Corette J. Wierenga
Cell Biology, Faculty of Science, Utrecht University
Kruytgebouw, room N511
Padualaan 8, 3584 CH Utrecht
Corette Wierenga studied physics at the VU in Amsterdam, followed by a PhD (2002) in neurobiology at the University of Amsterdam with Prof. Dr. Wytse Wadman. During her PhD thesis, she studied the role of interneurons in the hippocampal CA1 area. She worked as a postdoctoral researcher in the lab of Prof. Dr. Gina Turrigiano at Brandeis University (2002-2006), where she studied homeostatic plasticity of excitatory synapses in visual cortex cultures, and at the Max Planck Institute of Neurobiology in the department of Prof. Dr. Tobias Bonhoeffer (2006-2011), where she focused on the formation and plasticity of inhibitory synapses. In October 2011 she returned to the Netherlands and she is now an Assistant Professor at the Cell Biology Division at Utrecht University. In 2012 she received a ZonMW-VIDI grant.
Studying synapses (article International Innovation jan 2015)
Chemical synapses are the key connective elements in neuronal networks. They are not only crucial for information processing but their plasticity also endows the brain with its outstanding capacity for adaptation to the environment. Understanding synapses, and how they are formed, is therefore a fundamentally important task in neuroscience. So far, most studies have focused on the formation of glutamatergic synapses while the formation of the other major type of synapses in the brain, which use the inhibitory transmitter gamma aminobutyric acid (GABA), remains less examined, in spite of the fact that GABAergic synapses form 10-20 % of all synapses in the brain and are indispensable for proper and stable functioning of in the brain.
Basic information, well known for glutamatergic synapses, such as the specific pre- and postsynaptic protein complexes that are present and the time course by which proteins are recruited to new synapses, is not yet well understood for GABAergic synapses. Also, many molecular tools such as specific promoters or fluorescent synaptic proteins are designed specifically for glutamatergic and have yet to be developed for GABAergic synapses. This makes studying GABAergic synapse formation more challenging, but perhaps also more exciting.
Glutamatergic synapses on excitatory neurons in the hippocampus are almost exclusively located on dendritic spines. It has been shown that dendrites play an active role in the formation of new glutamatergic synapses by growing out small protrusions which make contact with presynaptic axons and boutons. In contrast to glutamatergic synapses, GABAergic synapses are usually not located on spines, but directly on the dendritic shaft.
We use high-resolution two-photon imaging to examine the formation of GABAergic synapses in the CA1 area of organotypical hippocampal cultures (Figure 1). We make use of GAD65-GFP mice (López-Bendito et al., 2004), in which a subset of GABAergic interneurons express GFP (Wierenga et al., 2010). CA1 pyramidal neurons are filled with Alexa Fluor 594 through a patch pipette.
Figure 1. GABAergic axons (green) make inhibitory synapses on dendrites of CA1 pyramidal neurons (red).
We found that GABAergic synapses are formed via a fundamentally different process than glutamatergic spine synapses (Wierenga et al., 2008). Outgrowing dendritic protrusions can distinguish between potential presynaptic partners. Whereas contacts with glutamatergic boutons could be long-lasting, contacts with GABAergic boutons were always short-lived and resulted in retraction of the dendritic protrusions. Similarly, contacts made by GABAergic axonal protrusions were always transient. This strongly suggests that axonal and dendritic protrusions do not mediate the formation of GABAergic synapses. New GABAergic contacts were formed exclusively at locations where GABAergic axons and postsynaptic dendrite are already in close proximity: by the appearance of new boutons at preexisting axon-dendrite crossings (Figure 1).
Our findings imply that GABAergic axons in a mature network can make new synapses only with postsynaptic partners that are in their immediate neighborhood, which is in marked contrast to the way glutamatergic synapses are made. This puts significant structural constraints on the generation and plasticity of GABAergic and glutamatergic synapses which will be important to be kept in mind when trying to understand development and plasticity of the intricate neural networks of the brain.
Figure 2: Formation of an inhibitory synapse.
At the crossing of an inhibitory axon (green) and a dendrite (red) a new bouton (yellow overlap) is formed. We have shown that such new boutons recruit pre- and postsynaptic proteins within a few hours. Upper row: 3D renderings of image stacks; Lower row: original two-photon images.
Time-lapse two-photon imaging of inhibitory axons showed that inhibitory boutons are highly dynamic structures. They can appear, disappear, re-appear or change shape or size over the course of a few minutes to hours. We recently showed that these dynamics are affected by activity of nearby neurons and we are currently examining this in greater detail.
It is currently not known what determines when and where new GABAergic boutons appear. We are particularly interested in unraveling the molecular pathways underlying interactions between nearby excitatory and inhibitory synapses.
René van Dorland R.vanDorland@uu.nl
Danielle Counotte (now at Danone Research)
Bas van Bommel
Research paper – Review
Lenz M, Galanis C, Müller-Dahlhaus F, Opitz A, Wierenga CJ, Szabó G, Ziemann U, Deller T, Funke K, Vlachos A. Repetitive magnetic stimulation induces plasticity of inhibitory synapses. Nat Commun. 2016 Jan 8;7:10020. doi: 10.1038/ncomms10020. PMID: 26743822
Esteves da Silva M, Adrian M, Schätzle P, Lipka J, Watanabe T, Cho S, Futai K, Wierenga CJ, Kapitein LC, Hoogenraad CC. Positioning of AMPA Receptor-Containing Endosomes Regulates Synapse Architecture. Cell Rep. 2015 Nov 3;13(5):933-43. doi: 10.1016/j.celrep.2015.09.062. Epub 2015 Oct 22. PubMed PMID: 26565907.
Müllner F, Wierenga CJ*, Bonhoeffer T* (2015) Precision of inhibition: Dendritic inhibition by individual GABAergic synapses on hippocampal pyramidal cells is confined in space and time. Neuron 87, 576-589. * co-senior author
Gomis-Rüth S, Stiess M, Wierenga CJ, Meyn L, Bradke F. Single-cell axotomy of cultured hippocampal neurons integrated in neuronal circuits. Nat Protoc. 2014 May;9(5):1028-37. doi: 10.1038/nprot.2014.069. Epub 2014 Apr 3. PubMed PMID: 24705599.
Schümann A, Klawiter A, Bonhoeffer T, Wierenga CJ (2013) Structural plasticity of GABAergic axons is regulated by network activity and GABAA receptor activation. Frontiers in Neural Circuits 7: 113. Pubmed PMID: 23805077.
Vogels TP, Froemke RC, Doyon N, Gilson M, Haas JS, Liu R, Maffei A, Miller P, Wierenga CJ, Woodin MA, Zenke F and Sprekeler H (2013) Inhibitory synaptic plasticity: spike timing-dependence and putative network function. Frontiers in Neural Circuits 7: 119.
Keck T, Scheuss V, Jacobsen I, Wierenga CJ, Eysel U, Bonhoeffer T, Hübener M (2011) Large decrease in inhibitory pre- and postsynaptic structures following retinal lesions. Neuron, 71: 869-882.
Wierenga CJ, Müllner FE, Rinke I, Keck T, Stein V, Bonhoeffer T (2010) Molecular and electrophysiological characterization of GFP-expressing interneurons in GAD65-GFP mice. PLoS One, 5: e15915.
Wierenga CJ, Becker N, Bonhoeffer T (2008) Formation of GABAergic synapses in hippocampal slice cultures occurs largely without the involvement of filopodia. Nature Neurosci, 11: 1044-1052.
Becker N, Wierenga CJ, Fonseca R, Bonhoeffer T, Nägerl UV (2008) Presynaptic boutons show a large degree of turnover after hippocampal LTD resulting in the removal of synaptic connections. Neuron 60:590-597.
Gomis-Rüth S, Wierenga CJ, Bradke F (2008) Plasticity of polarization: changing axonal and dendritic identity in mature neurons. Curr Biol 18: 992-1000.
Wierenga CJ, Walsh MF, Turrigiano GG (2006) Temporal regulation of the expression locus of homeostatic plasticity. J Neurophysiol 96: 2127-2133.
Wierenga CJ, Ibata K, Turrigiano GG (2005) Postsynaptic expression of homeostatic plasticity at neocortical synapses. J Neurosci 25: 2895-2905.
Wierenga CJ, Wadman WJ (2003) Functional relation between interneuron input and population activity in the hippocampal CA1 area. Neuroscience 118: 1129-1139.
Wierenga CJ, Wadman WJ (2003) Excitatory inputs to CA1 interneurons show selective synaptic dynamics. J Neurophysiol 90:811-821.
Wierenga CJ, Wadman WJ (1999) Miniature inhibitory postsynaptic currents in CA1 pyramidal neurons after kindling epileptogenesis. J Neurophysiol 82:1352-1362.
Adrian M, Kusters R, Wierenga CJ, Storm C, Hoogenraad CC, Kapitein LC. Barriers in the brain: resolving dendritic spine morphology and compartmentalization. Front Neuroanat. 2014 Dec 4;8:142. doi: 10.3389/fnana.2014.00142. eCollection 2014. Review. PubMed PMID: 25538570; PubMed Central PMCID: PMC4255500.
Frias CP and Wierenga CJ. Activity-dependent adaptations in inhibitory axons. Front Cell Neurosci. 2013, 7: 219. PMID: 24312009.