Bassem Hassan

Background

About Bassem Hassan

The central question of my research is: how does the genome build the brain? Biology is the emergent property of the self-organizing capacity of molecular networks. The most fundamental of these networks is the genome. The most sophisticated is the brain. The genomic network produces a set of instructions that builds the neuronal network. We try to understand what that set of instructions is. Specifically, we deal with the two extremes of neuronal network features. At one end during developmental time, there is cell fate specification. At the other end, there is the formation of precise neuronal connections. Because each neuron is characterized by specific connections, the two features must be linked. Over the past decade, we have made major contributions to understanding these questions. We have unraveled the gene regulatory basis of cell fate specification in the fly retina (Aerts et al, 2009, 2010; Quan et al, 2016). In the process, we linked cell fate commitment in stem cells to tumor suppression (Bossuyt et al, 2009a, b; van Es et al, 2010). On the other hand, we began a long-term effort towards understanding the mechanisms that regulate the specificity, variability and robustness of brain wiring. Our data clearly show that wiring the brain is a more complex and plastic process than has been appreciated in studies using the fly PNS as a model. We have concentrated on how single neurons integrate various attractive and repulsive signals during brain wiring, and how they interact with one another to make wiring choices (Srahna et al, 2006; Langen et al, 2013; Zschaetzsch et al, 2014; Oliva et al, 2016) and how that influences behavior (Linneweber et al, 2020). Many genes that regulate brain wiring are associated with human disease. We have unraveled the roles of the Drosophila homologues of the Fragile X protein (Morales et al, 2002; Reeve et al, 2005, 2008; Okray et al, 2015; Franco et al, 2017) and the Amyloid Precursor Protein (Leyssen et al, 2005; Soldano et al, 2013) in axonal growth and guidance. Finally, we have put considerable effort into developing novel computational, genetic and cell biological tools for mapping both genetic networks and neural networks (Aerts et al, 2006; Ayaz et al, 2008; Choi et al, 2009; Nicolaï et al, 2010). These tools are used by many in the field to deliver novel insights into brain development.