Detection of differentially expressed wound-healing-related glycogenes in galectin-3-deficient mice.
OBJECTIVE
A prior study showed that exogenous galectin-3 (Gal-3) stimulates re-epithelialization of corneal wounds in wild-type (Gal-3(+/+)) mice but, surprisingly, not in galectin-3-deficient (Gal-3(-/-)) mice. In an effort to understand why the injured corneas of Gal-3(-/-) mice are unresponsive to exogenous Gal-3, the present study was designed to determine whether genes encoding the enzymes that regulate the synthesis of glycan ligands of Gal-3 are differentially expressed in Gal-3(-/-) corneas compared with the Gal-3(+/+) corneas.


METHODS
Glycogene microarray technology was used to identify differentially expressed glycosyltransferases in healing Gal-3(+/+) and Gal-3(-/-) corneas.


RESULTS
Of approximately 2000 glycogenes on the array, the expression of 8 was upregulated and that of 14 was downregulated more than 1.3-fold in healing Gal-3(-/-) corneas. A galactosyltransferase, beta3GalT5, which has the ability to synthesize Gal-3 ligands was markedly downregulated in healing Gal-3(-/-) corneas. The genes for polypeptide galactosaminyltransferases (ppGalNAcT-3 and -7) that are known to initiate O-linked glycosylation and N-aspartyl-beta-glucosaminidase, which participates in the removal of N-glycans, were found to be upregulated in healing Gal-3(-/-) corneas. Microarray data were validated by qRT-PCR.


CONCLUSIONS
Based on the known functions of the differentially expressed glycogenes, it appears that the glycan structures on glycoproteins and glycolipids, synthesized as a result of the differential glycogene expression pattern in healing Gal-3(-/-) corneas may lead to the downregulation of specific counterreceptors for Gal-3. This may explain, at least in part, why, unlike healing Gal-3(+/+) corneas, the healing Gal-3(-/-) corneas are unresponsive to the stimulatory effect of exogenous Gal-3 on re-epithelialization of corneal wounds.
Saravanan
Chandrassegar
C
Department of Ophthalmology and The New England Eye Center.
Cao
Zhiyi
Z
Head
Steven R
SR
Panjwani
Noorjahan
N
D000818:Animals; D065306:Corneal Injuries; D005131:Eye Injuries / Q000235:genetics*; D037502:Galectin 3 / Q000172:deficiency / Q000502:physiology*; D020869:Gene Expression Profiling; D005786:Gene Expression Regulation / Q000502:physiology*; D006026:Glycoside Hydrolases / Q000235:genetics*; D016695:Glycosyltransferases / Q000235:genetics*; D007834:Lasers / Q000009:adverse effects; D054018:Lasers, Excimer; D051379:Mice; D018345:Mice, Knockout; D020411:Oligonucleotide Array Sequence Analysis; D020133:Reverse Transcriptase Polymerase Chain Reaction; D015854:Up-Regulation; D014945:Wound Healing / Q000502:physiology*
D037502:Galectin 3; D016695:Glycosyltransferases; D006026:Glycoside Hydrolases