Fig. 2.

Intracellular PCSK9 content in Caco-2 cells decreases with cell maturation. Differentiated Caco2 cells at d8 and at d16 were recovered after a 2-h secretion assay, and intracellular proteins were extracted from cells. A: Intracellular PCSK9 content (ng extracted from cells) in samples from six independent experiments were measured by ELISA. B: Intracellular pro-PCSK9, PCSK9 and β-actin contents were analyzed by WB. Representative images from three independent experiments are shown (left panel). Pro-PCSK9 and PCSK9 contents relative to b-actin content from seven independent experiments are shown (right panel). C: Cells lysates were denatured and incubated 3 h at 37°C in presence or not of endoH or PNGase F enzymes, followed by WB for PCSK9. Bands corresponding to undigested Pro-PCSK9 (Pro-PCSK9), undigested PCSK9 (PCSK9), digested PCSK9 (Dig-PCSK9), and digested Pro-PCSK9 (Dig-Pro-PCSK9) by enzymes are indicated. One representative result from two independent experiments is shown. Histograms represents the median ± interquartile. ∗P value< 0.05, ∗∗∗P value <0.001. PCSK9, proprotein convertase subtilisin/kexin type 9; WB, Western blot.