Secretion of pre-beta-migrating apoA-I by cynomolgus monkey hepatocytes in culture.

Cynomolgus monkey hepatocytes that had been stored frozen were thawed, established in culture, and used to study apoA-I secretion. Protein synthetic activity was low at first, but increased with time, approaching what appeared to be the constitutive levels of the intact liver by day 7. During the first week, cellular RNA levels increased from 5.3 f 0.3 to 18.6 * 1.0 pg/106 cells; albumin secretion rates increased from undetectable to 55.4 pg/106 cells per day; apoA-I mRNA levels increased from 174 5 12 to 564 f 145 ng/106 cells; and apoA-I secretion rates increased from undetectable to 2.11 5 0.27 pg/106 cells per day. Analysis of day 7-conditioned media by agarose electrophoresis, gradient gel electrophoresis-immuno- blotting, and column chromatography, showed that the apoA-I produced by the cells was present in three distinct forms. One had an apparent molecular mass greater than 1 million Da, migrated pre-0, and accounted for 11 * 3 (mean * SD)% of the total; one had an apparent molecular mass of 104 kDa, had (Y migration, and accounted for 27 * 2% of the total; and one had an apparent molecular mass of 50 kDa, migrated pre-0, and accounted for 46 * 9% of the total. These data support the pro- position that the pre-0-migrating, 50 kDa, apoA-I-containing particles identified in the plasma of cynomolgus monkeys are nascent hepatic HDL.-Castle, C. K., M. E. Pape, K. R. Marotti, and G. W. Melchior. Secretion of pre-beta-migrating apoA-I by cynomolgus monkey hepatocytes in culture J Lipid Res. 1991. 32: 439-447.