Glucocorticoid has been widely accepted to induce Alzheimer9s disease (AD), but the nongenomic effect of glucocorticoid on amyloid β (Aβ) generation has yet to be studied. Here, we investigated the effect of the nongenomic pathway induced by glucocorticoid on amyloid precursor protein (APP) processing enzymes as well as Aβ production using male ICR mice and human neuroblastoma SK-N-MC cells. Mice groups exposed to restraint stress or intracerebroventricular (i.c.v.) injection of Aβ showed impaired cognition, decreased intracellular glucocorticoid receptor (GR) level, but elevated level of membrane GR (mGR). In this respect, we identified the mGR dependent pathway evoked by glucocorticoid using impermeable cortisol conjugated to BSA (cortisol-BSA) on SK-N-MC cells. Cortisol-BSA augmented the expression of beta-site amyloid precursor protein cleaving enzyme 1 (BACE1), the level of C-Terminal Fragment β of APP (C99) and Aβ production which were maintained even after blocking intracellular GR. We also found that cortisol-BSA enhanced the interaction between mGR and Gαs which co-localized in the lipid raft. The subsequently activated CREB by cortisol-BSA bound to the CRE site of the BACE1 promoter increasing its expression, which was downregulated by inhibiting CBP. Consistently, blocking CBP attenuated cognitive impairment and Aβ production induced by corticosterone treatment or i.c.v. injection of Aβ more efficiently than inhibiting intracellular GR in mice. In conclusion, glucocorticoid couples mGR with Gαs and triggers cAMP-PKA-CREB axis dependent on the lipid raft to stimulate BACE1 upregulation and Aβ generation. SIGNIFICANCE STATEMENT Patients with Alzheimer9s disease (AD) have been growing sharply and stress is considered as the major environment factor of AD. Glucocorticoid is the primarily responsive factor to stress and is widely known to induce AD. However, most AD patients usually have impaired genomic pathway of glucocorticoid due to intracellular glucocorticoid receptor (GR) deficiency. In this respect, the genomic mechanism of glucocorticoid faces difficulties in explaining the consistent amyloid β (Aβ) production. Therefore, it is necessary to investigate the novel pathway of glucocorticoid on Aβ generation to find a more selective therapeutic approach to AD patients. In this study, we revealed the importance of nongenomic pathway induced by glucocorticoid where membrane GR plays an important role in Aβ formation.

Alzheimer’s disease (AD) and Parkinson’s disease (PD) are representative neurodegenerative diseases with abnormal energy metabolism and altered distribution and deformation of mitochondria within neurons, particularly in brain regions such as the hippocampus and substantia nigra. Neurons have high energy demands; thus, maintaining a healthy mitochondrial population is important for their biological function. Recently, exosomes have been reported to have mitochondrial regulatory potential and antineurodegenerative properties. This review presents the mitochondrial abnormalities in brain cells associated with AD and PD and the potential of exosomes to treat these diseases. Specifically, it recapitulates research on the molecular mechanisms whereby exosomes regulate mitochondrial biogenesis, fusion/fission dynamics, mitochondrial transport, and mitophagy. Furthermore, this review discusses exosome-triggered signaling pathways that regulate nuclear factor (erythroid-derived 2)-like 2-dependent mitochondrial antioxidation and hypoxia inducible factor 1α-dependent metabolic reprogramming. In summary, this review aims to provide a profound understanding of the regulatory effect of exosomes on mitochondrial function in neurons and to propose exosome-mediated mitochondrial regulation as a promising strategy for AD and PD.

Diabetic retinopathy (DR) is a leading cause of blindness in diabetic patients. Umbilical cord blood-derived mesenchymal stem cells (UCB-MSCs) are emerging as a promising new drug for degenerative disease associated with diabetes. Recent studies have shown that high glucose-increased excessive calcium levels are a major risk factor for mitochondrial reactive oxygen species (mtROS) accumulation and apoptosis. This study aimed to investigate the role of high glucose-induced NFATC1 signaling in mitochondrial oxidative stress-stimulated apoptosis and the effect of tacrolimus on the therapeutic efficacy of subconjunctival transplantation of UCB-MSCs in a DR rat model. High glucose increased mtROS and cleaved caspase-9 expression in UCB-MSCs. High glucose conditions increased O-GlcNAcylated protein expression and nuclear translocation of NFATC1. Tacrolimus pretreatment recovered high glucose-induced mtROS levels and apoptosis. In the DR rat model, subconjunctival transplantation of tacrolimus-pretreated MSCs improved retinal vessel formation, retinal function, and uveitis. In high glucose conditions, tacrolimus pretreatment reduced protein and mRNA expression levels of DRP1 and inhibited mitochondrial fission. In conclusion, we demonstrated that high glucose-induced O-GlcNAcylation activates NFATC1 signaling, which is important for DRP1-mediated mitochondrial fission and mitochondrial apoptosis. Finally, we proposed NFATC1 suppression by tacrolimus as a promising therapeutic strategy to improve the therapeutic efficacy of UCB-MSC transplantation for DR treatment.

Seok JH, et al. J Vet Sci. 2022 Aug;23(5):e74. https://doi.org/10.4142/jvs.22097

Obesity results from excessive body fat accumulation. Leash-walking is a practical way to increase activity in treating obesity; however, limited studies have focused on the frequency and duration of dog leash-walking. There is few research reporting on whether initiating exercise or increasing physical activity in obese dogs can induce stress. Therefore, the present study conducted a clinical trial of the leash-walking effect on weight management and identified the relationship between stress and weight management. Thirty-one dogs participated in a 4-week weight management and were divided into four groups according to their leash-walking frequency and duration. Low walking group (LW): approximately 30 min, 3 times per week; Group 1: approximately 60 min, 3 times per week; Group 2: approximately 30 min, 5 to 7 times per week; Group 3: approximately 60 min, 5 to 7 times per week. Body weight and hair cortisol concentrations of participated dogs were also evaluated. There were significant () differences in the weight loss rate between the Group 2 (−1.08 ± 0.34%/week) and Group 3 (−1.26 ± 0.54%/week) compared to the LW (−0.13 ± 0.49%/week). However, there was an increasing tendency of hair cortisol concentration in Group 1 (0.15 ± 0.10 μg/dl to 0.20 ± 0.19 μg/dl) and Group 3 (0.19 ± 0.19 μg/dl to 0.45 ± 0.76 μg/dl) which are approximately 60 min of leash-walking duration groups. The results of this study suggest that it is more efficient to increase leash-walking frequency than duration for weight loss. However, suddenly increasing leash-walking may be a stress-inducing factor during weight management in overweight dogs. Therefore, it is important to start weight management with appropriate frequency and manageable duration of leash-walking and gradually increase the leash-walking times step by step.

Background:Diabetic retinopathy (DR) is a leading cause of blindness in diabetic patients. Human umbilical cord blood-derived mesenchymal stem cells (UCB-MSCs) are emerging as a promising new drug for degenerative disease associated with diabetes. Recent studies have shown that high glucose-increased excessive calcium levels are a major risk factor for mitochondrial reactive oxygen species (mtROS) accumulation and apoptosis. This study aimed to investigate the role of high glucose-induced NFATC1 signaling in mitochondrial oxidative stress-stimulated apoptosis and the effect of tacrolimus on the therapeutic efficacy of subconjunctival transplantation of UCB-MSCs in a DR rat model.Methods:The UCB-MSCs were pretreated with the drugs prior to high glucose treatment. Then, we conducted experiments using western blot, LDH release, mitoSOX staining, qPCR analysis and MitoTacker staining. For animal experiment, tacrolimus or vehicle-pretreated MSCs were injected subconjunctivally in STZ-induced DR rat model.Results:High glucose increased cytotoxicity, mtROS, and cleaved caspase-9 expression in UCB-MSCs, and high glucose-induced mtROS was critical for apoptosis. High glucose conditions increased O-GlcNAcylated protein expression and nuclear translocation of NFATC1. However, nuclear translocation of NFATC1 was reduced by ST045849 pre-treatment, an O-GlcNAc transferase inhibitor. Tacrolimus pretreatment recovered high glucose-induced mtROS levels and apoptosis. In DR rat model, subconjunctival transplantation of tacrolimus-pretreated MSCs improved retinal vessel formation, retinal function, and uveitis. In high glucose conditions, tacrolimus pretreatment reduced protein and mRNA expression levels of DRP1 and inhibited mitochondrial fission. In addition, Mdivi-1 pretreatment, DRP1 inhibitor, reduced mtROS levels and apoptosis of UCB-MSCs under high glucose conditions.Conclusions: In conclusion, we demonstrated that high glucose-induced O-GlcNAcylation activates NFATC1 signaling, important for DRP1-mediated mitochondrial fission and mitochondrial apoptosis. Finally, we proposed NFATC1 suppression by tacrolimus as a promising therapeutic strategy to improve the therapeutic efficacy of UCB-MSC transplantation for DR treatment.