Abstract
Abstract: :
Purpose: The lens capsule, a specialized thickened basement membrane that surrounds the lens, is comprised of a number of extracellular matrix proteins. Heparan sulfate proteoglycan (HSPG) a major component of the capsule, functions to sequester growth factors, such as bFGF and may directly interact with receptors on lens cell surfaces. In this study, the lenticular expression patterns of two HSPGs, perlecan and agrin are investigated during development in order to explore their potential roles in the lens capsule. Methods: Immunohistochemistry and confocal imaging were used to detect expression of agrin and perlecan in cryosectioned murine embryos. Results: Perlecan expression was detected in the basement membrane underlying the lens placode (embryonic day 9.5, or E9.5) and remained high in the lens capsule throughout development. In contrast, agrin was expressed transiently between E10.5 and E12.5 in the lens capsule, but in postnatal mice its expression was restricted to portions of the capsule adjacent to the transition zones. Conclusion: Perlecan, the first HSPG described in the lens, is expressed early in capsule development in the basement membrane underlying the lens placode, while agrin, an HSPG first known for its role in neuromuscular junctions, is expressed in a unique pattern in the developing lens. The burst of agrin expression at E10.5, provides evidence that early events in the development of the lens capsule may include a significant role for agrin, and its transition zone-restricted expression, which was observed in adult mouse lens capsules, suggests a potential role for agrin in lens fiber cell differentiation or zonular attachment.
Keywords: 529 proteoglycans/glycosaminoglycans • 417 gene/expression • 434 immunohistochemistry