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High density lipoprotein promotes nascent apolipoprotein A-V secretion from mRNA transfected cells

Romenskaia, Irina, DeAntonis, Christine M., Presnyak, Vladimir, Schultz, Joshua R., Ryan, Robert O.
Biochemical and biophysical research communications 2019 v.512 no.2 pp. 387-391
apolipoprotein A, culture media, fetal bovine serum, high density lipoprotein, human cell lines, messenger RNA, secretion, signal peptide, transfection, triacylglycerols
Despite its exceptionally low circulating concentration, apolipoprotein (apo) A-V is a potent modulator of plasma triacylglycerol levels. The secretion efficiency of nascent apoA-V was investigated in cultured cells transfected with mRNA. Following transfection of HepG2 cells with wild type apoA-V mRNA, apoA-V protein was detectable in cell lysates by 6 h. At 24 h post transfection, evidence of apoA-V secretion into media was obtained, although most apoA-V was recovered in the cell lysate fraction. By contrast, apoA-I was efficiently secreted into the culture medium. A positive correlation between culture medium fetal bovine serum content and the percentage of apoA-V recovered in conditioned media was observed. When transfected cells were cultured in serum-free media supplemented with increasing amounts of high density lipoprotein, a positive correlation with apoA-V secretion was observed. The data indicate that, following signal sequence cleavage, the bulk of nascent apoA-V remains cell associated. Transit of nascent apoA-V out of cultured cells is enhanced by the availability of extracellular lipid particle acceptors.