A preliminary study of metalloproteins in CSF by CapLC-ICPMS and NanoLC-CHIP/ITMS

Identification of Hybrid Insulin Peptides (HIPs) in Mouse and Human Islets by Mass Spectrometry

We recently discovered hybrid insulin peptides (HIPs) as a novel class of post-translationally modified peptides in murine-derived beta cell tumors, and we demonstrated that these molecules are autoantigens in type 1 diabetes (T1D). A HIP consists of an insulin fragment linked to another secretory granule peptide via a peptide bond. We verified that autoreactive CD4 T cells in both mouse and human autoimmune diabetes recognize these modified peptides. Here, we use mass spectrometric analyses to confirm the presence of HIPs in both mouse and human pancreatic islets. We also present criteria for the confident identification of these peptides. This work supports the hypothesis that HIPs are autoantigens in human T1D and provides a foundation for future efforts to interrogate this previously unknown component of the beta cell proteome.

A Peptidomic Approach to Characterize Peptides Involved in Cerebellar Cortex Development Leads to the Identification of the Neurotrophic Effects of Nociceptin

The cerebellum is a brain structure involved in motor and cognitive functions. The development of the cerebellar cortex (the external part of the cerebellum) is under the control of numerous factors. Among these factors, neuropeptides including PACAP or somatostatin modulate the survival, migration and/or differentiation of cerebellar granule cells. Interestingly, such peptides contributing to cerebellar ontogenesis usually exhibit a specific transient expression profile with a low abundance at birth, a high expression level during the developmental processes, which take place within the first two postnatal weeks in rodents, and a gradual decline toward adulthood. Thus, to identify new peptides transiently expressed in the cerebellum during development, rat cerebella were sampled from birth to adulthood, and analyzed by a semi-quantitative peptidomic approach. A total of 33 peptides were found to be expressed in the cerebellum. Among these 33 peptides, 8 had a clear differential expression pattern during development, 4 of them i.e. cerebellin 2, nociceptin, somatostatin and VGF [353-372], exhibiting a high expression level during the first two postnatal weeks followed by a significative decrease at adulthood. A focus by a genomic approach on nociceptin, confirmed that its precursor mRNA is transiently expressed during the first week of life in granule neurons within the internal granule cell layer of the cerebellum, and showed that the nociceptin receptor is also actively expressed between P8 and P16 by the same neurons. Finally, functional studies revealed a new role for nociceptin, acting as a neurotrophic peptide able to promote the survival and differentiation of developing cerebellar granule neurons.

Isolation and chemical analysis of nanoparticles from English ivy (Hedera helix L.)

Bio-inspiration for novel adhesive development has drawn increasing interest in recent years with the discovery of the nanoscale morphology of the gecko footpad and mussel adhesive proteins. Similar to these animal systems, it was discovered that English ivy (Hedera helix L.) secretes a high strength adhesive containing uniform nanoparticles. Recent studies have demonstrated that the ivy nanoparticles not only contribute to the high strength of this adhesive, but also have ultraviolet (UV) protective abilities, making them ideal for sunscreen and cosmetic fillers, and may be used as nanocarriers for drug delivery. To make these applications a reality, the chemical nature of the ivy nanoparticles must be elucidated. In the current work, a method was developed to harvest bulk ivy nanoparticles from an adventitious root culture system, and the chemical composition of the nanoparticles was analysed. UV/visible spectroscopy, inductively coupled plasma mass spectrometry, Fourier transform infrared spectroscopy and electrophoresis were used in this study to identify the chemical nature of the ivy nanoparticles. Based on this analysis, we conclude that the ivy nanoparticles are proteinaceous.

Detection of metals and metalloproteins in the plasma of stroke patients by mass spectrometry methods

Stroke is the leading cause of adult disability, worldwide. Metalloproteins and metals play key roles in epigenetic events in living organisms, including hypertension, the most important modifiable risk factor for stroke. Thus, metalloproteins may be important target biomarkers for disease diagnosis. The primary goal of this study was to assess metal containing proteins in blood plasma, detected by ICP-MS, followed by ESIMS for peptide/protein identification. We then compared the relative concentration differences between samples from patients with ischemic stroke, hemorrhagic stroke and stroke mimics. In 29 plasma samples (10 stroke mimics, 10 ischemic stroke and 9 hemorrhagic stroke patients) previously collected from patients who presented to the University of Cincinnati Emergency Department within 12 hours of symptom onset for a plasma banking project. For the metal associated protein study, Mg, Mn, Cu, Se concentrations were statistically different when compared between stroke mimics vs. ischemic stroke patients and ischemic stroke patients vs. hemorrhagic stroke patients. Pb concentrations were statistically different when compared between stroke mimics vs. ischemic stroke patients and Mo levels were statistically the same among the three groups. In addition, we also report concentration levels and preliminary correlation studies for total elemental analysis among the three sets of patients. This pilot study demonstrates that mass spectrometry methods may be highly valuable in detecting novel stroke biomarkers in blood plasma. Expanded studies are warranted to confirm these findings.

Probing the viral metallome: searching for metalloproteins in bacteriophage λ-- the hunt begins

Although the proteome and genome of bacteriophages are well developed, there is little knowledge about metals and their interactions with the phages, even though metals have been observed in stabilizing phage particles. With expanding studies of phage display and its promising applications, metalloprotein investigations in the bacteriophage areas are necessary to understand whether or not metalloproteins are included in the viral coat proteome. Since these virus studies are still in their infancy, lambda phage was chosen due to its high metal-binding potential as suggested by the cysteine/methionine rich proteins in the viral coat. After large-scale preparation and further purification of lambda phage according to standard protocols, state-of-the-art metallomics techniques via combinations of chromatographies and mass spectrometries were utilized for screening metal-associated species in lambda phage. The lambda phage sample was first separated using non-denaturing size exclusion chromatography with selective metal detection by ICPMS for screening associated metals and generating size distribution fractions for the various metal species, some of which include metalloproteins. Various molecular size distribution patterns were exhibited for the metals detected, Mn, Fe, Co, Ni, Cu and Zn, at different molecular weight ranges. On the other hand numerous other metals were not associated with the coat proteins, as they were not detected in the different molecular weight fractions. Further identification for putative metallopeptides and metalloproteins was accomplished by collecting various metal species' fractions offline and subsequently analyzing tryptically-digested fractions via nanoLC-Chip-ESI-MS. By searching appropriate MS databases with both Spectrum Mill and MASCOT search engines, the main capsid protein, gpE, a capsid decoration protein, gpD, and main tail component protein, gpV, were found and are known for associations with the detected transition metals. These findings will likely provide valuable information for lambda phage engineered applications.