Abstract
Purpose::
. Crim1 (cysteine-rich motor neuron 1), a transmembrane protein that has been identified as an antagonist of members of the TGFß superfamily of growth factors (Kolle et al., 1999: MOD), has been shown to play a role in ocular development (Lovicu et al., 2000: MOD; Pennisi et al., 2006: Dev Dyn). The aim of this study was to characterise the effects of reduced levels of Crim1 in normal lens and ocular development.
Methods::
. Lens and ocular development was examined in KST264 gene trap lacZ knock-in mice deficient for Crim1 (Pennisi et al., 2006: Dev Dyn). Transgenic mice overexpressing Crim1 or TGFß1, specifically to the lens, were used to rescue the effects of Crim1 deficiency in these mice.
Results::
. Mice deficient for Crim1 display microphthalmia. At embryonic day 13.5, lenses and eyes appear relatively normal, however, are notably smaller in size. By E15.5, the developing lens starts to progressively lose its epithelium as the most peripheral cells exit the cell cycle and differentiate into fibre cells. This anterior shift of the lens equator is associated with the anterior encroachment of the developing optic cup. Another prominent phenotype in these mice is the disruption of the developing hyaloid vasculature, with aberrant accumulation of vascular precursor cells accumulating in the vitreous. The ocular phenotype described in these lines of mice can be mostly rescued by overexpressing Crim1 or TGFß1.
Conclusions::
. Consistent with the specificity and strength of Crim1 expression throughout lens/ocular development, our in vivo studies support an important role for Crim1 in the normal development of the lens and/or eye, possibly by regulating TGFß signaling. The exact nature and degree by which this molecule regulates TGFß and plays a role in ocular development is yet to be determined.
Keywords: development • transgenics/knock-outs • vascular cells