Impairment of mitochondrial unfolded protein response contribute to resistance declination of H₂O₂‐induced injury in senescent MRC‐5 cell model

Abstract

Accumulation of oxidative proteins within mitochondria leads to loss of mitochondrial function, which may lead to age-related degenerative diseases. Mitochondrial antioxidant defense capacity reflects the expression of mitochondrial unfolded protein response (mtUPR)-related proteins. Senescent cells are considered to be less resistant to cellular stress stimuli than exponentially growing cells. In this study, we aimed to investigate the ability of mitochondrial stress response in senescent cells to cope with the accumulation of mitochondrial unfolded proteins induced by hydrogen peroxide (H 2 O 2 ) and to understand the relevant molecular mechanisms. We report here that senescence-associated β-galactosidase (SA-β-gal) and senescence marker protein-30 (SMP-30), commonly used replicative senescence biomarkers, changed remarkably between population doubling (PD) 25 (exponentially growing cells) and PD50 (senescent cells) of MRC-5 fibroblasts. Mitochondrial unfolded proteins were significantly accumulated in H 2 O 2 -treated senescent cells, whereas mtUPR-related molecular chaperones (heat shock protein Hsp60 and Hsp10) and proteases (caseinolytic Clp protease) were not concomitantly elevated in senescent cells. In addition, decreased expression of stromal interacting molecule 1-Orai1-mediated store-operated Ca 2+ entry following an declined intracellular calcium level after 2 mM calcium treatment together with H 2 O 2 addition, implying impairment of calcium influx in senescent MRC-5 during H 2 O 2 -induced injury. These findings suggest that senescent fibroblasts expressed higher vulnerability to H 2 O 2 -induced injury involving the imbalance of calcium homeostasis and impaired mitochondrial nuclear communication. This may Abbreviations: [Ca 2+ ]i, intracellular calcium concentration; C/EBPβ, CAAT/enhancer-binding protein-β; CHOP, C/EBP homologous protein; ClpP, caseinolytic Clp protease; CRAC, Ca 2+ releaseactivated Ca 2+ ; ECL, enhanced chemiluminescence; ER, endoplasmic reticulum; GAPDH, glyceraldehyde-3-phosphate dehydrogenase; H2O2, hydrogen peroxide; Hsp10, heat shock protein 10; Hsp60, heat shock protein 60; JNK, c-Jun N-terminal kinase; mtUPR, mitochondrial unfolded protein response; PBS, phosphate-buffered saline; PD, population doubling; PM, plasma membrane; SA-β-gal, senescence-associated β-galactosidase; SERCA, sarcoendoplasmic reticulum calcium transport ATPase; SMP-30, senescence marker protein-30; SOCE, store-operated Ca 2+ entry; STIM1, stromal interacting molecule 1; TBS, Tris-buffer saline; VDAC, voltage-dependent anion channel; X-Gal, 5-bromo-4-chloro-3-indolyl-beta-D-galactoside.

Regulation of Cr(VI)-Induced Premature Senescence in L02 Hepatocytes by ROS-Ca2+-NF-κB Signaling

“…The common notion is that there is an increase in the intracellular Ca 2+ during senescence progression. It has been reported that a higher Ca 2+ concentration in replicative senescent fibroblasts was noted compared to that in nonsenescent cells [49]. Another research demonstrated that rotenone-induced premature senescence in human neuroblastoma cells was accompanied with cytosolic Ca 2+ rise [50].…”

Targeting Mitochondria to Control Ageing and Senescence

“…In senescent hepatocytes, most of the UPRmt factors levels were found significantly reduced and the pathway compromised [ 108 ], suggesting that UPRmt targeting could have a role in preventing senescence. Similarly, experiments in senescent human lung fibroblasts showed a reduced ability to cope with the accumulation of mitochondrial unfolded proteins [ 109 ]. Additional research is needed to investigate this hypothesis.…”