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Pinolenic Acid Downregulates Lipid Anabolic Pathway in HepG2 Cells

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Lipids

Abstract

Pine nut oil (PNO) was reported to reduce lipid accumulation in the liver. However, the specific effect of pinolenic acid (18:3, all-cis-Δ5,9,12), a unique component of PNO, on lipid metabolism has not been studied. We hypothesized that pinolenic acid downregulates the lipid anabolic pathway in HepG2 cells. HepG2 cells were incubated in serum-free medium supplemented with 50 μM bovine serum albumin (BSA), palmitic acid, oleic acid, γ-linolenic acid, pinolenic acid, eicosapentaenoic acid (EPA), or α-linolenic acid for 24 h. Lipid accumulation was determined by Oil Red O (ORO) staining. The mRNA levels of genes related to fatty acid biosynthesis (SREBP1c, FAS, SCD1, and ACC1), fatty acid oxidation (ACC2, PPARα, CPT1A, and ACADL), cholesterol synthesis (SREBP2 and HMGCR), and lipoprotein uptake (LDLr) and of genes that may be involved in the downregulation of the lipogenic pathway (ACSL3, ACSL4, and ACSL5) were determined by qPCR. LDLR protein levels were measured by Western blot analysis. The mRNA levels of SREBP1c, FAS, and SCD1 were significantly downregulated by pinolenic acid treatment compared to BSA control (53, 54, and 38 % lower, respectively). In addition, the mRNA levels of HMGCR, ACSL3, and LDLr were significantly lower (30, 30, and 43 % lower, respectively), and ACSL4 tended to be lower in the pinolenic acid group (20 % lower, P = 0.082) relative to the control group. In conclusion, pinolenic acid downregulated the lipid anabolic pathway in HepG2 cells by reducing expression of genes related to lipid synthesis, lipoprotein uptake, and the regulation of the lipogenic pathway.

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Abbreviations

ACADL:

Acyl-CoA dehydrogenase long chain

ACC:

Acetyl-CoA carboxylase

ACSL:

Long chain acyl coenzyme A synthase

ARA:

Arachidonic acid

BSA:

Bovine serum albumin

CPT1A:

Carnitine palmitoyl transferase 1

DHA:

Docosahexaenoic acid

EPA:

Eicosapentaenoic acid

FAS:

Fatty acid synthase

HMGCR:

3-Hydroxy-3-methyl-glutaryl-CoA reductase

LDL:

Low density lipoprotein

LDLr:

Low density lipoprotein receptor

OLA:

Oleic acid

PAM:

Palmitic acid

PNA:

Pinolenic acid

PNO:

Pine nut oil

PPARα:

Peroxisome proliferator-activated receptor alpha

PUFA:

Polyunsaturated fatty acid

SCD1:

Stearoyl-CoA desaturase 1

SREBP:

Sterol regulatory element-binding protein

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Acknowledgments

This work was supported by Basic Science Research Program through the National Research Foundation of Korea funded by the Ministry of Education (Grant Number NRF-2010-0024878).

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Authors and Affiliations

  1. Department of Food and Nutrition, College of Human Ecology, Seoul National University, 1 Gwanak-ro, Gwanak-gu, Seoul, 08826, Korea

    Ah Ron Lee & Sung Nim Han

  2. Research Institute of Human Ecology, College of Human Ecology, Seoul National University, Seoul, Korea

    Sung Nim Han

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  1. Ah Ron Lee
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Correspondence to Sung Nim Han.

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Lee, A.R., Han, S.N. Pinolenic Acid Downregulates Lipid Anabolic Pathway in HepG2 Cells. Lipids 51, 847–855 (2016). https://doi.org/10.1007/s11745-016-4149-6

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  • DOI: https://doi.org/10.1007/s11745-016-4149-6

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