Protein Degradation Pathways in Neurogenesis: The Critical Role of Fbox E3 ligases

The long-term objective of this project is to understand the functional properties of F-box proteins, specifically Fbxo16, in the context of neurogenesis. F-box proteins are part of the ubiquitin-proteasome system and play crucial roles in protein degradation across various cellular processes. Fbxo16 is of particular interest as it is specifically expressed in neural tissue and is involved in regulating neuronal differentiation. This project uses Xenopus laevis embryos as a simple in vivo test system to investigate the properties of Fbxo16. We plan two approaches. The first is to test the hypothesis that Fbxo16 alters neuron development at the level of Neurog2, a key proneural factor. We will manipulate Fbxo16 levels specifically in neural tissue during neurogenesis using temporal and spatial approaches. We will assess effects on Neurog2 target gene expression, test whether Neurog2 or its phosphomutant forms can rescue Fbxo16 loss-of-function phenotypes, examine interactions with the Neurog2 partner protein E47, and determine if altered neuron numbers result from changes in cell proliferation or apoptosis. Our second approach is to elucidate the mechanism by which Fbxo16 regulates neuron formation. Since preliminary data indicates that Fbxo16 affects Neurog2 activity indirectly, the two main objectives of this aim are: 1) To identify the protein targets of Fbxo16 that are crucial for neurogenesis and 2) To determine how Fbxo16 affects these targets. Specifically, we will investigate whether Fbxo16 functions as part of the SCFFbxo16 complex to promote protein degradation, or alters the activity and stability of proteins through other mechanisms, such as changing their cellular location. In both approaches, we will use gain and loss of function assays combined with target injections of hormone inducible and phosphomutant versions of key proteins combined with protein stability and ubiquitin analyses. Because Xenopus is a vertebrate model system, our studies will provide insights that are highly relevant to understanding neurogenesis in humans as well as insight into the fundamental properties of F- box proteins in neural development. Furthermore, the studies provide high-impact biomedical research experiences to undergraduates and graduate students in a supportive training environment. Project Number: 1R15NS145029-01A1 | Fiscal Year: 2026 | NIH Institute/Center: National Institute of Neurological Disorders and Stroke (NINDS) | Principal Investigator: ELENA Silva | Institution: GEORGETOWN UNIVERSITY, WASHINGTON, DC | Award Amount: $585,000 | Activity Code: R15 | Study Section: Neurogenesis and Cell Fate Study Section[NCF] View on NIH RePORTER: https://reporter.nih.gov/project-details/11359949