Lipogenesis

What is lipogenesis?

The process of synthesizing triglycerides and fatty acids from smaller precursors

What are triglycerides and their structure?

What: Primary form of energy storage in animals

Structure: 3 fatty acids esterified to a glycerol backbone

Where does lipogenesis occur?

Liver and adipose tissue during fed state (after meal)

What are the 5 steps in lipogenesis?

• Glucose metabolism and acetyl-CoA production

• Cytoplasmic Acetyl-CoA formation

• Formation of Malonyl-CoA

• Fatty acid synthesis

• Triglyceride assembly

Triglyceride Assembly

• How are FA activated

  • Forms

• How is triglycerides formed

• How are TGs stored

How are FA activated: By CoA

• Forms: Fatty acyl-CoA

How is triglycerides formed: Glycerol-3-phosphate derived from glucose metabolism is esterified with fatty acyl-CoA

How are TGs stored: In lipid droplets within adipocytes or exported as VLDL from the liver

Regulation of Lipogenesis

• How is it activated?

Activated by:

• Insulin because it promotes

  • Acetyl-CoA carboxylase activity, glucose uptake and glycerol-3-phosphate availability

• High carbohydrate diets because it increases glycolysis and Acetyl-CoA availability

• Citrate since it is an allosteric activator of ACC

Regulation of Lipogenesis

• How is it inhibited?

Inhibited by:

• Glucagon and epinephrine due to cAMP-mediated phosphorylation and inhibition of ACC

• Long chain fatty acyl-CoA

The process

The process