Wh. Tao et al., ET(B) AND EPIDERMAL GROWTH-FACTOR RECEPTOR STIMULATION OF WOUND CLOSURE IN BOVINE CORNEAL EPITHELIAL-CELLS, Investigative ophthalmology & visual science, 36(13), 1995, pp. 2614-2622
Purpose, To determine if there is a heterogeneous pattern of endotheli
n (ET) receptor subtype (i.e., ET(A) and ET(B)) gene expression in the
bovine corneal epithelium (BCE). To determine if ET receptor subtype
stimulation increases the effectiveness of epidermal growth factor (EG
F) to accelerate wound closure in a primary culture of bovine corneal
epithelial cells (BCEC). Methods, In situ hybridization histochemistry
was used to characterize ET(A) and ET(B) gene expression in the BCE.
A wound closure assay evaluated wound healing rates in BCEC after 4 to
7 days in culture. [H-3] thymidine incorporation and MTT assay measur
ed proliferation. Results, ET(A) gene expression was appreciably highe
r in the basal cells than in the suprabasal cells, whereas the pattern
for ET(B) was reversed. Epidermal growth factor (5 ng/ml) maximally i
ncreased wound closure by 145% above the control. With 5 ng/ml EGF, ei
ther 10(-9) M ET-1 or 10(-8) M sarafotoxin-6-c (s-6-c) increased wound
closure by an additional 39% (P < 0.001) above that measured with 5 n
g/ml EGF alone. BQ123 (10(-7) M) did not alter any of these effects of
ET-1 or s-6-c. Epidermal growth factor stimulated wound closure throu
gh a selective increase in proliferation. Neither ET-1 nor s-6-c alone
had any effect on proliferation or migration. Conclusions. Both ET(A)
and ET(B) genes are expressed in BCE. However, in BCEC only, ET(B) st
imulation increases the effectiveness of EGF to stimulate wound closur
e. This response was caused by an increase in cell migration rather th
an proliferation because, after treatment with mitomycin C, neither ET
-1 nor EGF stimulated wound closure.