Developmental Expression of Eph and Ephrin Family Genes in Mammalian Small Intestine
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Eph receptor tyrosine kinases EphB2 and EphB3, and ephrin-B1 ligand play a critical role in regulating small intestinal epithelial cell migration. Although well studied in developing brain, the expression pattern of Ephs/ephrins has not been delineated in the developing small intestine.
To examine the gene expression of all known members of Ephs/ephrins during development of mouse small intestine.
We examined the expression of 21 A- and B-Ephs/ephrins in mouse small intestine or the Caco-2 cell line using reverse-transcription polymerase chain reaction (RT-PCR), quantitative (q)RT-PCR, and immunohistochemical analyses. EphB2-expressing cells from isolated crypts were detected by immunofluorescence and fluorescence-activated cell sorting (FACS) analyses.
With the exception of EphA5, all family members were expressed throughout the intestine at all ages examined. Most were uniformly expressed. In contrast, levels of EphA4, EphA8, EphB4, and ephrin-B2 messenger RNA (mRNA) were highest during early fetal development and declined with age. At E15, EphB2 and EphB4 proteins were diffusely expressed in proliferating stratified intestinal epithelial cells. By E18, the proteins had become localized to cell membranes of columnar epithelial cells within intervillus regions, and later were expressed on epithelial cell membranes in adult crypts. EphB2-expressing cells can be specifically isolated from crypt cell fractions.
The current study represents the first analysis of Ephs/ephrins during intestinal development. The elevated expression of EphA4, EphA8, EphB4, and ephrin-B2 during the fetal period of intestinal morphogenesis suggests an important role in development. Continued intestinal expression of other family members implicates a role in differentiation.
KeywordsDevelopment Small intestine Eph Ephrin Receptor Ligands
We would like to thank Dr. Stephen D Krasinski (Division of Gastroenterology and Nutrition, Children’s Hospital Boston, Boston, MA) for statistical analysis of EphB4 expression data, NanaYaa Baffour-Awuah for technical help in qRT-PCR experiments, Sacha de Stoppelaar for maintaining Caco-2 cell-lines, and Dr. Daniel J Liebl (University of Miami, FL) for providing primer sequence for EphB3/B4. We thank Ms. Suzanne White (Histology Core, Harvard Digestive Disease Center, Boston, MA) for preparation of paraffin-embedded tissue sections. Grant Sponsor: NIH Research Grant (MERIT) and Harvard Digestive Disease Center. Grant number: R37 DK32658 and P30 DK34854.
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