TY - JOUR
T1 - PCBP1 and PCBP2 both bind heavily oxidized RNA but cause opposing outcomes, suppressing or increasing apoptosis under oxidative conditions
AU - Ishii, Takashi
AU - Igawa, Tatsuhiro
AU - Hayakawa, Hiroshi
AU - Fujita, Tsugumi
AU - Sekiguchi, Mutsuo
AU - Nakabeppu, Yusaku
N1 - Funding Information:
Funding and additional information—This work was supported by grants from the Ministry of Education, Culture, Sports, Science, and Technology of Japan, including the MEXT supported Program for the Strategic Research Foundation at Private Universities (Grant S1411042) and Japan Society for the Promotion of Science (JSPS) Grants-in-aid for Scientific Research 16K07260 and 20K06495 (to T. I.) and 17H01391 (to Y. N).
PY - 2020/8/21
Y1 - 2020/8/21
N2 - PCBP1, a member of the poly(C)-binding protein (PCBP) family, has the capability of binding heavily oxidized RNA and therefore participates in the cellular response to oxidative conditions, helping to induce apoptosis. There are four other members of this family, PCBP2, PCBP3, PCBP4, and hnRNPK, but it is not known whether they play similar roles. To learn more, we first tested their affinity for an RNA strand carrying two 8-oxo-guanine (8-oxoG) residues at sites located in close proximity to each other, representative of a heavily oxidized strand or RNA with one 8-oxoG or none. Among them, only PCBP2 exhibited highly selective binding to RNA carrying two 8-oxoG residues similar to that observed with PCBP1. In contrast, PCBP3, PCBP4, and hnRNPK bound RNA with or without 8-oxoG modifications and exhibited slightly increased binding to the former. Mutations in conserved RNA-binding domains of PCBP2 disrupted the specific interaction with heavily oxidized RNA. We next tested PCBP2 activity in cells. Compared with WT HeLa S3 cells, PCBP2-KO cells established by gene editing exhibited increased apoptosis with increased caspase-3 activity and PARP1 cleavage under oxidative conditions, which were suppressed by the expression of WT PCBP2 but not one of the mutants lacking binding activity. In contrast, PCBP1-KO cells exhibited reduced apoptosis with much less caspase-3 activity and PARP cleavage than WT cells. Our results indicate that PCBP2 as well as PCBP1 bind heavily oxidized RNA; however, the former may counteract PCBP1 to suppress apoptosis under oxidative conditions.
AB - PCBP1, a member of the poly(C)-binding protein (PCBP) family, has the capability of binding heavily oxidized RNA and therefore participates in the cellular response to oxidative conditions, helping to induce apoptosis. There are four other members of this family, PCBP2, PCBP3, PCBP4, and hnRNPK, but it is not known whether they play similar roles. To learn more, we first tested their affinity for an RNA strand carrying two 8-oxo-guanine (8-oxoG) residues at sites located in close proximity to each other, representative of a heavily oxidized strand or RNA with one 8-oxoG or none. Among them, only PCBP2 exhibited highly selective binding to RNA carrying two 8-oxoG residues similar to that observed with PCBP1. In contrast, PCBP3, PCBP4, and hnRNPK bound RNA with or without 8-oxoG modifications and exhibited slightly increased binding to the former. Mutations in conserved RNA-binding domains of PCBP2 disrupted the specific interaction with heavily oxidized RNA. We next tested PCBP2 activity in cells. Compared with WT HeLa S3 cells, PCBP2-KO cells established by gene editing exhibited increased apoptosis with increased caspase-3 activity and PARP1 cleavage under oxidative conditions, which were suppressed by the expression of WT PCBP2 but not one of the mutants lacking binding activity. In contrast, PCBP1-KO cells exhibited reduced apoptosis with much less caspase-3 activity and PARP cleavage than WT cells. Our results indicate that PCBP2 as well as PCBP1 bind heavily oxidized RNA; however, the former may counteract PCBP1 to suppress apoptosis under oxidative conditions.
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U2 - 10.1074/jbc.ra119.011870
DO - 10.1074/jbc.ra119.011870
M3 - Article
C2 - 32647012
AN - SCOPUS:85089814742
VL - 295
SP - 12247
EP - 12261
JO - Journal of Biological Chemistry
JF - Journal of Biological Chemistry
SN - 0021-9258
IS - 34
ER -