Aldehyde dehydrogenase class 3 expression: Identification of a cornea-preferred gene promoter in transgenic mice

Abstract

Aldehyde dehydrogenase class 3 (ALDH3) constitutes 20-40% of the total water-soluble proteins in the mammalian cornea. Here, we show by Northern blot analysis that ALDH3 expression in the mouse is at least 500-fold higher in the cornea than in any other tissue examined, with very low levels of expression detected in the stomach, urinary bladder, ocular lens, and lung. Histochemical localization reveals that this exceptional level of expression in the mouse cornea occurs in the anterior epithelial cells and that little ALDH3 is present in the keratocytes or corneal endothelial cells. A 13-kbp mouse ALDH3 promoter fragment containing >12 kbp of the 5 flanking sequence, the 40-bp untranslated first exon, and 29 bp of intron 1 directed cat reporter gene expression to tissues that express the endogenous ALDH3 gene, except that transgene promoter activity was higher in the stomach and bladder than in the cornea. By contrast, when driven by a 4.4-kbp mouse ALDH3 promoter fragment [1,050-bp 5 flanking region, exon 1, intron 1 (3.4 kbp), and 7 bp of exon 2] expression of the cat reporter gene was confined to the corneal epithelial cells, except for very low levels in the liver, effectively reproducing the corneal expression pattern of the endogenous ALDH3 gene. These results indicate that tissue-specific expression of ALDH3 is determined by positive and negative elements in the 5 flanking region of the gene and suggests putative silencers located in intron 1. We demonstrate regulatory sequences capable of directing cornea-specific gene expression, affording the opportunity for genetic engineering in this transparent tissue.

Antioxidant protection in cultured corneal cells and whole corneas submitted to UV-B exposure

“…Indeed SIRC, being basically fibroblasts (keratocytes), possess a low (or absent) expression of some epithelial enzymes suitable to inhibit the ROS attack [48,55,56].…”

Corneal development associated with eyelid opening

“…In the second group of proteins, which includes keratins 3 (Chaloin-Dufau et al, 1990;Rodrigues et al, 1987) and 12 (Chaloin-Dufau et al, 1990;Liu et al, 1993), transketolase (Sax et al, 2000), connexin 43 (Wolosin et al, 2002), and aldehyde dehydrogenase (Burton et al, 1999;Downes and Holmes, 1992;Kays and Piatigorsky, 1997), increased expression has been observed in conjunction with eyelid opening. These proteins exhibit a reciprocal localization with those in the first group, in that they are present at low levels at birth and increase as the epithelium stratifies and matures.…”

Opossum Aldehyde Dehydrogenases: Evidence for Four ALDH1A1-like Genes on Chromosome 6 and ALDH1A2 and ALDH1A3 Genes on Chromosome 1

“…These enzymes have been shown to catalyze the final step of retinoic acid biosynthesis, causing retinoic acid signaling influencing vertebrate embryogenesis including the growth and development of the eye (Niederreither et al 1999;Duester et al 2006). Other ALDH classes have also been extensively investigated, particularly ALDH2, which plays a major role in liver acetaldehyde clearance following ethanol consumption (Goedde et al 1983), and ALDH3, which performs multiple roles in the eye, especially the cornea, serving as a corneal ''crystallin'' and detoxifying peroxidic aldehydes following ultraviolet absorption (Abedinia et al 1990; Kays and Piatigorsky 1997;Pappa et al 2003).…”