The role of the lens epithelium in development of UV cataract

Abstract

In view of renewed interest in the lens epithelium as the initiation site for cataract development, it seemed timely to review recent studies which appear to establish UV damage in the lens epithelium as the cause of UV cataract. While UV photons can and do interact with lens proteins in the cortex and nucleus, experimental results from cultured lenses and tissue cultured epithelial cells also demonstrate both mutagenic and cytotoxic effects in the epithelium. This minireview examines UV-induced changes in lens physiology that appear to follow epithelial cell damage, including inactivation of critical enzymes of transport and metabolic processes. Changes in membrane function include altered cation transport, increased permeability, and altered biosynthesis. One potential scenario for the propagation of damage from the epithelium to the underlying fiber cells includes calcium elevation, an early event in cataract development and critical to many physiological processes.

Transcriptionally correlated subcellular dynamics of MBNL1 during lens development and their implication for the molecular pathology of myotonic dystrophy type 1

“…We have demonstrated here the presence of CUG exp RNA foci in the nuclei of lens epithelial cells from DM1 patients and the accumulation of MBNL1 protein in these foci. Defects in the epithelial layer of the lens can lead to cataract both during development and in the mature lens [34]. The presence of CUGexp RNA foci in the epithelial cells of DM1 patients could therefore explain the strong association of cataract with DM1.…”

“…The lens is the first tissue to present the DM1 phenotype, as cataracts, in patients. The lens is known to be extremely sensitive to many forms of insult including ultra violet light, glycation, oxidation and the ageing process, because it is unable easily to replace and repair damaged cells [34]. Indeed the lens is rich in mechanisms to resist these insults including small--heat--shock protein chaperones and high levels of glutathione [48--51].…”

Nonresonant Raman imaging of protein distribution in single human cells

“…Among the active cells, LECs were of interest because of the possible relation between controlled cell death (apoptosis) and the occurrence of cataractous changes. 15,16 These results will be presented in a future article.…”

Identification and functional clustering of global gene expression differences between age-related cataract and clear human lenses and aged human lenses

“…In the present survey, we have sought to identify those gene expression differences between clear human lenses relative to age-related cataracts and we have focused on the lens epithelium since this monolayer of cells is essential for the growth, differentiation and homeostasis of the entire organ (Bloemendal, 1981;Piatigorsky, 1981), contains the highest levels of enzymes and transport systems in the lens (Reddy, 1971;Reddan, 1982;Spector, 1982) and is the first part of the lens exposed to environmental insults (Reddan, 1982;Spector, 1982). Multiple studies suggest that the lens epithelium is capable of communicating with the underlying fiber cells (Rae et al, 1996) and direct damage to the lens epithelium and its enzyme systems is known to result in cataract formation (Harding and Crabbe, 1984;Hightower, 1995;Spector, 1995;Phelps Brown, 1996). Importantly, the majority of transcription occurs in the epithelial cells of the lens, and therefore these cells make up the majority of lens cells capable of responding to environmental insults and/or the presence of cataract through altered gene expression.…”