Am J Hypertens. 2020 Dec 22. pii: hpaa218. [Epub ahead of print]
BACKGROUND: Amyloid-β (Aβ) induces cerebrovascular damage and is reported to stimulate endothelial cell senescence. We previously demonstrated that angiotensin II (Ang II) promoted vascular senescence. We examined the possible cross-talk between Ang II and Aβ in regulating brain vascular smooth muscle cell (BVSMC) senescence.METHODS: BVSMC were prepared from adult male mice and stimulated with Ang II (0, 0.1, 1, 10, 100 nmol/L) and/or Aβ 1-40 (0, 0.1, 0.3, 0.5, 1, 3, 5 µmol/L) for the indicated times. Cellular senescence was evaluated by senescence-associated β-galactosidase staining.
RESULTS: Treatment with Ang II (100 nmol/L) or Aβ (1 µmol/L) at a higher dose increased senescent cells compared with control at 6 days. Treatment with Ang II (10 nmol/L) or Aβ (0.5 µmol/L) at a lower dose had no effect on senescence whereas a combined treatment with lower doses of Ang II and Aβ significantly enhanced senescent cells. This senescence enhanced by lower dose combination was markedly blocked by valsartan (Ang II type 1 receptor inhibitor) or TAK-242 (Aβ receptor TLR4 inhibitor) treatment. Moreover, lower dose combination caused increases in superoxide anion levels and p-ERK expression for 2 days, NF-κB activity, p-IκB, p-IKKα/β, p16 and p53 expression for 4 days, and an obvious decrease in pRb expression. These changes by lower dose combination, except in p-IκB expression and NF-κB activity, were significantly inhibited by pretreatment with U0126 (ERK inhibitor).
CONCLUSIONS: Ang II and Aβ synergistically promoted BVSMC senescence at least due to enhancement of the p-ERK-p16-pRb signaling pathway, oxidative stress and NF-κB/IκB activity.
Keywords: BVSMC senescence; amyloid-β; angiotensin II; cerebrovascular disorders; signal transduction