Agnes Thalhammer studied Biochemistry at the University of Vienna, Austria, and subsequently received further training in protein chemistry at the Hormone Receptor Laboratory of Prof. JL Wittliff at the University of Louisville, Kentucky, USA. For her Ph.D., she joined the group of Prof. Michael Hollmann, first at the Max-Planck Institute for Experimental Medicine, Goettingen, and afterwards at the Ruhr-Universitaet Bochum, Germany, investigating the biophysical properties of glutamate receptors. She did her Postdoc in the group of Prof. Ralf Schoepfer at University College London (UCL), UK, where she investigated synaptic NMDAR-mediated calcium signaling and the postsynaptic density complex on a proteomic scale, in collaboration with Prof. Burlingame’s mass-spectrometry unit at UCSF. She joined the Italian Institute of Technology (IIT) as external consultant in 2013 and was awarded the Italian habilitation in biochemistry in 2014.
My aim is to investigate synaptic cell adhesion at the proteomic scale. A comprehensive knowledge of the composition of the ‘synaptic adhesome’ is fundamental for understanding how the brain wires up and what goes wrong in neurodevelopmental diseases.
There are about 1015 synapses in the human brain, which enable neurons to communicate with each other in a very specific and highly organized fashion. This shapes how we behave and think and, ultimately, who we are.
Synapses can be considered as asymmetric intercellular junctions specialized in mediating neuronal communication. Synaptic cell adhesion molecules (CAMs), which bridge the synaptic cleft between pre- and postsynaptic terminals, coordinate the function of the two sides of the synapse by mediating cell-cell recognition and signaling processes. Correct functioning of synaptic CAMs is required throughout the lifespan of a synapse, (i) for establishing the initial contact between pre- and postsynaptic neurons, (ii) for promoting and coordinating the assembly of the pre- and postsynaptic machinery, (iii) for conferring specific properties to a developing synapse and (iv) for remodeling synaptic structure and function in adulthood in an activity-dependent manner.
In each single synapse, these processes are mediated by dynamic and activity-dependent interactions involving multiple CAMs, rather than a single one. I refer to the full set of CAMs specifying a type of synapse as synaptic adhesome and postulate that the code for synaptic specificity must be searched at the level of the full synaptic adhesome. Likewise, the etiological mechanisms of connectopathies and synaptopathies can be understood only as perturbations affecting the composition of the full synaptic adhesome.
Proteomic analysis of synaptic adhesomes – delineating signaling pathways altered in neurodevelopmental disorders
While the genetic origin of diseases such as autism and epilepsy is very heterogenous, a large proportion of gene mutations is affecting synaptic protein function and seem to converge on relatively few common pathways. The most intriguing question in the field of synaptopathies is how impairment of a single component can compromise correct function of synapses, molecular machineries consisting out of many hundreds of components. To address this, single aberrant protein function has to be studied in context of the affected interacting protein complexes and pathway components. Only when considering the full scale of alterations introduced by a single faulty synaptic protein, we can expect to identify possible targets for therapeutic strategies.
In this context, I am studying which signaling pathways are altered in synaptosomes of the integrin beta3 knock-out mouse, a well-established mouse model for autism spectrum disorder. Because integrins are as adhesion molecules easily accessible to pharmacological treatment, they present an ideal target for eventual therapeutic strategies for many ASD genes found affected in our integrin ASD mouse model.
Genome-editing approaches for personalized medicine in inherited diseases
This project aims to developing novel strategies for personalized medicine in inherited brain diseases with a complex and multifactorial genetic architecture. To this end, we employ CRISPR/Cas9-based genome-editing technology to correct the genetic defects at the base of inherited forms of autism and ataxia.
Development of new sensors for simultaneous detection of Ca2+ and neurotransmitter release at single synapses
A long-standing goal in neuroscience has been to ‘see’ the Ca2+ that triggers synaptic transmission. The lab has engineered activity-dependent indicators to image Ca2+ signals and vesicle release in the same synapse in response to single action potentials, thus allowing simultaneous imaging of neurotramsmitter release and its trigger (Ca2+). The current spatial resolution for Ca2+ signal is at the level of single synapses (~1 µm). The lab aims to improve spatial resolution down to a single active zone (~200 nm), to directly detect the Ca2+ responsible for vesicle release. I am currently using these new approaches to investigate the contribution of voltage-gated calcium channel splice variants to synaptic plasticity and ataxia.
Optimization of contacts between brain implant devices and neuronal cells by nano-structured diamond coatings and manipulation of integrin adhesion
An emerging therapeutic approach for a variety of neuropsychiatric disorders, such as Parkinson’s disease, epilepsy and depression, is to stimulate the patient’s neurons electrically with implants (the so called ‘brain pacemakers’). For this approach to succeed, the implant surface properties and the neuronal cell surface receptors are especially important since they must guarantee close apposition between the device and the neurons for optimal electrical stimulation. This project investigates the nature of the interface between nanodiamond-coated materials and neuronal/glial cell adhesion molecules with the ultimate goal of improving the long-term functionality of brain implants.
Master thesis and postgraduate internship training positions are available in our group at the Center for Synaptic Neuroscience and Technology (NSYN), IIT, Genoa.
For further information, please contact Dr. Agnes Thalhammer (email@example.com) or Dr. Lorenzo Cingolani (firstname.lastname@example.org).
Thalhammer, A., Jaudon, F. and Cingolani, L.A. (2017) Combining Optogenetics with Artificial microRNAs to Characterize the Effects of Gene Knockdown on Presynaptic Function within Intact Neuronal Circuits. J. Vis. Exp. (133), e57223, doi:10.3791/57223.
Thalhammer, A., Contestabile, A., Ermolyuk, Y.S., Ng, T., Volynski, K.E., Soong, T.W., Goda, Y. and Cingolani, L.A. (2017) Alternative Splicing of P/Q-Type Ca2+ Channels Shapes Presynaptic Plasticity. Cell Reports, 20 (2), 333-343.full text
Ronzitti, G., Bucci, G., Emanuele, M., Leo, D., Sotnikova, T.D., Mus, L.V., Soubrane C.H., Dallas, M.L., Thalhammer, A., Cingolani, L.A., Mochida, S., Gainetdinov, R.R., Stephens, G. and Chieregatti, E. (2014) Exogenous alpha-synuclein decreases raft-partitioning of Cav2.2 channels inducing dopamine release. J. Neurosci, 34(32):10603–10615.
Thalhammer, A.*, Edgington, R.J.*, Welch, J., Bongrain, A., Bergonzo, P., Scorsone, E., Jackman, R.B. and Schoepfer, R. (2013) Patterned neuronal networks using nanodiamonds and the effect of varying nanodiamond properties on neuronal adhesion and outgrowth. J. Neural Engineering, 10, 056022. *Shared first-authorships.
Thalhammer, A. and Cingolani, L. (2013) Cell adhesion and homeostatic synaptic plasticity. Neuropharmacology, invited review for special issue on homeostatic plasticity, Neuropharmacology, 78, 23-30.
Thalhammer, A.*, Trinidad, J.C.*, Burlingame, A.L. and Schoepfer, R. Activity-dependent protein dynamics define interconnected cores of co-regulated postsynaptic proteins. (2013) Mol Cell Proteomics, 12, 29-41. *Shared first-authorships.
Trinidad, J.C., Barkan, D.T., Gulledge, B.F., Thalhammer, A., Sali, A., Schoepfer, R. and Burlingame, A.L. (2012) Global Identification and Characterization of Both O-GlcNAcylation and Phosphorylation at the Murine Synapse. Mol Cell Proteomics, 8, 215-229.
Thalhammer, A., Edgington, R.J., Cingolani, L.A., Schoepfer, R., and Jackman, R.B. (2010) The use of nanodiamond monolayer coatings to promote the formation of functional neuronal networks. Biomaterials, 31(8), 2097-2104.
Chalkley, R.J., Thalhammer, A., Schoepfer, R., and Burlingame, A.L. (2009). Identification of protein O-GlcNAcylation sites using electron transfer dissociation mass spectrometry on native peptides. Proc Natl Acad Sci U S A, 106(22), 8894-8899.
Thalhammer, A.*, Trinidad, J.C., Burlingame, A.L. and Schoepfer, R. (2009) Densin-180: revised membrane topology, domain structure and phosphorylation status. J Neurochem, 109(2), 297-302. *Co-corresponding author.
Cingolani, L.A., Thalhammer, A., Yu, L.M., Catalano, M., Ramos, T., Colicos, M.A., and Goda, Y. (2008) Activity-dependent regulation of synaptic AMPA receptor composition and abundance by beta3 integrins. Neuron, 58(5), 749-762.
Trinidad, J.C., Thalhammer, A., Specht, C.G., Lynn, A.J., Baker, P.R., Schoepfer, R. and Burlingame, A.L. (2008) Quantitative Analysis of Synaptic Phosphorylation and Protein Expression. Mol Cell Proteomics, 7, 684-696.
Thalhammer, A., Rudhard, Y., Tigaret, C.M., Volynski, K.E., Rusakov, D.A. and Schoepfer, R. (2006) CaMKII translocation requires local NMDA receptor-mediated Ca2+ signaling. EMBO J, 25, 5873-5883.
Vosseller, K., Trinidad, J.C., Chalkley, R.J., Specht, C.G., Thalhammer, A., Lynn, A.J., Snedecor, J.O., Guan, S., Medzihradszky, K.F., Maltby, D.A., Schoepfer, R. and Burlingame, A.L. (2006) O-linked N-acetylglucosamine proteomics of postsynaptic density preparations using lectin weak affinity chromatography and mass spectrometry. Mol Cell Proteomics, 5, 923-934.
Tigaret, C.M., Thalhammer, A., Rast, G.F., Specht, C.G., Auberson, Y.P., Stewart, M.G. and Schoepfer, R. (2006) Subunit dependencies of N-methyl-D-aspartate (NMDA) receptor-induced alpha-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid (AMPA) receptor internalization. Mol Pharmacol, 69, 1251-1259.
Trinidad, J.C., Specht, C.G., Thalhammer, A., Schoepfer, R. and Burlingame, A.L. (2006) Comprehensive identification of phosphorylation sites in postsynaptic density preparations. Mol Cell Proteomics, 5, 914-922.
Trinidad, J.C., Thalhammer, A., Specht, C.G., Schoepfer, R. and Burlingame, A.L. (2005) Phosphorylation state of postsynaptic density proteins. J Neurochem, 92, 1306-1316.
Specht, C.G., Tigaret, C.M., Rast, G.F., Thalhammer, A., Rudhard, Y. and Schoepfer, R. (2005) Subcellular localisation of recombinant alpha- and gamma-synuclein. Mol Cell Neurosci, 28, 326-334.
Thalhammer, A., Everts, I. and Hollmann, M. (2002) Inhibition by lectins of glutamate receptor desensitization is determined by the lectin's sugar specificity at kainate but not AMPA receptors. Mol Cell Neurosci, 21, 521-533.
Strutz, N., Villmann, C., Thalhammer, A., Kizelsztein, P., Eisenstein, M., Teichberg, V.I. and Hollmann, M. (2001) Identification of domains and amino acids involved in GLuR7 ion channel function. J Neurosci, 21, 401-411.
Thalhammer, A., Morth, T., Strutz, N. and Hollmann, M. (1999) A desensitization-inhibiting mutation in the glutamate binding site of rat alpha-amino-3-hydroxy-5-methyl-4-isoxazole propionic acid receptor subunits is dominant in heteromultimeric complexes. Neurosci Lett, 277, 161-164.