PIN1 Protects Hair Cells and Auditory HEI-OC1 Cells against Senescence by Inhibiting the PI3K/Akt/mTOR Pathway

A growing amount of evidence has confirmed the crucial role of the prolyl isomerase PIN1 in aging and age-related diseases. However, the mechanism of PIN1 in age-related hearing loss (ARHL) remains unclear. Pathologically, ARHL is primarily due to the loss and dysfunction of hair cells (HCs) and spiral ganglion cells (SGCs) in the cochlea. Therefore, in this study, we aimed to investigate the role of PIN1 in protecting hair cells and auditory HEI-OC1 cells from senescence. Enzyme-linked immunosorbent assays, immunohistochemistry, and immunofluorescence were used to detect the PIN1 protein level in the serum of ARHL patients and C57BL/6 mice in different groups, and in the SGCs and HCs of young and aged C57BL/6 mice. In addition, a model of HEI-OC1 cell senescence induced by H2O2 was used. Adult C57BL/6 mice were treated with juglone, or juglone and NAC, for 4 weeks. Interestingly, we found that the PIN1 protein expression decreased in the serum of patients with ARHL, in senescent HEI-OC1 cells, and in the cochlea of aged mice. Moreover, under H2O2 and juglone treatment, a large amount of ROS was produced, and phosphorylation of p53 was induced. Importantly, PIN1 expression was significantly increased by treatment with the p53 inhibitor pifithrin-α. Overexpression of PIN1 reversed the increased level of p-p53 and rescued HEI-OC1 cells from senescence. Furthermore, PIN1 mediated cellular senescence by the PI3K/Akt/mTOR signaling pathway. In vivo data from C57BL/6 mice showed that treatment with juglone led to hearing loss. Taken together, these findings demonstrated that PIN1 may act as a vital modulator in hair cell and HEI-OC1 cell senescence.

Pathological Role of Pin1 in the Development of DSS-Induced Colitis

Inflammatory bowel diseases (IBDs) are serious disorders of which the etiologies are not, as yet, fully understood. In this study, Peptidyl-prolyl cis-trans isomerase NIMA-interacting 1 (Pin1) protein was shown to be dramatically upregulated in the colons of dextran sodium sulfate (DSS)-induced ulcerative colitis model mice. Interestingly, Pin1 knockout (KO) mice exhibited significant attenuation of DSS-induced colitis compared to wild-type (WT) mice, based on various parameters, including body weight, colon length, microscopic observation of the intestinal mucosa, inflammatory cytokine expression, and cleaved caspase-3. In addition, a role of Pin1 in inflammation was suggested because the percentage of M1-type macrophages in the colon was decreased in the Pin1 KO mice while that of M2-type macrophages was increased. Moreover, Pin1 KO mice showed downregulation of both Il17 and Il23a expression in the colon, both of which have been implicated in the development of colitis. Finally, oral administration of Pin1 inhibitor partially but significantly prevented DSS-induced colitis in mice, raising the possibility of Pin1 inhibitors serving as therapeutic agents for IBD.

Design, Synthesis, Anticancer Activity and Molecular Docking Studies of 2,5-Disubstituted-1,3,4-Oxadiazoles Containing Benzimidazole Moiety

A series of benzimidazolyl-1,3,4-oxadiazoles (7a-k) were synthesized and evaluated for in vitro anticancer activity against HeLa, MCF7, A549, and HEK293 cell lines. The results indicate that compounds 7b, 7j and 7k have shown excellent anticancer activity and while most of the compounds were non toxic to normal HEK293 cell lines. Molecular docking results of the synthesized compounds with the target Pin1 protein were also discussed.

VDR Agonist Prevents Diabetic Endothelial Dysfunction through Inhibition of Prolyl Isomerase-1-Mediated Mitochondrial Oxidative Stress and Inflammation

Background and aim. Upregulation of prolyl isomerase-1 (Pin1) protein expression and activity was associated with the pathogenesis of diabetic vasculopathy through induction of endothelial oxidative stress and inflammation. Moreover, VDR agonist protects against high glucose-induced endothelial apoptosis through the inhibition of oxidative stress. We aimed to explore the effects of the VDR agonist on diabetes-associated endothelial dysfunction and the role of Pin1 in this process. Methods. Streptozocin-induced diabetic mice were randomly treated with vehicle, VDR agonist (10 μg/kg/d, i.g., twice a week), or Pin1 inhibitor, Juglone (1 mg/kg/d, i.p., every other day), for eight weeks. In parallel, human umbilical vein endothelial cells (HUVECs) exposed to high-glucose condition were treated with 1,25-dihydroxyvitamin D3 and Juglone or vehicle for 72 hours. Organ chamber experiments were performed to assess endothelium-dependent relaxation to acetylcholine. Circulatory levels of Pin1, SOD, MDA, IL-1β, IL-6, and NO in diabetic mice, Pin1 protein expression and activity, subcellular distribution of p66Shc, and NF-κB p65 in high glucose-cultured HUVECs were determined. Results. Both VDR agonist and Juglone significantly improved diabetes-associated endothelial dysfunction and reduced high glucose-induced endothelial apoptosis. Mechanistically, the circulatory levels of SOD and NO were increased compared with those of vehicle-treated diabetic mice. Additionally, Pin1 protein expression and activity, p66Shc mitochondrial translocation, and NF-κB p65 in high glucose-cultured HUVECs were also inhibited by VDR agonist and Juglone. Knockdown of VDR abolished the inhibitory effects of VDR agonist on high glucose-induced upregulation of Pin1 protein expression and activity. Conclusions. VDR agonist prevents diabetic endothelial dysfunction through inhibition of Pin1-mediated mitochondrial oxidative stress and inflammation.