No abstract

Triptolide (TP), an active component isolated from Tripterygiumwilfordii Hook F, has therapeutic potential against rheumatoid arthritis (RA). However, the underlying molecular mechanism has not been fully elucidated. The aim of this study is to investigate the mechanisms of TP acting on RA by combining bioinformatics analysis with experiment validation. The human protein targets of TP and the human genes of RA were found in the PubChem database and NCBI, respectively. These two dataset were then imported into Ingenuity Pathway Analysis (IPA) software online, and then the molecular network of TP on RA could be set up and analyzed. After that, both in vitro and in vivo experiments were done to further verify the prediction. The results indicated that the main canonical signal pathways of TP protein targets networks were mainly centered on cytokine and cellular immune signaling, and triggering receptors expressed on myeloid cells (TREM)-1 signaling was searched to be the top one shared signaling pathway and involved in the cytokine and cellular immune signaling. Further in vitro experiments indicated that TP not only remarkably lowered the levels of TREM-1 and DNAX-associated protein (DAP)12, but also significantly suppressed the activation of janus activating kinase (JAK)2 and signal transducers and activators of transcription (STAT)3. The expression of tumor necrosis factor (TNF)-α, interleukin (IL)-1β and IL-6 in lipopolysaccharides (LPS)-stimulated U937 cells also decreased after treatment with TP. Furthermore, TREM-1 knockdown was able to interfere with the inhibition effects of TP on these cytokines production. In vivo experiments showed that TP not only significantly inhibited the TREM-1 mRNA and DAP12 mRNA expression, and activation of JAK2 and STAT3 in ankle of rats with collagen-induced arthritis (CIA), but also remarkably decreased production of TNF-α, IL-1β and IL-6 in serum and joint. These findings demonstrated that TP could modulate the TREM1 signal pathway to inhibit the inflammatory response in RA.

BAG3 protein, a member of the BAG co-chaperones family, sustains cell survival in a variety of normal and neoplastic cell types, via its interaction with a variety of partners, such as the heat shock protein (HSP) 70, Bcl-2, Raf-1 and others. Expression of BAG3 is induced by some stressful stimuli, such as heat shock, heavy metal exposure. We have reported that proteasome inhibitors can also induce BAG3 expression at the transcriptional level and the induction of BAG3 compromises proteasome inhibitors-mediated apoptosis. However, the molecular mechanism of BAG3 upregulation has not been elucidated. In the current study, we provide evidence that heat shock transcription factor 1 (HSF1) is involved in BAG3 induction by proteasome inhibitor MG132. Using a series of varying lengths of 5'-flanking region of the BAG3 gene into luciferase reporter vectors, we found that MG132 stimulated the promoter activity via the -326/-233 and -825/-689 regions, which contains one putative heat shock-responsive element (HSE) for HSF1-binding, respectively. Site-directed deletion of the sites abrogated the enhanced reporter activity in response to MG132 treatment. Chromatin immunoprecipitation assay demonstrated that HSF1 directly bound to the MG132-responsive site on the BAG3 promoter. Activation of HSF1 occurred with MG132 along with BAG3 upregulation. Furthermore, knockdown HSF1 by small interfering RNA attenuated the BAG3 upregulation due to MG132.These results indicate that the proteasome inhibitor MG132 induces BAG3 expression through HSF1 activation.

No abstract

Bcl-2 associated athanogene 3 (BAG3) is an important molecule that maintains oncogenic features of cancer cells via diverse mechanisms. One of the important functions assigned to BAG3 is implicated in selective macroautophagy/autophagy, which attracts much attention recently. However, the mechanism underlying regulation of autophagy by BAG3 has not been well defined. Here, we describe that BAG3 enhances autophagy via promotion of glutamine consumption and glutaminolysis. Glutaminolysis initiates with deamination of glutamine by glutaminase (GLS), by which yields glutamate and ammonia in mitochondria. The current study demonstrates that BAG3 stabilizes GLS via prohibition its interaction with SIRT5, thereby hindering its desuccinylation at Lys158 and Lys164 sites. As an underlying molecular mechanism, we demonstrate that BAG3 interacts with GLS and decreases SIRT5 expression. The current study also demonstrates that occupation by succinyl at Lys158 and Lys164 sites prohibits its Lys48-linked ubiquitination, thereby preventing its subsequent proteasomal degradation. Collectively, the current study demonstrates that BAG3 enhances autophagy via stabilizing GLS and promoting glutaminolysis. For the first time, this study reports that succinylation competes with ubiquitination to regulate proteasomal GLS degradation.

Abstract:Monoclonal antibodies are the dominant agents used in inhibition of biological target molecules for disease therapeutics, but there are concerns of immunogenicity, production, cost and stability. Oligonucleotide aptamers have comparable affinity and specificity to targets with monoclonal antibodies whilst they have minimal immunogenicity, high production, low cost and high stability, thus are promising inhibitors to rival antibodies for disease therapy. In this review, we will compare the detailed advantages and disadvantages of antibodies and aptamers in therapeutic applications and summarize recent progress in aptamer selection and modification approaches. We will present therapeutic oligonucleotide aptamers in preclinical studies for skeletal diseases and further discuss oligonucleotide aptamers in different stages of clinical evaluation for various disease therapies including macular degeneration, cancer, inflammation and coagulation to highlight the bright commercial future and potential challenges of therapeutic oligonucleotide aptamers.

Osteoporosis is a progressive skeletal disorder characterized by low bone mass and increased risk of fracture in later life. The incidence and costs associated with treating osteoporosis cause heavy socio-economic burden. Currently, the diagnosis of osteoporosis mainly depends on bone mineral density and bone turnover markers. However, these indexes are not sensitive and accurate enough to reflect the osteoporosis progression. Metabolomics offers the potential for a holistic approach for clinical diagnoses and treatment, as well as understanding of the pathological mechanism of osteoporosis. In this review, we firstly describe the study subjects of osteoporosis and bio-sample preparation procedures for different analytic purposes, followed by illustrating the biomarkers with potentially predictive, diagnosis and pharmaceutical values when applied in osteoporosis research. Then, we summarize the published metabolic pathways related to osteoporosis. Furthermore, we discuss the importance of chronological data and combination of multi-omics in fully understanding osteoporosis. The application of metabolomics in osteoporosis could provide researchers the opportunity to gain new insight into the metabolic profiling and pathophysiological mechanisms. However, there is still much to be done to validate the potential biomarkers responsible for the progression of osteoporosis and there are still many details needed to be further elucidated.

Background and purpose: Proteasome inhibitors represent a novel class of anti-tumour agents that have clinical efficacy against haematological and solid cancers. The anti-apoptotic protein BAG3 is a member of the Bcl-2-associated athanogene family. We have previously shown that BAG3 is up-regulated after exposure to proteasome inhibitors and that inhibition of BAG3 sensitized cells to apoptosis induced by proteasome inhibition. However, the mechanisms by which proteasome inhibition induced BAG3 expression remained unclear and the present experiments were designed to elucidate these mechanisms. Experimental approach: Effects of the proteasome inhibitor MG132 on activation of mitogenic signalling pathways were evaluated in kidney cancer cells (A498, Caki1, Caki2), with Western blotting. Specific inhibitors against individual mitogenic signalling pathways, real-time reverse transcription-polymerase chain reaction and luciferase reporter assays were used to investigate the roles of mitogenic signalling pathways in BAG3 induction after proteasome inhibition. Cell death was evaluated using Annexin V/propidium iodide staining and subsequent FACS. Key results: MG132 activated several key mitogenic signalling pathways including extracellular signal-regulated kinase (ERK), c-Jun N-terminal kinase (JNK) and p38 mitogen-activated protein kinase (MAPK) activities. Induction of BAG3 by MG132 was inhibited by blocking JNK, but not ERK1/2 and p38 MAPK signalling pathways. In addition, SP600125 and dominant-negative JNK1 suppressed BAG3 promoter-driven reporter gene expression. Furthermore, activation of the JNK pathway induced BAG in kidney cancer cells after treatment with MG132. Conclusions and implications:Our results suggested that the JNK pathway was associated with the protective response against proteasome inhibition, by mediating induction of BAG3.