Abstract
Abstract: :
Purpose: The eye lens consists of a single layer of epithelial cells that differentiate into fiber cells making the lens an ideal model system for studying the molecular events underlying epithelial cell differentiation. Here, the global gene expression profiles between human lens epithelial cells and fiber cells were compared. Methods: RNA was extracted from microdissected adult human lens epithelia and matching cortical fibers. Gene expression changes were identified by microarray hybridization using chips containing 22,215 genes. The identified gene expression changes were confirmed at the transcript level by semi–quantitative RT–PCR, and at the protein level by western blotting and immunohistochemistry. Genes participating in common functional pathways were clustered using the EASE bioinformatics software package. Results: Analysis of three separate microarray hybridizations revealed 657 transcripts that are increased and 228 transcripts that are decreased at the 2–fold or greater level between lens epithelial cells and cortical fiber cells. Of these, 265 transcripts were increased and 25 transcripts were decreased at the 5–fold or greater level. Semi–quantitative RT–PCR revealed that 12 out of 13 examined genes exhibited identical expression patterns as detected by microarray hybridization indicating that the microarray data is approximately 93% accurate. Analysis of the identified gene expression patterns using the EASE clustering program revealed a wide variety of cellular pathways that exhibit increased expression in the lens epithelium including regulation of transcription, cell growth pathways, cell adhesion components and intracellular signaling cascades. In contrast, protein biosynthesis pathways, mitotic cell cycle pathways, apoptosis pathways and small GTPase mediated signal transduction pathways are all increased in lens fiber cells. Conclusions:These data establish those genes and pathways specific for lens epithelial and fiber cells and provide evidence that differentiation of lens epithelial cells into fiber cells is associated with specific cellular events whose ongoing functional analysis will provide insight into lens development, growth and disease.
Keywords: gene microarray • proliferation • apoptosis/cell death