| 2021 | SIRT2 inhibition exacerbates p53-mediated ferroptosis in mice following experimental traumatic brain injury. | Neuroreport | Ferroptosis plays an important role in traumatic brain injury (TBI). The p53 protein is a major mediator of ferroptosis. However, the role of p53-mediated ferroptosis in TBI has not been studied. Sirtuin 2 (SIRT2) exerts a protective effects role in TBI, although the underlying mechanism of this protection remains unclear. In the present study, we tested the hypothesis that that SIRT2 mitigates TBI by regulating p53-mediated ferroptosis.To model TBI in mice, we used the controlled cortical impact (CCI) injury method. We found that ferroptosis was significantly activated by CCI, and peaked 3 days following CCI, as evidenced by upregulation of GPX4 and SLC7A11, increased content of decreases glutathione, lipid peroxidation, malondialdehyde and ferrous ion. Inhibition of ferroptosis significantly alleviated neurological indications and brain edema. In addition, knockout of p53 significantly blocked ferroptosis following CCI. Furthermore, we found that inhibition of SIRT2 upregulated the acetylation of p53, as well as p53 expression, and exacerbated ferroptosis following CCI. Interestingly, knockout of p53 rescued the SIRT2 inhibition-induced exacerbation of ferroptosis.These findings indicate that p53-mediated ferroptosis contributes to the pathogenesis of TBI. Furthermore, we demonstrate that SIRT2 exerts a neuroprotective effect against TBI by suppressing p53-mediated ferroptosis. |
| C57BL/6 substrain differences in inflammatory and neuropathic nociception and genetic mapping of a major quantitative trait locus underlying acute thermal nociception. | Mol Pain | Sensitivity to different pain modalities has a genetic basis that remains largely unknown. Employing closely related inbred mouse substrains can facilitate gene mapping of nociceptive behaviors in preclinical pain models. We previously reported enhanced sensitivity to acute thermal nociception in C57BL/6J (B6J) versus C57BL/6N (B6N) substrains. Here, we expanded on nociceptive phenotypes and observed an increase in formalin-induced inflammatory nociceptive behaviors and paw diameter in B6J versus B6N mice (Charles River Laboratories). No strain differences were observed in mechanical or thermal hypersensitivity or in edema following the Complete Freund's Adjuvant model of inflammatory pain, indicating specificity in the inflammatory nociceptive stimulus. In the chronic constrictive nerve injury, a model of neuropathic pain, no strain differences were observed in baseline mechanical threshold or in mechanical hypersensitivity up to one month post-chronic constrictive nerve injury. We replicated the enhanced thermal nociception in the 52.5°C hot plate test in B6J versus B6N mice from The Jackson Laboratory. Using a B6J × B6N-F2 cross (N = 164), we mapped a major quantitative trait locus underlying hot plate sensitivity to chromosome 7 that peaked at 26 Mb (log of the odds [LOD] = 3.81, p < 0.01; 8.74 Mb-36.50 Mb) that was more pronounced in males. Genes containing expression quantitative trait loci associated with the peak nociceptive marker that are implicated in pain and inflammation include Ryr1, Cyp2a5, Pou2f2, Clip3, Sirt2, Actn4, and Ltbp4 (false discovery rate < 0.05). Future studies involving positional cloning and gene editing will determine the quantitative trait gene(s) and potential pleiotropy of this locus across pain modalities. |
| 2016 | SIRT2 inhibition exacerbates neuroinflammation and blood-brain barrier disruption in experimental traumatic brain injury by enhancing NF-κB p65 acetylation and activation. | J Neurochem | Sirtuin 2 (SIRT2) is a member of the sirtuin family of NAD(+) -dependent protein deacetylases. In recent years, SIRT2 inhibition has emerged as a promising treatment for neurodegenerative diseases. However, to date, there is no evidence of a specific role for SIRT2 in traumatic brain injury (TBI). We investigated the effects of SIRT2 inhibition on experimental TBI using the controlled cortical impact (CCI) injury model. Adult male mice underwent CCI or sham surgery. A selective brain-permeable SIRT2 inhibitor, AK-7, was administrated 30 min before injury. The volume of the brain edema lesion and the water content of the brain were significantly increased in mice treated with AK-7 (20 mg/kg), compared with the vehicle group, following TBI (p < 0.05 at 1 day and p < 0.05 at 3 days, respectively). Concomitantly, AK-7 administration greatly worsened neurobehavioral deficits on days 3 and 7 after CCI. Furthermore, blood-brain barrier disruption and matrix metalloproteinases (MMP)-9 activity increased following SIRT2 inhibition. AK-7 treatment increased TBI-induced microglial activation both in vivo and in vitro, accompanied by a large increase in the expression and release of inflammatory cytokines. Mechanistically, SIRT2 inhibition increased both K310 acetylation and nuclear translocation of NF-κB p65, leading to enhanced NF-κB activation and up-regulation of its target genes, including aquaporin 4 (AQP4), MMP-9, and pro-inflammatory cytokines. Together, these data demonstrate that SIRT2 inhibition exacerbates TBI by increasing NF-κB p65 acetylation and activation. Our findings provide additional evidence of an anti-inflammatory effect of SIRT2. SIRT2 is a member of the sirtuin family of NAD+-dependent protein deacetylases. Our study suggests that the SIRT2 inhibitor AK-7 exacerbates traumatic brain injury (TBI) via a potential mechanism involving increased acetylation and nuclear translocation of NF-κB p65, resulting in up-regulation of NF-κB target genes, including aquaporin 4 (AQP4), matrix metalloproteinase 9 (MMP-9), and pro-inflammatory cytokines. Our findings provide additional evidence of an anti-inflammatory effect of SIRT2. |