Metabolism and Metabolomics by MRS

Abstract

The main use of MRS is for the assessment of metabolism in vivo; that is because it has the unique ability to monitor metabolism noninvasively without the use of ionizing radiation. In recent years MRS has also become widely used for metabolomics, the science that aspires to monitor the metabolomethe totality of small-molecule metabolites in an organism, a cell or a disease. This chapter discusses the properties of MRS that make it suitable for metabolomic studies and the reasons why they are mainly performed ex vivo, as well as the methods used for preparing samples, performing the MRS and analyzing the resulting data. Further sections discuss MRS detection of metabolic aspects of the common cellular processes apoptosis, necrosis and autophagy. A final section summarizes metabolic studies of some diseases by MRS: cancer, cardiovascular disease, neurological and neurodegenerative diseases, and muscle disease.

Robust detection of oncometabolic aberrations by 1H–13C heteronuclear single quantum correlation in intact biological specimens

“…MRS has the potential to address this challenge, but the utility of this technique (as 1D 1 H-MRS) is currently limited to the detection and quantification of unusually abundant metabolites, which are uninformative for the purposes outlined above. The 1D 1 H-MRS sequence is routinely employed in the clinic; however, it suffers from broadening of peaks and lack of specificity 29 . For example, in the case of 2-HG detection, it is difficult to differentiate chemical shifts of metabolites like 2-HG from similarly structured metabolites such as glutamine and glutamate.…”

“…Compared to the 1D 1 H spectrum of cells, the 2D 1 H-13 C HSQC spectrum is more resolved, facilitating the assignment of specific peaks to specific metabolites since each 2D HSQC peak is defined by chemical shift information in both 1 H and 13 C axes. For example, in 2D 1 H-13 C HSQC spectra of tumors, one can easily differentiate the lactate peak from the broad mobile lipid peak at (1.2 ppm, 30 ppm), which is elevated in high grade GBMs (necrosis) 29 , while these two peaks cannot be differentiated in 1D 1 H spectrum. We pioneer a phase-sensitive HSQC (HSQCETGPSISP3.2) pulse sequence to detect specific oncometabolite aberrations in biologically intact oncology samples for the purposes of precision oncology.…”

Robust detection of oncometabolic aberrations by1H-13C heteronuclear single quantum correlation in live cells and intact tumorsex-vivo

“…MRS has the potential to address this challenge, but the utility of this technique (as 1D 1 H MRS) is currently limited to the detection and quantification of unusually abundant metabolites, which are uninformative for the purposes outlined above. The 1D 1 H MRS sequence is employed routinely in the clinic; however, it suffers from broadening of peaks and lack of specificity 29 . For example, in the case of 2-HG detection, it is difficult to differentiate chemical shifts of metabolites like 2-HG from similarly structured metabolites such as glutamine and glutamate.…”

Magnetic Resonance Spectroscopy to Study Glycolytic Metabolism During Autophagy

“…In this chapter we will describe the technical details of how to measure endogenous cellular lactate and glucose in autophagic cells and tissues by 1 H-MRS, how to measure the rate of lactate secretion and glucose uptake in autophagic cells by 1 H-MRS as well as the measurement of the real-time exchange of 13 C-labelled pyruvate to lactate in cells by 13 C-MRS-DNP and the derivation of simple kinetic parameters from these measurements. The methods described here are generally applicable in cells and tissues to investigate cellular processes, cellular metabolism alternations following genetic perturbations or in disease state, as well as monitoring treatment response (Chung, Basetti & Griffiths, 2015; Chung & Griffiths, 2011).…”

“…Nevertheless MRS and MR spectroscopic imaging offer chemically specific analysis of metabolite concentrations in body fluids, cell or tissue extracts, intact tissues or in vivo. In combination with metabolomics and statistical methods such as Principle Component Analysis (PCA), MRS has become a widely used tool to measure a wide range of metabolites in cell extracts, whole cells or tissue biopsy samples (Beckonert, Keun, Ebbels, Bundy, Holmes, Lindon, et al, 2007; Chung, Basetti & Griffiths, 2015; Chung & Griffiths, 2011)). Furthermore the ability to perform metabolic imaging in vivo using MRS (de Graaf, 2007) and the translation of these techniques clinically in humans allows for the development of molecular biomarkers of response to therapeutics that act directly on metabolic enzymes and transporters or through the inhibition of cell signalling pathways that transcriptionally control and regulate metabolic enzymes.…”