2.1 lipogenesis

lipogenesis involves both imported and newly synthesised nefa

which act as a substrate for conversion into stored TAG droplets which are further stabalised by associating with perilipin to form storage depot

lipogenesis occurs primarily in the liver and adipose tissue

• hepatic lipogenesis

• adipose tissue lipogenesis

hepatic lipogenesis

this process is central to hepatic lipid metabolism and maintaining lipid homeostasis  it contributes to the synthesis of cholestrol and thus cholesterol metabolism

adipose tissue lipogenesis

adipose tissue specialises in the storage of triglycerises playying a vital role in regulating lipid balance and energy storage excess fat accumulation can lead to conditions like insulin resistance and obesity

the biochemicla pathways comprising lipogenesis

• de novo fatty acid synthesis

• trigylceride formation

• de novo fatty acid synthesis

primatily occuring in the liver and adipose tissue as a multistep process involding fatty acid synthesis FAS which catalyses a serious of reactions

that convert acetyl CoA into long chain fatty acids and acetyle CoA carboxylase

catalyses the carbocylation of acetyl-CoA to form malonyl CoA

• triglyceride formation

essential for storing excess calories from excessively high carbohydrate or high fat diet in the form of fat

fatty acids are esterified with glycerol resulting in the formation of triglycerides

these molecules are stored in adipose tissue and can be mobilized when th e body requires additional energy serving a crucial role in maintaining metabolic homeostasis

in the rpesence of high insuling levels

lipogenisis predominates over lypolysis

insulin induces a cascade of reactions that lead to the reduciton of cAMP levels

slowing dow lypolysis and inducing lypogenesis

this ensurea lypolysis and lypogenesis dont occur at the same time

insulin also stimulates pyruvate dehydrogenase phosphatase that removes phosphate from pyruvate dehydrogenase

activating the latter to convery pyruvate to acetyle CoA

the acetyke CoA is carboxylated to form malonly CoA through the action of actyle CoA carboxylase

The malonyl-CoA plays a role in the chain elongation in fatty acid biosynthesis.

the liver cells release of triglycerides in the for of very low density lipoproteins VLDL

into the bloodstream

growth hormones inhibits lypogenesis by interfering with the expression and activity of key enzymes for lipogenesis

like FAS

acetyl CoA  carboxylase

growht hormones alsor educe insuling sensitivity

especialy in the liver and the adipose tissue while stimulating lipolysis

by increasing lypolysis GH metabolise stored triglycerise for energy utilisation

opposing the enrgy storage role of lypogenesis