Bassem Hassan
Neurogenetics
VIB Department of Molecular and Developmental Genetics, K.U.Leuven

PhD: Ohio State Univ., Ohio, USA, '96 Postdoc: Baylor Coll. of Medicine, Houston, Texas, USA, '96-'01 VIB Group leader since 2001 EMBO Young Investigator, 2003 EMBO Member since October 2009

e-mail phone +32 16 34 62 26 ADDRESS

Current team members
Group leader: Bassem Hassan
Postdoctoral scientists: Ariane Ramaekers, Marta Koch, Xiao-Jiang Quan
Ph.D. Students: Alessia Soldano, Laura Nicolaï, Marion Langen, Marlen Schlieder, Zeynep Okray
Visiting young scientists: Duygu Esen Ozel, Julio Cesar Carrera Montoya
Support personnel: Annelies Claeys, Fatima Sharafeddine, Genia De Brauwer, Jiekun Yan, Martine Noblet, Natalie De Geest

Keywords
brain - neural circuit - genetics - Drosophila - neuronal cell biology

Science
We are interested in the mechanisms of the development and differentiation of neurons. We use genetic, molecular and cell biological approaches to unravel the interactions which determine neural precursor cells and lead to the differentiation of neurons using the fruit fly Drosophila melanogaster. We are also interested in neuropathological processes.

To achieve these goals we have established three major lines of research

Transcriptional gene regulatory networks in neuronal fate specification
Proneural genes encoding bHLH transcription factors are determinants of neuronal fate. They sit on top of a regulatory hierarchy that results in the differentiation of neural precursors cells. What we don't know is how many genes bHLH proteins regulate and what the structure of their gene regulatory network is. To address this question we are integrating bioinformatics, forward genetics and functional genomics into a single entity we call Genetomics (Hiesinger and Hassan, 2005; Aerts et al., 2006; Aerts et al., 2007) to identify proneural target genes in vivo.

Neuronal circuit development
Are neuronal connectivity decisions predetermined or established through synaptic activity-? There is little disagreement among neuroscientists that synaptic activity is key in plasticity. In contrast, there is sharp disagreement on its role in development. We use a set of visual system neurons called the DCN (Hassan et al., 2000). The evidence we have so far is that the choice of the precise number of DCN axons in different target areas is genetically determined and activity-independent (Srahna et al., 2006). What we are now trying to determine is whether the arrangement of these axons, their branches and their synaptic buotons is also genetically determined. Conversely we are asking if genes involved in activity play a role in shaping brain development. To do this we combine classical forward and reverse genetic approaches with computational modeling, and high resolution imaging.

Axonal pathology injury and regeneration
Can injured fly CNS axons regenerate and if so, how? To tackle this issue we created a novel CNS axon injury paradigm and asked if injured fly CNS axons can regenerate. They cannot! This gives us the opportunity to search for genes which induce regeneration. The second approach is to ask whether the injured axon responds to injury by transporting mRNA to the site of injury and what kinds of molecules are being transported. Our evidence so far indicates that the brain responds to injury by up-regulating several signaling molecules (Leyssen et al., 2005) that can induce injured adult CNS axons to regenerate and in some cases target them towards and beyond the injury site.

Link to Group's website for more details.

Press releases
See also press release (23/02/2009): Anti-cancer gene discovered: perspective for therapy - based on a publication in PloS Biology (Bossuyt et al., PLoS Biology, 2009)

See also press release (04/06/2008): Microsurgery on the brain of the fruit fly leads to new insights into irreparable nerve injuries - based on a publication in The Journal of Neuroscience (Ayaz et al., The Journal of Neuroscience, 2008).

Bossuyt W, De Geest N, Aerts S, Leenaerts I, Marynen P, Hassan B
The atonal proneural transcription factor links differentiation and tumor formation in Drosophila
PLOS BIOL 7, e40, 2009



Choi C, Vilain S, Langen M, Van Kelst S, De Geest N, Yan J, Verstreken P, Hassan B
Conditional mutagenesis in Drosophila
SCIENCE 324, 54, 2009



Ayaz D, Leyssen M, Koch M, Yan J, Srahna M, Sheeba V, Fogle K, Holmes T, Hassan B
Axonal injury and regeneration in the adult brain of Drosophila
J NEUROSCI 28, 6010-21, 2008



Aerts S, Lambrechts D, Maity S, Van Loo P, Coessens B, De Smet F, Tranchevent L, De Moor B, Marynen P, Hassan B, Carmeliet P, Moreau Y
Gene prioritization through genomic data fusion
NAT BIOTECHNOL 24, 537-544, 2006



Srahna M, Leyssen M, Choi C, Fradkin L, Noordermeer J, Hassan B
A Signaling Network for Patterning of Neuronal Connectivity in the Drosophila Brain
PLOS BIOL 4, e348, 2006

print friendly