Impairment of cognitive function induced by Shati/Nat8l overexpression in the prefrontal cortex of mice

L-carnitine Modulates Cognitive Impairment Induced by Doxorubicin and Cyclophosphamide in Rats; Insights to Oxidative Stress, Inflammation, Synaptic Plasticity, Liver/brain, and Kidney/brain Axes

Chemotherapy-induced cognitive impairment in cancer patients is known as "chemobrain". Doxorubicin and Cyclophosphamide are two chemotherapeutic agents used in combination to treat solid tumors. L-carnitine was reported for its anti-oxidant and anti-inflammatory activities. The goal of the present study was to elucidate the neuroprotective effect of L-carnitine against chemobrain induced by Doxorubicin and Cyclophosphamide in rats. Rats were divided into five groups: Control group; Doxorubicin (4mg/kg, IV) and Cyclophosphamide (40mg/kg, IV)-treated group; two L-carnitine-treated groups (150 and 300mg/kg, ip) with Doxorubicin and Cyclophosphamide; and L-carnitine alone-treated group (300mg/kg). Doxorubicin and Cyclophosphamide induced histopathological changes in rats' hippocampi and prefrontal cortices, as well as reduced memory as evidenced by behavioural testing. L-carnitine treatment showed opposite effects. In addition, chemotherapy treatment enhanced oxidative stress via reducing catalase and glutathione levels, and inducing lipid peroxidation. By contrast, L-carnitine treatment showed powerful antioxidant effects reversing chemotherapy-induced oxidative damage. Moreover, chemotherapy combination induced inflammation via their effect on nuclear factor kappa B (p65), interleukin-1β, and tumor necrosis factor-α. However, L-carnitine treatment corrected such inflammatory responses. Furthermore, Doxorubicin and Cyclophosphamide reduced synaptic plasticity via hindering expression of brain-derived neurotrophic factor, phosphorylated cyclase response element binding protein, synaptophysin, and postsynaptic density protein 95 whereas protein expression of such synaptic plasticity biomarkers was enhanced by L-carnitine treatment. Finally, acetylcholinesterase activity was found to be enhanced by chemotherapy treatment affecting rats' memory while L-carnitine treatment reduced acetylcholinesterase activity. L-carnitine also showed hepatoprotective and renal protective effects suggesting liver/brain and kidney/brain axes as possible mechanisms for its neuroprotective effects.

Downregulation of CHCHD2 may Contribute to Parkinson's Disease by Reducing Expression of NFE2L2 and RQCD1

BACKGROUND

Parkinson's disease (PD) is associated with coiled-coil-helix-coiled-coil-helix domain containing 2 (CHCHD2) downregulation, which has been linked to reduced cyclocytase activity and increased levels of oxygen free radicals, leading to mitochondrial fragmentation and apoptosis. Little is known about how CHCHD2 normally functions in the cell and, therefore, how its downregulation may contribute to PD.

OBJECTIVE

This study aimed to identify such target genes using chromatin immunoprecipitation sequencing from SH-SY5Y human neuroblastoma cells treated with neurotoxin 1-methyl-4-phenylpyridinium (MPP+) as a PD model.

METHODS

In this study, we established a MPP+ -reated SH-SY5Y cell model and evaluated the effects of CHCHD2 overexpression on cell proliferation and apoptosis. At the same time, we used high-throughput chromatin immunoprecipitation sequencing to identify its downstream target gene in SH-SY5Y cells. In addition, we verified the possible downstream target genes and discussed their mechanisms.

RESULTS

The expression level of α-synuclein increased in SH-SY5Y cells treated with MPP+, while the protein expression level of CHCHD2 decreased significantly, especially after 24 h of treatment. Chip-IP results showed that CHCHD2 may regulate potential target genes such as HDX, ACP1, RAVER2, C1orf229, RN7SL130, GNPTG, erythroid 2 Like 2 (NFE2L2), required for cell differentiation 1 homologue (RQCD1), solute carrier family 5 member 7 (SLA5A7), and N-Acetyltransferase 8 Like (NAT8L). NFE2L2 and RQCD1 were validated as targets using PCR and western blotting of immunoprecipitates, and these two genes together with SLA5A7 and NAT8L were upregulated in SH-SY5Y cells overexpressing CHCHD2. Downregulation of CHCHD2 may contribute to PD by leading to inadequate expression of NFE2L2 and RQCD1 as well as, potentially, SLA5A7 and NAT8L.

CONCLUSION

Our results suggest that CHCHD2 plays a protective role by maintaining mitochondrial homeostasis and promoting proliferation in neurons. In this study, the changes of CHCHD2 and downstream target genes such as NFE2L2/RQCD1 may have potential application prospects in the future. These findings provide leads to explore PD pathogenesis and potential treatments.

Neuroligin-1 plays an important role in methamphetamine-induced hippocampal synaptic plasticity

The neurotoxic effects of methamphetamine (METH) include not only neuronal apoptosis and autophagy, but also lead to substance use disorder and have become increasingly prominent. Studies suggest that synaptic plasticity may be the structural basis of METH-induced neurological impairment. Neuroligins are postsynaptic adhesion molecules involved in the regulation of synaptic organization and function. Animal studies have shown that neuroligin (NLG)- 1 is involved in memory formation; however, its role in METH-induced neurotoxicity is not clear. In the present study, we used 1 mM METH in vitro; mice in the acute and subacute exposure groups received intraperitoneal injections of 30 mg/kg METH (1 injection) or 15 mg/kg METH (8 separate injections at 12-h intervals). We found that the expression of NLG-1, Synapsin-1, and postsynaptic density-95 were increased after METH exposure. We further observed that METH-induced inhibition of long-term potentiation and spatial memory loss could be alleviated when mice were pretreated with NLG-1 small interfering RNA. Therefore, our study provides evidence that NLG-1 is involved in METH-induced hippocampal synaptic plasticity and may be a potential target for the treatment of METH-induced neurotoxicity.

The cAMP Inducers Modify N-Acetylaspartate Metabolism in Wistar Rat Brain

Neuronal N-acetylaspartate production appears in the presence of aspartate N-acetyltransferase (NAT8L) and binds acetyl groups from acetyl-CoA with aspartic acid. Further N-acetylaspartate pathways are still being elucidated, although they seem to involve neuron-glia crosstalk. Together with N-acetylaspartate, NAT8L takes part in oligoglia and astroglia cell maturation, myelin production, and dopamine-dependent brain signaling. Therefore, understanding N-acetylaspartate metabolism is an emergent task in neurobiology. This project used in in vitro and in vivo approaches in order to establish the impact of maturation factors and glial cells on N-acetylaspartate metabolism. Embryonic rat neural stem cells and primary neurons were maturated with either nerve growth factor, trans-retinoic acid or activators of cAMP-dependent protein kinase A (dibutyryl-cAMP, forskolin, theophylline). For in vivo, adult male Wistar rats were injected with theophylline (20 mg/kg b.w.) daily for two or eight weeks. Our studies showed that the N-acetylaspartate metabolism differs between primary neurons and neural stem cell cultures. The presence of glia cells protected N-acetylaspartate metabolism from dramatic changes within the maturation processes, which was impossible in the case of pure primary neuron cultures. In the case of differentiation processes, our data points to dibutyryl-cAMP as the most prominent regulator of N-acetylaspartate metabolism.

Striatal Shati/Nat8l-BDNF pathways determine the sensitivity to social defeat stress in mice through epigenetic regulation

The global number of patients with depression increases in correlation to exposure to social stress. Chronic stress does not trigger depression in all individuals, as some remain resilient. The underlying molecular mechanisms that contribute to stress sensitivity have been poorly understood, although revealing the regulation of stress sensitivity could help develop treatments for depression. We previously found that striatal Shati/Nat8l, an N-acetyltransferase, was increased in a depression mouse model. We investigated the roles of Shati/Nat8l in stress sensitivity in mice and found that Shati/Nat8l and brain-derived neurotrophic factor (BDNF) levels in the dorsal striatum were increased in stress-susceptible mice but not in resilient mice exposed to repeated social defeat stress (RSDS). Knockdown of Shati/Nat8l in the dorsal striatum induced resilience to RSDS. In addition, blockade of BDNF signaling in the dorsal striatum by ANA-12, a BDNF-specific receptor tropomyosin-receptor-kinase B (TrkB) inhibitor, also induced resilience to stress. Shati/Nat8l is correlated with BDNF expression after RSDS, and BDNF is downstream of Shati/Nat8l pathways in the dorsal striatum; Shati/Nat8l is epigenetically regulated by BDNF via histone acetylation. Our results demonstrate that striatal Shati/Nat8l-BDNF pathways determine stress sensitivity through epigenetic regulation. The striatal Shati/Nat8l-BDNF pathway could be a novel target for treatments of depression and could establish a novel therapeutic strategy for depression patients.