Speaker: Bindesh Shrestha, Waters
Topic: Biomedical Applications of MALDI and DESI Imaging using High-Resolution Ion Mobility Mass Spectrometry
Date: Monday, June 21th, 2021
Time: 1:00 PM EDT Presentation
Location: Webinar – see emails on June 10 and 17 for invite link. Join the mailing list
Abstract: In the last decade, both matrix-assisted laser desorption/ionization (MALDI) and desorption electrospray ionization (DESI) imaging mass spectrometry (MS) have been developed to spatially map small molecules, such as metabolites, lipids and drugs, on tissue. DESI often detects a complementary set of molecules to MALDI due to preferential ionization of those species in electrospray. In this presentation, biomedical applications using both imaging modalities, MALDI and DESI, will be shown. Multimodal imaging using both techniques widens the molecular coverage of many small molecules, such as drugs – with some analyte preferentially ionizing more robustly with one ionization technique versus another. Analysis of ions detected by DESI and MALDI on consecutive sections using similar solvent composition eluded to the complementary coverage of the two mechanistically different ionization sources. In addition to showing the benefits of multimodal imaging MS strategy, the advantages of integrating ion mobility separations during the imaging MS process will also be discussed. Ion mobility separation can isolate ions based on their collision cross-section. For example, imaging a specific lipid molecule on tissue is often challenging because of the large structural diversity of similar lipids present in the sample. Multipass ultrahigh-resolution ion mobility separation can improve the specificity of lipid imaging by DESI, allowing us to image isobaric ions separately. All imaging MS experiments were performed on quadrupole time of flight mass spectrometers, such as SYNAPT XS and Cyclic IMS, with traveling wave ion mobility separation and using High Definition Imaging (HDI) software.
Speaker: Martin Jarrold, Indiana University
Topic: Charge Detection Mass Spectrometry: Recent Developments and Applications
Date: Monday, May 17th, 2021
Time: 1:00 PM EDT Presentation
Location: Webinar – see emails on May 6 and 13 for invite link. Join the mailing list
Abstract: Charge detection mass spectrometry (CDMS) provides a way to measure accurate masses for heterogeneous samples into the gigadalton regime. It is a single particle technique where the mass of each ion is determined from simultaneous measurements of its mass to charge ratio (m/z) and charge. CDMS opens the door to the analysis of high mass, heterogeneous samples such as vaccines and gene therapy products. Recent developments in instrumentation that have improved the resolution and speed of CDMS measurements will be described along with several recent examples of applications to the analysis of bio-pharmaceuticals, and virus assembly and disassembly.
Speaker: Stefani Thomas, University of Minnesota
Topic: Beyond the BRCA genes: A proteome-centric view of high-grade serous ovarian cancer
Date: Monday, April 19th, 2021
Time: 2:00 PM Presentation
Location: Webinar – see emails on April 9 and 15 for invite link. Join the mailing list
Abstract: The mutational status of a solid tumor can predict the therapeutic efficacy of a specific drug in a molecularly defined subset of patients. Poly (ADP-ribose) polymerase inhibitors (PARPi) have emerged as a novel class of drugs to treat advanced ovarian cancer with mutations in BRCA1/2 genes. Unfortunately, there is considerable inter-patient heterogeneity in BRCA1/2–based determinations of PARPi treatment sensitivity. Determining proteome-level mechanisms of PARPi sensitivity could enhance our ability to select the ovarian cancer patient population that would benefit the most from PARPi therapy, consequently improving survival and overall treatment response. Our laboratory is applying mass spectrometry-based proteomics to identify protein signatures of PARPi sensitivity. This presentation will provide an overview of the experimental models and analytical approaches that we are utilizing toward a long-term goal of identifying prognostic protein biomarkers of PARPi sensitivity in patients with high-grade serous ovarian cancer.
Speaker: Michael Marty, University of Arizona
Topic: Using native mass spectrometry and nanodiscs to study assembly of membrane protein and antimicrobial peptide complexes
Date: Monday, March 15th, 2021
Time: 1:00 PM Presentation
Location: Webinar – see emails on March 4 and 11 for invite link. Join the mailing list
Abstract: Native mass spectrometry (MS) has emerged as a powerful technique for studying the oligomeric state and interactions of membrane proteins. However, native MS can be challenging for smaller and more fragile membrane protein and transmembrane peptide complexes. To address this challenge, we have used native MS to study small viral membrane protein complexes in both detergent micelles and lipid nanodiscs. Using charge reduction reagents for stabilization and advanced data analysis techniques to unravel complex spectra, we discovered that viroporin complexes can be highly sensitive to their environment, showing different oligomeric states in different lipids/detergents, with different pH conditions, and with addition of antiviral drugs. Unexpected oligomeric states have been observed that do not match existing structural models, highlighting previously unseen behavior of these complexes. We have also studied assembly of antimicrobial peptide complexes in lipid nanodiscs. Antimicrobial peptides are also highly sensitive to the lipid environment, showing unique assembly pathways that are controlled by the thickness of the lipid bilayer. Ultimately, we expect these applications of native MS will reveal new insights into the biology of infectious disease and provide new directions for antiviral and antibacterial drug discovery.
Speaker: Allen Everett, Johns Hopkins University
Topic: Proteomics Discovery of Circulating Pulmonary Hypertension Biomarkers: IGF binding proteins are associated with disease severity
Date: Monday, February 15th, 2021
Time: 1:00 PM Presentation
Location: Webinar – see emails on Feb. 4 and 11 for invite link. Join the mailing list
Background: Pulmonary arterial hypertension is a progressive and fatal disease characterized by sustained elevations of pulmonary artery pressure. We lack circulating, diagnostic and prognostic markers to improve outcomes and develop new therapies.
Methods and Results: We performed proteomics discovery using high resolution mass spectrometry to identify new circulating biomarkers of pulmonary arterial hypertension. Plasma samples from patients with idiopathic pulmonary arterial hypertension (N=9, age 35.2 ± 11.2 years, 89% female) and normal controls (N=9, age 34.8 ± 10.6 years, 100% female) were processed by liquid chromatography/tandem mass spectrometry. A total of 826 (0.047 False Discovery Rate) idiopathic pulmonary arterial hypertension and 461 (0.087 False Discovery Rate) control proteins were identified. By Volcano plot, 153 proteins showed > 2 fold change, P<0.05. Carbonic anhydrase 2 (CA2) and Insulin like growth factor binding protein (IGFBP2) were top molecules by spectral counts. When all IGF axis molecules were examined, spectral counts for IGF1, IGF2, IGFBP1, IGFBP4, and IGFBP7 were also different between PAH and control. ELISA verification (N=41 PAH and N=39 controls) demonstrated that IGF1 and 2 were decreased and IGFBP1, 2, 4, 5, 7 and CA2 were increased in PAH. In association with disease severity, IGFBP2, 4 and 7 were associated with decreased 6MWD and IGFBP1, 2, 5 associated with PVR. IGFBP2, 4, and 7 were associated with survival (Kaplan Meier). CA2 was not associated with clinical severity.
Conclusions: We identified candidate plasma proteins that can distinguish PAH from control and verified CA2 and multiple members of the IGF axis associated with PAH and PAH severity. Suggesting that the IGF axis may play an important role in PAH pathogenesis and may be an important diagnostic for PAH, response to therapy and play a role in the pathogenesis of PAH.