Abstract
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.
| Original language | English |
|---|---|
| Pages (from-to) | 92-104 |
| Number of pages | 13 |
| Journal | Free Radical Biology and Medicine |
| Volume | 57 |
| DOIs | |
| State | Published - 1 Apr 2013 |
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Keywords
- Apoptosis
- Cell cycle
- Free radicals
- Oxidative stress
- Thioredoxin
- Thioredoxin-binding protein 2
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}
Overexpression of thioredoxin-binding protein 2increases oxidation sensitivity and apoptosis in human lens epithelialcells. / Yu, Yibo; Xing, Kuiyi; Badamas, Rilwan; Kuszynski, Charles A.; Wu, Hongli; Lou, Marjorie F.
In: Free Radical Biology and Medicine, Vol. 57, 01.04.2013, p. 92-104.Research output: Contribution to journal › Article
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 - 2013/4/1
Y1 - 2013/4/1
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 -