In situ imaging reveals disparity between prostaglandin localization and abundance of prostaglandin synthases

Abstract

Prostaglandins are important lipids involved in mediating many physiological processes, such as allergic responses, inflammation, and pregnancy. However, technical limitations of in-situ prostaglandin detection in tissue have led researchers to infer prostaglandin tissue distributions from localization of regulatory synthases, such as COX1 and COX2. Herein, we apply a novel mass spectrometry imaging method for direct in situ tissue localization of prostaglandins, and combine it with techniques for protein expression and RNA localization. We report that prostaglandin D2, its precursors, and downstream synthases co-localize with the highest expression of COX1, and not COX2. Further, we study tissue with a conditional deletion of transformation-related protein 53 where pregnancy success is low and confirm that PG levels are altered, although localization is conserved. Our studies reveal that the abundance of COX and prostaglandin D2 synthases in cellular regions does not mirror the regional abundance of prostaglandins. Thus, we deduce that prostaglandins tissue localization and abundance may not be inferred by COX or prostaglandin synthases in uterine tissue, and must be resolved by an in situ prostaglandin imaging.

Identification and Imaging of Prostaglandin Isomers Utilizing MS3 Product Ions and Silver Cationization

“…Thin tissue sections on regular glass slides from uterine implantation sites were obtained from Trp53 d/d mice on the eighth day of pregnancy and used after longer time storage in −80 °C freezer. 36 Training and Validation of Prediction Model. For model training and testing, standard solutions of PGE 2 , PGD 2 , and Δ12-PGD 2 , at various proportions (Table S1), were prepared and analyzed using flow injection analysis (FIA).…”

“…Flash frozen brain from healthy rats (Sprague–Dawley) was purchased from Innovative Research Inc. (Novi, MI, USA) and was used for creating a rat brain extract (RBE) that served as a complex sample (see Supporting Information for details). Thin tissue sections on regular glass slides from uterine implantation sites were obtained from Trp53 d/d mice on the eighth day of pregnancy and used after longer time storage in −80 °C freezer …”

Experimental Assessment of Mammalian Lipidome Complexity Using Multimodal 21 T FTICR Mass Spectrometry Imaging

“…While MALDI remains the dominant source for molecular MSI studies, an increasing array of ambient ionization sources have become commonplace, including desorption electrospray ionization (DESI), ,− nano-DESI, ,,− and laser ablation electrospray ionization (also called infrared matrix-assisted desorption electrospray ionization). ,− Multimodal imaging strategies have recently been demonstrated to offer highly complementary information. ,,, The use of additional modalities has become increasingly routine and often provides the necessary orthogonal information to extract deeper biological meaning . However, the levels of complexity that are obtained by each mode of MSI are yet to be fully benchmarked and investigated.…”

Integrating the potential of ion mobility spectrometry-mass spectrometry in the separation and structural characterisation of lipid isomers

“…The incorporation of the IMS-MS dimension into lipidomic workflows typically focuses on three main applications: 1) improving confidence in lipid annotation by providing mobility information of an ion as an additional descriptor ( Zhang et al, 2015 ; Leaptrot et al, 2019 ); 2) reducing the complexity of mass spectra by signal filtering; and 3) enhancing the resolution of isomeric lipid species ( Kliman et al, 2011 ; Dodds and Baker, 2019 ; Paglia et al, 2021 ). Accordingly, IMS-MS has been applied to the study of a large number of lipid classes ( Damen et al, 2014 ; Jónasdóttir et al, 2015 ; Kyle et al, 2016 ; 2018 ; Cole et al, 2020 ; Davis et al, 2021 ; Duncan et al, 2021 ).…”