Schizophrenia is a common, heritable mental illness that is costly for individuals, families and society. Recently, many seemingly unrelated genes have been genetically associated with schizophrenia (Scz). A major objective is to identify biochemical pathways that connect these seemingly unrelated Scz-associated genes. Further study of these biochemical pathways might help us gain a better understanding of the molecular basis of Scz and provide us with potential therapeutic targets. The biochemical pathways we chose to focus on involve several E3 ligases implicated in Scz. E3 ligases are enzymes that regulate the stability and function of proteins by catalyzing the transfer of ubiquitin or ubiquitin-like molecules to these proteins. We hypothesized that Scz-associated E3 ligases target other Scz genetically-associated proteins in neurons – the E3 ligases and their substrates would comprise a biochemical pathway. To identify E3 ligase substrates, we worked on developing biochemical tools that utilize affinity tagging in cells to identify substrates and binding partners of a specific E3 ligase called UFL1, identified by exome sequencing of schizophrenia patients. UFL1 catalyzes the transfer of the ubiquitin-like protein UFM1 to substrates. We created an Avitagged-UFM1 by genetically encoding an affinity tag called Avi that is expressed at the N-terminus of UFM1. To identify UFL1 substrates, we used biotinylation to recognize the Avitagged-UFM1 and capture UFM1-tagged proteins. Once UFL1 substrates are identified, we can compare them to products of Scz-implicated genes and search for an overlap. Finding an overlapping subset of UFL1 substrates and genes genetically associated with schizophrenia would represent a key step toward identifying biochemical pathways for further study and for eventual therapeutic intervention.
PROJECT: A pathway to understanding schizophrenia: Identification of substrates of the E3 ligase UFL1
My experience at the Broad far exceeded my expectations. Not only did I get to conduct research in a collaborative environment, I also learned how to effectively communicate my research thanks to the advice and feedback of my Broad colleagues and SRPG family. This summer was challenging because I was pushed outside my comfort zone, but it was also extremely rewarding. Along the way, I gained more confidence in myself and my future as a scientist.