TY - JOUR
T1 - Overexpression of thioredoxin-binding protein 2increases oxidation sensitivity and apoptosis in human lens epithelialcells
AU - Yu, Yibo
AU - Xing, Kuiyi
AU - Badamas, Rilwan
AU - Kuszynski, Charles A.
AU - Wu, Hongli
AU - Lou, Marjorie F.
PY - 2013/4
Y1 - 2013/4
N2 - Thioredoxin (Trx) is an important redox regulator with cytosolic Trx1 and mitochondrial Trx2 isozymes. Trx has multiple physiological functions in cells and its bioavailability is negatively controlled through active-site binding to a specific thioredoxin-binding protein (TBP-2). This paper describes the delicate balance between TBP-2 and Trx and the effect of overexpression of TBP-2 in human lens epithelial cells. Cells overexpressing TBP-2 (TBP-2 OE) showed a sevenfold increase in TBP-2 and a nearly 40% suppression of Trx activity but no change in Trx expression. The TBP-2 OE cells grew slower and their population decreased to 30% by day 7. Cell cycle analysis showed that TBP-2 OE cells arrested at the G2/M stage and that they displayed low expression of the cell cycle elements P-cdc2(Y15), cdc2, cdc25A, and cdc25C. Furthermore, TBP-2 OE cells were more sensitive to oxidation. Under H2O2 (200 μM, 24 h) treatment, these cells lost 80% viability and became highly apoptotic. Brief oxidative stress (200 μM, 30 min) to TBP-2 OE cells disrupted the Trx antiapoptotic function by dissociating the cytosolic and mitochondrial Trx-ASK binding complexes. The same H2O 2-treated cells also showed activated ASK (P-ASK), increased Bax, lowered Bcl-2, cytochrome c release, and elevated caspase 3/7 activity. We conclude from these studies that high cellular levels of TBP-2 can potentially suppress Trx bioavailability and increase oxidation sensitivity. Overexpression of TBP-2 also causes slow growth by mitotic arrest and apoptosis by activating the ASK death pathway.
AB - Thioredoxin (Trx) is an important redox regulator with cytosolic Trx1 and mitochondrial Trx2 isozymes. Trx has multiple physiological functions in cells and its bioavailability is negatively controlled through active-site binding to a specific thioredoxin-binding protein (TBP-2). This paper describes the delicate balance between TBP-2 and Trx and the effect of overexpression of TBP-2 in human lens epithelial cells. Cells overexpressing TBP-2 (TBP-2 OE) showed a sevenfold increase in TBP-2 and a nearly 40% suppression of Trx activity but no change in Trx expression. The TBP-2 OE cells grew slower and their population decreased to 30% by day 7. Cell cycle analysis showed that TBP-2 OE cells arrested at the G2/M stage and that they displayed low expression of the cell cycle elements P-cdc2(Y15), cdc2, cdc25A, and cdc25C. Furthermore, TBP-2 OE cells were more sensitive to oxidation. Under H2O2 (200 μM, 24 h) treatment, these cells lost 80% viability and became highly apoptotic. Brief oxidative stress (200 μM, 30 min) to TBP-2 OE cells disrupted the Trx antiapoptotic function by dissociating the cytosolic and mitochondrial Trx-ASK binding complexes. The same H2O 2-treated cells also showed activated ASK (P-ASK), increased Bax, lowered Bcl-2, cytochrome c release, and elevated caspase 3/7 activity. We conclude from these studies that high cellular levels of TBP-2 can potentially suppress Trx bioavailability and increase oxidation sensitivity. Overexpression of TBP-2 also causes slow growth by mitotic arrest and apoptosis by activating the ASK death pathway.
KW - Apoptosis
KW - Cell cycle
KW - Free radicals
KW - Oxidative stress
KW - Thioredoxin
KW - Thioredoxin-binding protein 2
UR - http://www.scopus.com/inward/record.url?scp=84873744581&partnerID=8YFLogxK
U2 - 10.1016/j.freeradbiomed.2012.12.022
DO - 10.1016/j.freeradbiomed.2012.12.022
M3 - Article
C2 - 23291592
AN - SCOPUS:84873744581
VL - 57
SP - 92
EP - 104
JO - Free Radical Biology and Medicine
JF - Free Radical Biology and Medicine
SN - 0891-5849
ER -