The association between PGC-1α and Alzheimer's disease

Study on the role of Dihuang Yinzi in regulating the AMPK/SIRT1/PGC-1α pathway to promote mitochondrial biogenesis and improve Alzheimer's disease

ETHNOPHARMACOLOGICAL RELEVANCE

Dihuang Yinzi (DHYZ) is a classic prescription in traditional Chinese medicine. Its therapeutic effect on Alzheimer's disease (AD) has been widely validated. However, the underlying molecular mechanisms of DHYZ in AD treatment remain unclear and require further research.

AIM OF THE STUDY

Elucidating DHYZ's promotion of mitochondrial biogenesis through the AMPK/SIRT1/PGC-1α pathway improves neuronal loss, mitochondrial damage, and memory deficits in AD.

MATERIALS AND METHODS

Administering DHYZ by gavage to SAMP8 mice, after completing behavioral tests, the effects of DHYZ on hippocampal neuron loss and mitochondrial structural damage in AD model mice were assessed using Nissl staining and transmission electron microscopy. Western blot was used to detect the expression of mitochondrial biogenesis-related proteins PGC-1α, CREB, mitochondrial fusion protein MFN2, and mitochondrial fission proteins DRP1 and FIS1. At the same time, immunofluorescence (IF) was employed to measure the relative fluorescence intensity of mitochondrial fusion protein MFN1. After determining the optimal dose of DYHZ for treating AD, we conducted mechanistic studies. By intraperitoneally injecting SAMP8 mice with the AMPK inhibitor (Compound C) to inhibit AMPK protein expression and subsequently treating them with DHYZ, the impact of DHYZ on hippocampal neurons in AD model mice was evaluated using Nissl and hematoxylin-eosin staining. Western blot was used to detect the protein expression of AMPK, p-AMPK, SIRT1, PGC-1α, NRF1, and TFAM. In contrast, IF was used to measure the relative fluorescence intensity of PGC-1α, NRF1, and TFAM proteins in the hippocampal CA1 region.

RESULTS

DHYZ significantly improved AD model mice's cognitive impairment and memory deficits and mitigated hippocampal neuron loss and degeneration. Additionally, it ameliorated mitochondrial morphological structures. DHYZ upregulated the protein expression of mitochondrial biogenesis-related proteins PGC-1α, CREB, and mitochondrial fusion proteins MFN1 and MFN2 while inhibiting the expression of mitochondrial fission proteins DRP1 and FIS1. Further studies revealed that DHYZ could upregulate the expression of the AMPK/SIRT1/PGC-1α pathway proteins and their downstream proteins NRF1 and TFAM.

CONCLUSION

DHYZ promotes mitochondrial biogenesis by activating the AMPK/SIRT1/PGC-1α signaling pathway, thereby improving memory deficits, neuronal loss, and mitochondrial dysfunction in AD.

The PGC-1α/ERRα/ULK1 pathway contributes to Perioperative neurocognitive disorders by inducing mitochondrial dysfunction and activating NLRP3 inflammasome in aged mice

Perioperative neurocognitive disorders (PND) are intractable, indistinct, and considerably diminish the postoperative quality of life of patients. It has been proved that Peroxisome proliferator-activated receptor-γ coactivator-1α (PGC-1α) was involved in neurodegenerative diseases by regulating mitochondrial biogenesis. The underlying mechanisms of PGC-1α and Nod-like receptor pyrin domain-containing protein 3 (NLRP3) inflammasome in PND are not well understood. In this study, we constructed a model of laparotomy in aged mice, and then examined the cognition changes with novel object recognition tests and fear condition tests. The protein levels of PGC-1α and NLRP3 in the hippocampus were detect after surgery. Our results showed that NLRP3 and downstream PI3K/AKT pathway expressions were augmented in the hippocampus after surgery, whereas, the expressions of PGC-1α/estrogen-related receptor α (ERRα)/Unc-51-like autophagy activating kinase 1 (ULK1) pathway were diminished after surgery. In addition, we found that NLRP3 was mainly co-localized with neurons in the hippocampus, and synaptic-related proteins were reduced after surgery. At the same time, transmission electron microscopy (TEM) showed that mitochondria were impaired after surgery. Pharmacological treatment of MCC950, a selective NLRP3 inhibitor, effectively alleviated PND. Activation of PGC-1α with ZLN005 significantly ameliorated PND by enhancing the PGC-1α/ERRα/ULK1 signaling pathway, and further suppressing NLRP3 activation. As a result, we conclude that suppression of the PGC-1α/ERRα/ULK1 signaling pathway is the primary mechanism of PND which caused mitochondrial dysfunction, and activated NLRP3 inflammasome and downstream PI3K/AKT pathway, eventually improved cognitive dysfunction.

The Protective Effects of Syringic Acid on Bisphenol A-Induced Neurotoxicity Possibly Through AMPK/PGC-1α/Fndc5 and CREB/BDNF Signaling Pathways

Bisphenol A (BPA), an endocrine disruptor, is commonly used to produce epoxy resins and polycarbonate plastics. Continuous exposure to BPA may contribute to the development of diseases in humans and seriously affect their health. Previous research suggests a significant relationship between the increased incidence of neurological diseases and the level of BPA in the living environment. Syringic acid (SA), a natural derivative of gallic acid, has recently considered much attention due to neuromodulator activity and its anti-oxidant, anti-apoptotic, and anti-inflammatory effects. Therefore, in this study, we aimed to investigate the effects of SA on oxidative stress, apoptosis, memory and locomotor disorders, and mitochondrial function, and to identify the mechanisms related to Alzheimer's disease (AD) in the brain of rats receiving high doses of BPA. For this purpose, male Wistar rats received BPA (50, 100, and 200 mg/kg) and SA (50 mg/kg) for 21 days. The results showed that BPA exposure significantly altered the rats' neurobehavioral responses. Additionally, BPA, by increasing the level of ROS, and MDA level, increased the level of oxidative stress while reducing the level of antioxidant enzymes, such as SOD, CAT, GPx, and mitochondrial GSH. The administration of BPA at 200 mg/kg significantly decreased the expression of ERRα, TFAM, irisin, PGC-1α, Bcl-2, and FNDC5, while it increased the expression of TrkB, cytochrome C, caspase 3, and Bax. Moreover, the Western blotting results showed that BPA increased the levels of P-AMPK, GSK3b, p-tau, and Aβ, while it decreased the levels of PKA, P-PKA, Akt, BDNF, CREB, P-CREB, and PI3K. Meanwhile, SA at 50 mg/kg reversed the behavioral, biochemical, and molecular changes induced by high doses of BPA. Overall, BPA could lead to the development of AD by affecting the mitochondria-dependent apoptosis pathway, as well as AMPK/PGC-1α/FNDC5 and CREB/BDNF/TrkB signaling pathways, and finally, by increasing the expression of tau and Aβ proteins. In conclusion, SA, as an antioxidant, significantly reduced the toxicity of BPA.

Signaling pathways in the treatment of Alzheimer's disease with acupuncture: a narrative review

BACKGROUND

To date, there is no effective treatment for Alzheimer's disease (AD), a progressive neurodegenerative disorder that is increasing in prevalence worldwide. The objective of this review was to summarize the core targets and signaling pathways involved in acupuncture treatment for AD.

METHODS

We reviewed numerous signaling pathways, including mammalian target of rapamycin (mTOR), phosphatidylinositol 3-kinase-protein kinase B (PI3 K/Akt), adenosine monophosphate-activated protein kinase (AMPK), mitogen-activated protein kinase (MAPK), nuclear factor (NF)-kB, p53, Wnt, nitric oxide (NO), Janus kinase / signal transducer and activator of transcription (JAK/ STAT), RhoA/ROCK (Rho-associated protein kinase) and Ca2+/ calmodulin-dependent protein kinase II (CaMKII) / cyclic adenosine monophosphate-response element-binding protein (CREB). The relevant data were obtained from PubMed, EMBASE, Web of Science, China National Knowledge Infrastructure (CNKI) and Wanfang databases.

RESULTS

In summary, the effects of acupuncture are mediated by multiple targets and pathways. Furthermore, acupuncture can improve pathological changes associated with AD (such as abnormal deposition of amyloid (A)β, tau hyperphosphorylation, synaptic dysfunction and neuronal apoptosis) through multiple signaling pathways.

CONCLUSION

Overall, our findings provide a basis for future research into the effects of acupuncture on AD.

Selected Functions and Disorders of Mitochondrial Metabolism under Lead Exposure

Mitochondria play a fundamental role in the energy metabolism of eukaryotic cells. Numerous studies indicate lead (Pb) as a widely occurring environmental factor capable of disrupting oxidative metabolism by modulating the mitochondrial processes. The multitude of known molecular targets of Pb and its strong affinity for biochemical pathways involving divalent metals suggest that it may pose a health threat at any given dose. Changes in the bioenergetics of cells exposed to Pb have been repeatedly demonstrated in research, primarily showing a reduced ability to synthesize ATP. In addition, lead interferes with mitochondrial-mediated processes essential for maintaining homeostasis, such as apoptosis, mitophagy, mitochondrial dynamics, and the inflammatory response. This article describes selected aspects of mitochondrial metabolism in relation to potential mechanisms of energy metabolism disorders induced by Pb.

A single-cell and spatial RNA-seq database for Alzheimer's disease (ssREAD)

Alzheimer's Disease (AD) pathology has been increasingly explored through single-cell and single-nucleus RNA-sequencing (scRNA-seq & snRNA-seq) and spatial transcriptomics (ST). However, the surge in data demands a comprehensive, user-friendly repository. Addressing this, we introduce a single-cell and spatial RNA-seq database for Alzheimer's disease (ssREAD). It offers a broader spectrum of AD-related datasets, an optimized analytical pipeline, and improved usability. The database encompasses 1,053 samples (277 integrated datasets) from 67 AD-related scRNA-seq & snRNA-seq studies, totaling 7,332,202 cells. Additionally, it archives 381 ST datasets from 18 human and mouse brain studies. Each dataset is annotated with details such as species, gender, brain region, disease/control status, age, and AD Braak stages. ssREAD also provides an analysis suite for cell clustering, identification of differentially expressed and spatially variable genes, cell-type-specific marker genes and regulons, and spot deconvolution for integrative analysis. ssREAD is freely available at https://bmblx.bmi.osumc.edu/ssread/ .

A Single-cell and Spatial RNA-seq Database for Alzheimer's Disease (ssREAD)

Alzheimer's Disease (AD) pathology has been increasingly explored through single-cell and single-nucleus RNA-sequencing (scRNA-seq & snRNA-seq) and spatial transcriptomics (ST). However, the surge in data demands a comprehensive, user-friendly repository. Addressing this, we introduce a single-cell and spatial RNA-seq database for Alzheimer's disease (ssREAD). It offers a broader spectrum of AD-related datasets, an optimized analytical pipeline, and improved usability. The database encompasses 1,053 samples (277 integrated datasets) from 67 AD-related scRNA-seq & snRNA-seq studies, totaling 7,332,202 cells. Additionally, it archives 381 ST datasets from 18 human and mouse brain studies. Each dataset is annotated with details such as species, gender, brain region, disease/control status, age, and AD Braak stages. ssREAD also provides an analysis suite for cell clustering, identification of differentially expressed and spatially variable genes, cell-type-specific marker genes and regulons, and spot deconvolution for integrative analysis. ssREAD is freely available at https://bmblx.bmi.osumc.edu/ssread/.

Effects of Dietary Restriction on PGC-1α Regulation in the Development of Age-associated Diseases

Ageing is the most significant risk factor for a number of non-communicable diseases, manifesting as cognitive, metabolic, and cardiovascular diseases. Although multifactorial, mitochondrial dysfunction and oxidative stress have been proposed to be the driving forces of ageing. Peroxisome proliferator-activated receptor γ coactivator α (PGC-1α) is a transcriptional coactivator central to various metabolic functions, of which mitochondrial biogenesis is the most prominent function. Inducible by various stimuli, including nutrient limitations, PGC-1α is a molecule of interest in the maintenance of mitochondrial function and, therefore, the prevention of degenerative diseases. This review involves a literature search for articles retrieved from PubMed using PGC-1α, ageing, and dietary restriction as keywords. Dietary restriction has been shown to promote tissue-specific PGC-1α expression. Both dietary restriction and PGC-1α upregulation have been shown to prolong the lifespans of both lower and higher-level organisms; the incidence of non-communicable diseases also decreased in fasting mammals. In conclusion, dietary interventions may delay ageing by regulating healthy mitochondria in various organs, presenting the possibility of a new primary prevention for many age-related diseases.

Mass Spectrometry Chromatography-Based Metabolomics: The Effect of Long-Term Aerobic Exercise on Learning Ability and the Metabolism of Intestinal Contents in Mice with Alzheimer's Disease

This study aimed to investigate the effect of long-term aerobic exercise on the metabolism of intestinal contents in APP/PS1 mice was studied using a non-targeted metabolomics technique based on high-performance liquid chromatography-mass spectrometry (HPLC-MS) coupling, providing a theoretical basis for exercise to regulate the metabolism of Alzheimer's disease (AD) organisms. Three-month-old male C57BL/6JNju mice, six wild-type (NC, n = 6); 12 APP/PS1 double transgenic species in total, were randomly divided into AD model (AM, n = 6) and AD model exercise (AE, n = 6) groups. The mice in the NC group were fed naturally, the mice in the AM group were statically placed on a running platform, and the mice in the AE group received a 20-week long-term moderate intensity running platform exercise intervention. Following the exercise intervention, the cecum contents of the mice in each group were collected and analyzed using the HPLC-MS technique, with those meeting both variable important in projection (VIP)> 1.5 and p < 0.05 being screened as differential metabolites. A total of 32 different metabolites were detected between the AM and NC groups, with 19 up-regulated in the AM group such as phosphatidic acid (PA) (18:4(6Z,9Z,12Z,15Z)/21:0) and 13 down-regulated in the AM group, such as 4,8-dimethylnonanoyl, compared to the NC group; 98 different metabolites were found between the AM and AE groups, 41 of which were upregulated such as Lyso phosphatidylcholine (LysoPC) and 57 of which were downregulated compared to the AM group such as Phosphatidylinositol (PI). The regulation of linoleic acid metabolism, glycerophospholipid metabolism, bile secretion, phenylalanine metabolism, and other pathways was predominantly regulated by nine metabolites, which were subsequently identified as indicators of exercise intervention to enhance metabolism in AD mice. The metabolomic technique can identify the metabolic problems of intestinal contents in AD mice and initially screen the biomarkers of exercise to improve the metabolic disorders in AD. These findings can help us better understand the impact of aerobic exercise on AD metabolism.

Exercise modulates APOE expression in brain cortex of female APOE3 and APOE4 targeted replacement mice

Apolipoprotein E (ApoE) is the main cholesterol carrier of the brain and the ε4 gene variant (APOE4) is the most prevalent genetic risk factor for Alzheimer's disease (AD), increasing risk up to 15-fold. Several studies indicate that APOE4 modulates critical factors for neuronal function, including brain-derived neurotrophic factor (BDNF) and peroxisome proliferator-activated receptor γ coactivator 1α (PGC-1α). Both proteins show exercise-induced upregulation, which is presumed to mediate many of the beneficial effects of physical activity including improved cognition; however, there is variability in results between individuals potentially in-part due to genetic variations including APOE isoform. This study aimed to determine if the two most prevalent human APOE isoforms influence adaptive responses to exercise-training. Targeted replacement mice, homozygous for either APOE3 or APOE4 were randomized into exercised and sedentary groups. Baseline locomotor function and voluntary wheel-running behavior was reduced in APOE4 mice. Exercised groups were subjected to daily treadmill running for 8 weeks. ApoE protein in brain cortex was significantly increased by exercise in both genotypes. PGC-1α mRNA levels in brain cortex were significantly lower in APOE4 mice, and only tended to increase with exercise in both genotypes. Hippocampal BDNF protein were similar between genotypes and was not significantly modulated by treadmill running. Behavioral and biochemical variations between APOE3 and APOE4 mice likely contribute to the differential risk for neurological and vascular diseases and the exercise-induced increase in ApoE levels suggests an added feature of the potential efficacy of physical activity as a preventative and therapeutic strategy for neurogenerative processes in both genotypes.

The role of microRNA-485 in neurodegenerative diseases

Neurodegenerative diseases (NDDs) are age-related disorders characterized by progressive neurodegeneration and neuronal cell loss in the central nervous system. Neuropathological conditions such as the accumulation of misfolded proteins can cause neuroinflammation, apoptosis, and synaptic dysfunction in the brain, leading to the development of NDDs including Alzheimer's disease (AD) and Parkinson's disease (PD). MicroRNAs (miRNAs) are small noncoding RNA molecules that regulate gene expression post-transcriptionally via RNA interference. Recently, some studies have reported that some miRNAs play an important role in the development of NDDs by regulating target gene expression. MiRNA-485 (miR-485) is a highly conserved brain-enriched miRNA. Accumulating clinical reports suggest that dysregulated miR-485 may be involved in the pathogenesis of AD and PD. Emerging studies have also shown that miR-485 plays a novel role in the regulation of neuroinflammation, apoptosis, and synaptic function in the pathogenesis of NDDs. In this review, we introduce the biological characteristics of miR-485, provide clinical evidence of the dysregulated miR-485 in NDDs, novel roles of miR-485 in neuropathological events, and discuss the potential of targeting miR-485 as a diagnostic and therapeutic marker for NDDs.

Tanshinone IIA ameliorates Aβ transendothelial transportation through SIRT1-mediated endoplasmic reticulum stress

BACKGROUND

The disruption of blood-brain barrier (BBB), predominantly made up by brain microvascular endothelial cells (BMECs), is one of the characteristics of Alzheimer's disease (AD). Thus, improving BMEC function may be beneficial for AD treatment. Tanshinone IIA (Tan IIA) has been proved to ameliorate the cognitive dysfunction of AD. Herein, we explored how Tan IIA affected the function of BMECs in AD.

METHODS

Aβ_1-42-treated brain-derived endothelium cells.3 (bEnd.3 cells) was employed for in vitro experiments. And we performed molecular docking and qPCR to determine the targeting molecule of Tan IIA on Sirtuins family. The APP^swe/PS^dE9 (APP/PS1) mice were applied to perform the in vivo experiments. Following the behavioral tests, protein expression was determined through western blot and immunofluorescence. The activities of oxidative stress-related enzymes were analyzed by biochemically kits. Nissl staining and thioflavin T staining were conducted to reflect the neurodegeneration and Aβ deposition respectively.

RESULTS

Molecular docking and qPCR results showed that Tan IIA mainly acted on Sirtuin1 (SIRT1) in Sirtuins family. The inhibitor of SIRT1 (EX527) was employed to further substantiate that Tan IIA could attenuate SIRT1-mediated endoplasmic reticulum stress (ER stress) in BMECs. Behavioral tests suggested that Tan IIA could improve the cognitive deficits in APP/PS1 mice. Tan IIA administration increased SIRT1 expression and alleviated ER stress in APP/PS1 mice. In addition, LRP1 expression was increased and RAGE expression was decreased after Tan IIA administration in both animals and cells.

CONCLUSION

Tan IIA could promote Aβ transportation by alleviating SIRT1-mediated ER stress in BMECs, which ameliorated cognitive deficits in APP/PS1 mice.

The Novel Role of Mitochondrial Citrate Synthase and Citrate in the Pathophysiology of Alzheimer's Disease

Citrate synthase is a key mitochondrial enzyme that utilizes acetyl-CoA and oxaloacetate to form citrate in the mitochondrial membrane, which participates in energy production in the TCA cycle and linked to the electron transport chain. Citrate transports through a citrate malate pump and synthesizes acetyl-CoA and acetylcholine (ACh) in neuronal cytoplasm. In a mature brain, acetyl-CoA is mainly utilized for ACh synthesis and is responsible for memory and cognition. Studies have shown low citrate synthase in different regions of brain in Alzheimer's disease (AD) patients, which reduces mitochondrial citrate, cellular bioenergetics, neurocytoplasmic citrate, acetyl-CoA, and ACh synthesis. Reduced citrate mediated low energy favors amyloid-β (Aβ) aggregation. Citrate inhibits Aβ25-35 and Aβ1-40 aggregation in vitro. Hence, citrate can be a better therapeutic option for AD by improving cellular energy and ACh synthesis, and inhibiting Aβ aggregation, which prevents tau hyperphosphorylation and glycogen synthase kinase-3 beta. Therefore, we need clinical studies if citrate reverses Aβ deposition by balancing mitochondrial energy pathway and neurocytoplasmic ACh production. Furthermore, in AD's silent phase pathophysiology, when neuronal cells are highly active, they shift ATP utilization from oxidative phosphorylation to glycolysis and prevent excessive generation of hydrogen peroxide and reactive oxygen species (oxidative stress) as neuroprotective action, which upregulates glucose transporter-3 (GLUT3) and pyruvate dehydrogenase kinase-3 (PDK3). PDK3 inhibits pyruvate dehydrogenase, which decreases mitochondrial-acetyl-CoA, citrate, and cellular bioenergetics, and decreases neurocytoplasmic citrate, acetyl-CoA, and ACh formation, thus initiating AD pathophysiology. Therefore, GLUT3 and PDK3 can be biomarkers for silent phase of AD.

E2F4DN Transgenic Mice: A Tool for the Evaluation of E2F4 as a Therapeutic Target in Neuropathology and Brain Aging

E2F4 was initially described as a transcription factor with a key function in the regulation of cell quiescence. Nevertheless, a number of recent studies have established that E2F4 can also play a relevant role in cell and tissue homeostasis, as well as tissue regeneration. For these non-canonical functions, E2F4 can also act in the cytoplasm, where it is able to interact with many homeostatic and synaptic regulators. Since E2F4 is expressed in the nervous system, it may fulfill a crucial role in brain function and homeostasis, being a promising multifactorial target for neurodegenerative diseases and brain aging. The regulation of E2F4 is complex, as it can be chemically modified through acetylation, from which we present evidence in the brain, as well as methylation, and phosphorylation. The phosphorylation of E2F4 within a conserved threonine motif induces cell cycle re-entry in neurons, while a dominant negative form of E2F4 (E2F4DN), in which the conserved threonines have been substituted by alanines, has been shown to act as a multifactorial therapeutic agent for Alzheimer’s disease (AD). We generated transgenic mice neuronally expressing E2F4DN. We have recently shown using this mouse strain that expression of E2F4DN in 5xFAD mice, a known murine model of AD, improved cognitive function, reduced neuronal tetraploidization, and induced a transcriptional program consistent with modulation of amyloid-β (Aβ) peptide proteostasis and brain homeostasis recovery. 5xFAD/E2F4DN mice also showed reduced microgliosis and astrogliosis in both the cerebral cortex and hippocampus at 3-6 months of age. Here, we analyzed the immune response in 1 year-old 5xFAD/E2F4DN mice, concluding that reduced microgliosis and astrogliosis is maintained at this late stage. In addition, the expression of E2F4DN also reduced age-associated microgliosis in wild-type mice, thus stressing its role as a brain homeostatic agent. We conclude that E2F4DN transgenic mice represent a promising tool for the evaluation of E2F4 as a therapeutic target in neuropathology and brain aging.

PGC-1α activity and mitochondrial dysfunction in preterm infants

Extremely low gestational age neonates (ELGANs) are born in a relatively hyperoxic environment with weak antioxidant defenses, placing them at high risk for mitochondrial dysfunction affecting multiple organ systems including the nervous, respiratory, ocular, and gastrointestinal systems. The brain and lungs are highly affected by mitochondrial dysfunction and dysregulation in the neonate, causing white matter injury (WMI) and bronchopulmonary dysplasia (BPD), respectively. Adequate mitochondrial function is important in providing sufficient energy for organ development as it relates to alveolarization and axonal myelination and decreasing oxidative stress via reactive oxygen species (ROS) and reactive nitrogen species (RNS) detoxification. Peroxisome proliferator-activated receptor gamma coactivator-1 alpha (PGC-1α) is a master regulator of mitochondrial biogenesis and function. Since mitochondrial dysfunction is at the root of WMI and BPD pathobiology, exploring therapies that can regulate PGC-1α activity may be beneficial. This review article describes several promising therapeutic agents that can mitigate mitochondrial dysfunction through direct and indirect activation and upregulation of the PGC-1α pathway. Metformin, resveratrol, omega 3 fatty acids, montelukast, L-citrulline, and adiponectin are promising candidates that require further pre-clinical and clinical studies to understand their efficacy in decreasing the burden of disease from WMI and BPD in preterm infants.

Epigenetic deregulation in cancer: Enzyme players and non-coding RNAs

Data obtained from cutting-edge research have shown that deregulated epigenetic marks are critical hallmarks of cancer. Rapidly emerging scientific evidence has helped in developing a proper understanding of the mechanisms leading to control of cellular functions, from changes in chromatin accessibility, transcription and translation, and in post-translational modifications. Firstly, mechanisms of DNA methylation and demethylation are introduced, as well as modifications of DNA and RNA, with particular focus on N6-methyladenosine (m6A), discussing the effects of these modifications in normal cells and in malignancies. Then, chromatin modifying proteins and remodelling complexes are discussed. Many enzymes and accessory proteins in these complexes have been found mutated or have undergone differential splicing, leading to defective protein complexes. Epigenetic mechanisms acting on nucleosomes by polycomb repressive complexes and on chromatin by SWI/SNF complexes on nucleosome assembly/disassembly, as well as main mutated genes linked to cancers, are reviewed. Among enzymes acting on histones and other proteins erasing the reversible modifications are histone deacetylases (HDACs). Sirtuins are of interest since most of these enzymes not only deacylate histones and other proteins, but also post-translationally modify proteins adding a Mono-ADP-ribose (MAR) moiety. MAR can be read by MACRO-domain containing proteins such as histone MacroH2A1, with specific function in chromatin assembly. Finally, recent advances are presented on non-coding RNAs with a scaffold function, prospecting their role in assembly of chromatin modifying complexes, recruiting enzyme players to chromatin regions. Lastly, the imbalance in metabolites production due to mitochondrial dysfunction is presented, with the potential of these metabolites to inhibit enzymes, either writers, readers or erasers of epitranscriptome marks. In the perspectives, studies are overwied on drugs under development aiming to limit excessive enzyme activities and to reactivate chromatin modifying complexes, for therapeutic application. This knowledge may lead to novel drugs and personalised medicine for cancer patients.

Icariin: A Potential Neuroprotective Agent in Alzheimer's Disease and Parkinson's Disease

Alzheimer's disease (AD) and Parkinson's disease (PD) are the most common neurodegenerative diseases worldwide. They are characterized by the loss of neurons and synapses in special parts of the central nervous system (CNS). There is no definitive treatment for AD and PD, but extensive studies are underway to identify the effective drugs which can slow the progression of these diseases by affecting the factors involved in their pathophysiology (i.e., aggregated proteins, neuroinflammation, and oxidative stress). Icariin, a natural compound isolated from Epimedii herba, is known because of its anti-inflammatory and anti-oxidant properties. In this regard, there are numerous studies indicating its potential as a natural compound against the progression of CNS disorders, such as neurodegenerative diseases. Therefore, this review aims to re-examine findings on the pharmacologic effects of icariin on factors involved in the pathophysiology of AD and PD.

Berberine Ameliorates Cognitive Disorder via GSK3β/PGC-1α Signaling in APP/PS1 Mice

Previous studies have revealed that Berberine (BBR) had therapeutic effects on Alzheimer's disease (AD). However, the underlying mechanism of BBR in the treatment of AD is unclear. The study was to investigate whether berberine ameliorates cognitive disorder in AD by regulating on GSK3β/PGC-1α signaling pathway. APP/PS1 mice were treated with BBR (50 mg/kg and 100 mg/kg) for 4 mo, and the cognitive function of mice was tested by Morris water maze. The levels of inflammatory cytokines IL-1β, TNF-α, and IL-6 in hippocampus of mice were detected by ELISA kits. The damage of neuronal in hippocampal CA1 was detected by Nissl staining. The tau and GSK3β protein were detected by western blot. The results showed that BBR treatment obviously improved spatial cognitive function of APP/PS1 mice. Meanwhile, the pro-inflammatory cytokines were decreased in hippocampus by the administration of BBR. Additionally, BBR significantly alleviated neuronal damage and reduced the levels of hyperphosphorylated tau at sites of Thr205 and Thr231 in hippocampus. Importantly, BBR inhibited the activity of GSK3β and increased the expression of PGC-1α. Consequently, our results demonstrates that BBR could improve the cognitive function by inhibiting the tau hyperphosphorylation and neuroinflammation. These beneficial effects of BBR may be attributed to the regulation of GSK3β/PGC-1α signaling pathway in APP/PS1 mice. These findings reveal a vital role for GSK3β/PGC-1α signaling pathway in retarding cognitive disorder, indicating that PGC-1α might be a potential target for the treatment of AD.

Effects of an Exercise Program Combining Aerobic and Resistance Training on Protein Expressions of Neurotrophic Factors in Obese Rats Injected with Beta-Amyloid

In this study, the effects of a 12-week exercise program combining aerobic and resistance training on high-fat diet-induced obese Sprague Dawley (SD) rats after the injection of beta-amyloid into the cerebral ventricle were investigated. Changes in physical fitness, cognitive function, blood levels of beta-amyloid and metabolic factors, and protein expressions of neurotrophic factors related to brain function such as BDNF (brain-derived neurotrophic factor) in the quadriceps femoris, hippocampus, and cerebral cortex were analyzed. The subjects were thirty-two 10-week-old SD rats (DBL Co., Ltd., Seoul, Korea). The rats were randomized into four groups: β-Non-Ex group (n = 8) with induced obesity and βA25-35 injection into the cerebral ventricle through stereotactic biopsy; β-Ex group (n = 8) with induced obesity, βA25-35 injection, and exercise; S-Non-Ex group (n = 8) with an injection of saline in lieu of βA25-35 as the control; and S-Ex group (n = 8) with saline injection and exercise. The 12-week exercise program combined aerobic training and resistance training. As for protein expressions of the factors related to brain function, the combined exercise program was shown to have a clear effect on activating the following factors: PGC-1α (peroxisome proliferator-activated receptor gamma coactivator 1-alpha), FNDC5 (fibronectin type III domain-containing protein 5), and BDNF in the quadriceps femoris; TrkB (Tropomyosin receptor kinase B), FNDC5, and BDNF in the hippocampus; PGC-1α, FNDC5, and BDNF in the cerebral cortex. The protein expression of β-amyloid in the cerebral cortex was significantly lower in the β-Ex group than in the β-Non-Ex group (p < 0.05). The 12-week intervention with the combined exercise program of aerobic and resistance training was shown to improve cardiopulmonary function, muscular endurance, and short-term memory. The results demonstrate a set of positive effects of the combined exercise program, which were presumed to have arisen mainly due to its alleviating effect on β-amyloid plaques, the main cause of reduced brain function, as well as the promotion of protein expressions of PGC-1α, FNDC5, and BDNF in the quadriceps femoris, hippocampus, and cerebral cortex.

Insulin and Its Key Role for Mitochondrial Function/Dysfunction and Quality Control: A Shared Link between Dysmetabolism and Neurodegeneration

Insulin was discovered and isolated from the beta cells of pancreatic islets of dogs and is associated with the regulation of peripheral glucose homeostasis. Insulin produced in the brain is related to synaptic plasticity and memory. Defective insulin signaling plays a role in brain dysfunction, such as neurodegenerative disease. Growing evidence suggests a link between metabolic disorders, such as diabetes and obesity, and neurodegenerative diseases, especially Alzheimer's disease (AD). This association is due to a common state of insulin resistance (IR) and mitochondrial dysfunction. This review takes a journey into the past to summarize what was known about the physiological and pathological role of insulin in peripheral tissues and the brain. Then, it will land in the present to analyze the insulin role on mitochondrial health and the effects on insulin resistance and neurodegenerative diseases that are IR-dependent. Specifically, we will focus our attention on the quality control of mitochondria (MQC), such as mitochondrial dynamics, mitochondrial biogenesis, and selective autophagy (mitophagy), in healthy and altered cases. Finally, this review will be projected toward the future by examining the most promising treatments that target the mitochondria to cure neurodegenerative diseases associated with metabolic disorders.

Neuroprotective Effects of a Small Mitochondrially-Targeted Tetrapeptide Elamipretide in Neurodegeneration

Neural mitochondrial dysfunction, neural oxidative stress, chronic neuroinflammation, toxic protein accumulation, and neural apoptosis are common causes of neurodegeneration. Elamipretide, a small mitochondrially-targeted tetrapeptide, exhibits therapeutic effects and safety in several mitochondria-related diseases. In neurodegeneration, extensive studies have shown that elamipretide enhanced mitochondrial respiration, activated neural mitochondrial biogenesis via mitochondrial biogenesis regulators (PCG-1α and TFAM) and the translocate factors (TOM-20), enhanced mitochondrial fusion (MNF-1, MNF-2, and OPA1), inhibited mitochondrial fission (Fis-1 and Drp-1), as well as increased mitophagy (autophagy of mitochondria). In addition, elamipretide has been shown to attenuate neural oxidative stress (hydrogen peroxide, lipid peroxidation, and ROS), neuroinflammation (TNF, IL-6, COX-2, iNOS, NLRP3, cleaved caspase-1, IL-1β, and IL-18), and toxic protein accumulation (Aβ). Consequently, elamipretide could prevent neural apoptosis (cytochrome c, Bax, caspase 9, and caspase 3) and enhance neural pro-survival (Bcl2, BDNF, and TrkB) in neurodegeneration. These findings suggest that elamipretide may prevent the progressive development of neurodegenerative diseases via enhancing mitochondrial respiration, mitochondrial biogenesis, mitochondrial fusion, and neural pro-survival pathway, as well as inhibiting mitochondrial fission, oxidative stress, neuroinflammation, toxic protein accumulation, and neural apoptosis. Elamipretide or mitochondrially-targeted peptide might be a targeted agent to attenuate neurodegenerative progression.

Covering the Role of PGC-1α in the Nervous System

The peroxisome proliferator-activated receptor-γ coactivator-1α (PGC-1α) is a well-known transcriptional coactivator involved in mitochondrial biogenesis. PGC-1α is implicated in the pathophysiology of many neurodegenerative disorders; therefore, a deep understanding of its functioning in the nervous system may lead to the development of new therapeutic strategies. The central nervous system (CNS)-specific isoforms of PGC-1α have been recently identified, and many functions of PGC-1α are assigned to the particular cell types of the central nervous system. In the mice CNS, deficiency of PGC-1α disturbed viability and functioning of interneurons and dopaminergic neurons, followed by alterations in inhibitory signaling and behavioral dysfunction. Furthermore, in the ALS rodent model, PGC-1α protects upper motoneurons from neurodegeneration. PGC-1α is engaged in the generation of neuromuscular junctions by lower motoneurons, protection of photoreceptors, and reduction in oxidative stress in sensory neurons. Furthermore, in the glial cells, PGC-1α is essential for the maturation and proliferation of astrocytes, myelination by oligodendrocytes, and mitophagy and autophagy of microglia. PGC-1α is also necessary for synaptogenesis in the developing brain and the generation and maintenance of synapses in postnatal life. This review provides an outlook of recent studies on the role of PGC-1α in various cells in the central nervous system.

Mitochondrial sirtuins, metabolism, and aging

Maintaining metabolic homeostasis is essential for cellular and organismal health throughout life. Of the multiple signaling pathways that regulate metabolism, such as PI3K/AKT, mTOR, AMPK, and sirtuins, mammalian sirtuins also play unique roles in aging. By understanding how sirtuins regulate metabolic processes, we can start to understand how they slow down or accelerate biological aging. Here, we review the biology of SIRT3, SIRT4, and SIRT5, known as the mitochondrial sirtuins due to their localization in the mitochondrial matrix. First, we will focus on canonical pathways that regulate metabolism more broadly and how these are integrated with aging regulation. Then, we will summarize the current knowledge about functional differences between SIRT3, SIRT4, and SIRT5 in metabolic control and integration in signaling networks. Finally, we will discuss how mitochondrial sirtuins regulate processes associated with aging and oxidative stress, calorie restriction and disease.

Alterations in tanycytes and related cell populations of arcuate nucleus in streptozotocin-induced Alzheimer disease model

It is assumed that dysfunction of tanycytes could be one of the components of pathogenesis of both Alzheimer disease and type 2 diabetes mellitus. The study was aimed to assess alterations in the tanycyte morphology in the Alzheimer disease model. The 3 mg/kg streptozotocin dose was injected in the lateral ventricles of Wistar rats in order to model the Alzheimer disease. Alterations in hypothalamic tanycytes were assessed 2 weeks, 4 weeks, 3 months and 6 months after administration of the toxin. Immunohistochemistry was used to identify the protein markers of tanycytes (vimentin, nestin), astrocytes (GFAP, glutamine synthetase) and neurons (HuC/D), as well as to assess cell proliferation (with the use of Ki67 protein) and mitochondrial alterations (mitochondrial complex IV, PGC1a). Administration of streptozotocin lead to β-amyloid accumulation in hypothalamus and ventricular enlargement (p < 0.001). Streptozotocin damaged both α1/α2 tanycytes and β1 tanycytes. The intensity of vimentin staining in α1/α2 tanycytes decreased by week 4 (p = 0.003), and in β1 tanycytes it decreased in three months (p < 0.001). The same trend was observed for nestin. The number of Ki67+ nuclei decreased (p < 0.05), and the expression of proteins associated with mitochondria changed. The density of hypothalamic tanycytes decreased by week 4 after administration of the toxin. Moreover, astrocyte activation was revealed. However, no prominent damage to both astrocytes and neurons was observed within four weeks after administration of streptozotocin. The revealed high tanycyte vulnerability to streptozotocin is in line with the hypothesis of the role of damage to hypothalamic structures in both local and systemic metabolic disorders occurring in the Alzheimer disease models.

Genetic Biomarkers in Association with Depressive Disorder in UAE Residents: A Pilot Case Study

Objectives

We sought to explore the expression of genes associated with depressive disorder in patients with depression compared to control patients. A large body of research in the area of genetics has shown familial aggregation for depressive disorders. The purpose of this study was to identify genetic risk factors in developing depression, particularly among the population residing in the UAE.

Methods

We investigated five associated genes (PPARGC1A, CAMKMT, HSD11B1, SLC6A4, and MAOA) previously linked to depression and anxiety in other populations. The study was carried out in Al Ain, although participants were from different nationalities. Blood samples were collected over a period of seven months, and lab work was carried out over a period of two months from September 1, 2018 to May 30, 2019. We screened the prevalence of the PPARGC1A, CAMKMT, HSD11B1, SLC6A4, and MAOA in 29 patients with depressive disorder and 30 controls using the quantitative real-time polymerase chain reaction method.

Results

The expression of the PPARGC1A gene, studied for the first time in the UAE population. The independent t-test was used to check the significance of difference between the expression levels of target genes where the control was set at a reference level of 1.0. PPARGC1A gene is lower among the depressed group which showed mean difference: 0.4 and p-value: 0.02, indicating a strong association with depression. No significant difference was found in the genes' expression of CAMKMT with p-value 0.150, MAOA p-value 0.070, SLC6A4 p-value 0.750, and HSD11B1 p-value 0.100 in two groups in comparison with (p < 0.050).

Conclusions

These results open several possibilities for further research to study the role of this gene as a protective factor against developing depression.

Increased P2×2 receptors induced by amyloid-β peptide participates in the neurotoxicity in alzheimer's disease

Amyloid beta peptide (Aβ) is tightly associated with the physiopathology of Alzheimer's Disease (AD) as one of the most important factors in the evolution of the pathology. In this context, we previously reported that Aβ increases the expression of ionotropic purinergic receptor 2 (P2×2R). However, its role on the cellular and molecular Aβ toxicity is unknown, especially in human brain of AD patients. Using cellular and molecular approaches in hippocampal neurons, PC12 cells, and human brain samples of patients with AD, we evaluated the participation of P2×2R in the physiopathology of AD. Here, we reported that Aβ oligomers (Aβo) increased P2×2 levels in mice hippocampal neurons, and that this receptor increases at late Braak stages of AD patients. Aβo also increases the colocalization of APP with Rab5, an early endosomes marker, and decreased the nuclear/cytoplasmic ratio of Fe65 and PGC-1α immunoreactivity. The overexpression in PC12 cells of P2×2a, but not P2×2b, replicated these changes in Fe65 and PGC-1α; however, both overexpressed isoforms increased levels of Aβ. Taken together, these data suggest that P2×2 is upregulated in AD and it could be a key potentiator of the physiopathology of Aβ. Our results point to a possible participation in a toxic cycle that increases Aβ production, Ca²⁺ overload, and a decrease of PGC-1α. These novel findings put the P2×2R as a key novel pharmacological target to develop new therapeutic strategies to treat Alzheimer's Disease.

Sirtuins as pharmacological targets in neurodegenerative and neuropsychiatric disorders

Histone deacetylases (HDACs) are enzymes that regulate several processes, such as transcription, cell proliferation, differentiation and development. HDACs are classified as either Zn²⁺ -dependent or NAD⁺ -dependent enzymes. Over the years, experimental and clinical evidence has demonstrated that HDAC modulation is a critical process in neurodegenerative and psychiatric disorders. Nevertheless, most of the studies have focused on the role of Zn²⁺ -dependent HDACs in the development of these diseases, although there is growing evidence showing that the NAD⁺ -dependent HDACs, known as sirtuins, are also very promising targets. This possibility has been strengthened by reports of decreased levels of NAD⁺ in CNS disorders, which can lead to alterations in sirtuin activation and therefore result in increased pathology. In this review, we discuss the role of sirtuins in neurodegenerative and neuropsychiatric disorders as well the possible rationale for them to be considered as pharmacological targets in future therapeutic interventions.

Nilotinib Improves Bioenergetic Profiling in Brain Astroglia in the 3xTg Mouse Model of Alzheimer's Disease

Current treatments targeting amyloid beta in Alzheimer's disease (AD) have minimal efficacy, which results in a huge unmet medical need worldwide. Accumulating data suggest that brain mitochondrial dysfunction play a critical role in AD pathogenesis. Targeting cellular mechanisms associated with mitochondrial dysfunction in AD create a novel approach for drug development. This study investigated the effects of nilotinib, as a selective tyrosine kinase inhibitor, in astroglia derived from 3xTg-AD mice versus their C57BL/6-controls. Parameters included oxygen consumption rates (OCR), ATP, cytochrome c oxidase (COX), citrate synthase (CS) activity, alterations in oxidative phosphorylation (OXPHOS), nuclear factor kappa B (NF-κB), key regulators of mitochondrial dynamics (mitofusin (Mfn1), dynamin-related protein 1 (Drp1)), and mitochondrial biogenesis (peroxisome proliferator-activated receptor gamma coactivator1-alpha (PGC-1α), calcium/calmodulin-dependent protein kinase II (CaMKII), and nuclear factor (erythroid-derived 2)-like 2 (Nrf2)). Nilotinib increased OCR, ATP, COX, Mfn1, and OXPHOS levels in 3xTg astroglia. No significant differences were detected in levels of Drp1 protein and CS activity. Nilotinib enhanced mitochondrial numbers, potentially through a CaMKII-PGC1α-Nrf2 pathway in 3xTg astroglia. Additionally, nilotinib-induced OCR increases were reduced in the presence of the NF-κB inhibitor, Bay11-7082. The data suggest that NF-κB signaling is intimately involved in nilotinib-induced changes in bioenergetics in 3xTg brain astroglia. Nilotinib increased translocation of the NF-κB p50 subunit into the nucleus of 3xTg astroglia that correlates with an increased expression and activation of NF-κB. The current findings support a role for nilotinib in improving mitochondrial function and suggest that astroglia may be a key therapeutic target in treating AD.

Physical Exercise and Alzheimer's Disease: Effects on Pathophysiological Molecular Pathways of the Disease

Alzheimer’s disease (AD), the most common form of neurodegenerative dementia in adults worldwide, is a multifactorial and heterogeneous disorder characterized by the interaction of genetic and epigenetic factors and the dysregulation of numerous intracellular signaling and cellular/molecular pathways. The introduction of the systems biology framework is revolutionizing the study of complex diseases by allowing the identification and integration of cellular/molecular pathways and networks of interaction. Here, we reviewed the relationship between physical activity and the next pathophysiological processes involved in the risk of developing AD, based on some crucial molecular pathways and biological process dysregulated in AD: (1) Immune system and inflammation; (2) Endothelial function and cerebrovascular insufficiency; (3) Apoptosis and cell death; (4) Intercellular communication; (5) Metabolism, oxidative stress and neurotoxicity; (6) DNA damage and repair; (7) Cytoskeleton and membrane proteins; (8) Synaptic plasticity. Moreover, we highlighted the increasingly relevant role played by advanced neuroimaging technologies, including structural/functional magnetic resonance imaging, diffusion tensor imaging, and arterial spin labelling, in exploring the link between AD and physical exercise. Regular physical exercise seems to have a protective effect against AD by inhibiting different pathophysiological molecular pathways implicated in AD.

Oxidative Damage and Antioxidant Response in Frontal Cortex of Demented and Nondemented Individuals with Alzheimer's Neuropathology

Alzheimer's disease (AD) is characterized by progressive neurodegeneration in the cerebral cortex, histopathologically hallmarked by amyloid β (Aβ) extracellular plaques and intracellular neurofibrillary tangles, constituted by hyperphosphorylated tau protein. Correlation between these pathologic features and dementia has been challenged by the emergence of "nondemented with Alzheimer's neuropathology" (NDAN) individuals, cognitively intact despite displaying pathologic features of AD. The existence of these subjects suggests that some unknown mechanisms are triggered to resist Aβ-mediated detrimental events. Aβ accumulation affects mitochondrial redox balance, increasing oxidative stress status, which in turn is proposed as a primary culprit in AD pathogenesis. To clarify the relationship linking Aβ, oxidative stress, and cognitive impairment, we performed a comparative study on AD, NDAN, and aged-matched human postmortem frontal cortices of either sex. We quantitatively analyzed immunofluorescence distribution of oxidative damage markers, and of SOD2 (superoxide dismutase 2), PGC1α [peroxisome proliferator-activated receptor (PPAR) γ-coactivator 1α], PPARα, and catalase as key factors in antioxidant response, as well as the expression of miRNA-485, as a PGC1α upstream regulator. Our results confirm dramatic redox imbalance, associated with impaired antioxidant defenses in AD brain. By contrast, NDAN individuals display low oxidative damage, which is associated with high levels of scavenging systems, possibly resulting from a lack of PGC1α miRNA-485-related inhibition. Comparative analyses in neurons and astrocytes further highlighted cell-specific mechanisms to counteract redox imbalance. Overall, our data emphasize the importance of transcriptional and post-transcriptional regulation of antioxidant response in AD. This suggests that an efficient PGC1α-dependent "safety mechanism" may prevent Aβ-mediated oxidative stress, supporting neuroprotective therapies aimed at ameliorating defects in antioxidant response pathways in AD patients.

Increasing Nrf2 Activity as a Treatment Approach in Neuropsychiatry

Nuclear factor erythroid 2-related factor 2 (Nrf2) is a transcription factor encoded by NFE2L2. Under oxidative stress, Nrf2 does not undergo its normal cytoplasmic degradation but instead travels to the nucleus, where it binds to a DNA promoter and initiates transcription of anti-oxidative genes. Nrf2 upregulation is associated with increased cellular levels of glutathione disulfide, glutathione peroxidase, glutathione transferases, thioredoxin and thioredoxin reductase. Given its key role in governing the cellular antioxidant response, upregulation of Nrf2 has been suggested as a common therapeutic target in neuropsychiatric illnesses such as major depressive disorder, bipolar disorder and schizophrenia, which are associated with chronic oxidative and nitrosative stress, characterised by elevated levels of reactive oxygen species, nitric oxide and peroxynitrite. These processes lead to extensive lipid peroxidation, protein oxidation and carbonylation, and oxidative damage to nuclear and mitochondrial DNA. Intake of N-acetylcysteine, coenzyme Q₁₀ and melatonin is accompanied by increased Nrf2 activity. N-acetylcysteine intake is associated with improved cerebral mitochondrial function, decreased central oxidative and nitrosative stress, reduced neuroinflammation, alleviation of endoplasmic reticular stress and suppression of the unfolded protein response. Coenzyme Q₁₀, which acts as a superoxide scavenger in neuroglial mitochondria, instigates mitohormesis, ameliorates lipid peroxidation in the inner mitochondrial membrane, activates uncoupling proteins, promotes mitochondrial biogenesis and has positive effects on the plasma membrane redox system. Melatonin, which scavenges mitochondrial free radicals, inhibits mitochondrial nitric oxide synthase, restores mitochondrial calcium homeostasis, deacetylates and activates mitochondrial SIRT3, ameliorates increased permeability of the blood-brain barrier and intestine and counters neuroinflammation and glutamate excitotoxicity.

Functional consequences of a close encounter between microglia and brain-infiltrating monocytes during CNS pathology and repair

Neuroinflammation is recognized as an important factor contributing to the development and progression of several central nervous system (CNS) disorders. Upon CNS trauma or disease, parenchymal microglia highly proliferate and accumulate in and around the lesion site. In addition, blood-derived monocytes can infiltrate the inflamed CNS in response to cellular damage and/or a compromised blood-brain barrier. Both microglia and infiltrating monocytes are characterized by multiple functional states and can either display highly proinflammatory properties or promote resolution of inflammation and tissue regeneration. Despite sharing some basic immunologic functions, microglia and monocytes display many distinctive features, which ultimately define their contribution to neuropathology. Understanding how the innate immune system participates to brain disease is imperative to identify novel treatment options for CNS inflammatory disorders. In this context, existing and newly developed in vitro platforms for disease modeling are fundamental tools to investigate and modulate microglia and monocyte immune functions within a specific neuropathologic context. In this review, we first briefly summarize the current knowledge on microglia and monocyte ontogenesis, as well as their complex and interconnected contributions to the development of various CNS pathologies. Following the well-recognized concept that both microglia and monocytes can either exert neuroprotective functions or exacerbate tissue damage, we provide a comprehensive overview of cellular models currently available for in vitro study of neuroinflammatory responses. In this context, we highlight how simplified single-cell models may not always correctly recapitulate in vivo biology, hence future research should move toward novel models with higher and multicellular complexity.

Insulin Resistance at the Crossroad of Alzheimer Disease Pathology: A Review

Insulin plays a major neuroprotective and trophic function for cerebral cell population, thus countering apoptosis, beta-amyloid toxicity, and oxidative stress; favoring neuronal survival; and enhancing memory and learning processes. Insulin resistance and impaired cerebral glucose metabolism are invariantly reported in Alzheimer's disease (AD) and other neurodegenerative processes. AD is a fatal neurodegenerative disorder in which progressive glucose hypometabolism parallels to cognitive impairment. Although AD may appear and progress in virtue of multifactorial nosogenic ingredients, multiple interperpetuative and interconnected vicious circles appear to drive disease pathophysiology. The disease is primarily a metabolic/energetic disorder in which amyloid accumulation may appear as a by-product of more proximal events, especially in the late-onset form. As a bridge between AD and type 2 diabetes, activation of c-Jun N-terminal kinase (JNK) pathway with the ensued serine phosphorylation of the insulin response substrate (IRS)-1/2 may be at the crossroads of insulin resistance and its subsequent dysmetabolic consequences. Central insulin axis bankruptcy translates in neuronal vulnerability and demise. As a link in the chain of pathogenic vicious circles, mitochondrial dysfunction, oxidative stress, and peripheral/central immune-inflammation are increasingly advocated as major pathology drivers. Pharmacological interventions addressed to preserve insulin axis physiology, mitochondrial biogenesis-integral functionality, and mitophagy of diseased organelles may attenuate the adjacent spillover of free radicals that further perpetuate mitochondrial damages and catalyze inflammation. Central and/or peripheral inflammation may account for a local flood of proinflammatory cytokines that along with astrogliosis amplify insulin resistance, mitochondrial dysfunction, and oxidative stress. All these elements are endogenous stressor, pro-senescent factors that contribute to JNK activation. Taken together, these evidences incite to identify novel multi-mechanistic approaches to succeed in ameliorating this pandemic affliction.

Functional Foods: An Approach to Modulate Molecular Mechanisms of Alzheimer's Disease

A new epoch is emerging with intense research on nutraceuticals, i.e., "food or food product that provides medical or health benefits including the prevention and treatment of diseases", such as Alzheimer's disease. Nutraceuticals act at different biochemical and metabolic levels and much evidence shows their neuroprotective effects; in particular, they are able to provide protection against mitochondrial damage, oxidative stress, toxicity of β-amyloid and Tau and cell death. They have been shown to influence the composition of the intestinal microbiota significantly contributing to the discovery that differential microorganisms composition is associated with the formation and aggregation of cerebral toxic proteins. Further, the routes of interaction between epigenetic mechanisms and the microbiota-gut-brain axis have been elucidated, thus establishing a modulatory role of diet-induced epigenetic changes of gut microbiota in shaping the brain. This review examines recent scientific literature addressing the beneficial effects of some natural products for which mechanistic evidence to prevent or slowdown AD are available. Even if the road is still long, the results are already exceptional.

Use of a Spinal Thermal Massage Device for Anti-oxidative Function and Pain Alleviation

Background: Elderly people are vulnerable to a variety of diseases, including chronic pain, which reduces their levels of physical fitness. Thermal massage has been shown to relieve pain and activate antioxidant enzymes. The objective of this study was to determine whether thermal massaging of the spinal column can reduce muscle pain and induce antioxidant function.

Methods: This study included participants aged ≥60 years with lower back pain. The participants were assigned to either an experimental group who received spinal column thermal massage and standard rehabilitative treatment or a control group who received standard rehabilitative treatment only. Data from a total of 116 participants (61 and 55 in the control and experimental groups, respectively) were used for analysis. Participants were assessed before treatment and at 4 (POST1) and 8 weeks (POST2) post-treatment, using a pain numeric rating scale (PNRS) and the Roland and Morris Disability Questionnaire (RMDQ), and by measuring the serum levels of superoxide dismutase (SOD), serum glutathione-peroxidase (GPx), and serum catalase (CAT).

Results: The extent of pain reduction, as measured by the PNRS, was greater in the experimental group. The RMDQ score in the control group decreased at POST1, but the decrease was not maintained at POST2, whereas the decrease in POST1 in the experimental group continued until POST2. SOD concentrations were significantly higher in the experimental group at POST1 and POST2, and GPx levels were significantly higher in the experimental group at POST2; however, there were no changes in CAT concentrations. Incidentally, there was a significant correlation between antioxidant activity and pain perception in the experimental group.

Conclusions: The study findings suggest that spinal column thermal massage reduces pain more effectively, improves self-reported levels of disability, and increases the antioxidant enzyme levels. Thermal massage may, therefore, be useful in the prevention and treatment of diseases associated with oxidation.

PGC-1α in Disease: Recent Renal Insights into a Versatile Metabolic Regulator

Peroxisome proliferator-activated receptor gamma co-activator 1 alpha (PGC-1α) is perhaps best known as a master regulator of mitochondrial biogenesis and function. However, by virtue of its interactions as a coactivator for numerous nuclear receptors and transcription factors, PGC-1α also regulates many tissue-specific tasks that include adipogenesis, angiogenesis, gluconeogenesis, heme biosynthesis, thermogenesis, and cellular protection against degeneration. Knowledge about these functions continue to be discovered with ongoing research. Unsurprisingly, alterations in PGC-1α expression lead to a range of deleterious outcomes. In this review, we provide a brief background on the PGC-1 family with an overview of PGC-1α's roles as an adaptive link to meet cellular needs and its pathological consequences in several organ contexts. Among the latter, kidney health is especially reliant on PGC-1α. Thus, we discuss here at length how changes in PGC-1α function impact the states of renal cancer, acute kidney injury (AKI) and chronic kidney disease (CKD), as well as emerging data that illuminate pivotal roles for PGC-1α during renal development. We survey a new intriguing association of PGC-1α function with ciliogenesis and polycystic kidney disease (PKD), where recent animal studies revealed that embryonic renal cyst formation can occur in the context of PGC-1α deficiency. Finally, we explore future prospects for PGC-1α research and therapeutic implications for this multifaceted coactivator.

Relationships between Mitochondrial Dysfunction and Neurotransmission Failure in Alzheimer's Disease

Besides extracellular deposition of amyloid beta and formation of phosphorylated tau in the brains of patients with Alzheimer's disease (AD), the pathogenesis of AD is also thought to involve mitochondrial dysfunctions and altered neurotransmission systems. However, none of these components can describe the diverse cognitive, behavioural, and psychiatric symptoms of AD without the pathologies interacting with one another. The purpose of this review is to understand the relationships between mitochondrial and neurotransmission dysfunctions in terms of (1) how mitochondrial alterations affect cholinergic and monoaminergic systems via disruption of energy metabolism, oxidative stress, and apoptosis; and (2) how different neurotransmission systems drive mitochondrial dysfunction via increasing amyloid beta internalisation, oxidative stress, disruption of mitochondrial permeabilisation, and mitochondrial trafficking. All these interactions are separately discussed in terms of neurotransmission systems. The association of mitochondrial dysfunctions with alterations in dopamine, norepinephrine, and histamine is the prospective goal in this research field. By unfolding the complex interactions surrounding mitochondrial dysfunction in AD, we can better develop potential treatments to delay, prevent, or cure this devastating disease.

Peroxisome Proliferator-Activated Receptor γ Coactivator 1α Activates Vascular Endothelial Growth Factor That Protects Against Neuronal Cell Death Following Status Epilepticus through PI3K/AKT and MEK/ERK Signaling

Status epilepticus may cause molecular and cellular events, leading to hippocampal neuronal cell death. Peroxisome proliferator-activated receptor γ coactivator 1-α (PGC-1α) is an important regulator of vascular endothelial growth factor (VEGF) and VEGF receptor 2 (VEGFR2), also known as fetal liver kinase receptor 1 (Flk-1). Resveratrol is an activator of PGC-1α. It has been suggested to provide neuroprotective effects in epilepsy, stroke, and neurodegenerative diseases. In the present study, we used microinjection of kainic acid into the left hippocampal CA3 region in Sprague Dawley rats to induce bilateral prolonged seizure activity. Upregulating the PGC-1α pathway will increase VEGF/VEGFR2 (Flk-1) signaling and further activate some survival signaling that includes the mitogen activated protein kinase kinase (MEK)/mitogen activated protein kinase (ERK) and phosphatidylinositol 3-kinase (PI3K)/protein kinase B (AKT) signaling pathways and offer neuroprotection as a consequence of apoptosis in the hippocampal neurons following status epilepticus. Otherwise, downregulation of PGC-1α by siRNA against pgc-1α will inhibit VEGF/VEGFR2 (Flk-1) signaling and suppress pro-survival PI3K/AKT and MEK/ERK pathways that are also accompanied by hippocampal CA3 neuronal cell apoptosis. These results may indicate that the PGC-1α induced VEGF/VEGFR2 pathway may trigger the neuronal survival signaling, and the PI3K/AKT and MEK/ERK signaling pathways. Thus, the axis of PGC-1α/VEGF/VEGFR2 (Flk-1) and the triggering of downstream PI3K/AKT and MEK/ERK signaling could be considered an endogenous neuroprotective effect against apoptosis in the hippocampus following status epilepticus.

Changes in PGC-1α/SIRT1 Signaling Impact on Mitochondrial Homeostasis in Amyloid-Beta Peptide Toxicity Model

Alzheimer's disease (AD) is a neurodegenerative disorder characterized by cognitive impairment that increasingly afflicts the elderly population. Soluble oligomers (AβOs) has been implicated in AD pathogenesis: however, the molecular events underlying a role for Aβ are not well understood. We studied the effects of AβOs on mitochondrial function and on key proteins that regulate mitochondrial dynamics and biogenesis in hippocampal neurons and PC-12 cells. We find that AβOs treatment caused a reduction in total Mfn1 after a 2 h exposure (42 ± 11%); while DRP1 increased at 1 and 2 h (205 ± 22% and 198 ± 27%, respectively), correlating to changes in mitochondrial morphology. We also observed that SIRT1 levels were reduced after acute and chronic AβOs treatment (68 ± 7% and 77 ± 6%, respectively); while PGC-1α levels were reduced with the same time treatments (68 ± 8% and 67 ± 7%, respectively). Interestingly, we found that chronic treatment with AβOs increased the levels of pSIRT1 (24 h: 157 ± 18%), and we observed changes in the PGC-1α and p-SIRT1 nucleus/cytosol ratio and SIRT1-PGC-1α interaction pattern after chronic exposure to AβOs. Our data suggest that AβOs induce important changes in the level and localization of mitochondrial proteins related with the loss of mitochondrial function that are mediated by a fast and sustained SIRT1/PGC-1α complex disruption promoting a “non-return point” to an irreversible synaptic failure and neuronal network disconnection.

Tannic Acid Provides Neuroprotective Effects Against Traumatic Brain Injury Through the PGC-1α/Nrf2/HO-1 Pathway

The present research was conducted to elucidate a possible molecular mechanism related to neuromodulatory effects of tannic acid (TA) supplementation against traumatic brain injury (TBI) in a rodent model. Oxidative damage and neuroinflammation play a critical role in TBI and lead to behavioral alterations and neuronal dysfunction and death. These changes suggest a potential avenue in neurotherapeutic intervention. The aim of the present study was to investigate the neuroprotective effects of TA and potential mechanism of these effects in a controlled cortical impact injury model of TBI in Wistar rats that were treated with TA (50 mg/kg body weight. i.p.) before 30 min and 6 and 18 h after TBI. TBI-induced rats were examined after 24 h for behavioral dysfunction, Nissl stain, lipid peroxidation rate, glutathione level, activities of antioxidant enzymes (catalase, glutathione S-transferase, glutathione peroxidase, and superoxide dismutase), the expression level of 4-hydroxynonenal, pro-inflammatory cytokines such as tumor necrosis factor alpha and interleukin-1 beta, as well as brain edema and immunoreactivity of glial fibrillary acidic protein. Results indicated that TA supplementation significantly modulated above mentioned alterations. Moreover, TA treatment effectively upregulated the protein expression of peroxisome proliferator-activated receptor gamma co-activator 1 alpha (PGC-1α) and nuclear factor-E2-related factor-2 (Nrf2) as well as mitochondrial transcription factor A and heme oxygenase-1 (HO-1) following TBI. Overall, our results suggest that TA effectively ameliorates the behavioral alterations, oxidative damage, mitochondrial impairment, and inflammation against TBI that may be attributed to activation of PGC-1α/Nrf-2/HO-1 signaling pathway.

Sirtuins and intervertebral disc degeneration: Roles in inflammation, oxidative stress, and mitochondrial function

Intervertebral disc degeneration (IDD) is one of the main causes of low back pain, which seriously reduces the quality of life of patients and places a heavy economic burden on their families. Cellular senescence is considered to be an important factor leading to IDD, and inflammatory response, oxidative stress, and mitochondrial dysfunction are closely related to intervertebral disc (IVD) senescence. Therefore, inhibition of the inflammatory response and oxidative stress, along with maintaining mitochondrial function, may be useful in treating IDD. The sirtuins are a family of evolutionarily conserved nicotinamide adenine dinucleotide (NAD⁺)-dependent histone deacetylases, which are the major molecules mediating life extension or delay of aging-related diseases. The sirtuin protein family consist of seven members (SIRT1 - 7), which are mainly involved in various aging-related diseases by regulating inflammation, oxidative stress, and mitochondrial function. Among them, SIRT1, SIRT2, SIRT3, and SIRT6 are closely related to IDD. In addition, some activators of sirtuin proteins, such as resveratrol, melatonin, magnolol, 1,4-dihydropyridine (DHP), SRT1720, and nicotinamide mononucleotide (NMN), have been evaluated in preclinical studies for their effects in preventing IDD. This review described the biological functions of sirtuins and the important roles of SIRT1, SIRT2, SIRT3, and SIRT6 in IDD by regulating oxidative stress, inflammatory response, and mitochondrial function. In addition, we introduce the status of some sirtuin activators in IDD preclinical studies. This review will provide a background for further clarification of the molecular mechanism underlying IDD and the development of potential therapeutic drugs.

Silent Mating-Type Information Regulation 2 Homolog 1 Attenuates the Neurotoxicity Associated with Alzheimer Disease via a Mechanism Which May Involve Regulation of Peroxisome Proliferator-Activated Receptor Gamma Coactivator 1-α

To investigate the neuroprotective role of silent mating-type information regulation 2 homolog 1 (SIRT1) in Alzheimer disease (AD), brain tissues from patients with AD and APP/PS1 mice as well as primary rat neurons exposed to oligomers of amyloid-β peptide were examined. The animals were treated with resveratrol (RSV) or suramin for 2 months. Cell cultures were treated with RSV, suramin, and the peroxisome proliferator-activated receptor gamma coactivator 1-α (PGC-1α) stimulator ZLN005. Cells were transiently transfected with PGC-1α silencing RNA. The level of SIRT1 in brain tissues from patients with AD and APP/PS1 mice, including nuclear and mitochondrial proteins, as well as in primary neurons exposed to oligomers of amyloid-β peptide, was decreased. Overexpression of APP/PS1 impaired learning and memory of mice; produced more senile plaques, disrupted membranes, and resulted in broken or absent cristae of mitochondria in the brain; decreased levels of A disintegrin and metallopeptidase domain 10, beta-secretase 2, 8-oxoguanine DNA glycosylase-1, PGC-1α, and NAD+; and increased levels of beta-secretase 1 and apoptosis. Interestingly, these changes were attenuated significantly by RSV treatment but enhanced by suramin administration. By activating PGC-1α but inhibiting SIRT1, apoptotic cell death was significantly decreased; however, by activating SIRT1 but inhibiting PGC-1α with small interfering PGC-1α, these levels remained unchanged. These findings indicate that SIRT1 may protect against AD-associated neurotoxicity, which might involve PGC-1α regulation.

Protective effect of d-tetramannuronic acid tetrasodium salt on UVA-induced photo-aging in HaCaT cells

UVA radiation from the sun is the main external stimulus in the pathogenesis of skin photo-aging. This process is associated with cellular oxidative stress. Here we aim at showing the protective effect of d-Tetramannuronic Acid Tetrasodium Salt (M4), a natural product, against UVA (30J/cm²) irradiation-induced oxidative stress and photo-aging in HaCaT cells, and to reveal the molecular mechanism underlying the protective efficacy. M4 pretreatment significantly increased HaCaT cell viability and MMP, suppressing UVA-induced ROS generation. Moreover, M4 treatment prevented the UVA-induced photo-aging of HaCaT cells (the reduction of cell viability, mitochondria dysfunction, and SIRT1/pGC-1α deregulation). Notably, the anti-photo-aging potential of M4 was directly associated with the increased expression of MMP and SIRT1, which was followed by the up-regulation of pGC-1α, D-LOOP, and Mt-TFA, and the transcriptional activation of NRF1/NRF2. Therefore, M4 is useful for the protection of skin cells from UVA-induced photo-aging.

The Novel Role of PPAR Alpha in the Brain: Promising Target in Therapy of Alzheimer's Disease and Other Neurodegenerative Disorders

Peroxisome proliferator activated receptor alpha (PPAR-α) belongs to the family of ligand-regulated nuclear receptors (PPARs). These receptors after heterodimerization with retinoid X receptor (RXR) bind in promotor of target genes to PPAR response elements (PPREs) and act as a potent transcription factors. PPAR-α and other receptors from this family, such as PPAR-β/δ and PPAR-γ are expressed in the brain and other organs and play a significant role in oxidative stress, energy homeostasis, mitochondrial fatty acids metabolism and inflammation. PPAR-α takes part in regulation of genes coding proteins that are involved in glutamate homeostasis and cholinergic/dopaminergic signaling in the brain. Moreover, PPAR-α regulates expression of genes coding enzymes engaged in amyloid precursor protein (APP) metabolism. It activates gene coding of α secretase, which is responsible for non-amyloidogenic pathway of APP degradation. It also down regulates β secretase (BACE-1), the main enzyme responsible for amyloid beta (Aβ) peptide release in Alzheimer Diseases (AD). In AD brain expression of genes of PPAR-α and PPAR-γ coactivator-1 alpha (PGC-1α) is significantly decreased. PPARs are altered not only in AD but in other neurodegenerative/neurodevelopmental and psychiatric disorder. PPAR-α downregulation may decrease anti-oxidative and anti-inflammatory processes and could be responsible for the alteration of fatty acid transport, lipid metabolism and disturbances of mitochondria function in the brain of AD patients. Specific activators of PPAR-α may be important for improvement of brain cells metabolism and cognitive function in neurodegenerative and neurodevelopmental disorders.

Protective Effect of L-Hexaguluroic Acid Hexasodium Salt on UVA-Induced Photo-Aging in HaCaT Cells

This study aimed to show the α-L-Hexaguluroic acid hexasodium salt (G6) protective effect against UVA-induced photoaging of human keratinocyte cells. We found that G6 localized to the mitochondria and improved mitochondrial functions. G6 increased respiratory chain complex activities, which led to increased cellular ATP content and NAD+/NADH ratio. Thus, G6 alleviated the oxidative stress state in UVA-irradiated cells. Moreover, G6 can regulate the SIRT1/pGC-1α pathway, which enhanced the cells' viability and mitochondria energy metabolism. Notably, the anti-photoaging potential of G6 was directly associated with the increased level of MMP and SIRT1, which was followed by the upregulation of pGC-1α, D-LOOP, and Mt-TFA, and with the transcriptional activation of NRF1/NRF2. Taking all of the results together, we conclude that G6 could protect HaCaT cells from UVA-induced photo-aging via the regulation of mitochondria energy metabolism and its downstream signaling pathways.

The neuroprotective effects of SIRT1 in mice carrying the APP/PS1 double-transgenic mutation and in SH-SY5Y cells over-expressing human APP670/671 may involve elevated levels of α7 nicotinic acetylcholine receptors

The aim was to determine whether the neuroprotective effect of SIRT1 in Alzheimer’s disease (AD), due to inhibition of aggregation of the β-amyloid peptide (Aβ), involves activation of α7 nAChR. In present study, four-month-old APP/PS1 mice were administered resveratrol (RSV) or suramin once daily for two months, following which their spatial learning and memory were assessed using the Morris water maze test. Deposits of Aβ in vivo were detected by near-infrared imaging (NIRI) and confocal laser scanning. SH-SY5Y/APP_swe cells were treated with RSV, suramin, U0126 or methyllycaconitine (MLA). Levels of proteins and mRNA were determined by Western blotting and qRT-PCR, respectively. The results show that activation of SIRT1 improved their spatial learning and memory and reduced the production and aggregation of Aβ in the hippocampus and cerebral cortex; whereas inhibition of SIRT1 had the opposite effects. In addition, activation of SIRT1 increased the levels of both α7 nAChR and αAPP in the brains these animals. Finally, activation of SIRT1 elevated the levels of pERK1/2, while inhibition of ERK1/2 counteracted the increase in α7 nAChR caused by RSV. These findings indicate that neuroprotection by SIRT1 may involve increasing levels of α7 nAChR through activation of the MAPK/ERK1/2 signaling pathway.

Targeting Aggrephagy for the Treatment of Alzheimer's Disease

Alzheimer’s disease (AD) is one of the most common neurodegenerative diseases in older individuals with specific neuropsychiatric symptoms. It is a proteinopathy, pathologically characterized by the presence of misfolded protein (Aβ and Tau) aggregates in the brain, causing progressive dementia. Increasing studies have provided evidence that the defect in protein-degrading systems, especially the autophagy-lysosome pathway (ALP), plays an important role in the pathogenesis of AD. Recent studies have demonstrated that AD-associated protein aggregates can be selectively recognized by some receptors and then be degraded by ALP, a process termed aggrephagy. In this study, we reviewed the role of aggrephagy in AD development and discussed the strategy of promoting aggrephagy using small molecules for the treatment of AD.

Current status and future prospects of pathophysiology-based neuroprotective drugs for the treatment of vascular dementia

Vascular dementia (VaD) is a progressive neurocognitive clinical syndrome that is caused by a decrease in cerebral blood flow and damage to the neurovascular unit. Given increasing life expectancy, VaD is emerging as one of the leading health problems in society. Despite the high global prevalence of cognitive impairment associated with VaD, diagnosis and treatment still remain limited because of the complexity of mechanisms of neuronal loss. Therefore, advances in our understanding of the pathophysiological mechanisms involved is crucial for the development of new therapeutic strategies. In this review, we highlight the pathophysiology, current pharmacology-based primary and secondary prevention strategies and emerging treatment options for VaD.