Hepatic Lipid Composition and Stearoyl-Coenzyme A Desaturase 1 mRNA Expression Can Be Estimated from Plasma VLDL Fatty Acid Ratios

Abstract

BACKGROUND:Stearoyl-coenzyme A desaturase 1 (SCD1) catalyzes the limiting step of monounsaturated fatty acid synthesis in humans and is an important player in triglyceride generation. SCD1 has been repeatedly implicated in the pathogenesis of metabolic and inflammatory diseases. Therefore it is of great importance to determine SCD1 activity in human samples. In this study we aimed to evaluate a hepatic SCD1 activity index derived from plasma VLDL triglyceride composition as a tool to estimate hepatic SCD1 expression in humans. Additionally, we further evaluated commonly used fatty acid ratios [elongase, de novo lipogenesis, and ⌬5 and ⌬6 desaturase] in plasma VLDL and hepatic lipid fractions.

The Δ9 Fatty Acid Desaturation Index as a Predictor of Metabolic Disease

“…Thus, when whole plasma fatty acid ratios from hyperlipidemic patients are analyzed, the increased TG content, and not necessarily a change in SCD activity, may yield an apparently higher 16:1n7/ 16:0 or 18:1n9/18:0 ratio simply because of the higher molar percentage of 16:1n7 and 18:1n9 found in the TG fraction relative to other lipid classes (14 ). This salient point is also conveyed by Peter et al, who show that the 16:1n7/16:0 and 18:1n9/18:0 ratios differ remarkably between liver lipid classes (8 ). One effect of hepatic insulin resistance is an increase in VLDL-TG production (2, 7 ).…”

“…These intracellular TG stores are used by the liver to assemble a TG-rich VLDL particle, which is secreted into the circulation during both the fed and fasted states (7 ). In this issue of Clinical Chemistry, Peter et al report the results of simultaneous analysis of the fatty acid composition of defined lipid fractions in human liver and plasma VLDL, as well as the determination of liver lipogenic gene expression (8 ). The authors first set out to determine whether hepatic stearoyl-CoA desaturase (delta-9-desaturase) (SCD) 3 gene expression correlates with the fatty acid composition of hepatic TG, diacylglycerols (DG), FFA, cholesterol ester (CE), and phospolipid (PL).…”

Insulin resistance: the conflict between biological settings of energy metabolism and human lifestyle (a glance at the problem from evolutionary viewpoint)

“…При нокауте у мышей гена стеарил-КоА-десатуразы содержание олеиновой ЖК в ТГ в тканях снижается, активируются параме-тры β-окисления митохондриями скелетных миоцитов, возрастает потребление энергии и синтез de novo цера-мидов [20]. У здоровых людей высокая активность стеа-рил-КоА-десатуразы коррелирует с низким содержанием жира в печени [21], и наблюдается позитивная корреля-ционная зависимость между содержанием в гепатоцитах мРНК стеарил-КоА-десатуразы и величиной отношения С18:1/С18:0 в ТГ в составе липопротеидов очень низ-кой плотности (ЛПОНП) плазмы крови [22]. У людей с ожирением и жировой дистрофией печени, напротив, наблюдается низкая экспрессия печеночной стеарил-КоА-десатуразы, ассоциированная с резистентностью к инсулину [23].…”

Efficacy of Habitual Exercise for Improving Lipid Profiles Depends on the PPRA^|^gamma; Genotype in Japanese Males

“…In human studies, fatty acid product : precursor ratios in adipose tissue and various blood lipid fractions have been used to investigate the association between SCD1 and the risk of a number of diseases (10). The expression of SCD1 mRNA can be estimated from the fatty acid ratios in plasma and liver lipid fractions (11). Here, we also analyzed the association between estimated SCD1 levels and PPARg variants.…”