Expression and distribution of distinct variants of E-MAP-115 during proliferation and differentiation of human intestinal epithelial cells.
Epithelial cell proliferation and differentiation occur concomitant with striking remodeling of the cytoskeleton. Microtubules (MTs) play important roles in these processes, during which the MTs themselves are reorganized and stabilized by microtubule-associated proteins (MAPs). Among the proteins classified as structural MAPs, E-MAP-115 (also named ensconsin) is preferentially expressed in cells of epithelial origin. The aims of this study were, first, to determine if E-MAP-115, like other MAPs, is expressed as different isoforms during differentiation and, second, to perform a detailed analysis of the expression and distribution of any E-MAP-115 variants detected in intestinal epithelial cells during their polarization/differentiation. It was our expectation that these data would help us to develop hypotheses concerning the role of this MAP in epithelial development. We report the expression of three E-MAP-115 transcripts encoding isoforms of 115, 105, and 95 kDa; two display an expression gradient inverse to the third one as Caco-2 cells progress from proliferation through the stages of differentiation. To monitor the proteins produced from each transcript, we used purified polyclonal antibodies against synthetic peptides contained within the 115, 105, and 95 kDa isoforms to assay proliferating and differentiating CaCo-2 cells. Our results indicate that the expression and MT-binding capacity of the 115, 105, and 95 kDa isoforms vary upon proliferation/differentiation of the cells. E-MAP-115 proteins colocalize with MTs in proliferative and differentiated Caco-2 cells; in vivo, they are expressed in both crypt and villus epithelial cells where they are mainly concentrated at the apical pole of the cells.
Vanier
Marie-Thérèse
MT
INSERM U.381, Strasbourg, France. Jean-Francois.Launay@inserm.u-strasbg.fr
Deck
Paula
P
Stutzmann
Jeanne
J
Gendry
Patrick
P
Arnold
Christiane
C
Dirrig-Grosch
Sylvie
S
Kedinger
Michèle
M
Launay
Jean-François
JF
D006801:Humans; D018938:Caco-2 Cells; D002454:Cell Differentiation; D002455:Cell Division; D003600:Cytosol / Q000378:metabolism; D004847:Epithelial Cells / Q000378:metabolism / Q000502:physiology; D005455:Fluorescent Antibody Technique; D007421:Intestine, Small / Q000166:cytology / Q000378:metabolism; D008869:Microtubule-Associated Proteins / Q000737:chemistry / Q000378:metabolism; D008870:Microtubules / Q000378:metabolism; D011485:Protein Binding; D020033:Protein Isoforms / Q000737:chemistry
D008869:Microtubule-Associated Proteins; D020033:Protein Isoforms; C000721969:MAP7 protein, human