Biological Functions of Lipids and Abnormalities of Lipid Metabolism

Lipid compounds have a wide variety of biological functions. They are an important constituent of cells, as a storage material for energy in living organisms, and can also participate in various cellular activities including material transport, energy metabolism, and information transfer.

With the development of lipidomic analysis techniques and the in-depth study of lipid metabolism, it is increasingly recognized that many physiological diseases are closely related to abnormal lipid metabolism. Lipids play an important role in disease generation, development, and treatment. The use of lipidomics to study the relationship between changes in lipid metabolic network and disease states at the systemic level, to find potential biomarkers, and to evaluate the efficacy of new drugs has become a new development direction.

Biological functions of lipids

1. Involved in cell composition

Lipid compounds can be used as cellular constituents, the most important of which is as structural components of cell membranes. The phospholipid bilayer consisting of glycerophospholipids is the basic backbone of the cell membrane. Glycerophospholipid molecules are amphiphilic, i.e. hydrophobic (fatty acyl chain tail) at one end and hydrophilic (polar head) at the other. In addition, sphingolipids are also important structural components of cell membranes.

In the stratum corneum of the skin, ceramides, cholesterol and fatty acids are the main constituents, with ceramides being the highest, which can exceed 50%. Together, these lipid compounds in certain proportions form the barrier between the skin and the outside world.

2. Involved in energy storage

Energy storage is the primary function of triglycerides. Triglycerides, in particular, are the main form of compounds in which the body stores energy in fat cells. When the body needs energy supply, triglycerides can be catalyzed by enzymes to form glycerol and fatty acids, which are further oxidized to release energy to meet the body's needs.

3. Involved in cellular life activities

Lipid compounds are closely related to a variety of cellular life activities. Sphingolipid compounds can act as cytokines and play an important role in the inflammatory response. Many lipid compounds or their metabolites can act as second messengers to regulate cellular functions and influence cell growth and apoptosis. Some lipid compounds can form a barrier between humans and the external environment, with functions such as water locking, moisturizing and protection. Other lipid compounds bind to sugars or proteins to form glycolipids or lipoproteins, which perform unique biological functions.

Abnormal lipid metabolism and disease

Abnormal lipid metabolism is closely associated with a variety of diseases.

Central nervous system (CNS)-related diseases

Abnormal lipid metabolism is an important factor in causing CNS injury. A variety of CNS-related diseases are closely related to lipid metabolism disorders, such as cerebral ischemia, vascular dementia (VD), and Alzheimer's disease. Nakane M et al. found that neuroacylcholine (SM) levels decreased and ceramide levels increased in the hippocampus of a rat model of transient forebrain ischemia. In human patients with Alzheimer's disease and cerebral ischemia, fatty acids, especially polyunsaturated fatty acids (PUFA), are strongly associated with disease status.

Cardiovascular diseases

High-density lipoprotein (HDL) removes cholesterol, while low-density lipoprotein (LDL) tends to accumulate cholesterol in the artery walls. The levels of these two types of compounds are closely related to atherosclerosis. Sphingolipids may be involved in regulating the interaction between LDL and arterial smooth muscle cells, and thus may aid in the treatment of cardiovascular diseases such as atherosclerosis and cardiomyopathy by regulating sphingolipid synthase.

Other diseases such as obesity, diabetes, and tumors are closely related to abnormal lipid metabolism.

Fig. 1 Lipid droplets as players in hallmarks of cancer (Cruz et al., 2020).

Creative Proteomics has extensive experience in lipidomics analysis. Based on advanced mass spectrometry and chromatography platforms, we can help our customers with lipidomics analysis and facilitate basic research.

Reference:

1. Cruz, A. L., Barreto, E. D. A., et al. (2020). Lipid droplets: platforms with multiple functions in cancer hallmarks. Cell death & disease, 11(2), 1-16.