Regulation of habenular G-protein gamma 8 on learning and memory via modulation of the central acetylcholine system.

Guanine nucleotide binding protein (G protein) gamma 8 (Gng8) is a subunit of G proteins and expressed in the medial habenula (MHb) and interpeduncular nucleus (IPN). Recent studies have demonstrated that Gng8 is involved in brain development; however, the roles of Gng8 on cognitive function have not yet been addressed. In the present study, we investigated the expression of Gng8 in the brain and found that Gng8 was predominantly expressed in the MHb-IPN circuit of the mouse brain. We generated Gng8 knockout (KO) mice by CRISPR/Cas9 system in order to assess the role of Gng8 on cognitive function. Gng8 KO mice exhibited deficiency in learning and memory in passive avoidance and Morris water maze tests. In addition, Gng8 KO mice significantly reduced long-term potentiation (LTP) in the hippocampus compared to that of wild-type (WT) mice. Furthermore, we observed that levels of acetylcholine (ACh) and choline acetyltransferase (ChAT) in the MHb and IPN of Gng8 KO mice were significantly decreased, compared to WT mice. The administration of nAChR α4ß2 agonist A85380 rescued memory impairment in the Gng8 KO mice, suggesting that Gng8 regulates cognitive function via modulation of cholinergic activity. Taken together, Gng8 is a potential therapeutic target for memory-related diseases and/or neurodevelopmental diseases.

Amphiphilic peptides with arginine and valine residues as siRNA carriers.

An efficient and safe delivery carrier is required for the therapeutic application of siRNA. In this research, amphiphilic peptides with arginine and valine residues were evaluated as siRNA carriers. The peptides were composed of 1-4 arginine-blocks and 6 valine-blocks. In the aqueous solution, the arginine-valine peptides (RV peptides) formed micelles with hydrophobic cores comprised of a valine block and a cationic surface comprised of an arginine block. In a gel retardation assay, the RV peptides completely retarded siRNA at a 1:10 weight ratio (siRNA:peptide). A heparin competition assay suggested that the RV peptides formed more stable complexes with siRNA than they did with polyethylenimine (25 kDa, PEI25k). In an in vitro silencing assay, a dual luciferase expression (Renilla and firefly luciferases) vector, psiCHECK2, was co-transfected into human embryonic kidney 293 cells with Renilla-siRNA using the RV peptides. The specific silencing effect of Renilla luciferase was analyzed in reference to firefly luciferase. The results showed that the R3V6 peptide was more efficient than the R1V6, R2V6, and R4V6 peptides in silencing Renilla luciferase. In the flow cytometry and in vitro silencing studies, the R3V6 peptide delivered Renila-siRNA as efficiently as PEI25k. The siVEGF/R3V6 peptide also reduced endogenous vascular endothelial growth factor (VEGF) expression in CT27 cells as efficiently as PEI25k. A cytotoxicity assay showed that RV peptides did not cause any cytotoxicity. Therefore, RV peptides may be useful for the development of a safe and efficient delivery carrier of siRNA.

Dexamethasone-loaded peptide micelles for delivery of the heme oxygenase-1 gene to ischemic brain.

The R3V6 peptides, which are composed of a 3-arginine block and a 6-valine block, formed self-assembled micelles in aqueous solution. Dye quenching assays showed that a hydrophobic fluorescent dye, 5-dodecanoylaminofluorescein (DAF), interacted with and was loaded into the hydrophobic core of the micelles. In this study, dexamethasone-loaded R3V6 peptide micelles (R3V6-Dexa) were evaluated as a gene carrier. R3V6-Dexa had higher gene delivery efficiency in human embryonic kidney 293 cells compared to those of the R3V6 peptides and poly-L-lysine (PLL). Dexamethasone might stabilize the micelle structure of the R3V6 peptides by forming strong hydrophobic cores and enhanced the transfection efficiency. Furthermore, R3V6-Dexa reduced the expression of an inflammatory cytokine, interleukin-6 (IL-6), more efficiently in lipopolysaccharide (LPS)-induced Raw264.7 cells than did dexamethasone, suggesting that R3V6-Dexa is also a useful carrier for dexamethasone delivery. A focal brain ischemia-reperfusion model was produced by middle cerebral artery occlusion (MCAO). A heme oxygenase-1 (HO-1) expression plasmid DNA, pSV-HO-1, was delivered into the brain using R3V6-Dexa as a carrier. The pSV-HO-1/R3V6-Dexa complex was injected into the brain 1hr prior to MCAO. Twenty-four hours later, the HO-1 expression of the pSV-HO-1/R3V6-Dexa injection group was higher than those of the MCAO control, pß-Luc/R3V6-Dexa, and pSV-HO-1/PEI25k injection groups. In addition, the infarct size was reduced due to the delivery of pSV-HO-1/R3V6-Dexa complex. Therefore, R3V6-Dexa may be a useful carrier for HO-1 gene delivery and stroke gene therapy.

Dexamethasone conjugation to polyamidoamine dendrimers G1 and G2 for enhanced transfection efficiency with an anti-inflammatory effect.

Polyamidoamine (PAM) dendrimers with low generation such as PAM generation 1 (PAMG1) and PAM generation 2 (PAMG2) have been widely used as a gene carrier due to low toxicity, albeit their low transfection efficiency. In this study, dexamethasone was conjugated to PAMG1 and PAMG2 in order to increase the transfection efficiency. In a gel retardation assay, the dexamethasone conjugated PAMG1 and PAMG2 (PAMG1-Dexa and PAMG2-Dexa) retarded plasmid DNA (pDNA) completely at 5:1 and 3:1 weight ratios (polymer:pDNA), respectively. In transfection assays, PAMG1-Dexa and PAMG2-Dexa had the highest transfection efficiency at 20:1 and 10:1 weight ratios, respectively. In addition, PAMG1-Dexa and PAMG2-Dexa had higher transfection efficiencies than PAMG1, PAMG2, PEI25k, and lipofectamine. In a MTT assay, PAMG1-Dexa and PAMG2-Dexa were less cytotoxic than lipofectamine. In addition, PAMG1-Dexa and PAMG2-Dexa decreased the TNF-α level more efficiently than dexamethasone only in the lipopolysaccharide (LPS)-induced Raw264.7 cells. Therefore, PAMG1-Dexa and PAMG2-Dexa may prove to be useful as gene delivery carriers with an anti-inflammatory effect.

The influence of Sam-Chil-Geun (Panax notoginseng) on the serum lipid levels and inflammations of rats with hyperlipidemia induced by poloxamer-407.

PURPOSE: Atherosclerosis is characterized by the progressive deposition of lipids and inflammatory process. We attempted to develop a chemically-induced hyperlipidemic mice model, using poloxamer-407 and evaluated the lipid lowering and anti-inflammatory effect of P. notoginseng compared with that of atorvastatin, an antihyperlipidemic drug. MATERIALS AND METHODS: Male Wistar rats were randomly divided into 5 groups: control group without any intervention (normal), poloxamer 500 mg/kg i.p. (P), poloxamer plus atorvastatin 1.34 mg/kg p.o. (P + ST), poloxamer plus P. notogin-seng 40 mg/kg p.o. (P + NG40), and poloxamer plus P. notoginseng 100 mg/kg p.o. (P + NG100). After 3 weeks, we measured serum total cholesterol, low-density lipoprotein (LDL), high-density lipoprotein (HDL), triglyceride, interleukin (IL)-1, tumor necrosis factor (TNF)-alpha levels, and reports of cyclo-oxygenase (COX)-2 and intercellular adhesion molecule (ICAM) appearances in each group. RESULTS: After 3 weeks, serum cholesterol levels significantly decreased in P + ST and P + NG40 groups. Significant decrease of LDL level was only noted in the P + ST group. P + ST, P + NG40, and P + NG100 also had decreased serum triglyceride levels; however, P + ST and P + NG40 showed no statistical difference of the triglyceride lowering effect. The results of IL-1 and TNF-alpha and the appearance of COX-2 and ICAM were statistically not different in each group. CONCLUSION: P. notoginseng 40 mg/kg showed significantly lowering effects on serum total cholesterol and triglyceride levels. We suggest a well-designed study showing the effects of regulating blood lipids with combined administration of P. notoginseng and statin-drug.