Isoform- and species-specific control of inositol 1,4,5-trisphosphate (IP3) receptors by reactive oxygen species.
Reactive oxygen species (ROS) stimulate cytoplasmic [Ca(2+)] ([Ca(2+)]c) signaling, but the exact role of the IP3 receptors (IP3R) in this process remains unclear. IP3Rs serve as a potential target of ROS produced by both ER and mitochondrial enzymes, which might locally expose IP3Rs at the ER-mitochondrial associations. Also, IP3Rs contain multiple reactive thiols, common molecular targets of ROS. Therefore, we have examined the effect of superoxide anion (O2) on IP3R-mediated Ca(2+) signaling. In human HepG2, rat RBL-2H3, and chicken DT40 cells, we observed [Ca(2+)]c spikes and frequency-modulated oscillations evoked by a O2 donor, xanthine (X) + xanthine oxidase (XO), dose-dependently. The [Ca(2+)]c signal was mediated by ER Ca(2+) mobilization. X+XO added to permeabilized cells promoted the [Ca(2+)]c rise evoked by submaximal doses of IP3, indicating that O2 directly sensitizes IP3R-mediated Ca(2+) release. In response to X+XO, DT40 cells lacking two of three IP3R isoforms (DKO) expressing either type 1 (DKO1) or type 2 IP3Rs (DKO2) showed a [Ca(2+)]c signal, whereas DKO expressing type 3 IP3R (DKO3) did not. By contrast, IgM that stimulates IP3 formation, elicited a [Ca(2+)]c signal in every DKO. X+XO also facilitated the Ca(2+) release evoked by submaximal IP3 in permeabilized DKO1 and DKO2 but was ineffective in DKO3 or in DT40 lacking every IP3R (TKO). However, X+XO could also facilitate the effect of suboptimal IP3 in TKO transfected with rat IP3R3. Although in silico studies failed to identify a thiol missing in the chicken IP3R3, an X+XO-induced redox change was documented only in the rat IP3R3. Thus, ROS seem to specifically sensitize IP3Rs through a thiol group(s) within the IP3R, which is probably inaccessible in the chicken IP3R3.
From the MitoCare Center, Department of Pathology, Anatomy and Cell Biology, Thomas Jefferson University, Philadelphia, Pennsylvania 19107.
Száva
S
Bánsághi
Tünde
T
Golenár
Muniswamy
M
Madesh
György
G
Csordás
Satish
S
RamachandraRao
Kumar
K
Sharma
David I
DI
Yule
Suresh K
SK
Joseph
György
G
Hajnóczky
D000595:Amino Acid Sequence; D000818:Animals; D020013:Calcium Signaling; D002460:Cell Line; D002645:Chickens; D006801:Humans; D015544:Inositol 1,4,5-Trisphosphate / Q000378:metabolism; D053496:Inositol 1,4,5-Trisphosphate Receptors / Q000737:chemistry / Q000378:metabolism*; D008928:Mitochondria / Q000378:metabolism; D008969:Molecular Sequence Data; D020033:Protein Isoforms / Q000378:metabolism; D051381:Rats; D017382:Reactive Oxygen Species / Q000378:metabolism*; D016415:Sequence Alignment; D013045:Species Specificity
D053496:Inositol 1,4,5-Trisphosphate Receptors; D020033:Protein Isoforms; D017382:Reactive Oxygen Species; D015544:Inositol 1,4,5-Trisphosphate
Calcium Signaling; Endoplasmic Reticulum (ER); IP3 Receptor; Inositol 1,4,5-Trisphosphate; Mitochondria; Reactive Oxygen Species (ROS)