Browse
Submit Data
Databases
API
Help

Dataset Information

20 Views

0 Connections

0 Citations

0 Reanalyses

0 Downloads

Omics score: 0

MALDI imaging mass spectrometry of β- and γ-crystallins in the ocular lens.

ABSTRACT: Lens crystallin proteins make up 90% of expressed proteins in the ocular lens and are primarily responsible for maintaining lens transparency and establishing the gradient of refractive index necessary for proper focusing of images onto the retina. Age-related modifications to lens crystallins have been linked to insolubilization and cataractogenesis in human lenses. Matrix-assisted laser desorption/ionization (MALDI) imaging mass spectrometry (IMS) has been shown to provide spatial maps of such age-related modifications. Previous work demonstrated that, under standard protein IMS conditions, α-crystallin signals dominated the mass spectrum and age-related modifications to α-crystallins could be mapped. In the current study, a new sample preparation method was optimized to allow imaging of β- and γ-crystallins in ocular lens tissue. Acquired images showed that γ-crystallins were localized predominately in the lens nucleus whereas β-crystallins were primarily localized to the lens cortex. Age-related modifications such as truncation, acetylation, and carbamylation were identified and spatially mapped. Protein identifications were determined by top-down proteomics analysis of lens proteins extracted from tissue sections and analyzed by LC-MS/MS with electron transfer dissociation. This new sample preparation method combined with the standard method allows the major lens crystallins to be mapped by MALDI IMS.

SUBMITTER: Anderson DM

PROVIDER: S-EPMC8184062 | biostudies-literature |

REPOSITORIES: biostudies-literature

ACCESS DATA

Json Xml

Similar Datasets

Modeling phase transitions in mixtures of β-γ lens crystallins.

Project description:We analyze the experimentally determined phase diagram of a γD-βB1 crystallin mixture. Proteins are described as dumbbells decorated with attractive sites to allow inter-particle interaction. We use thermodynamic perturbation theory to calculate the free energy of such mixtures and, by applying equilibrium conditions, also the compositions and concentrations of the co-existing phases. Initially we fit the Tcloudversus packing fraction η measurements for a pure (x2 = 0) γD solution in 0.1 M phosphate buffer at pH = 7.0. Another piece of experimental data, used to fix the model parameters, is the isotherm x2vs. η at T = 268.5 K, at the same pH and salt content. We use the conventional Lorentz-Berthelot mixing rules to describe cross interactions. This enables us to determine: (i) model parameters for pure βB1 crystallin protein and to calculate; (ii) complete equilibrium surface (Tcloud-x2-η) for the crystallin mixtures. (iii) We present the results for several isotherms, including the tie-lines, as also the temperature-packing fraction curves. Good agreement with the available experimental data is obtained. An interesting result of these calculations is evidence of the coexistence of three phases. This domain appears for the region of temperatures just out of the experimental range studied so far. The input parameters, leading good description of experimental data, revealed a large difference between the numbers of the attractive sites for γD and βB1 proteins. This interesting result may be related to the fact that γD has a more than nine times smaller quadrupole moment than its partner in the mixture.

| S-EPMC5131804 | biostudies-literature

MALDI imaging mass spectrometry--painting molecular pictures.

Project description:MALDI Imaging Mass Spectrometry is a molecular analytical technology capable of simultaneously measuring multiple analytes directly from intact tissue sections. Histological features within the sample can be correlated with molecular species without the need for target-specific reagents such as antibodies. Several studies have demonstrated the strength of the technology for uncovering new markers that correlate with disease severity as well as prognosis and therapeutic response. This review describes technological aspects of imaging mass spectrometry together with applications in cancer research.

| S-EPMC2981679 | biostudies-other

Rapid MALDI mass spectrometry imaging for surgical pathology.

Project description:Matrix assisted laser desorption ionization mass spectrometry imaging (MALDI MSI) is an emerging analytical technique, which generates spatially resolved proteomic and metabolomic images from tissue specimens. Conventional MALDI MSI processing and data acquisition can take over 30 min, limiting its clinical utility for intraoperative diagnostics. We present a rapid MALDI MSI method, completed under 5 min, including sample preparation and analysis, providing a workflow compatible with the clinical frozen section procedure.

| S-EPMC6609678 | biostudies-other

MALDI Imaging Mass Spectrometry Spatially Maps Age-Related Deamidation and Truncation of Human Lens Aquaporin-0.

Project description:PurposeTo spatially map human lens Aquaporin-0 (AQP0) protein modifications, including lipidation, truncation, and deamidation, from birth through middle age using matrix-assisted laser desorption ionization (MALDI) imaging mass spectrometry (IMS).MethodsHuman lens sections were water-washed to facilitate detection of membrane protein AQP0. We acquired MALDI images from eight human lenses ranging in age from 2 months to 63 years. In situ tryptic digestion was used to generate peptides of AQP0 and peptide images were acquired on a 15T Fourier transform ion cyclotron resonance (FTICR) mass spectrometer. Peptide extracts were analyzed by liquid chromatography-tandem mass spectrometry (LC-MS/MS) and database searched to identify peptides observed in MALDI imaging experiments.ResultsUnmodified, truncated, and fatty acid-acylated forms of AQP0 were detected in protein imaging experiments. Full-length AQP0 was fatty acid acylated in the core and cortex of young (2- and 4-month) lenses. Acylated and unmodified AQP0 were C-terminally truncated in older lens cores. Deamidated tryptic peptides (+0.9847 Da) were mass resolved from unmodified peptides by FTICR MS. Peptide images revealed differential localization of un-, singly-, and doubly-deamidated AQP0 C-terminal peptide (239-263). Deamidation was present at 4 months and increases with age. Liquid chromatography-MS/MS results indicated N246 undergoes deamidation more rapidly than N259.ConclusionsResults indicated AQP0 fatty acid acylation and deamidation occur during early development. Progressive age-related AQP0 processing, including deamidation and truncation, was mapped in human lenses as a function of age. The localization of these modified AQP0 forms suggests where AQP0 functions may change throughout lens development and aging.

| S-EPMC4675204 | biostudies-literature

The molecular refractive function of lens γ-Crystallins.

Project description:γ-Crystallins constitute the major protein component in the nucleus of the vertebrate eye lens. Present at very high concentrations, they exhibit extreme solubility and thermodynamic stability to prevent scattering of light and formation of cataracts. However, functions beyond this structural role have remained mostly unclear. Here, we calculate molecular refractive index increments of crystallins. We show that all lens γ-crystallins have evolved a significantly elevated molecular refractive index increment, which is far above those of most proteins, including nonlens members of the βγ-crystallin family from different species. The same trait has evolved in parallel in crystallins of different phyla, including S-crystallins of cephalopods. A high refractive index increment can lower the crystallin concentration required to achieve a suitable refractive power of the lens and thereby reduce their propensity to aggregate and form cataracts. To produce a significant increase in the refractive index increment, a substantial global shift in amino acid composition is required, which can naturally explain the highly unusual amino acid composition of γ-crystallins and their functional homologues. This function provides a new perspective for interpreting their molecular structure.

| S-EPMC3146585 | biostudies-literature

Physiological expression of lens α-, β-, and γ-crystallins in murine and human corneas.

Project description:PurposeHow corneal transparency is formed/maintained remains largely unclear. A group of enzymes which are referred to as enzymatic crystallins were proposed to contribute to corneal transparency in various animals. This study investigated whether the three classical lens crystallins, namely α-, β-, and γ-crystallins, exist in mouse and human corneas.MethodsMice, human tissues, and cultured corneal cells were studied. The expression of lens crystallins in corneas or in cultured corneal cells were detected at the mRNA level by quantitative reverse transcription-PCR (QRT-PCR) and at the protein level by immunohistochemistry or western blotting. To check the effect of exogenous factor on expression of lens crystallins, cultured corneal cells were challenged with lipopolysaccharide or hydrogen peroxide and the expression of lens crystallins was monitored.ResultsQRT-PCR revealed that the relative expression level of lens crystallins in C57BL/6 corneas were higher than in Balb/c corneas. Immunohistochemistry study showed that expression of αA-crystallin started from the embryonic stage, lasted untill old age, and was largely restricted to the epithelium or endothelium of the corneas. β- and γ-crystallins also were found in murine corneal epithelium. Upon treatment with lipopolysaccharide or hydrogen peroxide of cultured corneal epithelial cells, lens crystallins expression was significantly increased as detected by QRT-PCR or western blot assay. Further, both fetal corneal epithelial cultures and limbal stem cell cultures from adult human tissues were positive for lens crystallin immunofluorescence or immunohistochemistry staining.ConclusionsLens crystallins are expressed in mammalian corneas and cultured corneal cells. The expression levels depended on the animal strains or cell status. The physiologic and pathological significance of lens crystallins in corneas deserves more investigation.

| S-EPMC3003712 | biostudies-literature

MALDI mass spectrometry imaging of neuronal cell cultures.

Project description:Mass spectrometry imaging (MSI) provides the ability to detect and identify a broad range of analytes and their spatial distributions from a variety of sample types, including tissue sections. Here we describe an approach for probing neuropeptides from sparse cell cultures using matrix-assisted laser desorption/ionization time-of-flight (MALDI-TOF) MSI--at single cell spatial resolution-in both MS and tandem MS modes. Cultures of Aplysia californica neurons are grown on an array of glass beads embedded in a stretchable layer of Parafilm M. As the membrane is stretched, the beads/neurons are separated physically and the separated beads/neurons analyzed via MALDI TOF MS. Compared with direct MS imaging of samples, the stretching procedure enhances analyte extraction and incorporation into the MALDI matrix, with negligible analyte spread between separated beads. MALDI tandem MSI using the stretched imaging approach yields localization maps of both parent and fragment ions from Aplysia pedal peptide, thereby confirming peptide identification. This methodology represents a flexible platform for MSI investigation of a variety of cell cultures, including functioning neuronal networks.

| S-EPMC3113696 | biostudies-literature

Stretched tissue mounting for MALDI mass spectrometry imaging.

Project description:Matrix-assisted laser desorption/ionization (MALDI) mass spectrometry imaging (MSI) combines information-rich chemical detection with spatial localization of analytes. For a given instrumental platform and analyte class, the data acquired can represent a compromise between analyte extraction and spatial information. Here, we introduce an improvement to the spatial resolution achievable with MALDI MSI conducted with standard mass spectrometric systems that also reduces analyte migration during matrix application. Tissue is placed directly on a stretchable membrane that, when stretched, fragments the tissue into micrometer-sized pieces. Scanning electron microscopy analysis shows that this process produces fairly homogeneous distributions of small tissue fragments separated and surrounded by areas of hydrophobic membrane surface. MALDI matrix is then applied by either a robotic microspotter or an artist's airbrush. Rat spinal cord samples imaged with an instrumental resolution of 50-250 μm demonstrate lipid distributions with a 5-fold high spatial resolution (a 25-fold increase in pixel density) after stretching compared to tissues that were not stretched.

| S-EPMC3229305 | biostudies-literature

Matrix Selection for the Visualization of Small Molecules and Lipids in Brain Tumors Using Untargeted MALDI-TOF Mass Spectrometry Imaging

Project description:Matrix-assisted laser desorption/ionization mass spectrometry imaging allows for the study of metabolic activity in the tumor microenvironment of brain cancers. The detectable metabolites within these tumors are contingent upon the choice of matrix, deposition technique, and polarity setting. In this study, we compared the performance of three different matrices, two deposition techniques, and the use of positive and negative polarity in two different brain cancer types and across two species. Optimal combinations were confirmed by a comparative analysis of lipid and small-molecule abundance by using liquid chromatography-mass spectrometry and RNA sequencing to assess differential metabolites and enzymes between normal and tumor regions. Our findings indicate that in the tumor-bearing brain, the recrystallized α-cyano-4-hydroxycinnamic acid matrix with positive polarity offered superior performance for both detected metabolites and consistency with other techniques. Beyond these implications for brain cancer, our work establishes a workflow to identify optimal matrices for spatial metabolomics studies.

2024-10-09 | GSE279139 | GEO

Identification of gamma heavy chain disease using MALDI-TOF mass spectrometry.

Project description:We describe the use of MALDI-TOF mass spectrometry in the analysis of a suspected case of gamma heavy chain disease. The patient had an abnormal serum immunofixation result where a monoclonal gamma heavy chain band was present without a corresponding light chain. Analysis by MALDI-TOF mass spectrometry revealed large peaks in the spectrum following IgG-specific purification. The m/z values of the peaks were outside the expected range for normal heavy chains or light chains. Corresponding peaks were not present in mass spectra of the kappa- or lambda-specific purifications. MALDI-TOF MS confirmed the presence of a truncated heavy chain without associated light chains. This case report demonstrates the value of mass spectrometry in interpreting challenging cases such as the identification of heavy chain disease.

| S-EPMC7046309 | biostudies-literature

OmicsDI is part of the ELIXIR infrastructure

OmicsDI is an Elixir interoperability service. Learn more ›

Tweets

OmicsDI Databases

PRIDE
PeptideAtlas
MassIVE
JPOST Repository
Physiome Model Repository

EGA
EVA
ENA
LINCS
PAXDB
Cell Collective

MetaboLights
Metabolomics Workbench
MetabolomeExpress
GNPS
BioModels
FAIRDOMHub

ArrayExpress
dbGaP
ExpressionAtlas
GEO
NODE

Information

Databases
Help
API
Contact us
Code on GitHub
Terms of use
Submit Data