H. de Wit

Interview

CONTACT
Name : Heidi de Wit
Department  : Functional Genomics
Position   : Assistant Prof. (tenured track)

CURRICULUM VITAE
De Wit studied Biology (cum laude) at the VU. In 2000 she finished her PhD research in the Geuze/Klumperman group at UMC on ‘Formation of synaptic vesicles in neuroendocrine PC12 cells’. Part of her PhD research was performed in the group of Regis Kelly at UCSF.
At the start of her post-doc career she received a VENI-NWO grant and used this funding to set-up a unique docking assay to investigate the molecular mechanisms and spatial organization of secretory vesicle docking in primary cultured mouse (mutant) chromaffin cells. De Wit succeeded to perform a systematic analysis of the genetic cascades that orchestrate docking of secretory vesicles at their target. To dissect vesicle docking principles, she applied EM combined with secretion assays in collaboration with members of the group of Dr. Neher (Göttingen, Germany) and Dr. Südhof (Dallas, USA). Her successful approach resulted this year September in a publication in Cell. Besides major contributions to existing research lines her research also opened opportunities for new complementary approaches. This year De Wit initiated the ‘BrainTrain’ consortium that was granted by the EU to train 15 PhD students at their start of their scientific career amongst different universities/enterprises in the EU and Japan. In addition, De Wit coordinates the EM core facility of NCA. She knows her position: ‘For the NCA research groups we will be a last stop after they have performed all their other experiments: electron microscopy opens a world you cannot see in any other way.’

CURRENT PROJECTS
Within the secretory pathway, proteins and other cargo are transferred from one compartment to another by vesicular traffic. Transport vesicles bud from donor membranes and dock to specific acceptor compartments. Over the past years many of the research involved in the secretory pathway has been performed on non-neuronal cells. The research of De Wit and her team focuses on neuronal cells. My team focuses on the mechanism by which secretory vesicles are transported to and dock into the synapse as well as biogenesis and recycling of secretory vesicles. As a model system we use genetically/pharmacologically manipulated synapses and adrenal chromaffin cells from several mutant mice that show a defect in the transport pathways of secretory vesicles to the synapse. Some mutants are linked to diseases like Schizophrenia and Epilepsy. To elucidate molecular and cellular mechanisms of neurosecretion her lab use mainly electron microscopical (EM) studies. Morphometry and subcellular immunogold labelling techniques allow us to identify the distribution/structure of cell organelles as well as the localization of certain regulatory/cargo proteins involved in the secretory pathway. When these proteins/organelles are not transported well this will be revealed by electron microscopy. Visualising this gives additional insight in the function of disease proteins, and is complementary with other techniques used in the NCA. For example, the subcellular distribution of synaptic vesicles as well as large-dense core vesicles can be analyzed and will address if ‘morphological’ docking is affected after genetic/pharmacological manipulation. Together, EM studies are important for a fundamental understanding of neuronal protein (dys)function.

KEY PUBLICATIONS
Toonen RF*, Kochubey O*, de Wit H*, Gulyas-Kovacs A*, Konijnenburg B, Sørensen JB, Klingauf J, and Verhage M (2006). Dissecting docking and tethering of secretory vesicles at the target membrane. EMBO J 25(16): 3725-3737

de Wit H, Cornelisse LN, Toonen RFG, and Verhage, M (2006). Docking of secretory vesicles is syntaxin dependent. PloS ONE 1: e126

Wierda KD *, Toonen RF *, de Wit H, Brussaard AB, and Verhage M (2007). Interdependence of PKC-dependent and PKC-independent pathways for presynaptic plasticity. Neuron 19, 54 (2): 275-290

Gerber SH*, Jong-Cheol R*, Sang-Won M*, Xinran L, de Wit H, Dulubova I, Meyer AC, Rizo J, Arancillo M, Hammer RE, Verhage M, Rosenmund C, and Südhof TC (2008). Conformational switch of syntaxin-1 controls synaptic vesicle fusion. Science, 321(5895):1507-1510

de Wit H, Walter AM, Gulyás-Kovács A, Milosevic I, Riedel D, Sørensen JB, and Verhage M (2009). Munc18 promotes SNAP25/Syntaxin docking acceptor for Synaptotagmin secretory vesicles. Cell 4th September issue.

* these authors made equal contributions