Lipids

, Volume 41, Issue 11, pp 1017–1027

Characterization of scavenger receptor class B, type I in Atlantic salmon (Salmo salar L.)

Authors

  • E. J. Kleveland
    • Department of Pharmaceutical Biosciences, School of PharmacyUniversity of Oslo
  • B. L. Syvertsen
    • Department of Pharmaceutical Biosciences, School of PharmacyUniversity of Oslo
  • B. Ruyter
    • AKVAFORSKInstitute of Aquaculture Research
  • A. Vegusdal
    • AKVAFORSKInstitute of Aquaculture Research
  • S. M. Jørgensen
    • Department of Pharmaceutical Biosciences, School of PharmacyUniversity of Oslo
    • Department of Pharmaceutical Biosciences, School of PharmacyUniversity of Oslo
Articles

DOI: 10.1007/s11745-006-5052-3

Cite this article as:
Kleveland, E.J., Syvertsen, B.L., Ruyter, B. et al. Lipids (2006) 41: 1017. doi:10.1007/s11745-006-5052-3

Abstract

The scavenger receptor class B, type I (SR-BI) is an important player in regulation of mammalian lipid homeostasis. We therefore wanted to study this receptor in Atlantic salmon (Salmo salar L.), which requires a diet with particular high lipid content. We have for the first time cloned and characterized SR-BI from a salmonid fish. The predicted 494 amino acid protein contained two transmembrane domains, several putative N-glycosylation sites, and showed 72% sequence identity with the predicted homolog from zebrafish. SR-BI expression was analyzed by reverse transcription Real-Time PCR in several tissues, and a high relative expression in salmon midgut was detected, which may suggest that SR-BI has a role in uptake of lipids from the diet. We also expressed a construct of salmon myc-tagged SR-BI in salmon TO cells and HeLa cells, which gave a protein of approximately 80 kDa on reducing SDS-PAGE using an antibody against the myc-epitope. Immunofluorescence microscopy analyses of the salmon SR-BI protein in transiently transfected HeLa cells revealed staining in the cell periphery and in some intracellular membranes, but not in the nucleus, which indicated that the salmon protein may be a functional membrane protein. We also observed a high degree of co-localization using an anti-peptide SR-BI antiserum. We found that 20 μg mL−1 insulin up-regulated the SR-BI mRNA levels in primary cultures of salmon hepatocytes relative to untreated cells. Oleic acid, EPA, DHA, or dexamethasone did not affect the relative expression of SR-BI in this liver model system. In conclusion, the salmon SR-BI cDNA encoded a protein with several features common to those of mammalian species. SR-BI gene expression was high in the intestine, which leads us to propose that SR-BI may contribute to the uptake of lipids from the diet.

Abbreviations

aa

amino acid

AB

antibody

BSA

bovine serum albumin

CLA-1

CD36 and LIMPII analogous-1

D

dermis

Dex

dexamethasone

DHA

docosahexaenoic acid

EF1A

elongation factor 1 alpha

EPA

eicosapentaenoic acid

FA

fatty acid

FBS

fetal bovine serum

G

gills

H

heart

HDL

high-density lipoprotein

HG

hindgut

HK

head kidney

Ins

insulin

L

liver

LDL

low-density lipoprotein

MG

midgut

nt

nucleotides

OA

oleic acid

ORF

open reading frame

PBS

phosphate buffered saline

PPAR

peroxisome proliferator-activated receptor

PUFA

polyunsaturated FA

RACE

rapid amplification of cDNA ends

REST

relative expression software tool

S

spleen

SR-BI/II/III

scavenger receptor class B, type I/II/III

SDS-PAGE

sodium dodecyl sulfate polyacrylamide gel electrophoresis

TAG

triacylglycerol

UTR

untranslated region

VLDL

very low-density lipoprotein

Copyright information

© AOCS Press 2006