title: Dab2, megalin, cubilin and amnionless receptor complex might mediate intestinal endocytosis in the suckling rat.
abstract: We previously proposed that Dab2 participates in the endocytosis of milk macromolecules in rat small intestine. Here we investigate the receptors that may mediate this endocytosis by studying the effects of age and diet on megalin, VLDLR, and ApoER2 expression, and that of age on the expression of cubilin and amnionless. Of megalin, VLDLR and ApoER2, only the megalin expression pattern resembles that of Dab2 previously reported. Thus the mRNA and protein levels of megalin and Dab2 are high in the intestine of the suckling rat, down-regulated by age and up-regulated by milk diet, mainly in the ileum. Neither age nor diet affect ApoER2 mRNA levels. The effect of age on VLDLR mRNA levels depends on the epithelial cell tested but they are down-regulated by milk diet. In the suckling rat, the intestinal expressions of both cubilin and amnionless are similar to that of megalin and megalin, cubilin, amnionless and Dab2 co-localize at the microvilli and in the apical endocytic apparatus. Co-localization of Dab2 with ApoER2 and VLDLR at the microvilli and in the apical endocytic apparatus is also observed. This is the first report showing intestinal co-localization of: megalin/cubilin/amnionless/Dab2, VLDLR/Dab2 and ApoER2/Dab2. We conclude that the megalin/cubilin/amnionless/Dab2 complex/es participate in intestinal processes, mainly during the lactation period and that Dab2 may act as an adaptor in intestinal processes mediated by ApoER2 and VLDLR.
authors.affiliation: Departamento de Fisiología, Facultad de Farmacia, Universidad de Sevilla, Spain.
authors.forename: María D
authors.initials: MD
authors.lastname: Vázquez-Carretero
authors.forename: Marta
authors.initials: M
authors.lastname: Palomo
authors.forename: Pablo
authors.initials: P
authors.lastname: García-Miranda
authors.forename: Inmaculada
authors.initials: I
authors.lastname: Sánchez-Aguayo
authors.forename: María J
authors.initials: MJ
authors.lastname: Peral
authors.forename: María L
authors.initials: ML
authors.lastname: Calonge
authors.forename: Anunciación A
authors.initials: AA
authors.lastname: Ilundain
mesh_terms: D033942:Adaptor Proteins, Vesicular Transport / Q000096:biosynthesis* / Q000378:metabolism; D000818:Animals; D000833:Animals, Suckling / Q000378:metabolism / Q000502:physiology; D004705:Endocytosis / Q000235:genetics; D005260:Female; D007421:Intestine, Small / Q000378:metabolism; D026502:LDL-Receptor Related Proteins / Q000378:metabolism; D007774:Lactation / Q000235:genetics / Q000378:metabolism; D026561:Low Density Lipoprotein Receptor-Related Protein-2 / Q000378:metabolism*; D008871:Microvilli / Q000648:ultrastructure; D011506:Proteins / Q000378:metabolism*; D012333:RNA, Messenger / Q000378:metabolism; D051381:Rats; D011956:Receptors, Cell Surface / Q000378:metabolism*; D011973:Receptors, LDL / Q000378:metabolism
chemical_list: D033942:Adaptor Proteins, Vesicular Transport; C527306:Amn protein, rat; C501404:Dab2 protein, rat; D026502:LDL-Receptor Related Proteins; D026561:Low Density Lipoprotein Receptor-Related Protein-2; D011506:Proteins; D012333:RNA, Messenger; D011956:Receptors, Cell Surface; D011973:Receptors, LDL; C036053:VLDL receptor; C029486:intrinsic factor-cobalamin receptor; C098773:low density lipoprotein receptor-related protein 8
keywords: AMNIONLESS; CUBILIN; Dab2; INTESTINE; MEGALIN