. 2021 Sep 10;128(3):389–406. doi: 10.1017/S0007114521003524

Table 3.

The effects of in vivo PSI administration on the enzymes involved in lipid metabolism

Enzyme	Role	Effect of PSI	References
Hepatic lipase	Hydrolysis of triacylglyceride	Increased activity	⁽⁴⁸⁾
Hepatic CPT1	Catalyses the rate-limiting step in the β-oxidation of long-chain fatty acids	Increased expression or activity	^(41,71,73)
Hepatic ME	Catalyses conversion of malate to pyruvate, replenishing TCA cycle intermediates. Provides a source of NADPH for lipogenesis	Decreased activity	⁽⁷¹⁾
Hepatic G6PDH	Provides a source of NADPH for lipogenesis	Decreased activity	^{(65,68,71,73)}
ACC	Catalyses the committed step in fatty acid synthesis	Reduced expression	⁽⁴⁸⁾
FAS	Catalyses the synthesis of long-chain fatty acids	No significant difference in activity	⁽⁴¹⁾
FAS	Catalyses the synthesis of long-chain fatty acids	Decreased activity or expression	^{(41,48,68,71,76)}
Adipose tissue CPT1	Catalyses the rate-limiting step in the β-oxidation of long-chain fatty acids	Increased expression	⁽⁷¹⁾
HSL	Hydrolysis of long-chain fatty acids inhibited by insulin	Increased expression	^(41,48)
PAP	Catalyses the conversion of phosphatidate to diacylglycerol, regulates TAG synthesis	Decreased activity	^(68,73)
LPL	Hydrolyses TAG in lipoproteins	Decreased expression	⁽⁴¹⁾
ACAT	Catalyses key step in the mevalonate pathway, promotes cholesterol storage	Decreased activity	⁽⁷³⁾
PCSK9	Binds to LDL receptor, reducing LDL-R recycling	Lower serum level	⁽⁶¹⁾
HMGCR	Catalyses the rate-limiting step in cholesterol synthesis	Increased activity	⁽⁷³⁾

CPT, carnitine palmitoyltransferase; ME, malic enzyme; G6PDH, glucose 6-phosphate dehydrogenase; ACC, acetyl-CoA carboxylase; FAS, fatty acid synthase; HSL, hormone-sensitive lipase; PAP, phosphatidate phosphatase; LPL, lipoprotein lipase; ACAT, acetyl-co-enzyme A acetyltransferase; PCSK9, proprotein convertase subtilisin/kexin type 9; HMGCR, 3-hydroxy-3-methyl-glutaryl-co-enzyme A reductase.