Developmental and Regional Expression and Localization of mRNAs Encoding Proteins Involved in RNA Translocation
Shabana Islam 1, Robert K Montgomery 1, John J Fialkovich 1 and Richard J Grand 1*
1 Gastrointestinal Cell and Molecular Biology Laboratories, Division of Gastroenterology and Nutrition, Children’s Hospital Boston and Department of Pediatrics, Harvard Medical School, Boston, Massachusetts
* To whom correspondence should be addressed. E-mail: richard.grand{at}childrens.harvard.edu.
Submitted on February 17, 2005
Accepted on 7 June 2005
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Abstract |
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RNA localization is a regulated component of gene expression of fundamental importance in development and differentiation. Several RNA binding proteins involved in RNA localization during development in Drosophila have been identified, of which Y14, Mago, Pumilio, and IMP-1 are known to be expressed in adult mammalian intestine. The present study was undertaken to define the developmental and regional expression of these proteins, as well as Staufen-1, in mouse intestinal cells and in other tissues and cell lines using RT-PCR, and localization using in situ hybridization and immunohistochemistry. Staufen-1, Y14, Mago-m, and Pumilio-1 were expressed in intestinal epithelial cells of both villus and crypt and in Caco-2 and IEC-6 cells. In contrast, expression of IMP-1 was age and region specific, showing clear expression in distal fetal and newborn intestine but very low or no expression in adult. The mRNAs were cytosolic, with more apical than basal expression in enterocytes. Staufen protein showed a similar localization pattern to that of its cognate mRNA. Overall, the data suggest an essential role for these proteins in intestinal cells. Age and regional expression of IMP-1 may indicate a role in regulation of site-specific translation of intestinal genes, or in RNA localization.
Key Words:
intestine, enterocytes, RNA binding proteins, RNA localization, differentiation.
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