Polyamines in cultured rabbit corneal cells.
OBJECTIVE
To determine whether polyamines are present in corneal cells, whether corneal cell polyamines can be depleted by blocking the first rate-limiting enzyme in the polyamine synthesis pathway, ornithine decarboxylase (ODC), and whether polyamines are required for proliferation in all three corneal cell types.


METHODS
Cultured corneal epithelial cells, keratocytes, and endothelial cells were exposed to the specific ODC blocker difluoromethylornithine (DFMO), and ODC activity, intracellular polyamine concentrations, and cell proliferation were measured.


RESULTS
DFMO blocked ODC activity in a dose- and time-dependent manner in all three cell types. DFMO treatment completely depleted putrescine and spermidine by 2 days and also significantly depleted spermine. DFMO treatment also inhibited cell growth in all three cell types and this inhibition could be completely reversed by adding exogenous putrescine to the culture medium.


CONCLUSIONS
Polyamines are present in all cell types of the cornea, their formation is catalyzed at least in part by ODC, and they are an important component of corneal cell proliferation.
Du
Haiming
H
Department of Physiology, The University of Tennessee Health Science Center, Memphis, Tennessee 38163, USA.
Viar
Mary Jane
MJ
Johnson
Leonard R
LR
Watsky
Mitchell A
MA
D000818:Animals; D015317:Biogenic Polyamines / Q000378:metabolism*; D002455:Cell Division / Q000187:drug effects; D002478:Cells, Cultured; D003319:Corneal Stroma / Q000166:cytology; D004305:Dose-Response Relationship, Drug; D000518:Eflornithine / Q000494:pharmacology; D004728:Endothelium, Corneal / Q000187:drug effects / Q000378:metabolism*; D004791:Enzyme Inhibitors / Q000494:pharmacology; D019573:Epithelium, Corneal / Q000187:drug effects / Q000378:metabolism*; D005347:Fibroblasts / Q000187:drug effects / Q000378:metabolism*; D009955:Ornithine Decarboxylase / Q000378:metabolism; D065108:Ornithine Decarboxylase Inhibitors; D011700:Putrescine / Q000378:metabolism; D011817:Rabbits; D013095:Spermidine / Q000378:metabolism; D013096:Spermine / Q000378:metabolism; D013997:Time Factors
D015317:Biogenic Polyamines; D004791:Enzyme Inhibitors; D065108:Ornithine Decarboxylase Inhibitors; D013096:Spermine; D009955:Ornithine Decarboxylase; D013095:Spermidine; D011700:Putrescine; D000518:Eflornithine