TransOmic analysis of forebrain sections in Sp2 conditional knockout embryonic mice using IR-MALDESI imaging of lipids and LC-MS/MS label-free proteomics

Abstract

Quantitative methods for detection of biological molecules are needed more than ever before in the emerging age of “omics” and “big data.” Here, we provide an integrated approach for systematic analysis of the “lipidome” in tissue. To test our approach in a biological context, we utilized brain tissue selectively deficient for the transcription factor Specificity Protein 2 (Sp2). Conditional deletion of Sp2 in the mouse cerebral cortex results in developmental deficiencies including disruption of lipid metabolism. Silver (Ag) cationization was implemented for infrared matrix-assisted laser desorption electrospray ionization (IR-MALDESI) to enhance the ion abundances for olefinic lipids, as these have been linked to regulation by Sp2. Combining Ag-doped and conventional IR-MALDESI imaging, this approach was extended to IR-MALDESI imaging of embryonic mouse brains. Further, our imaging technique was combined with bottom-up shotgun proteomic LC-MS/MS analysis and western blot for comparing Sp2 conditional knockout (Sp2-cKO) and wild-type (WT) cortices of tissue sections. This provided an integrated omics dataset which revealed many specific changes to fundamental cellular processes and biosynthetic pathways. In particular, step-specific altered abundances of nucleotides, lipids, and associated proteins were observed in the cerebral cortices of Sp2-cKO embryos.

Lipid Phosphate Phosphatases and Cancer

“…LPP1 can be induced by DAF-16, an orthologue of FOXO (class O forkhead box protein) transcription factors in Ancylostoma caninum [ 213 ]. The conditional knockout of SP2 in the mouse cerebral cortex leads to a decrease in LPP1 expression [ 214 ]. Oxidized low-density lipoprotein increases LPP3 expression in human macrophages through transcription factor C/EBPβ (CCAAT-enhancer-binding protein β) [ 215 ].…”

Establishment of a post‐race biomarkers database and application of pathway analysis to identify potential biomarkers in post‐race equine plasma

“…Omics approaches such as proteomics, 7,10,12,[22][23][24][25] genomics, [7][8][9]11,12,[22][23][24][26][27][28] and metabolomics 1,7,10,12,22,24,25,29,30 have often been used to identify suitable biomarkers. It might be difficult to apply proteomics approaches to horses because comprehensive protein databases for horses do not yet exist, and expressed proteins differ between humans and horses.…”

Infrared matrix-assisted laser desorption electrospray ionization mass spectrometry imaging analysis of biospecimens

“…IR-MALDESI is well suited for untargeted metabolite and lipid analysis of biospecimens, allowing researchers to better understand underlying biological factors in health and disease 46, 48 . Ionization by electrospray allows facile acquisition in either positive or negative mode.…”

“…Polarity switching MSI of cancerous vs. healthy ovarian tissue IR-MALDESI is well suited for untargeted metabolite and lipid analysis of biospecimens, allowing researchers to better understand underlying biological factors in health and disease. 46,48 Ionization by electrospray allows facile acquisition in either positive or negative mode. A strategy for repeated acquisition of both polarities in a spatially resolved manner was originally applied to the forensic analysis of fibres and dyes.…”