Bassem Hassan Lab

Research focus

​How do you make a nervous system that works… and keep it that way?

Diversity is a beautiful thing and unity is a powerful thing. Put them together, and what do you get? You get the most beautiful and powerful of all things: evolution! Much like human beings, cells of the nervous system are exquisitely diverse. They have diverse shapes and perform diverse functions. Yet, also like humans, underneath this bewildering diversity lies a profound unity: the genome. How can exactly the same genome produce so many different cells? The answer is that it depends on how a cell interprets its genome. Different cells extract differential information from their genomes, using transcription factors that activate or repress different genes. Our lab is interested in understanding the contribution of the information encoded by cell type specific transcription factors to cell fate specification. For this, we use the development and evolution of sensory organs - the eye, ear and nose - in the fruit fly Drosophila melanogaster as a model system. We compare the genetic programs of different sensor cells within one species, as well as the genetic programs of the same sensory organs across different Drosophila species. In this way we hope to learn about the rules of cellular diversity and specialization. Because cellular specialization goes wrong in cancer, these findings have profound implications for human health.

Making a brand new specialized nervous system cell is just the beginning. Now it has to grow axons and dendrites and begin its journey. Axons of young brain neurons have a promiscuous wanderlust! They like to travel, explore new environments, search for suitable partners and establish as many connections as they can. They cannot help it. It’s an irresistible drive.- it’s in their genes, you could say! After a certain age, however, they settle down, and, satisfied with the extensive network of connections they have made, stop searching for new ones. They devote their lives to their jobs, and generally perform exceptionally well, given the monumental task they have: making the formidable machine that is the organism live, behave and reproduce. This dedication however, comes at a price: the loss of their youthful sense of wanderlust. If their connections are cut, they are unable to get themselves to travel, make new connections and start all over again. Using the mighty fruit fly as a model organism, we study the genes that allow young axons to grow and establish connections. We also ask why the same axons, now older and wiser, are unable to grow again and re-establish lost connections if they are injured or struck down by disease.

We combine powerful molecular genetic tools, innovative whole-brain culture approaches and high-resolution imaging to search for genes and gene ensembles that control axonal growth during development. We also ask if the same genes might help injured or diseased axons to regenerate and survive.


Post-translational Control of the Temporal Dynamics of Transcription Factor Activity Regulates NeurogenesisQuan X, Yuan L, Tiberi L, Claeys A, De Geest N, Yan J, van der Kant R, Xie W, Klisch T, Schymkowitz J, Rousseau F, Bollen M, Beullens M, Zoghbi H, Vanderhaeghen P, Hassan BCELL, 164, 460-75, 2016
Beyond Molecular Codes: Simple Rules to Wire Complex BrainsHassan B, Hiesinger PCELL, 163, 285-91, 2015
A novel fragile X syndrome mutation reveals a conserved role for the carboxy-terminus in FMRP localization and functionOkray Z, De Esch C, Van Esch H, Devriendt K, Claeys A, Yan J, Verbeeck J, Froyen G, Willemsen R, De Vrij FEMBO MOLECULAR MEDICINE, 7, 423-37, 2015
The Drosophila Homologue of the Amyloid Precursor Protein Is a Conserved Modulator of Wnt PCP SignalingSoldano A, Okray Z, Janovska P, Tmejová K, Reynaud E, Claeys A, Yan J, Atak Z, De Strooper B, Dura J, Bryja VPLOS BIOLOGY, 11, e1001562, 2013
Mutual inhibition among postmitotic neurons regulates robustness of brain wiring in DrosophilaLangen M, Koch M, Yan J, De Geest N, Erfurth M, Pfeiffer B, Schmucker D, Moreau Y, Hassan BeLife, 2, e00337, 2013

Job openings


Insects can taste and therefore detect poisonous foods

14/06/2016 - Our senses of smell and taste are particularly important for survival: they allow us to know if some food is potentially tainted, poisoned, or expired, thanks to sensory neurons. Are these protection mechanisms also present in animals?

Neurogenesis - Discovery of a new regulatory mechanism

28/01/2016 - A mechanism, found by Bassem Hassan's team, is a simple reversible chemical modification, critical for the production of sufficient number of neurons, their differentiation and the development of the nervous system.

A new strategy required in the search for Alzheimer's drugs?

24/05/2013 - Alessia Soldano and Bassem Hassan (VIB/KU Leuven) were the first to unravel the function of APPL – the fruit-fly version of APP – in the brain of healthy fruit flies.