Lack of type XVIII collagen results in anterior ocular defects.
Mice lacking type XVIII collagen have defects in the posterior part of the eye, including delayed regression of the hyaloid vasculature and poor outgrowth of the retinal vessels. We report here that these mice also have a fragile iris and develop atrophy of the ciliary body. The irises of Col18a1-/- mice can be seen to adhere to the lens and cornea. After the pupils begin to function, the double layer of epithelial cells separates at the apical cell contacts, leading to defoliation of its posterior pigment epithelial cell layer, and extracellular material begins to accumulate in the basement membrane zones of the iris. In contrast to the iris epithelia, where no clear signs of cellular atrophy were detected, the lack of type XVIII collagen resulted in atrophy of the pigmented epithelial cells of the ciliary body, and there were also ultrastructural abnormalities in the basement membrane zones. These changes did not lead to chronically elevated intraocular pressures, however. Our results indicate that type XVIII collagen is needed for the integrity of the epithelial basement membranes of the iris and the ciliary body and that its gene should therefore be taken into account as a new potential cause of anterior segment disorders in the eye.
Ylikärppä
Ritva
R
Collagen Research Unit, Biocenter Oulu and Department of Medical Biochemistry and Molecular Biology, University of Oulu, Finland.
Eklund
Lauri
L
Sormunen
Raija
R
Kontiola
Antti I
AI
Utriainen
Aino
A
Määttä
Marko
M
Fukai
Naomi
N
Olsen
Björn R
BR
Pihlajaniemi
Taina
T
D000818:Animals; D001485:Basement Membrane / Q000033:anatomy & histology; D002924:Ciliary Body / Q000002:abnormalities* / Q000033:anatomy & histology; D043170:Collagen Type XVIII / Q000235:genetics / Q000502:physiology*; D005123:Eye / Q000033:anatomy & histology; D007429:Intraocular Pressure; D007498:Iris / Q000002:abnormalities* / Q000033:anatomy & histology; D051379:Mice; D018345:Mice, Knockout; D008856:Microscopy, Fluorescence; D008954:Models, Biological; D010857:Pigment Epithelium of Eye / Q000033:anatomy & histology
D043170:Collagen Type XVIII