Vol. 284, Issue 4, G722-G727, April 2003
mRNA localization in polarized intestinal epithelial
cells
Vicki M.
Houle1,
Wei
Li2,
Robert K.
Montgomery1, and
Richard J.
Grand1
1 Gastrointestinal Cell Biology Research, Division
of Gastroenterology and Nutrition, Harvard Digestive Disease
Center, Children's Hospital, Harvard Medical School, Boston 02115; and
2 Department of Immunology, New England Medical
Center, Tufts University School of Medicine, Boston, Massachusetts
02111
An
important feature of enterocyte maturation is the asymmetrical
distribution of cellular functions including protein localization. mRNA
sorting is one mechanism for establishment and maintenance of this
process in other systems, and we have previously demonstrated differential localization of mRNAs in human enterocytes. To study regulation of mRNA sorting, we established a model in polarized Caco-2
cells. Proxy cDNA constructs containing
-galactosidase (
-gal)/green fluorescence protein (GFP) and the 3'-untranslated region (3'-UTR) of either human sucrase-isomaltase or villin were transfected transiently or stably. A control construct contained poly-A
sequence in place of 3'-UTR. Expression of GFP was observed by confocal
microscopy; intracellular location of the construct mRNA was imaged by
in situ hybridization. The sucrase-isomaltase mRNA proxy localized to
an apical position in Caco-2 cells as in native enterocytes; the villin
mRNA proxy did not show significant localization. The control construct
was not localized and was found diffusely throughout the cell. Proxy
GFP proteins tended to localize with their mRNA proxies, but with less
precision. This study establishes a valuable model for the
investigation of mRNA localization in intestinal epithelial cells.
Mechanisms controlling asymmetrical distribution of intestinal mRNAs
can be now be elucidated.
enterocyte; Caco-2 cells; sucrase-isomaltase; villin