4E-BP1 counteracts human mesenchymal stem cell senescence via maintaining mitochondrial homeostasis

Abstract

Although the mTOR-4E-BP1 signaling pathway is implicated in aging and aging-related disorders, the role of 4E-BP1 in regulating human stem cell homeostasis remains largely unknown. Here, we report that the expression of 4E-BP1 decreases along with the senescence of human mesenchymal stem cells (hMSCs). Genetic inactivation of 4E-BP1 in hMSCs compromises mitochondrial respiration, increases mitochondrial reactive oxygen species (ROS) production, and accelerates cellular senescence. Mechanistically, the absence of 4E-BP1 destabilizes proteins in mitochondrial respiration complexes, especially several key subunits of the complex III including UQCRC2. Ectopic expression of 4E-BP1 attenuates mitochondrial abnormalities and alleviates cellular senescence in 4E-BP1-deficient hMSCs as well as in physiologically aged hMSCs. These findings together demonstrate that 4E-BP1 functions as a geroprotector to mitigate human stem cell senescence and maintain mitochondrial homeostasis, particularly for the mitochondrial respiration complex III, thus providing a new potential target to counteract human stem cell senescence.

MAVS Antagonizes Human Stem Cell Senescence as a Mitochondrial Stabilizer

“…Mitochondrial dysfunction, characterized by swollen mitochondria, fragmentation of the mitochondrial network, and imbalance of mitochondrial functions, is a hallmark of aging [ 18 , 57 – 59 ]. This phenomenon has been observed in aged flies, worms, and human stem cells [ 16 , 45 , 60 – 64 ]. Our study revealed that MAVS depletion impaired mitochondrial dynamics and homeostasis, as reflected by abnormal mitochondrial morphology and compromised mitochondrial functions.…”

“…Co-IP assays were performed following previous studies [ 16 , 45 ]. MAVS-interacting proteins were identified through Co-IP using plasmids expressing Flag-Luc or Flag-MAVS transfected into HEK293T cells.…”

“…TEM was used to observe the fine structure of mitochondrion following previous studies [ 16 , 84 , 85 ]. Briefly, approximately 5 × 10 6 cells per sample were harvested after trypsinization, washed with PBS, and centrifuged for 5 min at a speed of 1,000 rpm.…”

Reducing oxidative protein folding alleviates senescence by minimizing ER‐to‐nucleus H2O2 release

“…The primary hMSCs were isolated from a 76‐year‐old healthy male gingiva tissues according to previous report (Hu et al , 2020; He et al , 2022). Briefly, the gingiva tissues were cut into granule and digested in TrypLE (Thermo Fisher Scientific) and Dispase IV (Thermo Fisher Scientific) at 37°C for 30 min.…”

SESN1 is a FOXO3 effector that counteracts human skeletal muscle ageing

“…Western blot analysis was performed as previously described. 25,26 Tissues or cells were lysed with SDS lysis buffer containing 2% SDS and 62.5 mM Tris-HCl (pH = 6.8) and incubated at 100 C for 10 min.…”