Synthesis and accumulation of a receptor regulatory protein associated with lipid droplet accumulation in 3T3-L1 cells.
Synthesis and accumulation of the recently identified prostaglandin F2alpha receptor regulatory protein (FPRP) was found to correlate closely with lipid droplet accumulation by 3T3-L1 preadipose cells. FPRP, a transmembrane glycoprotein, has been shown to regulate the binding of ligand to certain seven-transmembrane receptors. Anti-FPRP immunohistochemistry, Western blotting, and metabolic labeling/immunoprecipitation experiments demonstrated that FPRP was not detectable in undifferentiated 3T3-L1 cells. Interestingly, low levels of FPRP mRNA were detected in the undifferentiated 3T3-L1 cells. After induction of adipose differentiation, FPRP mRNA increased approximately 3 fold whereas FPRP synthesis increased approximately 50 fold. Differentiation induction with either dexamethasone/insulin/isobutylmethylxanthine or the thiazolidinedione derivative ADD 4743 were both effective at inducing FPRP accumulation and accumulation of lipid droplets. By co-immunohistochemical and lipid staining, greater than 99% of the cells accumulating lipid droplets possessed FPRP. FPRP mRNA and protein are also found in rat adipose tissue. Treatment of 3T3-L1 cells with an FPRP anti-sense oligonucleotide during differentiation decreased FPRP accumulation and resulted in a decrease in lipid droplets without altering the level of induction of a late marker of adipocyte differentiation, glycerol-3-phosphate dehydrogenase activity. Transient expression of an FPRP cDNA in undifferentiated 3T3-L1 cells was insufficient to induce lipid droplet accumulation.
Orlicky
D J
DJ
Department of Pathology, University of Colorado Health Sciences Center, Denver 80262, USA.
Lieber
J G
JG
Morin
C L
CL
Evans
R M
RM
D016475:3T3 Cells; D017667:Adipocytes / Q000166:cytology / Q000378:metabolism*; D000818:Animals; D001483:Base Sequence; D002454:Cell Differentiation; D017931:DNA Primers; D051379:Mice; D009363:Neoplasm Proteins; D016376:Oligonucleotides, Antisense / Q000494:pharmacology; D016133:Polymerase Chain Reaction; D014176:Protein Biosynthesis; D011506:Proteins / Q000378:metabolism; D012333:RNA, Messenger / Q000096:biosynthesis; D051381:Rats; D011982:Receptors, Prostaglandin / Q000096:biosynthesis; D011994:Recombinant Proteins / Q000096:biosynthesis / Q000378:metabolism; D013997:Time Factors; D014158:Transcription, Genetic; D014162:Transfection
D017931:DNA Primers; D009363:Neoplasm Proteins; D016376:Oligonucleotides, Antisense; D011506:Proteins; C104480:Ptgfrn protein, rat; D012333:RNA, Messenger; D011982:Receptors, Prostaglandin; D011994:Recombinant Proteins