Abstract
Purpose: :
Fibrillin and related extracellular matrix proteins in lens zonules have been implicated in the pathogenesis of Marfan’s syndrome. Some of these proteins have been found in mammalian ocular tissues, but much remains unknown about their presence and interactions. We are characterizing several key proteins of the extracellular matrix of the bovine lens. By establishing their presence and geographic location around the lens, we can enhance the molecular model of how these proteins interact.
Methods: :
Adult bovine eyes were purchased from a local abattoir and placed on ice immediately upon harvesting. The sclera was trimmed and each eye bisected into anterior and posterior halves at the equator. The anterior portion was embedded cornea down into a sterile specimen container containing OCT histological freezing media. Each specimen was frozen in dry ice/isopentane and placed at -80 until sectioning. The sections were blocked with PBS/BSA, washed, and incubated with antibodies specific for fibrillin 1, MAGP-1, MAGP-2, fibronectin, elastin, laminins γ1, β1 & β2 subunits, Tsp-4, and COMP/Tsp-5. Fluorescent microscopy was carried out using a Nikon Optiphot-2 fluorescent microscope mounted with a Spot RT CCD digital camera driven by SPOT software v3.5 (Diagnostic Instruments, Inc.) for image capture.
Results: :
We identified elastin in the pigmented ciliary epithelium, fibrocytes, and stroma of the ciliary body. Fibronectin staining was absent in the zonules. MAGP-2 staining was detected in the elastic fibers of the ciliary body, and also on the zonules. Fibrillin staining was detected within the lens capsule as well as the expected staining within adjacent zonular fibers.
Conclusions: :
Our findings suggest a possible segregation of these proteins at different quadrants around the lens. A more in-depth investigation of the geographic composition of the lens-zonule-ciliary body complex will help explain these findings, and offer clues to how zonular fibril proteins interact.
Keywords: extracellular matrix • immunohistochemistry • gene/expression