Increased DNA breaks and up-regulation of both G(1) and G(2) checkpoint genes p21(WAF1/CIP1) and 14-3-3 sigma in circulating leukocytes of glaucoma patients and vasospastic individuals.
OBJECTIVE
Vascular disorder leading to local ischemia/reperfusion has been shown to play an important role in the glaucomatous damage. A decreased expression level of XPGC-gene has been found in circulating leukocytes of normal-tension glaucoma patients. Although decreased activity of XPGC-gene leads to insufficient DNA-repair, no leukopenia has been observed in glaucoma. Molecular mechanisms ensuring cell survival have not been elucidated yet for glaucoma with vascular disorder.


METHODS
Using the ex vivo optical imaging method of alkaline "comet assay" comparative quantification of DNA breaks was performed in circulating leukocytes of non-glaucomatous non-vasospastic and vasospastic individuals as well as both normal-tension and high-tension glaucoma patients. Relative expression levels of the anti-apoptotic factors P21(WAF1/CIP1) and 14-3-3 sigma were investigated in all groups tested.


CONCLUSIONS
The quantification of P21(WAF1/CIP1) showed the highest expression rates in high-tension glaucoma patients which were significantly higher than those in all other groups tested. The highest expression rates of 14-3-3 sigma were found in both groups of glaucoma patients. These expression levels correlated well with DNA breaks measured. Since the expression of P21(WAF1/CIP1) in leukocytes was shown to be crucial for their survival under stress conditions, we suppose further that the up-regulation of this gene is the key event in the survival mechanisms of leukocytes in glaucoma accompanied with vascular disorder. The p21(WAF1/CIP1) gene should be further taken into consideration as a potential marker, the up-regulation of which in circulating leukocytes of vasospastic individuals may indicate an increased risk for the developing glaucoma.
Moenkemann
H
H
Department of Radiology, Friedrich-Wilhelms-University of Bonn, Bonn, Germany.
Flammer
J
J
Wunderlich
K
K
Breipohl
W
W
Schild
H H
HH
Golubnitschaja
O
O
D048948:14-3-3 Proteins / Q000096:biosynthesis*; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D050759:Cyclin-Dependent Kinase Inhibitor p21 / Q000096:biosynthesis*; D004249:DNA Damage; D005901:Glaucoma / Q000378:metabolism* / Q000473:pathology; D006801:Humans; D007962:Leukocytes / Q000378:metabolism* / Q000473:pathology; D008297:Male; D008875:Middle Aged; D015427:Reperfusion Injury / Q000378:metabolism / Q000473:pathology; D015854:Up-Regulation
D048948:14-3-3 Proteins; C493956:CDKN1A protein, human; D050759:Cyclin-Dependent Kinase Inhibitor p21