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J.W. McAvoy, S.L. Ang, R.J. Stump, F.J. Lovicu; The Expression and Regulation of Wnts in the Developing Murine Lens . Invest. Ophthalmol. Vis. Sci. 2003;44(13):4493.
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© ARVO (1962-2015); The Authors (2016-present)
Purpose: Research in our laboratory indicates that the Wnt growth factor family has a role in regulating the behaviour of lens epithelial cells. To gain a better understanding of Wnt signalling in the lens, we investigated the presence and expression patterns of Wnts and the Wnt signalling regulators, the Dickkopfs (Dkks), during lens development. Methods: RNA was isolated from rat lens capsules (with adherant epithelial cells), then reverse transcribed (RT) to cDNA and amplified by PCR using designed primers for Wnts 5a, 5b, 7a, 7b, 8a and 8b and Dkks 1, 2 and 3. For in situ hybridisation (ISH), the amplified cDNA was inserted into a transcription vector and cloned for subsequent sequencing and riboprobe synthesis. RNA anti-sense and sense probes were prepared with digoxigenin as a label. Paraffin sections of mice from embryonic day 10.5 (E10.5) to E18.5 and mouse eyes at postnatal days 7 (P7) and P21 were analysed for Wnt and Dkk expression using an anti-DIG-AP conjugate. Results: RT-PCR showed that all of the Wnts and Dkks tested were present in the lens. ISH showed that Wnts 5a, 5b, 7a, 7b, 8a and 8b were expressed in the lens pit at E10.5 and in the developing lens epithelium and primary fibres at E12.5. At E14.5, expression of all Wnts was reduced in the primary fibres, except for Wnt7b which remained strongly expressed. At later embryonic stages, Wnt expression in the lens was localised to the epithelium and equatorial region, including the transitional zone. Expression was absent from the differentiated fibres. During postnatal development expression generally became weaker in the anterior epithelium compared with the equatorial region, this was particularly true for Wnts 5a and 7a at P21. Expression of the Dkks was similar to the majority of the Wnts during lens morphogenesis. Postnatally, Dkks 1, 2 and 3 had similar patterns of expression, although there was some overlap. Conclusions: Multiple Wnts are expressed in the lens and their expression appears to be greatest during early differentiation of epithelial cells and fibre cells. All Dkk genes are expressed in the lens and have similar patterns of expression to the majority of the Wnts. How Dkks influence the Wnt signalling pathways in different lens compartments remains to be determined.
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