PURPOSE: The study was carried out to investigate the molecular mechanisms underlying the anti-inflammatory properties of the standardized 80% ethanol extract of Z. zerumbet through its effect on mitogen-activated protein kinase (MyD88)-dependent nuclear factor-kappa B (NF-кB), mitogen activated protein kinase (MAPK) and phosphatidylinositol 3-kinase/Akt (PI3K-Akt) signaling pathways in lipopolysaccharide (LPS)-induced U937 human macrophages.
METHODS: Standardization of the 80% ethanol extract of Z. zerumbet was performed by using a validated reversed-phase HPLC method, while LC-MS/MS was used to profile the secondary metabolites. The release of pro-inflammatory markers, tumor necrosis factor (TNF)-α, interleukin (IL)-1β and prostaglandin E2 (PGE2) was evaluated by enzyme-linked immunosorbent assay (ELISA), while the Western blot technique was executed to elucidate the expression of mediators linked to MyD88-dependent respective signaling pathways. Real-time quantitative reverse transcription polymerase chain reaction (qRT-PCR) assay was carried out to quantify the relative gene expression of cyclooxygenase (COX)-2 and pro-inflammatory mediators at the transcriptional level.
RESULTS: The quantitative and qualitative analyses of Z. zerumbet extract showed the presence of several compounds including the major chemical marker zerumbone. Z. zerumbet extract suppressed the release of pro-inflammatory mediators, COX-2 protein expression and downregulated the mRNA expression of pro-inflammatory markers. Z. zerumbet-treatment also blocked NF-κB activation by preventing the phosphorylation of IKKα/β and NF-κB (p65) as well as the phosphorylation and degradation of IκBα. Z. zerumbet extract concentration-dependently inhibited the phosphorylation of respective MAPKs (JNK, ERK, and p38) as well as Akt. Correspondingly, Z. zerumbet extract suppressed the upstream signaling adaptor molecules, TLR4 and MyD88 prerequisite for the NF-κB, MAPKs, and PI3K-Akt activation.
CONCLUSION: The findings suggest that Z. zerumbet has impressive role in suppressing inflammation and related immune disorders by inhibition of various pro-inflammatory markers through the imperative MyD88-dependent NF-κB, MAPKs, and PI3K-Akt activation.
OBJECTIVE: This study aims to determine the effect of age on the function of rostral C1 (rC1) neurons in mediating feeding response.
METHOD: Male Sprague Dawley rats at 3-months (n = 22) and 24-months (n = 22) old were used and further divided into two subgroups; 1) treatment group with 2-deoxy-d-glucose (2DG) and 2) vehicle group. Feeding hormones such as cholecystokinin (CCK), ghrelin and leptin were analysed using enzyme-linked immunosorbent assay (ELISA). Rat brain was carefully dissected to obtain the brainstem RVLM region. Further analysis was carried out to determine the level of proteins and genes in RVLM that were associated with feeding pathway. Protein expression of tyrosine hydroxylase (TH), phosphorylated TH at Serine40 (pSer40TH), AMP-activated protein kinase (AMPK), phosphorylated AMPK (phospho AMPK) and neuropeptide Y Y5 receptor (NPY5R) were determined by western blot. Expression of TH, AMPK and NPY genes were determined by real-time PCR.
RESULTS: This study showed that blood glucose level was elevated in young and old rats following 2DG administration. Plasma CCK-8 concentration was higher in the aged rats at basal and increased with 2DG administration in young rats, but the leptin and ghrelin showed no changes. Old rats showed higher TH and lower AMPK mRNA levels. Glucoprivation decreased AMPK mRNA level in young rats and decreased TH mRNA in old rats. Aged rC1 neurons showed higher NPY5R protein level. Following glucoprivation, rC1 neurons produced distinct molecular changes across age in which, in young rats, AMPK phosphorylation level was increased and in old rats, TH phosphorylation level was increased.
CONCLUSION: These findings suggest that glucose-counterregulatory responses by rC1 neurons at least, contribute to the ability of young and old rats in coping glucoprivation. Age-induced molecular changes within rC1 neurons may attenuate the glucoprivic responses. This situation may explain the impairment of feeding response in the elderly.
METHODS: This study belongs to a part of an ongoing Singapore/Malaysia cross-sectional genetics and epidemiological study (SMCSGES). Genotype-phenotype associations were assessed by performing a genotyping assay on n = 4,348 ethnic Chinese individuals from the SMCSGES cohort. The phosphorylation levels of receptors and signaling proteins in the MAPK signaling cascades, including ErbB2, EGFR, and ERK1/2, were compared across the genotypes of asthma-associated SNPs through in vitro and ex vivo approaches.
RESULTS: The ERBB2 tag-SNP rs1058808 was significantly associated with allergic asthma, with the allele "G" identified as protective against the disease (adjusted logistic p = 6.56 × 10-9, OR = 0.625, 95% CI: 0.544-0.718). The allele "G" of rs1058808 resulted in a Pro1170Ala mutation that results in lower phosphorylation levels of ErbB2 in HaCat cells (p < 0.001), whereas the overall ERBB2 mRNA expression and the phosphorylation levels of EGFR remained unaffected. In the SMCSGES cohort, individuals carrying the genotype "GG" of rs1058808 had lower phosphorylated ERK1/2 proteins in the MAPK signaling cascade. A lower phosphorylation level of ERK1/2 was also associated with reduced asthma risk.
CONCLUSIONS: The present findings highlighted the involvement of a functional exonic variant of ERBB2 in asthma development via modulating the MAPK signaling cascade.
METHODS AND RESULTS: Selective agonists of PKA and EPAC synergistically inhibited Egr1 expression, which was essential for VSMC proliferation. Forskolin, adenosine, A2B receptor agonist BAY60-6583 and Cicaprost also inhibited Egr1 expression in VSMC but not in endothelial cells. Inhibition of Egr1 by cAMP was independent of cAMP response element binding protein (CREB) activity but dependent on inhibition of serum response element (SRE) activity. SRF binding to the Egr1 promoter was not modulated by cAMP stimulation. However, Egr1 expression was dependent on the SRF co-factors Elk1 and 4 but independent of MAL. Inhibition of SRE-dependent Egr1 expression was due to synergistic inhibition of Rac1 activity by PKA and EPAC, resulting in rapid cytoskeleton remodelling and nuclear export of ERK1/2. This was associated with de-phosphorylation of the SRF co-factor Elk1.
CONCLUSION: cAMP inhibits VSMC proliferation by rapidly inhibiting Egr1 expression. This occurs, at least in part, via inhibition of Rac1 activity leading to rapid actin-cytoskeleton remodelling, nuclear export of ERK1/2, impaired Elk1-phosphorylation and inhibition of SRE activity. This identifies one of the earliest mechanisms underlying the anti-mitogenic effects of cAMP in VSMC but not in endothelial cells, making it an attractive target for selective inhibition of VSMC proliferation.
METHOD: Intriguing evidences discussed the contribution of different intracellular compartments in autophagy membrane formation. Furthermore, autophagy serves to mobilise membranes within cells, thereby promoting cytoplasmic components reorganisation. The intent of this review is to focus on the possibility of autophagy to act as a carrier for GLUT4 through regulating GLUT4 endocytosis, intracellular trafficking in different compartments, and translocation to cell membrane.
RESULTS: The common themes of autophagy and GLUT4 have been highlighted. The review discussed the overlapping of endocytosis mechanism and intracellular compartments, and has shown that autophagy and GLUT4 utilise similar proteins (SNAREs) which are used for exocytosis. On top of that, PI3K and AMPK also control both autophagy and GLUT4.
CONCLUSION: The control of GLUT4 trafficking through autophagy could be a promising field for treating type 2 diabetes.