Neurochemical characterization of basal ganglia neuropeptides and proteins in levodopa-induced dyskinesia in experimental Parkinson’s disease using Imaging Mass Spectrometry and Peptidomics

Per Andrén, Anna Nilsson, Patrik Källback, Maria Fälth, Henrik Wadensten, MMS, Per Svenningsson, Karolinska Institutet, Alan Crossman, University of Manchester, UK, Erwan Bezard, Univ. of Bordeaux 2, France.

The main objective of the present research is to study neurochemical processes in Parkinson disease and specifically L-Dopa-induced dyskinesias (LID). No treatment exists yet for the management of LID, a debilitating complication of L-dopa therapy for PD. The aim is to define neuropeptides and proteins that are differentially expressed in the basal ganglia complex of animals with striatal dopamine depletions, with and without LID.

Integration of resources and studies to elucidate neuropeptide signaling

Per Andrén, Anna Nilsson, Maria Fälth, MMS, Jonathan Sweedler and Sandra Rodrigues-Zas, University of Illinois Urbana-Champaign, IL, USA 

We propose to develop a public and comprehensive neuropeptide resource much needed by the research community by collectively analyzing proteomic and transcriptomic experiments to augment the understanding of extracellular signaling peptides both at the fundamental neuroscience as well as the applied substance abuse levels. To accomplish these objectives, we plan to integrate complementary peptide repositories and develop tools to assemble and effectively query a comprehensive and public resource of experimental and in silico predictions; mine this resource to perform secondary and joint analysis of available high proteomic experiments; and perform integrated analysis of proteomic and transcriptomic experiments. The overarching strategy is to integrate complementary information across databases, experiments and platforms to provide a unique and comprehensive understanding of the dynamic neuropeptide complement. The outcome of this project will be resources, tools and information that will fill critical gaps in the knowledge on intercellular signaling systems.

Identification and functional characterization of protein-protein interactions in cerebrospinal fluid and brain tissue from Parkinson’s disease (PD) patients and experimental PD models

Per Andrén, Anna Nilsson, MMS, Per Svenningsson, Karolinska Institutet, Peter Verhaert, University of Delft, the Netherlands

Using surface plasmon resonance technique (Biacore 3000) coupled to mass spectrometry technology, new protein partners of α-synuclein and parkin have been captured and identified in cerebrospinal fluid or post-mortem human tissue from PD patients. In addition to using native α-synuclein and parkin, mutated forms of these proteins seen in familiar forms of PD will be immobilized on the sensor chip and used as baits.

Fine mapping the spatial distribution and concentration of unlabeled drugs within tissue micro-compartments using imaging mass spectrometry

Per Andrén, Anna Nilsson, MMS, AstraZeneca, Lund

In respiratory inhalation drug discovery projects, one key objective is to optimize retention of compound in the lung and consequently achieve duration of effect. Current technologies only provide information on the total amount of compound in the whole lung with no possibility to address microenvironmental localization of the compound or metabolic derivatives. The application of MALDI imaging mass spectrometry in such studies would provide a new tool to accurately measure local tissue concentrations of drug/drug metabolite in context with efficacy achieved with the targeted biology or in the context of safety. Such technology could provide new and important information.

Structural Proteomics

We develop new methods where mass spectrometry is used for the study of structure–function relationships of ligand–receptor interactions. While G-protein coupled receptors (GPCRs) remain the major target (~35% of all therapeutic drugs) for drug development, experimental verification of the interaction sites where their cognate ligands bind are still lacking for many GPCRs. These efforts allow us to characterize the structural location of the binding site for a ligand in a receptor, the binding affinity and effects of competitive binding, and the reaction kinetics for the binding event at submillisecond temporal resolution. In turn, these studies provide fundamental knowledge of physicochemical properties of ligand-receptor interactions that are key for design of future biological therapeutics.

We also focus on method development where mass spectrometry is used to probe the proteome at temporal resolution down to the single-cell level. In contrast to ensemble average measurements, single-cell studies aim to unravel information about cellular heterogeneity, and will determine how much variability there is within a certain cell type in a tissue compared to others. Recent efforts have showed how peptide hormone processing differs between gamma-cells located in different sites of the rat pancreas with single-cell mass spectrometry,