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Editorial
, Volume: 19( 2)Lipid Metabolism: Pathways, Regulation, and Physiological Significance
Lipid metabolism encompasses the biochemical pathways responsible for the synthesis, breakdown, and utilization of lipids, which serve as essential energy sources, structural components of membranes, and signaling molecules. Key pathways include fatty acid synthesis, β-oxidation, triglyceride metabolism, cholesterol synthesis, and phospholipid turnover. Lipid metabolism is tightly regulated by enzymatic control, hormonal signaling, and nutritional status to maintain energy homeostasis and support physiological functions. This article provides an overview of lipid metabolic pathways, their regulation, and their significance in health and disease. Keywords: Lipid metabolism; Fatty acid synthesis; β-oxidation; Triglycerides; Cholesterol; Phospholipids; Lipoproteins; Hormonal regulation; Energy homeostasis; Metabolic diseases
Abstract
Lipid metabolism refers to the complex network of biochemical reactions that manage the synthesis, degradation, and utilization of lipids. Lipids are critical for energy storage, membrane structure, and cellular signaling. The major lipid classes include fatty acids, triglycerides, phospholipids, and sterols, each of which participates in essential cellular and physiological processes.Fatty acid metabolism involves two complementary pathways: synthesis and breakdown. Fatty acid synthesis occurs primarily in the cytoplasm and is catalyzed by fatty acid synthase complexes, converting acetyl-CoA and malonyl-CoA into long-chain fatty acids. These fatty acids can be esterified into triglycerides for storage in adipose tissue or incorporated into phospholipids for membrane biosynthesis. Fatty acid oxidation, or β-oxidation, occurs in the mitochondria and peroxisomes, where fatty acids are broken down into acetyl-CoA, generating NADH, FADH?, and ATP to meet energy demands, especially during fasting or prolonged exercise.Triglycerides serve as the primary storage form of energy, mobilized through lipolysis into glycerol and free fatty acids. Hormones such as insulin, glucagon, and epinephrine regulate the balance between lipid storage and mobilization. Insulin promotes lipid synthesis and storage, whereas glucagon and epinephrine stimulate lipolysis to provide energy substrates for other tissues.Cholesterol metabolism is central to membrane structure, steroid hormone synthesis, and bile acid production. Cholesterol can be synthesized de novo from acetyl-CoA through a multi-step pathway involving the rate-limiting enzyme Citation: Hiroshi Tanaka. Lipid Metabolism: Pathways, Regulation, and Physiological Significance. Biochem Ind J. 17(1):187. 1 © 2023 Trade Science Inc. www.tsijournals.com | December-2023 HMG-CoA reductase. Cellular cholesterol levels are regulated by feedback mechanisms, including transcriptional control of HMG-CoA reductase and uptake via low-density lipoprotein (LDL) receptors.Phospholipids, essential components of cellular membranes, are synthesized through glycerolipid pathways and can be remodeled via the Lands cycle to maintain membrane fluidity and signaling functions. Lipoproteins such as chylomicrons, very-low-density lipoprotein (VLDL), LDL, and high-density lipoprotein (HDL) facilitate lipid transport in the bloodstream, distributing energy and structural lipids to tissues while maintaining lipid homeostasis.Disruptions in lipid metabolism contribute to metabolic diseases such as obesity, type 2 diabetes, atherosclerosis, and non-alcoholic fatty liver disease (NAFLD). Excess lipid accumulation, altered lipoprotein profiles, or dysregulated fatty acid oxidation can impair energy balance and promote inflammation. Advances in lipidomics, molecular biology, and metabolic research have deepened understanding of lipid regulation, enabling the development of therapeutic interventions targeting lipid-associated disorders. Conclusion Lipid metabolism is a multifaceted network of pathways responsible for energy production, storage, membrane composition, and signaling. The interplay of fatty acid synthesis and oxidation, triglyceride metabolism, cholesterol synthesis, and phospholipid turnover ensures energy homeostasis and cellular function. Hormonal and enzymatic regulation maintains metabolic balance, while dysregulation contributes to metabolic disorders. Understanding lipid metabolism is critical for elucidating physiological processes, metabolic disease mechanisms, and the development of effective therapeutic strategies.
