Overexpression of SIRT1 Promotes High Glucose–Attenuated Corneal Epithelial Wound Healing via p53 Regulation of the IGFBP3/IGF-1R/AKT Pathway

Abstract

PURPOSE. To investigate how Sirtuin (silent mating type information regulation 2 homolog) 1 (SIRT1) promotes high glucose-attenuated corneal epithelial wound healing.METHODS. The effects of high glucose on SIRT1 expression were assessed in primary human corneal epithelial cells (CECs) in treatment of 5 mM D-glucose (normal glucose [NG]) and 25 mM D-glucose (high glucose [HG]) and corneas from Ins2 Akita/þ mice by Western blotting. The osmotic pressure of the NG medium was adjusted to that of the HG medium by adding 20 mM mannitol. Pifithrin-a (PFT-a) was used to inhibit the expression of p53 and an adenovirus was used for overexpression of SIRT1 in vivo and in vitro. How overexpression of SIRT1 promotes HG-attenuated corneal epithelial wound healing via p53 regulation of the IGFBP3 (insulin-like growth factor binding protein-3)/IGF-1 (insulin-like growth factor-1)/AKT pathway was investigated in CECs and Ins2 Akita/þ mice. RESULTS. HG induced the downregulation of SIRT1 and the upregulation of p53 acetylation in primary human CECs and corneas from Ins2Akita/þ mice. The results of cell migration assay and corneal wound healing from Ins2Akita/þ mice demonstrated that SIRT1 overexpression strongly promoted wound healing in the presence of HG levels via the downregulation of the IGFBP3 protein. The levels of total p53 expression and acetylated p53 decreased dramatically in the presence of PFT-a, whereas the IGF-1R/AKT pathway was activated in CECs. The results of cell migration assay suggested this posttranslational modification of p53 was involved in the response to cell injury under HG conditions in CECs.CONCLUSIONS. The molecular mechanism by which SIRT1 promotes corneal epithelial wound healing was involved in an enhancement of the IGFBP3/IGF-1/AKT pathway through the deacetylation of p53. This study also suggests that SIRT1 has a protective role in the pathogenesis of diabetic keratopathy.

microRNA-182 Mediates Sirt1-Induced Diabetic Corneal Nerve Regeneration

“…Total RNA was isolated and cDNA was synthesized as described previously (13). The real-time PCR array and data analyses were performed using a RT 2 Profiler PCR Array (Mouse Oxidative Stress and Antioxidant Defense PCR Array, PAMM-065A; SABiosciences, Frederick, MD).…”

“…In our previous study, overexpression of Sirt1 promoted epithelial wound healing in diabetic corneas (13,14). However, the underlying mechanism by which Sirt1 induces diabetic corneal nerve regeneration remains elusive.…”

Sirtuins and their interactions with transcription factors and poly(ADP-ribose) polymerases

“…This enhances the inhibitory influence FOXO1 exerts on PPARγ, thus mediating the changes in adipose metabolism induced by nutrient deprivation or exposure to low temperature [208]. FOXO3 and FOXO4 are also deacetylated by SIRT1 and 2; this exerts a complex influence on their downstream mediators including superoxide dismutase, p27 kip1 , and GADD45 (growth arrest and DNA damage 45) and target processes such as stress resistance cell cycle and death [25,78,101,173,207] C SIRT1 enhances IIS signalling -it occurs through at least two ways: -deacetylation of p53 leads to reduction of its protein levels, relieving IIS inhibition by the IGF-binding protein-3 [215]; -SIRT1 can also directly deacetylate Akt, restoring its ability to bind phosphoinositides and become activated by phosphoinositide-dependent protein kinase 1 [192]). These dependencies have already been confirmed to impact metabolic deregulation, cardiac dysfunctions and tumour formation, and might result in inhibition of the IIS target FOXO1 [67].…”

Substance P Promotes Diabetic Corneal Epithelial Wound Healing Through Molecular Mechanisms Mediated via the Neurokinin-1 Receptor

“…Diabetic corneal pathology always exhibits epithelial basement membrane abnormalities, reduced hemidesmosome density, and delayed wound healing (3,4). However, hyperglycemia also directly impairs the cellular metabolism and causes abnormal changes of corneal epithelium, such as Akt-, epidermal growth factor receptor (EGFR)-, and Sirt1-mediated cell responses to environmental challenges (5)(6)(7). Moreover, excess oxidative stress, resulting from enhanced accumulation of reactive oxygen species (ROS) and impaired antioxidant capabilities in response to hyperglycemia, has been postulated as an important pathological mechanism, whereas the reduction of ROS attenuated the progression of various diabetes complications (8)(9)(10)(11)(12)(13), including in the cornea (5,14).…”