Anatomical-Molecular Distribution of EphrinA1 in Infarcted Mouse Heart Using MALDI Mass Spectrometry Imaging

Abstract

EphrinA1 is a tyrosine kinase receptor localized in the cellular membrane of healthy cardiomyocytes, the expression of which is lost upon myocardial infarction (MI). Intra-cardiac injection of the recombinant form of ephrinA1 (ephrinA1-Fc) at the time of ligation in mice has shown beneficial effects by reducing infarct size and myocardial necrosis post-MI. To date, immunohistochemistry and Western blotting comprise the only experimental approaches utilized to localize and quantify relative changes of ephrinA1 in sections and homogenates of whole left ventricle, respectively. Herein, we used matrix-assisted laser desorption ionization mass spectrometry imaging (MALDI-MSI) coupled with a time-of-flight mass spectrometer (MALDI/TOF MS) to identify intact as well as tryptic fragments of ephrinA1 in healthy controls and acutely infarcted murine hearts. The purpose of the present study was 3-fold: (1) to spatially resolve the molecular distribution of endogenous ephrinA1, (2) to determine the anatomical expression profile of endogenous ephrinA1 after acute MI, and (3) to identify molecular targets of ephrinA1-Fc action post-MI. The tryptic fragments detected were identified as the ephrinA1-isoform with 38% and 34% sequence coverage and Mascot scores of 25 for the control and MI hearts, respectively. By using MALDI-MSI, we have been able to simultaneously measure the distribution and spatial localization of ephrinA1, as well as additional cardiac proteins, thus offering valuable information for the elucidation of molecular partners, mediators, and targets of ephrinA1 action in cardiac muscle. Graphical Abstractᅟ Electronic supplementary materialThe online version of this article (10.1007/s13361-017-1869-7) contains supplementary material, which is available to authorized users.

Antineuroinflammatory effects of dl-3-n-butylphthalide conferred by stimulation of Foxp3 and Ki-67 in an ischemic stroke model

“…We used MALDI-TOF MSI technology to detect the distribution of phospholipid molecules in the brains of pMCAO rat models, which was very important for our study of the effect of NBP on the brain. 25 We found that PA (16:0/18:1), PA We demonstrated that NBP can reduce inflammatory damage, maintain immune tolerance, improve vascular density, and promote nerve cell regeneration through mechanisms that are shown in Fig. 5.…”

Trends in mass spectrometry imaging for cardiovascular diseases

“…Depending on the analyte of interest, the protocol can include washing and/or digestion steps. Washing steps reduce ion suppression by the removal of salts, small molecules, and/or lipids [ 28 , 29 ]. Therefore, these steps are used for protein/peptide and in general not for lipid and or metabolite imaging.…”

“…Commonly used matrices for peptide and protein MSI are DHB, CHCA, and sinapinic acid (SA) [ 12 , 13 , 26 , 28 , 34 , 47 , 56 – 59 ]. A MALDI TOF-TOF is the most frequently used instrument for peptide and protein MSI for cardiovascular diseases, operated in positive ion mode with a range up to 30 kDa [ 12 , 13 , 26 , 28 , 34 , 47 , 56 , 60 ]. Linear mode was mostly used to enhance the signal of high-mass molecules, while the reflectron mode was used for small proteins and peptides.…”

“…The role of different peptides and proteins in myocardial infarction (MI) has been studied in a mouse MI model [ 28 ]. The spatial distribution of the tyrosine kinase receptor ephrinA1, both as intact protein and tryptic peptides, was investigated by Lefcoski et al and revealed a higher expression of ephrinA1 fragments in healthy compared with MI mouse hearts.…”

“…In the cardiovascular field, information on the metabolic distributions might provide further insight into pathways involved or the origin of these changes. For example, the metabolite creatine is used for the identification of the infarcted region in cardiac tissue; it was previously described as abundant in healthy tissue and reduced in ischemic tissue [ 28 , 36 ]. As creatine is part of the creatine-phosphocreatine system, these results hint to changes in the energy-related pathways.…”