Adenoviral gene transfer of BMP-7, Id2, or Id3 suppresses injury-induced epithelial-to-mesenchymal transition of lens epithelium in mice

Departments of 1 Ophthalmology and 2 Pathology, Wakayama Medical University, Wakayama; Department of 3 Anatomy, Graduate School of Medicine, Osaka City University, Osaka, Japan; and 4 Laboratory of Cell Regulation and Carcinogenesis, National Cancer Institute, National Institutes of Health, Bethesda, Maryland Submitted 27 June 2005 ; accepted in final form 17 August 2005 We have examined the effect of adenovirus-mediated expression of bone morphogenic protein-7 (BMP-7) and inhibitors of differentiation 2 and 3 (Id2 and Id3) on injury-induced epithelial-to-mesenchymal transition (EMT) of lens epithelium in mice. Id2 and Id3 are known to be upregulated by BMP-7 and to antagonize Smad2/3 signaling. The Cre-LoxP system adenoviral gene transfer was used. Three microliters of adenoviral solution (2 x 10 7 PFU/µl) were injected into the right lens of adult male C57BL/6 mice ( n = 144) at the time of capsular injury induced using a hypodermic needle under both general and topical anesthesia. A mixture of Cre-adenovirus (Cre-Ad) and vector encoding mBMP-7, mId2, or mId3 was administered in a test group. Control lenses were treated with Cre-Ad alone. After healing intervals of 5 or 10 days, the animals were killed and then we performed histological processes or RNA extraction from the lens. RT-PCR, real-time RT-PCR, and immunohistochemistry showed expression of each introduced gene in the lens. Exogenous BMP-7 upregulated expression of Id2 and Id3 in injured lenses, and gene introduction of Id2 or Id3 also upregulated BMP-7 expression. Gene transfer of BMP-7, Id2, or Id3 delayed injury-induced EMT of the lens epithelial cells as evaluated by histology and expression patterns of -smooth muscle actin and collagens in association with reduction of Smad2 COOH-terminal phosphorylation. Gene transfer of BMP-7, Id2, or Id3 delayed injury-induced EMT of lens epithelial cells and subsequent sealing of the capsular break with fibrous tissue in mice. lens epithelial cell; bone morphogenic protein-7; inhibitor of differentiation; Smad Address for reprint requests and other correspondence: S. Saika, Dept. of Ophthalmology, Wakayama Medical Univ., 811-1 Kimiidera, Wakayama 641-0012, Japan (e-mail: shizuya{at}wakayama-med.ac.jp )