Investigation of astrocytic regulation of neuronal physiology in Fragile X Syndrome

Fragile X Syndrome (FXS) is the leading monogenic cause of intellectual disability and is frequently associated with autism spectrum disorder. FXS is caused by the loss of expression of the Fragile X messenger ribonucleoprotein (FMRP) which is a well characterized RNA-binding protein known to be critical for the regulation of protein synthesis and synaptic plasticity. Traditional studies of FXS have focused on the neuronal mechanisms and consequences of altered protein synthesis, yet recent studies have suggested the importance of astrocytes in regulating FXS neuronal physiology. Studies in both human and mouse models of FXS demonstrate that culturing FXS neurons with control astrocytes can ameliorate FXS neuronal alterations while culture of control neurons with FXS astrocytes can induce FXS-like physiology. Interestingly, each of these studies demonstrate that the observed alterations can be induced by the respective astrocyte conditioned medium, suggesting a secretory molecule may be responsible for these alterations. These results suggest that astrocyte genotype controls neuronal phenotype in FXS, yet the mechanism and molecules underlying these alterations have not been comprehensively identified. This proposal will address two questions: 1) What are the underlying changes to astrocyte protein synthesis and secretion follow FMRP loss? 2) What are the co-culture induced astrocyte-dependent changes to neuronal protein synthesis and which astrocyte-derived molecules are responsible? To identify the consequences of FMRP loss on astrocyte protein synthesis and secretion this proposal aims to apply ribosome profiling and astrocyte-specific secreted proteomics. To identify the co-culture induced astrocyte-dependent neuronal changes in protein synthesis this proposal applies ribosome profiling of human neurons in four co-culture conditions to test the impact of cell autonomous versus non-cell autonomous FMRP loss. Finally, this proposal aims to identify the astrocyte-derived neuron-internalized molecules responsible for these alterations using astrocyte-specific secretome labeling in combination with neuronal proximity labeling. All together this work aims to undercover novel modes of co-regulation between neurons and astrocytes critical to our understanding of neurological disease. It is the hope that these findings provide novel avenues for innovative therapeutic approaches for the treatment of FXS and other neurodevelopmental disorders. Project Number: 1F32HD121352-01 | Fiscal Year: 2026 | NIH Institute/Center: Eunice Kennedy Shriver National Institute of Child Health and Human Development (NICHD) | Principal Investigator: Charles Sheehan | Institution: NEW YORK UNIVERSITY, NEW YORK, NY | Award Amount: $76,300 | Activity Code: F32 | Study Section: Special Emphasis Panel[ZRG1 F03A-Z (21)] View on NIH RePORTER: https://reporter.nih.gov/project-details/11317604