Inhibition of VDAC1 Rescues Aß 1-42-Induced Mitochondrial Dysfunction and Ferroptosis via Activation of AMPK and Wnt/ß-Catenin Pathways.

Beta-amyloid (Aß) accumulation in the brains of Alzheimer's disease (AD) patients leads to mitochondrial dysfunction and ferroptosis in neurons. Voltage-dependent anion channel 1 (VDAC1) is a major protein in the mitochondrial outer membrane. It has been reported that VDAC1 associated with mitochondrial dysfunction and ferroptosis. However, the mechanism by which VDAC1 regulates mitochondrial dysfunction and ferroptosis of neurons in AD remains unclear. This study is aimed at investigating the mechanism of action of VDAC1 in mitochondrial dysfunction and ferroptosis in neurons of the AD model. In this study, we determined cell viability after treatment with Aß 1-42 via the MTT assay. The SOD, MDA, ROS, and MMP production was measured via the SOD kit, MDA kit, DCFDA staining, and JC-1 staining. The memory abilities of mice were detected via the Morris water maze test. The expression of AMPK/mTOR, Wnt/ß-catenin, and GPX4 regulated by VDAC1 was detected via western blotting. Our present study showed that PC12 cells had decreased cell viability, increased LDH release, and decreased GPX4 expression after Aß 1-42 treatment. Meanwhile, Aß 1-42 induced MMP and SOD downregulation and increased MDA and ROS generation in PC12 cells. In addition, the expression of VDAC1 is increased in the brain tissue of AD mice and Aß 1-42-treated PC12 cells. Further investigation of the role of VDAC1 in regulating AD found that all effects induced by Aß 1-42 were reversed by inhibition of VDAC1. Additionally, inhibition of VDAC1 activates the AMPK/mTOR and Wnt/ß-catenin pathways. Taken together, these findings demonstrate that inhibition of VDAC1 alleviates mitochondrial dysfunction and ferroptosis in AD neurons by activating AMPK/mTOR and Wnt/ß-catenin.

Maternal separation affects anxiety-like behavior beginning in adolescence and continuing through adulthood and related to Dnmt3a expression.

Early life stress, including maternal separation, is among one of the main causes of anxiety in adolescents. DNA methyltransferase 3A (Dnmt3a) is a key molecule that regulates DNA methylation and is found to be associated with anxiety-like behavior. It is not clear whether maternal separation affects anxiety levels in mice at different developmental stages or whether Dnmt3a plays a role in this process. Here, by using the open field test to explore the effect of maternal separation on anxiety-like behavior in mice of different ages, it was found that maternal separation could successfully induce anxiety-like behavior in adolescent mice, which continued through adulthood. By using Western blot, we found that the levels of Dnmt3a in the hippocampus and cortex showed different trends in maternal separation mice on postnatal day (P)17. Furthermore, by using immunostaining, we found that the expression levels of Dnmt3a in the cortex and hippocampus were significantly different and decreased to varying degrees with the age of mice, which was the reason for different trends. Our results provide an experimental basis for further development of anxiety/depression treatment programs more suitable for adolescence.NEW & NOTEWORTHY Most anxiety disorders begin in adolescence and continue through adulthood, and research on adolescent anxiety's pathogenesis and treatment options is insufficient. In this research, our results show that maternal separation can successfully induce anxiety-like behavior in adolescent mice that continues through adulthood, further accompanied by abnormal expression of Dnmt3a, which provides an experimental basis for further development of anxiety/depression treatment programs more suitable for adolescence.

Cellular and molecular insight into the inhibition of primary root growth of Arabidopsis induced by peptaibols, a class of linear peptide antibiotics mainly produced by Trichoderma spp.

Trichoderma spp. are well known biocontrol agents that produce a variety of antibiotics. Peptaibols are a class of linear peptide antibiotics mainly produced by Trichoderma Alamethicin, the most studied peptaibol, is reported as toxic to plants at certain concentrations, while the mechanisms involved are unclear. We illustrated the toxic mechanisms of peptaibols by studying the growth-inhibitory effect of Trichokonin VI (TK VI), a peptaibol from Trichoderma longibrachiatum SMF2, on Arabidopsis primary roots. TK VI inhibited root growth by suppressing cell division and cell elongation, and disrupting root stem cell niche maintenance. TK VI increased auxin content and disrupted auxin response gradients in root tips. Further, we screened the Arabidopsis TK VI-resistant mutant tkr1. tkr1 harbors a point mutation in GORK, which encodes gated outwardly rectifying K(+)channel proteins. This mutation alleviated TK VI-induced suppression of K(+)efflux in roots, thereby stabilizing the auxin gradient. The tkr1 mutant also resisted the phytotoxicity of alamethicin. Our results indicate that GORK channels play a key role in peptaibol-plant interaction and that there is an inter-relationship between GORK channels and maintenance of auxin homeostasis. The cellular and molecular insight into the peptaibol-induced inhibition of plant root growth advances our understanding of Trichoderma-plant interactions.

Activation of AMPA Receptors in the Lateral Habenula Produces Anxiolytic Effects in a Rat Model of Parkinson's Disease.

Background: Parkinson's disease (PD) is commonly accompanied with anxiety disorder, however, the mechanisms underlying PD-mediated anxiety remain elusive. The lateral habenula (LHb) is a critical brain region that influences the activity of the monoaminergic system in the midbrain and consequently modulates anxiety. Most neurons in the LHb express AMPA receptors (AMPARs). The PD model for the pharmacological intervention of AMPA receptors was established by the unilateral lesion of the substantia nigra pars compacta (SNc) with 6-hydroxydopamine (6-OHDA). Methods: The AMPAR agonist (S)-AMPA and antagonist NBQX were microinjected into the LHb, respectively, to examine whether anxiety-like behaviors were altered in sham-operated and SNc-lesion rats, measured with the paradigms of the open-field test (OPT) and elevated plus maze (EPM). Furthermore, dopamine (DA) and 5-hydroxytryptamine (5-HT) levels in the basolateral amygdala (BLA) were measured using in vivo microdialysis immediately following the injections of (S)-AMPA and NBQX into the LHb. Results: Activation of LHb AMPA receptors by (S)-AMPA produced anxiolytic-like behaviors and enhanced the extracellular DA and 5-HT in the BLA. Conversely, NBQX induced anxiety-like effects and suppressed the extracellular DA and 5-HT in the BLA. In addition, the minimal doses inducing the effects in the SNc-lesion rats were lower than those in sham-operated rats. Conclusion: These findings suggest that the effects of AMPA receptors in the LHb on anxiety-like behaviors likely involve the extracellular levels of DA and 5-HT in the BLA. The present results may improve our understanding of the neuropathology and/or treatment of PD.

Neuronal activity in the dorsal dentate gyrus during extinction regulates fear memory extinction and renewal.

Memory extinction and renewal are major factors that limits the efficacy of exposure therapy. The dorsal dentate gyrus (dDG) plays a crucial role in spatial memory, and epigenetic modifications in the dDG play an important role in fear memory renewal. However, whether dDG activity regulates fear memory extinction and renewal remains unclear. In this study, we showed that an extinction procedure that prevents fear memory renewal (extinction within the reconsolidation window) leads to increased c-fos expression in the dDG. Chemicogenetic activation of dDG excitatory neurons during extinction training elevated fear memory extinction and prevented renewal, whereas inhibition of dDG excitatory neurons inhibited fear memory extinction. We also demonstrated that inhibiting fear engram cells (neurons active during fear acquisition) during extinction training inhibits fear memory extinction. Therefore, dDG activity during fear extinction plays an important role in fear memory extinction and renewal.

Elevated Level of PKMζ Underlies the Excessive Anxiety in an Autism Model.

Anxiety affects the life quality of a significant percentage of autism patients. To understand the possible biological basis of this high anxiety level, we used a valproic acid (VPA) model of autism. Anxiety level is significantly higher in VPA-injected mice, at both P35 and P70. In addition, protein kinase Mζ (PKMζ) level in the basolateral amygdala (BLA) is significantly higher in VPA mice at both ages. Consistent with this finding, infusion of a PKMζ-blocking peptide z-pseudosubstrate inhibitory peptide (ZIP) into BLA significantly reduced anxiety levels in VPA mice. Furthermore, viral overexpression of PKMζ in the BLA led to elevated anxiety level in Wild Type (WT) mice, with concomitant higher intrinsic excitability of BLA excitatory neurons. Altogether, our results indicate a key contribution of BLA PKMζ level to anxiety, especially in autism; and this finding may provide a further understanding of the pathogenesis as well as treatment of anxiety symptoms in autism patients.

Dnmt3a in the dorsal dentate gyrus is a key regulator of fear renewal.

Renewal of extinguished fear memory in an altered context is widely believed to be a major limiting issue for exposure therapy in treating various psychiatric diseases. Effective prevention of fear renewal will significantly improve the efficacy of exposure therapy. DNA methyltransferase (DNMTs) mediated epigenetic processes play critical roles in long term memory, but little is known about their functions in fear memory extinction or renewal. Here we investigated whether DNMTs regulate fear renewal after extinction. We found that elevated Dnmt3a level in the dorsal dentate gyrus (dDG) of hippocampus was associated with the absence of fear renewal in an altered context after extinction training. Overexpression and knockdown of Dnmt3a in the dDG regulated the occurrence of fear renewal in a bi-directional manner. In addition, Dnmt3a overexpression was associated with elevated expression of c-Fos in the dDG during extinction training. Furthermore, we found that renewal of remote fear memory can be prevented, and the absence of renewal was concurrent with an elevated Dnmt3a level. Our results indicate that Dnmt3a in the dDG is a key regulator of fear renewal after extinction, and Dnmt3a may play a critical role in controlling fear memory return and thus has therapeutic values.

Trichokonins from Trichoderma pseudokoningii SMF2 induce resistance against Gram-negative Pectobacterium carotovorum subsp. carotovorum in Chinese cabbage.

Peptaibols, mainly produced by Trichoderma, play a pivotal role in controlling plant disease caused by fungi, virus, and Gram-positive bacteria. In the current study, we evaluated the control effect of Trichokonins, antimicrobial peptaibols from Trichoderma pseudokoningii SMF2, on soft rot disease of Chinese cabbage caused by a Gram-negative bacterium Pectobacterium carotovorum subsp. carotovorum and analyzed the mechanism involved. Trichokonins treatment (0.3 mg L(-1) ) enhanced the resistance of Chinese cabbage against Pcc infection. However, Trichokonins could hardly inhibit the growth of Pcc in vitro, even at high concentration (500 mg L(-1) ). Therefore, the direct effect of Trichokonins on Pcc may not the main reason why Trichokonins could control soft rot of Chinese cabbage. Trichokonin treatment led to an obvious increase in the production of reactive oxygen species hydrogen peroxide and superoxide radical, a significant enhance of the activities of pathogenesis-related enzymes catalase, polyphenoloxidase and peroxidase, and upregulation of the expression of salicylic acid - responsive pathogenesis-related protein gene acidic PR-1a in Chinese cabbage. These results indicate that Trichokonins induce resistance in Chinese cabbage against Pcc infection through the activation of salicylic acid signaling pathway, which imply the potential of Trichoderma and peptaibols in controlling plant disease caused by Gram-negative bacteria.

Comparative genomics provide insights into evolution of trichoderma nutrition style.

Saprotrophy on plant biomass is a recently developed nutrition strategy for Trichoderma. However, the physiology and evolution of this new nutrition strategy is still elusive. We report the deep sequencing and analysis of the genome of Trichoderma longibrachiatum, an efficient cellulase producer. The 31.7-Mb genome, smallest among the sequenced Trichoderma species, encodes fewer nutrition-related genes than saprotrophic T. reesei (Tr), including glycoside hydrolases and nonribosomal peptide synthetase-polyketide synthase. Homology and phylogenetic analyses suggest that a large number of nutrition-related genes, including GH18 chitinases, ß-1,3/1,6-glucanases, cellulolytic enzymes, and hemicellulolytic enzymes, were lost in the common ancestor of T. longibrachiatum (Tl) and Tr. dN/dS (ω) calculation indicates that all the nutrition-related genes analyzed are under purifying selection. Cellulolytic enzymes, the key enzymes for saprotrophy on plant biomass, are under stronger purifying selection pressure in Tl and Tr than in mycoparasitic species, suggesting that development of the nutrition strategy of saprotrophy on plant biomass has increased the selection pressure. In addition, aspartic proteases, serine proteases, and metalloproteases are subject to stronger purifying selection pressure in Tl and Tr, suggesting that these enzymes may also play important roles in the nutrition. This study provides insights into the physiology and evolution of the nutrition strategy of Trichoderma.