Endothelial senescence is induced by phosphorylation and nuclear export of telomeric repeat binding factor 2–interacting protein
Sivareddy Kotla, Hang Thi Vu, Kyung Ae Ko, Yin Wang, Masaki Imanishi, Kyung-Sun Heo, Yuka Fujii, Tamlyn N. Thomas, Young Jin Gi, Hira Mazhar, Jesus Paez-Mayorga, Ji-Hyun Shin, Yunting Tao, Carolyn J. Giancursio, Jan L.M. Medina, Jack Taunton, Aldos J. Lusis, John P. Cooke, Keigi Fujiwara, Nhat-Tu Le, Jun-ichi Abe
Sivareddy Kotla, Hang Thi Vu, Kyung Ae Ko, Yin Wang, Masaki Imanishi, Kyung-Sun Heo, Yuka Fujii, Tamlyn N. Thomas, Young Jin Gi, Hira Mazhar, Jesus Paez-Mayorga, Ji-Hyun Shin, Yunting Tao, Carolyn J. Giancursio, Jan L.M. Medina, Jack Taunton, Aldos J. Lusis, John P. Cooke, Keigi Fujiwara, Nhat-Tu Le, Jun-ichi Abe
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Research Article Cardiology Vascular biology

Endothelial senescence is induced by phosphorylation and nuclear export of telomeric repeat binding factor 2–interacting protein

Abstract

The interplay among signaling events for endothelial cell (EC) senescence, apoptosis, and activation and how these pathological conditions promote atherosclerosis in the area exposed to disturbed flow (d-flow) in concert remain unclear. The aim of this study was to determine whether telomeric repeat-binding factor 2–interacting protein (TERF2IP), a member of the shelterin complex at the telomere, can regulate EC senescence, apoptosis, and activation simultaneously, and if so, by what molecular mechanisms. We found that d-flow induced p90RSK and TERF2IP interaction in a p90RSK kinase activity–dependent manner. An in vitro kinase assay revealed that p90RSK directly phosphorylated TERF2IP at the serine 205 (S205) residue, and d-flow increased TERF2IP S205 phosphorylation as well as EC senescence, apoptosis, and activation by activating p90RSK. TERF2IP phosphorylation was crucial for nuclear export of the TERF2IP-TRF2 complex, which led to EC activation by cytosolic TERF2IP-mediated NF-κB activation and also to senescence and apoptosis of ECs by depleting TRF2 from the nucleus. Lastly, using EC-specific TERF2IP-knockout (TERF2IP-KO) mice, we found that the depletion of TERF2IP inhibited d-flow–induced EC senescence, apoptosis, and activation, as well as atherosclerotic plaque formation. These findings demonstrate that TERF2IP is an important molecular switch that simultaneously accelerates EC senescence, apoptosis, and activation by S205 phosphorylation.

Authors

Sivareddy Kotla, Hang Thi Vu, Kyung Ae Ko, Yin Wang, Masaki Imanishi, Kyung-Sun Heo, Yuka Fujii, Tamlyn N. Thomas, Young Jin Gi, Hira Mazhar, Jesus Paez-Mayorga, Ji-Hyun Shin, Yunting Tao, Carolyn J. Giancursio, Jan L.M. Medina, Jack Taunton, Aldos J. Lusis, John P. Cooke, Keigi Fujiwara, Nhat-Tu Le, Jun-ichi Abe

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Figure 9

Endothelial activation and apoptosis, as well as subsequent atherosclerosis formation, were decreased in Terf2iphet-EKO/Ldlr mice in vivo.

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Endothelial activation and apoptosis, as well as subsequent atherosclero...
(A and B) En face preparations of mouse aortas were coimmunostained with antibodies against vascular endothelial–cadherin (VE-Cad) and VCAM-1 (A) or cleaved caspase 3 (CCS3) (B). Fluorescent images of VCAM-1 and CCS3 expression in areas exposed to d-flow were recorded using an Olympus confocal laser scanning microscope (FV1200 MPE) with a 60× objective lens (NA 1.35na Oil) (left). Scale bars: 20 μm. (C and D) The histogram shows the reduced intensity of anti–VCAM-1 (C) and anti-CC3 (D) staining in the d-flow region of the Terf2iphet-EKO/Ldlr mice. Data are presented as mean ± SD (n = 4/group), **P < 0.01, *P < 0.05 by unpaired 2-tailed t test. (E–H) Mice were fed a high-fat diet for 2 weeks, and PLCL surgery was performed. Four weeks after the surgery, the gross plaque size (plaque length/total left carotid length) in the Terf2iphet-EKO/Ldlr mice (E and G, top) and in the Terf2iphomo-EKO/Ldlr mice (H) were measured. Data are shown as mean ± SD, n = 9–12, *P < 0.05 by unpaired 2-tailed t test. (F) Representative images of H&E-stained sections of the left carotid artery (LCA) and right carotid artery (RCA), obtained from Ldlr or Terf2iphet-EKO/Ldlr mice after 4 weeks of partial LCA ligation. After ligation, neointima formation in the LCA of WT mice occurred, which was inhibited in Terf2iphet-EKO/Ldlr mice. Scale bars: 200 μm. (G, bottom) The LCA plaque size (intima + media)/RCA media ratios in H&E-stained LCA and RCA sections were calculated as described in the Methods. Data are presented as mean ± SD, n = 9–12, *P < 0.05 by unpaired 2-tailed t test.