Na+, K+-ATPase inhibitors down-regulate gene expression of the intracellular signaling protein 14-3-3 in rat lens.
To identify genes that are differentially expressed by Na+, K+-ATPase inhibitors, we used the differential display technique to compare mRNA expression patterns in rat lens. Lenses were treated with 10 microM ouabain, bufalin, or 19-norbufalin derivative for 24 h and were compared with control lenses. Differential display analysis revealed that one of the down-regulated genes was 14-3-3 theta. Down-regulation was confirmed by Northern blot and by reverse transcription-polymerase chain reaction analysis. Reverse transcription-polymerase chain reaction of additional 14-3-3 isoforms revealed that the eta and gamma isoforms of 14-3-3 are also down-regulated by ouabain, bufalin, and 19-norbufalin derivative, whereas the zeta isoform is down-regulated only by bufalin. Down-regulation of the 14-3-3 isoforms occurred without a significant change in gamma-crystallin gene expression. These results demonstrate that one of the consequences of Na+, K+-ATPase inhibition by exogenous or endogenous inhibitors is the down-regulation of mRNA transcripts encoding several isoforms of 14-3-3. Because the 14-3-3 proteins are multifunctional regulatory proteins, the reduction in the abundance of various isoforms will have profound effects on cell function.
McGowan
M H
MH
Laboratory of Mechanisms of Ocular Diseases, National Eye Institute, Bethesda, Maryland, USA.
Russell
P
P
Carper
D A
DA
Lichtstein
D
D
D048948:14-3-3 Proteins; D000818:Animals; D002018:Bufanolides / Q000494:pharmacology*; D003459:Crystallins / Q000235:genetics; D004791:Enzyme Inhibitors / Q000378:metabolism / Q000494:pharmacology*; D005786:Gene Expression Regulation / Q000187:drug effects*; D007908:Lens, Crystalline / Q000187:drug effects / Q000378:metabolism*; D009924:Organ Culture Techniques; D010042:Ouabain / Q000494:pharmacology*; D020033:Protein Isoforms / Q000235:genetics; D011506:Proteins / Q000235:genetics*; D012333:RNA, Messenger / Q000235:genetics; D051381:Rats; D017207:Rats, Sprague-Dawley; D020133:Reverse Transcriptase Polymerase Chain Reaction; D000254:Sodium-Potassium-Exchanging ATPase / Q000037:antagonists & inhibitors*; D014158:Transcription, Genetic / Q000187:drug effects*; D014446:Tyrosine 3-Monooxygenase
D048948:14-3-3 Proteins; D002018:Bufanolides; D003459:Crystallins; D004791:Enzyme Inhibitors; D020033:Protein Isoforms; D011506:Proteins; D012333:RNA, Messenger; D010042:Ouabain; D014446:Tyrosine 3-Monooxygenase; D000254:Sodium-Potassium-Exchanging ATPase; C022777:bufalin