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Abstract The fatty acids regulate gene expression directly binding to nuclear receptors or affecting the protein content of transcription factors. In this work, supplementing primary cultures of neonatal rat cardiomyocytes with 60 µM EPA or DHA, we demonstrated by an ELISA assay an increased PPAR β/δ binding to DNA. n-3 PUFA supplementation deeply changed the acyl composition of both cytosolic and nuclear fractions. The high content of total fatty acids, particularly EPA and DHA, and its increase following supplementation suggested a selective accumulation of n-3 PUFAs in the nucleus, supporting the direct interaction of n-3 PUFA with PPAR. The activity of acyl-CoA thioesterase (ACOT), catalyzing the reaction leading to NEFA from acyl-CoA, increased in n-3 PUFA supplemented cells. The NEFA/acyl- CoA ratio is an important regulator of the fatty acid transport to the nucleus and consequent modulation of gene transcription, and although ACOT activity is not the only parameter of this ratio, it is important for the control of the NEFA pool composition. Our data further clarify what happens in cardiomyocytes following n-3 PUFA supplementation, linking the modification of acyl composition to ACOT activity and PPAR activation.
Keywords EPA * DHA * PPAR * Acyl-CoA thioesterase * Neonatal rat cardiomyocytes
Abbreviations
ACOT Acyl-CoA thioesterase
A-FABP Adipocyte fatty acid binding protein
B23 Nucleophosmin
BSA Bovine serum albumin
CF Cytoplasmic fraction
ChREBP Carbohydrate response element-binding protein
CVD Cardiovascular diseases
DHA Docosahexaenoic acid
DPA Docosapentaenoic acid
DTNB 5,5'-Dithiobis(2-nitrobenzoic acid)
EPA Eicosapentaenoic acid
FA Fatty acid
FABP Fatty acid binding protein
FCS Fetal calf serum
HNF-4α Hepatocyte nuclear factor 4α
HRP Horseradish peroxidase
HS Horse serum
K-FABP Keratinocyte FABP
LXR Liver X receptors
MEK1 Mitogen-activated protein kinase/ extracellular signal-regulated kinase 1
NEFA Nonesterified fatty acid
NF Nuclear fraction
NF kappa B Nuclear factor kappa B
PPAR Peroxisome proliferator activated receptor
PPRE Peroxisome proliferator responsive element
PUFA Polyunsaturated fatty acid
RXR Retinoid X receptor
SREBP Sterol regulatory element-binding protein
TNB 2-Nitro-5-thiobenzoic acid
WCL Whole cell lysate
Introduction
The role of nutrition in the management of diseases has often centered on correcting apparent nutrient deficiencies or meeting estimated nutritional requirements of patients. Recently, further understanding of the underlying mechanisms of various disease processes and how certain nutrients possess pharmacological properties have fueled an interest in exploring how nutritional therapies themselves...