Porcine CD38 exhibits prominent secondary NAD(+) cyclase activity

New Tiaoxin Recipe Alleviates Energy Metabolism Disorders in an APPswe/PS1DE9 Mouse Model of Alzheimer's Disease

BACKGROUND

Alzheimer's disease (AD) is a typical neurodegenerative disease with a complex etiology. Until now, there has been no effective treatment available for AD; however, improving energy dysmetabolism, the key pathological event in the early stage of AD, can effectively delay the progression of AD.

OBJECTIVE

This paper aims to investigate the therapeutic effect and potential mechanism of the new Tiaoxin recipe on early AD.

METHODS

APP/PS1 mice were divided into a model group, a new Tiaoxin recipe group, and a donepezil group, and C57/BL mice were used for the control group. Mouse cognitive and learning abilities were tested using the Morris water maze test and a new object-recognition experiment. The 42 amino acid form of amyloid β peptide (Aβ1-42) content was detected by enzyme-linked immunosorbent assay, the senile plaque area was detected by thioflavin S staining, and the senescence- associated β-galactosidase (SA-β-gal)-positive area was detected by chemical staining. Also, the adenosine triphosphate (ATP), nicotinamide adenine dinucleotide (NAD+), and nicotinamide adenine dinucleotide hydride (NADH) contents were detected using a biochemical method, and the cluster of differentiation 38 (CD38) and silent mating-type information regulation 2 homolog 3 (SIRT3) protein expression levels were detected by immunofluorescence and Western blot analysis.

RESULTS

Compared with those of the control group, the learning and memory abilities of the model group were impaired; the senile plaque deposition, Aβ1-42 content, and SA-βgal-positive staining area were increased; the ATP concentration, NAD+ concentration, and NAD+/NADH ratio were decreased; the CD38 protein expression level was increased; and the SIRT3 protein expression level was decreased. Following intervention with the new Tiaoxin recipe, the learning and memory abilities were improved; the senile plaque deposition, Aβ1-42 content, and SA-βgal-positive area were reduced; the ATP concentration, NAD+ concentration, and NAD+/NADH ratio were increased; CD38 protein expression was decreased, and SIRT3 protein expression was increased.

CONCLUSION

This study shows that the new Tiaoxin Recipe can improve cognitive ability and reduce the Aβ1-42 content and senile plaque deposition in APP/PS1 mice, which may occur through the downregulation of CD38 protein expression, upregulation of SIRT3 protein expression, restoration of the NAD+ level, promotion of ATP synthesis, mitigation of energy metabolism disorders.

CD38 Enhances TLR9 Expression and Activates NLRP3 Inflammasome after Porcine Parvovirus Infection

(1) Background: Porcine Parvovirus (PPV) is a single-stranded DNA virus without envelope which causes great harm in relation to porcine reproductive disorders in clinic. Cluster of Differentiation 38 (CD38) is a transmembrane protein widely existing in mammals. Its various functions make it a very popular research object, including in the viral infection field. (2) Methods: Western blotting and an EdU Cell Proliferation Kit were used to evaluate the effect of CD38-deficient cells. Relative quantitative real-time RT-PCR was used to detect the transcription levels of cytokines after PPV infection. The renilla luciferase reporter gene assay was used to verify the activation function of CD38 on downstream factors. The fluorescence probe method was used to detect the level of intracellular reactive oxygen species (ROS). (3) Results: This study found that the loss of CD38 function inhibited the up-regulated state of Toll-like Receptor 9 (TLR9), Interferon-α (IFN-α), and Myxovirus Resistance 1 (Mx1) after PPV infection. The luminescence of the group transfected with both CD38 expression plasmid and TLR9 promoter renilla luciferase reporter plasmid was significantly up-regulated compared with the control, suggesting that CD38 may activate the promoter of TLR9. In addition, CD38 deficiency not only activated the transcription of Sirtuin-1 (SIRT1), but also inhibited ROS level and the transcription of NLR Family Pyrin Domain Containing 3 (NLRP3). (4) Conclusion: (i) CD38 may participate in the TLR9/IFN-α/Mx1 pathway by activating the expression of TLR9 after PPV infected PK-15 cells; (ii) CD38 may activate the NLRP3/CASP1 pathway by increasing ROS level; (iii) CD38 deficiency activates the expression of SIRT1 and can prevent the normal proliferation of PPV.

Aβ promotes CD38 expression in senescent microglia in Alzheimer's disease

Background

In Alzheimer’s disease (AD), the neuroinflammatory response mediated by the activation of senescent microglia is closely related to energy dysmetabolism. However, the mechanism underlying the interaction between the energy metabolism of aging microglia and neuroinflammation remains unclear.

Methods

We used biochemical methods, enzyme-linked immunosorbent assay (ELISA), immunofluorescence, and western blot to determine the effects and mechanism of CD38 knockdown on energy metabolism and neuroinflammation in Aβ1-40 injured BV2 cells. Using AD model mice, we detected CD38 enzyme activity, energy metabolism factors (ATP, NAD +, and NAD + /NADH), and neuroinflammatory factors (IL-1β, IL-6, and TNF-α) following the addition of CD38 inhibitor. Using a combination of biochemical analysis and behavioral testing, we analyzed the effects of the CD38 inhibitor on energy metabolism disorder, the neuroinflammatory response, and the cognition of AD mice.

Results

Following Aβ1-40 injury, SA-β-Gal positive cells and senescence-related proteins P16 and P21 increased in BV2 cells, while energy-related molecules (ATP, NAD +, and NAD + /NADH) and mitochondrial function (mitochondrial ROS and MMP) decreased. Further studies showed that CD38 knockdown could improve Aβ1-40-induced BV2 cells energy dysmetabolism and reduce the levels of IL-1β, IL-6, and TNF-α. In vivo results showed an increase in senile plaque deposition and microglial activation in the hippocampus and cortex of 34-week-old APP/PS1 mice. Following treatment with the CD38 inhibitor, senile plaque deposition decreased, the number of Iba1 + BV2 cells increased, the energy metabolism disorder was improved, the proinflammatory cytokines were reduced, and the spatial learning ability was improved.

Conclusions

Our results confirm that senescent microglia appeared in the brain of 34-week-old APP/PS1 mice, and that Aβ1-40 can induce senescence of BV2 cells. The expression of CD38 increases in senescent BV2 cells, resulting in energy metabolism disorder. Therefore, reducing CD38 expression can effectively improve energy metabolism disorder and reduce proinflammatory cytokines. Following intervention with the CD38 inhibitor in APP/PS1 mice, the energy metabolism disorder was improved in the hippocampus and cortex, the level of proinflammatory cytokines was reduced, and cognitive impairment was improved.

Identification of Novel Molecular Targets of Four Microcystin Variants by High-Throughput Virtual Screening

Highly toxic microcystins (MCs) perform complex interactions with many proteins that induce cellular dysregulation, leading to the development of several diseases including cancer. There is significant diversity and chemical complexity among MC congeners, which makes it difficult to identify structure-dependent toxicity outcomes and their long-term effects. The aim of this study was to exploratory identify likely molecular targets of the main MC variants (MC-LA, MC-LR, MC-RR, and MC-LY) by conducting a computational binding affinity analysis using AutoDock Vina to evaluate the interaction of the toxins with 1000 proteins related to different biological functions. All four variants showed strong in silico interactions with proteins that regulate metabolism/immune system, CD38 (top scoring hit, −11.5 kcal/mol); inflammation, TLR4 (−11.4 kcal/mol) and TLR8 (−11.5 kcal/mol); neuronal conduction, BChE; renin–angiotensin signaling, (ACE); thyroid hormone homeostasis (TTR); and cancer-promoting processes, among other biochemical activities. The results show MCs have the potential to bind onto distinct molecular targets which could generate biochemical alterations through a number of signal transduction pathways. In short, this study broadens our knowledge about the mechanisms of action of different variants of microcystins and provides information for future direct experimentation.

Codonopsis pilosula Polysaccharides Alleviate Aβ 1-40-Induced PC12 Cells Energy Dysmetabolism via CD38/NAD+ Signaling Pathway

Background

Alzheimer's disease (AD) is the most common type of dementia and has a complex pathogenesis with no effective treatment. Energy metabolism disorders, as an early pathological event of AD,have attracted attention as a promising area of AD research. Codonopsis pilosula Polysaccharides are the main effective components of Codonopsis pilosula, which have been demonstrated to regulate energy metabolism.

Methods

In order to further study the roles and mechanisms of Codonopsis pilosula polysaccharides in AD, this study used an Aβ_1-40-induced PC12 cells model to study the protective effects of Codonopsis pilosula polysaccharides and their potential mechanisms in improving energy metabolism dysfunction.

Results

The results showed that Aβ_1-40 induced a decrease in PC12 cells viability, energy metabolism molecules (ATP, NAD+, and NAD+/NADH) and Mitochondrial Membrane Potential (MMP) and an increase in ROS. Additionally, it was found that Aβ_1-40 increased CD38 expression related to NAD+ homeostasis, whereas Silent Information Regulation 2 homolog1 (SIRT1, SIRT3), Peroxisome proliferator-activated receptor γ coactivator 1-α (PGC-1α) and SIRT3 activity were decreased. Codonopsis pilosula polysaccharides increased NAD+, NAD+/NADH, SIRT3, SIRT1, and PGC-1α related to NAD+, thus partially recovering ATP.

Conclusion

Our findings reveal that Codonopsis pilosula polysaccharides protected PC12 cells from Aβ_1-40-induced damage, suggesting that these components of the Codonopsis pilosula herb may represent an early treatment option for AD patients.