Constitutive and Inducible Systems for Genetic In Vivo Modification of Mouse Hepatocytes Using Hydrodynamic Tail Vein Injection

Prenatal diesel exhaust exposure alters hippocampal synaptic plasticity in offspring

Diesel exhaust particles (DEPs) are major air pollutants emitted from automobile engines. Prenatal exposure to DEPs has been linked to neurodevelopmental and neurodegenerative diseases associated with aging. However, the specific mechanism by DEPs impair the hippocampal synaptic plasticity in the offspring remains unclear. Pregnant C57BL/6 mice were administered DEPs solution via the tail vein every other day for a total of 10 injections, then the male offsprings were studied to assess learning and memory by the Morris water maze. Additionally, protein expression in the hippocampus, including CPEB3, NMDAR (NR1, NR2A, NR2B), PKA, SYP, PSD95, and p-CREB was analyzed using Western blotting and immunohistochemistry. The alterations in the histomorphology of the hippocampus were observed in male offspring on postnatal day 7 following prenatal exposure to DEPs. Furthermore, 8-week-old male offspring exposed to DEPs during prenatal development exhibited impairments in the Morris water maze test, indicating deficits in learning and memory. Mechanistically, the findings from our study indicate that exposure to DEPs during pregnancy may alter the expression of CPEB3, SYP, PSD95, NMDAR (NR1, NR2A, and NR2B), PKA, and p-CREB in the hippocampus of both immature and mature male offspring. The results offer evidence for the role of the NMDAR/PKA/CREB and CPEB3 signaling pathway in mediating the learning and memory toxicity of DEPs in male offspring mice. The alterations in signaling pathways may contribute to the observed damage to synaptic structure and transmission function plasticity caused by DEPs. The findings hold potential for informing future safety assessments of DEPs.

Quercetin relieves D-amphetamine-induced manic-like behaviour through activating TREK-1 potassium channels in mice

BACKGROUND AND PURPOSE

Quercetin is a well-known plant flavonoid with neuroprotective properties. Earlier work suggested it may relieve psychiatric disorders, cognition deficits and memory dysfunction through anti-oxidant and/or radical scavenging mechanisms. In addition, quercetin modulated the physiological function of some ion channels. However, the detailed ionic mechanisms of the bioeffects of quercetin remain unknown.

EXPERIMENTAL APPROACH

Effects of quercetin on neuronal activities in the prefrontal cortex (PFC) and its ionic mechanisms were analysed by calcium imaging using mice bearing a green fluorescent protein, calmodulin, and M13 fusion protein and patch clamp in acute brain slices from C57BL/6 J mice and in HEK 293 cells. The possible ionic mechanism of action of quercetin on D-amphetamine-induced manic-like effects in mice was explored with c-fos staining and the open field behaviour test.

KEY RESULTS

Quercetin reduced calcium influx triggered by PFC pyramidal neuronal activity. This effect involved increasing the rheobase of neuronal firing through decreasing membrane resistance following quercetin treatment. Spadin, a blocker of TREK-1 potassium channels, also blocked the effect of quercetin on the membrane resistance and neuronal firing. Further, spadin blocked the neuroprotective effects of quercetin. The effects of quercetin on TREK-1 channels could be mimicked by GF109203X, a protein kinase C inhibitor. In vivo, injection of quercetin relieved the manic hyperlocomotion in mice, induced by D-amphetamine. This action was partly alleviated by spadin.

CONCLUSION AND IMPLICATIONS

TREK-1 channels are a novel target for quercetin, by inhibiting PKC. This action could contribute to both the neuroprotective and anti-manic-like effects.

Chemoresistance-Associated Silencing of miR-4454 Promotes Colorectal Cancer Aggression through the GNL3L and NF-κB Pathway

Guanine nucleotide-binding protein-like-3-like (GNL3L) is a crucial regulator of NF-κB signaling that is aberrantly activated during diverse chemoresistance-associated cellular processes. However, the molecular mechanisms of GNL3L tumor initiation and resistant state are largely unknown. Moreover, the identification of predictive biomarkers is necessary to effectively generate therapeutic strategies for metastatic human colorectal cancer (CRC). This study aims to identify how cells acquire resistance to anticancer drugs and whether the downregulation of miR-4454 is associated with the progression of CRC. Here, we have shown that the overexpression of miR-4454 in resistant tumors is a crucial precursor for the posttranscriptional repression of GNL3L in human chemoresistant CRC progression, and we used doxycycline induced miR-4454 overexpression that significantly reduced tumor volume in a subcutaneous injection nude mice model. Together, these observations highlight that the downregulation of miR-4454 in resistant clones is prominently responsible for maintaining their resistance against anticancer drug therapy. Our study indicates that the development of miR-4454 as a microRNA-based therapeutic approach to silence GNL3L may remarkably reduce oncogenic cell survival that depends on GNL3L/NF-κB signaling, making miR-4454 a candidate for treating metastatic human CRC.

Targeted DNA demethylation of the Fgf21 promoter by CRISPR/dCas9-mediated epigenome editing

Recently, we reported PPARα-dependent DNA demethylation of the Fgf21 promoter in the postnatal mouse liver, where reduced DNA methylation is associated with enhanced gene expression after PPARα activation. However, there is no direct evidence for the effect of site-specific DNA methylation on gene expression. We employed the dCas9-SunTag and single-chain variable fragment (scFv)-TET1 catalytic domain (TET1CD) system to induce targeted DNA methylation of the Fgf21 promoter both in vitro and in vivo. We succeeded in targeted DNA demethylation of the Fgf 21 promoter both in Hepa1-6 cells and PPARα-deficient mice, with increased gene expression response to PPARα synthetic ligand administration and fasting, respectively. This study provides direct evidence that the DNA methylation status of a particular gene may determine the magnitude of the gene expression response to activation cues.