (VWMD), stems from mutations in eIF2B--a master regulator of mRNA translation initiation and mediator of cellular stress response. While astrocytes, the brains essential support cells, are known to be central to VWMD pathology, the molecular mechanisms underlying their dysfunction remain poorly understood. Our study reveals that even a mild mutation in eIF2B5 profoundly disrupts astrocyte mRNA translation regulation upon cytokine-mediated activation, affecting nearly one-third of all expressed genes. Through innovative integration of RNA-seq and Ribo-seq analyses using primary cell cultures of astrocytes isolated from eIF2B5R132H/R132H mice, we discovered attempts to compensate for impaired protein production by increasing mRNA levels. However, this compensation proves insufficient to maintain critical cellular functions. Our comprehensive analysis uncovered significant disruptions in cellular energy production and protein synthesis machinery. We also predicted previously unknown defects in cholesterol biosynthesis within mutant astrocytes. Moreover, a meta-analysis of translation initiation scores pinpointed, for the first time, a short list of specific effector gene candidates that may drive disease progression. This powerful combination of transcriptome and translatome illuminates the complex pathophysiology of VWMD and identifies promising new biomarkers and therapeutic target opportunities.