Abstract
Purpose: :
TXNL6 is a thioredoxin-like protein that has been reported to exist as two alternatively spliced forms. The short form, known as Rdcvf (rod-derived cone viability factor), has been implicated to be involved in cone viability and cone survival whereas the long form, TXNL6, is believed to have oxidoreductase activity and function similarly to thioredoxin (TRX) using the CXXC motif. Here, we examined the expression of TXNL6 in human lens and retinal tissues paying particular attention to its subcellular localization in these cells.
Methods: :
To establish the expression of TXNL6 in human lens and retina, we performed semi-quantitative RT-PCR from RNA isolated from tissues of human lens epithelia, human lens fiber, and human retina. We also examined the protein levels of TXNL6 using extracts isolated from human lens epithelia, human lens fibers, and monkey retina by western blot. We further explored the localization of TXNL6 in HLE and RPE cells by immunofluorescence staining visualized by confocal microscopy. All immunostaining experiments have been performed in two HLE cell lines (SRA01/04 and HLEB3) and in two RPE cell lines (D407 and ARPE19).
Results: :
Our results demonstrated the expression of TXNL6 in human lens and human/monkey retina at both the transcript and protein levels. Immunostaining of TXNL6 revealed co-localization to the mitochondria as well as throughout the cytosol of HLE and RPE cells. Immunofluorescence data also revealed co-localization of TXNL6 with the repair enzyme, MsrA, in HLE and RPE cells.
Conclusions: :
Our data show that TXNL6 is expressed in the human lens and retina, is co-localized to the mitochondria, and is co-localized with MsrA. Our results suggest that TXNL6 has an important reducing function in the lens and retina that likely involves serving as a reducing system for MsrA and other mitochondrial protective and repair enzymes.
Keywords: protective mechanisms • aging • mitochondria