Extracellular Degradation Into Adenosine and the Activities of Adenosine Kinase and AMPK Mediate Extracellular NAD+-Produced Increases in the Adenylate Pool of BV2 Microglia Under Basal Conditions

Cumulating evidence has indicated NAD+ deficiency as a common central pathological factor of multiple diseases and aging. NAD+ supplement is highly protective in various disease and aging models, while two key questions have remained unanswered: (1) Does extracellular NAD+ also produce its effects through its degradation product adenosine? (2) Does extracellular NAD+ produce the protective effects by affecting cells under pathological insults only, or by affecting both normal cell and the cells under pathological insults? Since extracellular NAD+ can be degraded into adenosine, and endogenous adenosine levels are in the nanomolar range under physiological conditions, extracellular NAD+ may produce its effects through its degradation into adenosine. In this study we used BV2 microglia as a cellular model to test our hypothesis that NAD+ treatment can increase the intracellular adenylate pool under basal conditions through its extracellular degradation into adenosine. Our study has shown that extracellular NAD+ is degraded into adenosine extracellularly, which enters BV2 microglia through equilibrative nucleoside transporters under basal conditions. The intracellular adenosine is converted to AMP by adenosine kinase, which increases the intracellular ATP levels by both activating AMPK and increasing the intracellular adenylate pool. Collectively, our study has suggested a novel mechanism underlying the protective effects of NAD+ administration, which is mediated by extracellular NAD+ degradation into adenosine as well as the activities of adenosine kinase and AMPK. Our findings have also suggested that NAD+ administration in various disease and aging models may also produce its effects by affecting the microglia that are not under pathological insults

Methylene blue reduces the serum levels of interleukin-6 and inhibits STAT3 activation in the brain and the skin of lipopolysaccharide-administered mice

It is valuable to search for novel and economical agents for inhibiting STAT3 activation and blocking increases in IL-6 levels, due to the important roles of STAT3 and IL-6 in inflammation. Since Methylene Blue (MB) has shown therapeutical potential for multiple diseases, it has become increasingly important to investigate the mechanisms underlying the effects of MB on inflammation. Using a mouse model of lipopolysaccharide (LPS)-induced inflammation, we investigated the mechanisms underlying the effects of MB on inflammation, obtaining the following findings: First, MB administration attenuated the LPS-induced increases in the serum levels of IL-6; second, MB administration attenuated LPS-induced STAT3 activation of the brain; and third, MB administration attenuated LPS-induced STAT3 activation of the skin. Collectively, our study has suggested that MB administration can decrease the levels of IL-6 and STAT3 activation - two important factors in inflammation. Since MB is a clinically used and relatively economical drug, our findings have suggested therapeutic potential of MB for multiple inflammation-associated diseases due to its effects on STAT3 activation and IL-6 levels

SIRT2, ERK and Nrf2 Mediate NAD+ Treatment-Induced Increase in the Antioxidant Capacity of PC12 Cells Under Basal Conditions

NAD+ (oxidized form of nicotinamide adenine dinucleotide) administration is highly beneficial in numerous models of diseases and aging. It is becoming increasingly important to determine if NAD+ treatment may directly increase the antioxidant capacity of cells under basal conditions. In the current study, we tested our hypothesis that NAD+ can directly enhance the antioxidant capacity of cells under basal conditions by using PC12 cells as a cellular model. We found that NAD+ treatment can increase the GSH/GSSG ratios in the cells under basal conditions. NAD+ can also increase both the mRNA and protein level of γ-glutamylcysteine ligase (γ-GCL)—a key enzyme for glutathione synthesis, which appears to be mediated by the NAD+-induced increase in Nrf2 activity. These NAD+-induced changes can be prevented by both SIRT2 siRNA and the SIRT2 inhibitor AGK2. The NAD+-induced changes can also be blocked by the ERK signaling inhibitor U0126. Moreover, the NAD+-induced ERK activation can be blocked by both SIRT2 siRNA and AGK2. Collectively, our study has provided the first evidence that NAD+ can enhance directly the antioxidant capacity of the cells under basal conditions, which is mediated by SIRT2, ERK, and Nrf2. These findings have suggested not only the great nutritional potential of NAD+, but also a novel mechanism underlying the protective effects of the NAD+ administration in the disease models: the NAD+ administration can enhance the resistance of the normal cells to oxidative insults by increasing the antioxidant capacity of the cells

Selective Down-Regulation of Nuclear Poly(ADP-Ribose) Glycohydrolase

The formation of ADP-ribose polymers on target proteins by poly(ADP-ribose) polymerases serves a variety of cell signaling functions. In addition, extensive activation of poly(ADP-ribose) polymerase-1 (PARP-1) is a dominant cause of cell death in ischemia-reperfusion, trauma, and other conditions. Poly(ADP-ribose) glycohydrolase (PARG) degrades the ADP-ribose polymers formed on acceptor proteins by PARP-1 and other PARP family members. PARG exists as multiple isoforms with differing subcellular localizations, but the functional significance of these isoforms is uncertain.Primary mouse astrocytes were treated with an antisense phosphorodiamidate morpholino oligonucleotide (PMO) targeted to exon 1 of full-length PARG to suppress expression of this nuclear-specific PARG isoform. The antisense-treated cells showed down-regulation of both nuclear PARG immunoreactivity and nuclear PARG enzymatic activity, without significant alteration in cytoplasmic PARG activity. When treated with the genotoxic agent MNNG to induced PARP-1 activation, the antisense-treated cells showed a delayed rate of nuclear PAR degradation, reduced nuclear condensation, and reduced cell death.These results support a preferentially nuclear localization for full-length PARG, and suggest a key role for this isoform in the PARP-1 cell death pathway

Simvastatin Prevents Dopaminergic Neurodegeneration in Experimental Parkinsonian Models: The Association with Anti-Inflammatory Responses

Background: In addition to their original applications to lowering cholesterol, statins display multiple neuroprotective effects. N-methyl-D-aspartate (NMDA) receptors interact closely with the dopaminergic system and are strongly implicated in therapeutic paradigms of Parkinson’s disease (PD). This study aims to investigate how simvastatin impacts on experimental parkinsonian models via regulating NMDA receptors. Methodology/Principal Findings: Regional changes in NMDA receptors in the rat brain and anxiolytic-like activity were examined after unilateral medial forebrain bundle lesion by 6-hydroxydopamine via a 3-week administration of simvastatin. NMDA receptor alterations in the post-mortem rat brain were detected by [3H]MK-801(Dizocilpine) binding autoradiography. 6-hydroxydopamine treated PC12 was applied to investigate the neuroprotection of simvastatin, the association with NMDA receptors, and the anti-inflammation. 6-hydroxydopamine induced anxiety and the downregulation of NMDA receptors in the hippocampus, CA1(Cornu Ammonis 1 Area), amygdala and caudate putamen was observed in 6- OHDA(6-hydroxydopamine) lesioned rats whereas simvastatin significantly ameliorated the anxiety-like activity and restored the expression of NMDA receptors in examined brain regions. Significant positive correlations were identified between anxiolytic-like activity and the restoration of expression of NMDA receptors in the hippocampus, amygdala and CA1 following simvastatin administration. Simvastatin exerted neuroprotection in 6-hydroxydopamine-lesioned rat brain and 6- hydroxydopamine treated PC12, partially by regulating NMDA receptors, MMP9 (matrix metalloproteinase-9), and TNF-a (tumour necrosis factor-alpha). Conclusions/Significance: Our results provide strong evidence that NMDA receptor modulation after simvastatin treatment could partially explain its anxiolytic-like activity and anti-inflammatory mechanisms in experimental parkinsonian models. These findings contribute to a better understanding of the critical roles of simvastatin in treating PD via NMDA receptors

A new species of Isoperla (Plecoptera: Perlodidae) from China

Cao, Zhishan, Wang, Ying, Li, Weihai (2020): A new species of Isoperla (Plecoptera: Perlodidae) from China. Zootaxa 4858 (2): 251-260, DOI: https://doi.org/10.11646/zootaxa.4858.2.

The complete mitochondrial genome of a Chinese endemic stonefly species, Sinacroneuria dabieshana (Plecoptera: Perlidae)

The complete mitochondrial genome of Sinacroneuria dabieshana Li & Murányi, the first representative of the genus Sinacroneuria, was sequenced and annotated. This mitogenome was 15,752 bp long and encoded 13 protein-coding genes (PCGs), 22 transfer RNA genes (tRNAs), two ribosomal RNA genes and a control region. The S. dabieshana mitogenome with an A + T content of 67.3% presented a positive AT-skew (0.058) and a negative GC-skew (−0.303). Ten PCGs started with a typical ATN codon, except ATP8, COI and ND1 initiated with GTG, CCG and TTG, respectively. Eleven PCGs use the typical stop codon TAA/TAG, except COII and ND5 gene terminated with a single T. The Bayesian (BI) and maximum-likelihood (ML) trees both showed that S. dabieshana and Acroneuria hainana are the sister group. Phylogenetic relationships among six genera within Perlidae were recovered as (Caroperla + ((Acroneuria + Sinacroneuria) + (Dinocras + (Togoperla + Kamimuria))))

Characterization of the complete mitochondrial genome of a stonefly species, Kamimuria klapaleki (Plecoptera: Pelidae)

We have sequenced and analyzed complete mitochondrial genome (mitogenomes) of the Kamimuria klapaleki, the third mitochondrial genome in the genus Kamimuria, which belongs to the family Pelidae in this paper. The mitogenome of K. klapaleki is circular with the length of 16,077 bp, which possessed 37 genes and a control region like other stonefly. The A + T content of the whole mitogenome was 67.1%. All PCGs were 11,217 bp in length, accounting for 65.3% of the content of A + T. The A + T content of lrRNA and srRNA were 72.3% and 66.4%. The highest A + T content was in the control region (76.2%). There are 15 gene overlaps and 9 gene intergenic spacers in this mitochondrial genome. In addition, we performed phylogenetic analysis by using the Bayesian (BI) and Maximum Likelihood (ML) methods based on the concatenated data set of PCGs from 11 species in Pelidae and two species in Styloperlidae (outgroups). The clade K. chungnanshana + K. wangi was a sister group to K. klapaleki, which is consistent with the traditional morphological classification