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FLRT2 prevents endothelial cell senescence and vascular aging by regulating the ITGB4/mTORC2/p53 signaling pathway
Hyun Jung Hwang, … , Myriam Gorospe, Jae-Seon Lee
Hyun Jung Hwang, … , Myriam Gorospe, Jae-Seon Lee
Published April 8, 2024
Citation Information: JCI Insight. 2024;9(7):e172678. https://doi.org/10.1172/jci.insight.172678.
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Research Article Cell biology Vascular biology

FLRT2 prevents endothelial cell senescence and vascular aging by regulating the ITGB4/mTORC2/p53 signaling pathway

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Abstract

The roles of fibronectin leucine-rich transmembrane protein 2 (FLRT2) in physiological and pathological processes are not well known. Here, we identify a potentially novel function of FLRT2 in preventing endothelial cell senescence and vascular aging. We found that FLRT2 expression was lower in cultured senescent endothelial cells as well as in aged rat and human vascular tissues. FLRT2 mediated endothelial cell senescence via the mTOR complex 2, AKT, and p53 signaling pathway in human endothelial cells. We uncovered that FLRT2 directly associated with integrin subunit beta 4 (ITGB4) and thereby promoted ITGB4 phosphorylation, while inhibition of ITGB4 substantially mitigated the induction of senescence triggered by FLRT2 depletion. Importantly, FLRT2 silencing in mice promoted vascular aging, and overexpression of FLRT2 rescued a premature vascular aging phenotype. Therefore, we propose that FLRT2 could be targeted therapeutically to prevent senescence-associated vascular aging.

Authors

Hyun Jung Hwang, Donghee Kang, Jae-Ryong Kim, Joon Hyuk Choi, Ji-Kan Ryu, Allison B. Herman, Young-Gyu Ko, Heon Joo Park, Myriam Gorospe, Jae-Seon Lee

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Figure 2

FLRT2 depletion induces cellular senescence through the regulation of mTORC2 in endothelial cells.

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FLRT2 depletion induces cellular senescence through the regulation of mT...
(A–F) HUVECs were transfected with 50 nM of control siRNA (Con Si) or FLRT2 siRNA (FLRT2 Si). (A) The numbers of viable cells were determined at the indicated days after transfection. (B) The cells were harvested at the indicated time points after transfection and subjected to immunoblot analysis. (C) Cell cycle distributions were analyzed using flow cytometry at day 3 after transfection. (D) Cell morphology and SA-β-Gal activity were assessed at day 3 after transfection, and the percentage of senescent cells was quantified. Scale bar: 10 μm. (E) The DNA synthesis rates of siRNA-transfected HUVECs were measured using the 5-bromo-2′-deoxy-uridine (BrdU) incorporation assay. (F) Whole-cell lysates were prepared from HUVECs transfected with Con Si and FLRT2 Si at the indicated days after transfection and subjected to immunoblot assays. (G and H) HUVECs were transfected with Con Si, Raptor Si, or Rictor Si (1st transfection) 6 hours before transfection with Con Si or FLRT2 Si (2nd transfection). At day 2 after transfection, the cells were harvested and subjected to immunoblotting using the indicated antibodies (G). SA-β-Gal activity was measured at day 3 after transfection (H). (I) HUVECs were transfected with Con Si or FLRT2 Si. At day 2 after transfection, cell lysates were subjected to immunoprecipitation with antibodies recognizing Raptor or Rictor, and immunoblot assays were performed with the indicated antibodies. The values represent mean ± SD (n = 3; #P > 0.05; *P < 0.05; **P < 0.01; ***P < 0.001). Two-tailed t test (A, D, and E), 1-way ANOVA (H).

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