A lipidomics platform to analyze the fatty acid compositions of non-polar and polar lipid molecular species from plant tissues: Examples from developing seeds and seedlings of pennycress (Thlaspi arvense)

Constitutively active mTORC1 signaling modifies the skeletal muscle metabolome and lipidome response to exercise

A chronic increase in the Mammalian Target of Rapamycin Complex 1 (mTORC1) signaling is implicated in reduced longevity, altered metabolism, and mitochondrial dysfunction. Abnormal mTORC1 signaling may also be involved in the etiology of sarcopenia. To better understand the role of mTORC1 signaling in the regulation of muscle metabolism, we developed an inducible muscle-specific knockout model of DEP domain-containing 5 protein (DEPDC5 mKO), which results in constitutively active mTORC1 signaling. We hypothesized that constitutively active mTORC1 signaling in skeletal muscle would alter the metabolomic and lipidomic response to an acute bout of exercise. Wild-type (WT) and DEPDC5 muscle-specific knockout (KO) mice were studied at rest and following a 1 h bout of treadmill exercise. Acute exercise induced an increased reliance on glycolytic and pentose phosphate pathway (PPP) metabolites in the muscle of mice with hyperactive mTORC1. Lipidomic analysis showed an increase in triglycerides (TGs) in KO mice. Although exercise had a pronounced effect on muscle metabolism, the genotype effect was larger, indicating that constitutively active mTORC1 signaling exerts a dominant influence on metabolic and lipidomic regulation. We conclude that increased mTORC1 signaling shifts muscle metabolism toward greater reliance on nonoxidative energy sources in response to exercise. Understanding the mechanisms responsible for these effects may lead to the development of strategies for restoring proper mTORC1 signaling in conditions such as aging and sarcopenia.NEW & NOTEWORTHY This study demonstrates that hyperactive mTORC1 alters the muscle metabolomic and lipidomic response to exercise, with genotype having a larger effect than exercise. Knockout mice exhibited an increase in reliance on glycolysis and pentose phosphate pathway and an increase in triglyceride turnover. Wild-type mice primarily showed an increase in utilization of TCA cycle and lipid metabolism intermediates.

Metabolic flux analysis to increase oil in seeds

Ensuring an adequate food supply and enough energy to sustainably support future global populations will require enhanced productivity from plants. Oilseeds can help address these needs; but the fatty acid composition of seed oils is not always optimal, and higher yields are required to meet growing demands. Quantitative approaches including metabolic flux analysis can provide insights on unexpected metabolism (i.e. when metabolism is different than in a textbook) and can be used to guide engineering efforts; however, as metabolism is context specific, it changes with tissue type, local environment, and development. This review describes recent insights from metabolic flux analysis in oilseeds and indicates engineering opportunities based on emerging topics and developing technologies that will aid quantitative understanding of metabolism and enable efforts to produce more oil. We also suggest that investigating the key regulators of fatty acid biosynthesis, such as transcription factors, and exploring metabolic signals like phytohormones in greater depth through flux analysis could open new pathways for advancing genetic engineering and breeding strategies to enhance oil crop production.

Exploring the plant lipidome: techniques, challenges, and prospects

Plant lipids are a diverse group of biomolecules that play essential roles in plant architecture, physiology, and signaling. To advance our understanding of plant biology and facilitate innovations in plant-based product development, we must have precise methods for the comprehensive analysis of plant lipids. Here, we present a comprehensive overview of current research investigating plant lipids, including their structures, metabolism, and functions. We explore major lipid classes, i.e. fatty acids, glyceroglycolipids, glycerophospholipids, sphingolipids, and phytosterols, and discuss their subcellular distributions. Furthermore, we emphasize the significance of lipidomics research techniques, particularly chromatography-mass spectrometry, for accurate lipid analysis. Special attention is given to lipids as crucial signal receptors and signaling molecules that influence plant growth and responses to environmental challenges. We address research challenges in lipidomics, such as in identifying and quantifying lipids, separating isomers, and avoiding batch effects and ion suppression. Finally, we delve into the practical applications of lipidomics, including its integration with other omics methodologies, lipid visualization, and innovative analytical approaches. This review thus provides valuable insights into the field of plant lipidomics and its potential contributions to plant biology.

Recent Analytical Methodologies in Lipid Analysis

Lipids represent a large group of biomolecules that are responsible for various functions in organisms. Diseases such as diabetes, chronic inflammation, neurological disorders, or neurodegenerative and cardiovascular diseases can be caused by lipid imbalance. Due to the different stereochemical properties and composition of fatty acyl groups of molecules in most lipid classes, quantification of lipids and development of lipidomic analytical techniques are problematic. Identification of different lipid species from complex matrices is difficult, and therefore individual analytical steps, which include extraction, separation, and detection of lipids, must be chosen properly. This review critically documents recent strategies for lipid analysis from sample pretreatment to instrumental analysis and data interpretation published in the last five years (2019 to 2023). The advantages and disadvantages of various extraction methods are covered. The instrumental analysis step comprises methods for lipid identification and quantification. Mass spectrometry (MS) is the most used technique in lipid analysis, which can be performed by direct infusion MS approach or in combination with suitable separation techniques such as liquid chromatography or gas chromatography. Special attention is also given to the correct evaluation and interpretation of the data obtained from the lipid analyses. Only accurate, precise, robust and reliable analytical strategies are able to bring complex and useful lipidomic information, which may contribute to clarification of some diseases at the molecular level, and may be used as putative biomarkers and/or therapeutic targets.