Department of Biochemistry and Molecular Biology, University of Nevada, Reno, NV, 89557, USA.
Moderna, Inc., 200 Technology Square, Cambridge, MA, 02139, USA.
Biochem Biophys Res Commun. 2019 Apr 30;512(2):387-391. doi: 10.1016/j.bbrc.2019.03.087. Epub 2019 Mar 20.
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.
尽管载脂蛋白 (apo) A-V 的循环浓度极低，但它是一种有效的血浆三酰甘油水平调节剂。本研究采用转染 mRNA 的方法在培养细胞中研究新生 apoA-V 的分泌效率。用野生型 apoA-V mRNA 转染 HepG2 细胞后，6 h 即可在细胞裂解物中检测到 apoA-V 蛋白。转染 24 h 后，apoA-V 分泌到培养基中的证据被获得，尽管大多数 apoA-V 被回收在细胞裂解物部分。相比之下，apoA-I 被有效地分泌到培养基中。观察到培养基胎牛血清含量与条件培养基中回收的 apoA-V 百分比之间呈正相关。当转染的细胞在补充有不同浓度高密度脂蛋白的无血清培养基中培养时，apoA-V 的分泌呈正相关。这些数据表明，在信号序列切割后，大部分新生 apoA-V 仍与细胞相关。新生 apoA-V 从培养细胞中逸出的过程是由细胞外脂质颗粒受体的可用性增强的。
