Our project focuses on a major unsolved problem in the neural stem cell field, which is how cells in this lineage respond to cues in the external environment and decide what type of mature cells to form. Interaction of proteins on the cell surface with cues from the environment encountered during development or after transplantation can induce stem cells to generate particular types of mature, functional cells. Thus, cell surface proteins are critical for directing transplanted stem cells to form the appropriate types of mature cells to treat injury or disease. A key modification regulating cell surface proteins is glycosylation, which is the addition of sugars onto proteins and has not been well studied in neural stem cells. We hypothesize key players directing cellular decisions are sugar-coated proteins controlling how stem cells respond to extracellular cues. This year on the project we used a novel approach that doesn’t require any cell-type specific labels to enrich cells in the neural stem cell lineage that preferentially form the mature cell type astrocytes (astrocyte precursor cells). Enriched astrocyte precursors show more activity in a particular glycosylation pathway that adds highly branched sugars to proteins. If we push cells to form more highly branched sugars, they shift in the types of mature cells they will form and generate fewer neurons. We are using protein analysis with large data sets to determine what types of proteins are preferentially sugar-coated as cells are forming different types of mature cells. Our goal is to better understand the regulation of how the mature cells, particularly astrocytes and neurons, are formed, which will improve the use of these cells to treat brain and spinal cord diseases and injuries.