Volume 121, Issue 5, Pages 1101-1108 (November 2001) Apolipoprotein B48 glycosylation in abetalipoproteinemia and Anderson's disease  Nathalie Berriot-Varoqueaux, A.Hayssam Dannoura, Alain Moreau, Nicole Verthier, Agnès Sassolas, Guillaume Cadiot, Alain Lachaux, Anne Munck, Jacques Schmitz, Lawrence P. Aggerbeck, Marie-Elisabeth Samson-Bouma  Gastroenterology  Volume 121, Issue 5, Pages 1101-1108 (November 2001) DOI: 10.1053/gast.2001.29331 Copyright © 2001 American Gastroenterological Association Terms and Conditions

Fig. 1 Typical aspect of enterocytes of patients with Anderson's disease showing lipid accumulation. (A) Intestinal biopsies from patients show vacuolization and marked staining with Oil Red O when examined by light microscopy (magnification 1000×). (B) Electron microscopy of biopsies from patients shows the accumulation of large lipid droplets, free in the cytoplasm (labeled L), and smaller chylomicrons and very-low-density lipoprotein–sized particles (stars) in membrane-bound vesicles (labeled with white arrows, magnification 5500×). Gastroenterology 2001 121, 1101-1108DOI: (10.1053/gast.2001.29331) Copyright © 2001 American Gastroenterological Association Terms and Conditions

Fig. 2 Acquisition of apo B48–complex glycans in intestinal organ culture. Intestinal biopsies were metabolically labeled, and the addition of complex glycans of Golgi apparatus origin was assessed by treatment of the biopsy lysates (L), or the medium (M) with Endo H and Endo F in normal individuals (A–C), in the Anderson's disease subject, So.B. (C, lanes 4-6), and in the abetalipoproteinemic patient, S.J. (C, lanes 7-12). Densitometry of the electrophoretic patterns of (C, lane 2) a control normal individual and (C, lane 5) an Anderson's disease patient shows (D, left) the presence of 2 bands of identical mobilities in each case. Phosphorimager scans of a control normal subject (not shown) and of an abetalipoproteinemic patient (C, lane 8) show that the patient has a single band corresponding to band a, in the normal subject, and indicating a complete removal of all N-linked glycans (D, right). The horizontal scale of D, right, is compressed compared with that of D, left. Figure 2A and C, arrow a: apo B48 completely sensitive to the action of endo H and F. Figure 2Aand C, arrow b: apo B48 partially sensitive to the action of endo H, as a result of the presence of complex glycans. Figure 2B: n, number of studied subjects; ●, minimum value; ♦, maximum value; ■, mean value. Figure 2C and D: *, unidentified protein band. Gastroenterology 2001 121, 1101-1108DOI: (10.1053/gast.2001.29331) Copyright © 2001 American Gastroenterological Association Terms and Conditions

Fig. 3 Effect of BFA on apo B48–complex glycan acquisition. (A) Intestinal biopsies were metabolically labeled in the absence or the presence of BFA, and the addition of complex glycans was assessed by treatment of the biopsy with Endo H and Endo F. The Instant Imager scans of A, lanes 2 and 5, are shown in B. (C) After incubation of the enterocytes with BFA, the electron microscopy shows disruption of the Golgi network and accumulation of lipid-like particles in the endoplasmic reticulum (43,500×). Figure 3A, arrow a: apo B48 completely sensitive to the action of endos H and F. Figure 3A, arrow b: apo B48 partially sensitive to the action of endo H, caused by the presence of complex glycans. *, unidentified protein band. Gastroenterology 2001 121, 1101-1108DOI: (10.1053/gast.2001.29331) Copyright © 2001 American Gastroenterological Association Terms and Conditions

Fig. 4 Intracellular processing of intestinal Apo B. In the endoplasmic reticulum of normal individuals and of patients with Anderson's disease, apo B containing only high mannose glycans binds to lipid in an MTP-dependent step to form the first step particle. In a second step, in which the role of the MTP is not firmly established, the first step particle fuses with the apo B–free triglyceride-rich particle (second step particle) to form the nascent lipoprotein. The apo B acquires complex glycans in the Golgi apparatus. In contrast, in abetalipoproteinemia and in BFA-treated intestinal biopsies, apo B does not reach the Golgi apparatus, as shown by the absence of complex glycans. In Anderson's disease, apo B48 does reach the Golgi because it contains complex glycans. The disease is probably caused by a defect in the Golgi-basolateral transport mechanism. —, high mannose glucids; ■, complex glucids. Gastroenterology 2001 121, 1101-1108DOI: (10.1053/gast.2001.29331) Copyright © 2001 American Gastroenterological Association Terms and Conditions