Research Paper Volume 13, Issue 9 pp 12308—12333

Shikimic acid protects skin cells from UV-induced senescence through activation of the NAD+-dependent deacetylase SIRT1

(A) Western-blot of BiP proteins levels in UVB or non UVB irradiated cells treated with SA at the indicated concentrations in presence or absence of EX-527 1 μM. (B) Quantification of n=3 experiments as (A). The levels of BiP are normalized by the loading control (histone H3) and represented related to the conditions in UVB irradiated cells in absence of SA and EX-527. Student T-test, *pC) Percentage of SA-β-Gal in assays performed as in Figure 3C. (D) Levels of spliced and unspliced XBP1 mRNA monitored by qPCR analysis in cells treated in the indicated conditions in presence or absence of SA and/or EX-527. The levels were normalized by internal controls and represented in each case related to the conditions in UVB irradiated cells in absence of SA and EX-527. Student T-test, *pE) LC3-II protein levels in experiments like in (A). The levels of LC3-II are normalized by the loading control (tubulin) and represented related to the conditions in UVB irradiated cells in absence of SA and EX-527. Student T-test, *pF) Proposed Model for the effect of SA on senescence through SIRT1. Other possible unexplored connections between SA and senescence are indicated by blue broken lines.

Figure 5. (A) Western-blot of BiP proteins levels in UVB or non UVB irradiated cells treated with SA at the indicated concentrations in presence or absence of EX-527 1 μM. (B) Quantification of n=3 experiments as (A). The levels of BiP are normalized by the loading control (histone H3) and represented related to the conditions in UVB irradiated cells in absence of SA and EX-527. Student T-test, *p<0.05. (C) Percentage of SA-β-Gal in assays performed as in Figure 3C. (D) Levels of spliced and unspliced XBP1 mRNA monitored by qPCR analysis in cells treated in the indicated conditions in presence or absence of SA and/or EX-527. The levels were normalized by internal controls and represented in each case related to the conditions in UVB irradiated cells in absence of SA and EX-527. Student T-test, *p<0.05, **p<0.01, ***p<0.001. (E) LC3-II protein levels in experiments like in (A). The levels of LC3-II are normalized by the loading control (tubulin) and represented related to the conditions in UVB irradiated cells in absence of SA and EX-527. Student T-test, *p<0.05. (F) Proposed Model for the effect of SA on senescence through SIRT1. Other possible unexplored connections between SA and senescence are indicated by blue broken lines.