Figure 9.

Carboxypeptidase-M (CPM) upregulation is mediated by lipids including low-density lipoprotein (LDL). (a) mRNA levels of CPM in differentiating macrophages (MAs) after 24-h treatments with LDL or oxidized LDL (oxLDL). Data (n=3) are plotted as ratios of the transcripts relative to cyclophilin expression. Error bars indicate the s.d. of the relative expression. ^*P<0.03, compared with the respective control value of cells kept in 10% fetal bovine serum (FBS), only. As shown, supplementation of 10% FBS with LDL, but not oxLDL, resulted in a significant CPM upregulation. (b–c) IF-stained MAs show no upregulation in CPM-protein expression when serum-depleted (0.5% FBS) culture medium is used (b), as opposed to normal elevated CPM level in cells (red fluorescence) kept in 10% FBS-containing medium (c). (d) In separate experiments (n=3) using cells obtained from other donors, MAs were maintained in either 1% FBS or charcoal-stripped serum (CCSS) for 24 h, instead of 10% FBS (control). As indicated in this figure, the CPM transcript remained significantly downrepresented (^*P<0.05) in both cases; however, when CCSS was supplemented with 20 μg/ml LDL, the CPM upregulation return to high levels, comparable with differentiating control cells kept in 10% FBS. Original magnification for immunofluorescence (IF) images with 4′-6-diamidino-2-phenylindole (DAPI) nuclear counterstain (blue): × 40.