BackgroundRice mutant, spl5 (spotted leaf 5), has spontaneous hypersensitive-like lesions on its leaves and shows enhanced resistance to pathogens, indicating that SPL5 plays a role in programmed cell death (PCD) and disease resistance. To understand the molecular mechanism of SPL5 gene, we investigated the transcriptome profiles of the spl5 mutant leaves with few lesions (FL) and leaves with many lesions (ML) compared to the wild-type (WT) leaves respectively by microarray.ResultsThe data from microarray revealed that 243 and 896 candidate genes (Fold change ≥ 3.0) were up- or down-regulated in the spl5-FL and spl5-ML, respectively, and a large number of these genes involved in biotic defense responses or reactive oxygen species (ROS) metabolism. Interestingly, according to our microarray and real-time PCR assays, the expressions of a transcription factor OsWRKY14 and genes responsible for the biosynthesis of serotonin, anthranilate synthase (AS), indole-3-glycerolphosphate synthase (IGPS), tryptophan synthase (TS) and tryptophan decarboxylase (TDC) were significantly up-regulated in the spl5 mutant. It has been reported previously that TS and TDC expressions are regulated by OsWRKY14 in rice, which raises the possibility that OsWRKY14 regulates serotonin production through the up-regulation of TS and TDC. Our HPLC analysis further confirmed that serotonin levels were higher in the leaves of spl5 mutant than that in WT.ConclusionsSince the serotonin plays a critical role in inducing disease-resistance, the increased serotonin level may contribute, at least partly, to the disease resistance in spl5. The SPL5 gene may act as a negative regulatory factor activating the serotonin metabolic pathway, and these results might provide a new insight into the spl5-induced defense response mechanisms in plants.Electronic supplementary materialThe online version of this article (doi:10.1186/s12284-015-0052-7) contains supplementary material, which is available to authorized users.

No abstract

Heat shock protein 27 (Hsp27) is a member of the small heat shock protein family expressed at high levels to protect cells against heat shock and other conditions of stress. Hsp27 has been indicated in the regulation of inflammation signaling pathway, and Hsp27 phosphorylation is vital for efficient control of host‐defense response in early stages of lipopolysaccharide (LPS)‐stimulated inflammation. The notion that CREB‐binding protein (CBP) is involved in the regulation of two major transcription factors, nuclear factor‐κB (NF‐κB) and AP‐1, suggests that CBP, as a coactivator protein, may also play an important role in the cellular response to inflammation. Here, we explored the mechanism underlying the regulatory relationships between Hsp27 and CBP in THP‐1 cells, and found that phosphorylated Hsp27 was critical to the protein level of CBP. Furthermore, in exploring the signaling mechanisms underlying its action, we found that p38MAPK‐MK2‐Hsp27 regulated NF‐κB via CBP, which acted as a multi‐protein complex assembly scaffold. Finally, we demonstrated that phosphorylated Hsp27 reduced reactive oxygen species accumulation thereby significantly repressed LPS‐induced excessive increase of CBP. Taken together, our data demonstrated that Hsp27, in its phosphorylation state, plays a critical role in controlling LPS‐induced inflammatory response by modulating CBP.

No abstract

CREB binding protein (CBP), a transcriptional coactivator and acetyltransferase, is involved in the pathogenesis of inflammation-related diseases. High mobility group box-1 protein (HMGB1) is a critical mediator of lethal sepsis, which has prompted investigation for the development of new treatment for inflammation. Here, we report that the potent and selective inhibition of CBP bromodomain by SGC-CBP30 blocks HMGB1-mediated inflammatory responses in vitro and in vivo. Our data suggest that CBP bromodomain inhibition suppresses LPS-induced expression and release of HMGB1, when the inhibitor was given 8 h post LPS stimulation; moreover, CBP bromodomain inhibition attenuated pro-inflammatory activity of HMGB1. Furthermore, our findings provide evidence that SGC-CBP30 down-regulated rhHMGB1-induced activation of MAPKs and NF-κB signaling by triggering the reactivation of protein phosphatase 2A (PP2A) and the stabilization of MAPK phosphatase 1 (MKP-1). Collectively, these results suggest that CBP bromodomain could serve as a candidate therapeutic target for the treatment of lethal sepsis via inhibiting LPS-induced expression and release of HMGB1 and suppressing the pro-inflammatory activity of HMGB1.