lipogênese

Lipogenesis refers to the biological process by which excess carbohydrates and proteins are converted into fatty acids and subsequently into triglycerides, which are stored as fat in the body. This metabolic pathway primarily occurs in the liver and adipose tissue, playing a crucial role in energy storage and homeostasis. The process is tightly regulated to balance energy intake and expenditure, ensuring that essential functions are not compromised by excessive fat accumulation.

The initial step in lipogenesis involves the conversion of excess glucose into acetyl-CoA through glycolysis and the citric acid cycle. Acetyl-CoA then enters the cytoplasm, where it is carboxylated by the enzyme acetyl-CoA carboxylase (ACC) to form malonyl-CoA. This reaction is the rate-limiting step and is highly regulated by nutritional status, hormonal signals, and enzymatic activity. The enzyme fatty acid synthase (FAS) then uses malonyl-CoA units to synthesize long-chain fatty acids through a series of condensation, reduction, and dehydration reactions.

Once synthesized, fatty acids are either incorporated into triglycerides for storage or used for membrane lipid synthesis. Triglycerides are formed by the esterification of glycerol-3-phosphate with three fatty acids, catalyzed by glycerol-3-phosphate acyltransferase and diacylglycerol acyltransferase. These triglycerides are then packaged into very low-density lipoproteins (VLDLs) for transport or stored in adipose tissue.

Lipogenesis is influenced by hormonal signals such as insulin, which promotes fat storage by activating ACC and FAS, while glucagon and catecholamines inhibit the process to mobilize stored fat during fasting or stress. Genetic and environmental factors, including diet and physical activity, also play significant roles in regulating lipogenesis and overall lipid metabolism. Dysregulation of this process can contribute to metabolic disorders such as obesity, diabetes, and cardiovascular diseases.