Localization of Secondary Metabolites in Marine Invertebrates: Contribution of MALDI MSI for the Study of Saponins in Cuvierian Tubules of H. forskali

peer reviewedBackground: Several species of sea cucumbers of the family Holothuriidae possess a particular mechanical defense system called the Cuvierian tubules (Ct). It is also a chemical defense system as triterpene glycosides (saponins) appear to be particularly concentrated in Ct. In the present study, the precise localization of saponins in the Ct of Holothuria forskali is investigated. Classical histochemical labeling using lectin was firstly performed but did not generate any conclusive results. Thus, MALDI mass spectrometry Imaging (MALDI-MSI) was directly applied and completed by statistical multivariate tests. A comparison between the tubules of relaxed and stressed animals was realized. Results: These analyses allowed the detection of three groups of ions, corresponding to the isomeric saponins of the tubules. Saponins detected at m/z 1287 and 1303 were the most abundant and were apparently localized in the connective tissue of the tubules of both relaxed and stressed individuals. Saponins at m/z 1125 and 1141 were detected in lower amount and were present in tissues of relaxed animals. Finally, saponin ions at 1433, 1449, 1463 and 1479 were observed in some Ct of stressed holothuroids in the outer part of the connective tissue. The saponin group m/z 14xx seems therefore to be stress-specific and could originate from modifications of the saponins with m/z of 11xx. Conclusions: All the results taken together indicate a complex chemical defense mechanism with, for a single organ, different sets of saponins originating from different cell populations and presenting different responses to stress. The present study also reflects that MALDI-MSI is a valuable tool for chemical ecology studies in which specific chemical signalling molecules like allelochemicals or pheromones have to be tracked. This report represents one of the very first studies using these tools to provide a functional and ecological understanding of the role of natural products from marine invertebrates

MALDI imaging and profiling MS of higher mass proteins from tissue.

peer reviewe

Spatial analysis of the glioblastoma proteome reveals specific molecular signatures and markers of survival

Molecular heterogeneity is a key feature of glioblastoma that impedes patient stratification and leads to large discrepancies in mean patient survival. Here, we analyze a cohort of 96 glioblastoma patients with survival ranging from a few months to over 4 years. 46 tumors are analyzed by mass spectrometry-based spatially-resolved proteomics guided by mass spectrometry imaging. Integration of protein expression and clinical information highlights three molecular groups associated with immune, neurogenesis, and tumorigenesis signatures with high intra-tumoral heterogeneity. Furthermore, a set of proteins originating from reference and alternative ORFs is found to be statistically significant based on patient survival times. Among these proteins, a 5-protein signature is associated with survival. The expression of these 5 proteins is validated by immunofluorescence on an additional cohort of 50 patients. Overall, our work characterizes distinct molecular regions within glioblastoma tissues based on protein expression, which may help guide glioblastoma prognosis and improve current glioblastoma classification

Localization of Secondary Metabolites in Marine Invertebrates: Contribution of MALDI MSI for the Study of Saponins in Cuvierian Tubules of H. forskali

BACKGROUND: Several species of sea cucumbers of the family Holothuriidae possess a particular mechanical defense system called the Cuvierian tubules (Ct). It is also a chemical defense system as triterpene glycosides (saponins) appear to be particularly concentrated in Ct. In the present study, the precise localization of saponins in the Ct of Holothuria forskali is investigated. Classical histochemical labeling using lectin was firstly performed but did not generate any conclusive results. Thus, MALDI mass spectrometry Imaging (MALDI-MSI) was directly applied and completed by statistical multivariate tests. A comparison between the tubules of relaxed and stressed animals was realized. RESULTS: These analyses allowed the detection of three groups of ions, corresponding to the isomeric saponins of the tubules. Saponins detected at m/z 1287 and 1303 were the most abundant and were apparently localized in the connective tissue of the tubules of both relaxed and stressed individuals. Saponins at m/z 1125 and 1141 were detected in lower amount and were present in tissues of relaxed animals. Finally, saponin ions at 1433, 1449, 1463 and 1479 were observed in some Ct of stressed holothuroids in the outer part of the connective tissue. The saponin group m/z 14xx seems therefore to be stress-specific and could originate from modifications of the saponins with m/z of 11xx. CONCLUSIONS: All the results taken together indicate a complex chemical defense mechanism with, for a single organ, different sets of saponins originating from different cell populations and presenting different responses to stress. The present study also reflects that MALDI-MSI is a valuable tool for chemical ecology studies in which specific chemical signalling molecules like allelochemicals or pheromones have to be tracked. This report represents one of the very first studies using these tools to provide a functional and ecological understanding of the role of natural products from marine invertebrates

Multiple Changes in Peptide and Lipid Expression Associated with Regeneration in the Nervous System of the Medicinal Leech

peer reviewe

Ovarian cancer molecular pathology.

Peer reviewe

Développements en imagerie par spectrométrie de masse et applications aux modèles invertébrés

A l'heure de la protéomique, la spectrométrie de masse s'est révélée un outil puissant pour la recherche et l'identification des biomolécules à partir d'échantillons purifiés. Une nouvelle ère s'ouvre, avec l'imagerie MALDI, permettant en plus la localisation de biomolécules telles que les peptides, les protéines ou les lipides au sein des tissus. Des développements cruciaux restent encore à réaliser pour améliorer les performances de cette technologie. Dans ce contexte, nous nous sommes tout d'abord intéressés à la mise au point de nouveaux protocoles adaptés à l'analyse directe et l'imagerie par spectrométrie de masse de petits organismes en particulier la sangsue Hirudo medicinalis. Ce modèle est particulièrement intéressant du point de vue des phénomènes de régénération nerveuse et nous avons débuté des études sur les lipides pouvant y être impliqués. Le deuxième point abordé est l'étude des apports de la métallisation pour la spectrométrie de masse. Tout d'abord un dépôt métallique sur des lames histologiques permet à la fois une corrélation des informations morphologiques obtenues en microscopie optique avec les images moléculaires d'IMS. La métallisation de l'échantillon quand à elle, a permis de supprimer les décalages de pics vers les plus hauts rapports m/z, d'obtenir des spectres MALDI de meilleures qualités et grâce à une reproductibilité plus importante entre 2 spectres, de produire des images MALDI de plus grandes qualités. Enfin, une partie des développements a été dédiée à la possibilité d'améliorer la résolution de l'image grâce à l'utilisation d'un système permettant de diminuer la zone accessible au laser.LILLE1-BU (590092102) / SudocSudocFranceF

Elucidation of structure / biological activity relationships of saponins in the starfish Asterias rubens by MALDI tissue profiling and MALDI imaging

Elucidation of structure/ biological activity relationships in saponins of the sea star Asterias rubens by MALDI tissue profiling and MALDI-imaging. M. Demeyera,b, M. Wisztorskic, I. Fournierc, P. Flammangb, P. Gerbauxa a Mass Spectrometry Research Group (MSRG), Université de Mons, 23 Place du Parc, B-7000 Mons - Belgium b Biology of Marine Organisms and Biomimetics (BOMB), Université de Mons, 23 Place du Parc, B-7000 Mons - Belgium c Laboratoire de Spectrométrie de Masse Biologique, Fondamentale & Appliquée Université Lille 1, F-59655 Villeneuve d'Ascq - France During the last decade, numerous papers related to the identification of natural compounds from marine resources appeared in the literature. Amongst all the reported molecules, saponins present a high interest and are found mainly in Echinoderms, more precisely in sea stars (asteroids) and sea cucumbers (holothuroids). These molecules reveal a large chemical diversity and different putative biological activities. They may indeed contribute to chemical defense and chemical communication between animals. Also, from a pharmacology point of view, such molecules show a high interest given their hemolytic, cytotoxic, antibacterial, antifungal, antiviral and anti-tumor properties. Amongst all the available analytical methodologies, mass spectrometry is definitely a first-choice technique for tackling the large diversity of saponins in echinoderm tissues. In this report, we would like to present the preliminary results of the identification of the saponin contents in the sea star Asterias rubens. Making use of MALDI-MS(MS) and MALDI imaging methods, we highlighted different saponin distributions between organs such as body wall, tube feet, gonads and pyloric caeca, and the specificity of some saponins for a specific organ. This variability can be probably related to the different roles played by saponins in the biological activities of sea stars

Integrated mass spectrometry imaging and omics workflows on the same tissue section using grid-aided, parafilm-assisted microdissection

International audienceBackground: In spite of the number of applications describing the use of MALDI MSI, one of its major drawbacks is the limited capability of identifying multiple compound classes directly on the same tissue section.Methods: We demonstrate the use of grid-aided, parafilm-assisted microdissection to perform MALDI MS imaging and shotgun proteomics and metabolomics in a combined workflow and using only a single tissue section. The grid is generated by microspotting acid dye 25 using a piezoelectric microspotter, and this grid was used as a guide to locate regions of interest and as an aid during manual microdissection. Subjecting the dissected pieces to the modified Folch method allows to separate the metabolites from proteins. The proteins can then be subjected to digestion under controlled conditions to improve protein identification yields.Results: The proof of concept experiment on rat brain generated 162 and 140 metabolite assignments from three ROIs (cerebellum, hippocampus and midbrain/hypothalamus) in positive and negative modes, respectively, and 890, 1303 and 1059 unique proteins. Integrated metabolite and protein overrepresentation analysis identified pathways associated with the biological functions of each ROI, most of which were not identified when looking at the protein and metabolite lists individually.Conclusions: This combined MALDI MS imaging and multi-omics approach further extends the amount of information that can be generated from single tissue sections.General significance: To the best of our knowledge, this is the first report combining both imaging and multi-omics analyses in the same workflow and on the same tissue section

Progress and Potential of Imaging Mass Spectrometry Applied to Biomarker Discovery

International audienceMapping provides a direct means to assess the impact of protein biomarkers and puts into context their relevance in the type of cancer being examined. To this end, mass spectrometry imaging (MSI) was developed to provide the needed spatial information which is missing in traditional liquid-based mass spectrometric proteomics approaches. Aptly described as a “molecular histology” technique, MSI gives an additional dimension in characterizing tumor biopsies, allowing for mapping of hundreds of molecules in a single analysis. A decade of developments focused on improving and standardizing MSI so that the technique can be translated into the clinical setting. This review describes the progress made in addressing the technological development that allows to bridge local protein detection by MSI to its identification and to illustrate its potential in studying various aspects of cancer biomarker discovery