Absence of Appl2 sensitizes endotoxin shock through activation of PI3K/Akt pathway

BACKGROUND: The adapter proteins Appl1 (adaptor protein containing pleckstrin homology domain, phosphotyrosine domain, and leucine zipper motif 1) and Appl2 are highly homologous and involved in several signaling pathways. While previous studies have shown that Appl1 plays a pivotal role in adiponectin signaling and insulin secretion, the physiological functions of Appl2 are largely unknown. RESULTS: In the present study, the role of Appl2 in sepsis shock was investigated by using Appl2 knockout (KO) mice. When challenged with lipopolysaccharides (LPS), Appl2 KO mice exhibited more severe symptoms of endotoxin shock, accompanied by increased production of proinflammatory cytokines. In comparison with the wild-type control, deletion of Appl2 led to higher levels of TNF-α and IL-1β in primary macrophages. In addition, phosphorylation of Akt and its downstream effector NF-κB was significantly enhanced. By co-immunoprecipitation, we found that Appl2 and Appl1 interacted with each other and formed a complex with PI3K regulatory subunit p85α, which is an upstream regulator of Akt. Consistent with these results, deletion of Appl1 in macrophages exhibited characteristics of reduced Akt activation and decreased the production of TNFα and IL-1β when challenged by LPS. CONCLUSIONS: Results of the present study demonstrated that Appl2 is a critical negative regulator of innate immune response via inhibition of PI3K/Akt/NF-κB signaling pathway by forming a complex with Appl1 and PI3K.published_or_final_versio

Harmine Induces Adipocyte Thermogenesis through RAC1-MEK-ERK-CHD4 Axis

© The Author(s) 2016.Harmine is a natural compound possessing insulin-sensitizing effect in db/db diabetic mice. However its effect on adipose tissue browning is unknown. Here we reveal that harmine antagonizes high fat diet-induced adiposity. Harmine-treated mice gained less weight on a high fat diet and displayed increased energy expenditure and adipose tissue thermogenesis. In vitro, harmine potently induced the expression of thermogenic genes in both brown and white adipocytes, which was largely abolished by inhibition of RAC1/MEK/ERK pathway. Post-transcriptional modification analysis revealed that chromodomain helicase DNA binding protein 4 (CHD4) is a potential downstream target of harmine-mediated ERK activation. CHD4 directly binds the proximal promoter region of Ucp1, which is displaced upon treatment of harmine, thereby serving as a negative modulator of Ucp1. Thus, here we reveal a new application of harmine in combating obesity via this off-target effect in adipocytes.published_or_final_versio

Colinearity and Similar Expression Pattern of Rice <em>DREB1s</em> Reveal Their Functional Conservation in the Cold-Responsive Pathway

<div><p>The clustered genes <u>C</u>-repeat (CRT) <u>b</u>inding <u>f</u>actor (<em>CBF)1/</em><u>d</u>ehydration-<u>r</u>esponsive <u>e</u>lement <u>b</u>inding protein <em>(DREB)1B</em>, <em>CBF2/DREB1C</em>, and <em>CBF3/DREB1A</em> play a central role in cold acclimation and facilitate plant resistance to freezing in <em>Arabidopsis thaliana</em>. Rice (<em>Oryza sativa</em> L.) is very sensitive to low temperatures; enhancing the cold stress tolerance of rice is a key challenge to increasing its yield. In this study, we demonstrate chilling acclimation, a phenomenon similar to <em>Arabidopsis</em> cold acclimation, in rice. To determine whether rice <em>CBF/DREB1</em> genes participate in this cold-responsive pathway, all putative homologs of <em>Arabidopsis DREB1</em> genes were filtered from the complete rice genome through a BLASTP search, followed by phylogenetic, colinearity and expression analysis. We thereby identified 10 rice genes as putative <em>DREB1</em> homologs: nine of these were located in rice genomic regions with some colinearity to the <em>Arabidopsis CBF1</em>–<em>CBF4</em> region. Expression profiling revealed that six of these genes (Os01g73770, Os02g45450, Os04g48350, Os06g03670, Os09g35010, and Os09g35030) were similarly expressed in response to chilling acclimation and cold stress and were co-expressed with genes involved in cold signalling, suggesting that these <em>DREB1</em> homologs may be involved in the cold response in rice. The results presented here serve as a prelude towards understanding the function of rice homologs of <em>DREB1</em> genes in cold-sensitive crops.</p> </div

The messages of relative genes in the study.

a<p>KOME FL-cDNA;</p>b<p>Community cDNA;</p>c<p>NCBI-EST;</p>d<p>No EST or FL-cDNA found.</p

Survival rate of 7-day-old rice seedlings after the low temperature stress with or without chilling acclimation.

<p>Cold treatment (CT): 7-day-old seedlings were first maintained for 4 days (for indica rice: 9311 and Kasalath) or 7 days (for japonica rice: Nipponbare and TP309) at a low temperature of 4°C, then restored for 10 days to normal growth temperature. Chilling acclimation treatment (CA): 7-day-old seedlings were first maintained for 2 days at a mild temperature of 12°C, then 4 days (for indica rice: 9311 and Kasalath) or 7 days (for japonica rice: Nipponbare and TP309) at a low temperature of 4°C, and finally restored for 10 days to normal growth temperature. Each rice varieties were treated with four times of independent experiments and the bars represent the standard deviation. P values of T-test for difference between CT and CA treatments of each variety were shown in Fig. 1.</p

Phylogenetic analysis and sequence alignment of <i>Arabidopsis DREB1</i>s and their homologs in rice using ClustalW2.

<p>A: The phylogenetic analysis was carried out by the neighbour-joining method of ClustalW2, and the tree was edited and viewed by TreeView software. SD: segmental duplication; TD: tandem duplication; Transposition: single gene duplication by transposition. Bootstrap values from 1000 replicates were indicated at each node. Scale bar represented 0.1 amino acid substitution per site. B: The NLS (nuclear localization signal), ERF/AP2 domain, DSAW motif, and LWSY motif are shown. The alignment of the 141–171 region of <i>CBF1</i> and the corresponding regions of its rice and <i>Arabidopsis</i> homologs has been omitted due to the absence of conserved motif.</p

Expression of rice <i>DREB1s</i> under drought, salt, and cold stresses in rice seedlings from the SALK RiceGE database.

<p>X axis: different stresses; Y axis: total RNA expression level of seven-day-old seedlings.</p

Colinearity among regions containing either <i>Arabidopsis CBF1–3</i> or their orthologs in rice.

<p>The dotted box indicates that the pairs of regions of chromosomes 2 and 4 contain lots of pairs of paralogs as showed by the dotted lines. The solid lines indicate that the genes are orthlogous to each other as they possess the highest E value or identities from reciprocal blast analyses.</p

Expression pattern of rice <i>DREB1</i> genes in the ZS97 cultivar during the entire life cycle of the plant.

<p>Expression pattern of rice <i>DREB1</i> genes in the ZS97 cultivar during the entire life cycle of the plant.</p

GO enrichment analysis of co-expressed genes of rice <i>DREB1</i> homologs using agriGO software.

<p>GO enrichment analysis of co-expressed genes of rice <i>DREB1</i> homologs using agriGO software.</p