Involvement of IGF-1R-PI3K-AKT-mTOR Pathway in Increased Number of GnRH3 Neurons During Androgen-induced Sex Reversal of the Brain in Female Tilapia

The neuroplastic mechanism of sex reversal in the fish brain remains unclear due to the difficulty in identifying the key neurons involved. Mozambique tilapia show different reproductive behaviours between sexes; males build circular breeding nests while females hold and brood fertilized eggs in their mouth. In tilapia, gonadotropin-releasing hormone 3 (GnRH3) neurons, located in the terminal nerve, regulate male reproductive behaviour. Mature males have more GnRH3 neurons than mature females, and these neurons have been indicated to play a key role in the androgen-induced female-to-male sex reversal of the brain. We aimed to elucidate the signalling pathway involved in the androgen-induced increase in GnRH3 neurons in mature female tilapia. Applying inhibitors to organotypic cultures of brain slices, we showed that the insulin-like growth factor (IGF)-1 receptor (IGF-1R)/PI3K/AKT/mTOR pathway contributed to the androgen-induced increase in GnRH3 neurons. The involvement of IGF-1 and IGF-1R in 11-ketotestosterone (11-KT)-induced development of GnRH3 neurons was supported by an increase in Igf-1 mRNA shortly after 11-KT treatment, the increase of GnRH3 neurons after IGF-1 treatment and the expression of IGF-1 in GnRH3 neurons. Our findings highlight the involvement of IGF-1 and its downstream signalling pathway in the sex reversal of the tilapia brain.

Vitexin as a Potential Inhibitor for the Activation of Microglial Cells: Insights from Molecular Docking and Molecular Dynamics

Background: Overly-activated microglia are known to be the culprit in chronic neuroinflammation in the presence of excessive lipopolysaccharide (LPS). Hence, abundance of pro-inflammatory cytokines are produced which later cause toxic and death to neurons. Tolllike receptor 4 (TLR4)/MD-2 complex found on the cell surface of microglia is responsible for the attachment of LPS and activation of nuclear factor-κB (NF-κB) downstream signalling pathway. Albeit vitexin has been shown to possess anti-inflammatory property, however, little is known on its ability to bind at the TLR4/MD-2 complex of microglia as well as to be an antagonist for LPS. Results: The molecular docking result shows that both vitexin and donepezil are able to bind at the close proximity of LPS binding site located at the TLR4/MD-2 complex with the binding energy of -4.35 and -9.14 kcal/mol, respectively. During molecular dynamic simulations, both vitexin and donepezil formed stable complex with TLR4/MD-2 throughout the 20 ns time length with the RMSD values of 1.9Å and 2.0Å, respectively. As for the RMSF, both compounds have the RMSF values of <1.2Å. Conclusions: Taken together, our results suggest that vitexin can be a potential antineuroinflammatory drug candidate by acting as an antagonist for LPS at the TLR4/MD-2 complex.

Interleukin-22 and connective tissue diseases: emerging role in pathogenesis and therapy

Interleukin-22 (IL-22), a member of the IL-10 family of cytokines, is produced by a number of immune cells involved in the immune microenvironment of the body. IL-22 plays its pivotal roles by binding to the IL-22 receptor complex (IL-22R) and subsequently activating the IL-22R downstream signalling pathway. It has recently been reported that IL-22 also contributes to the pathogenesis of many connective tissue diseases (CTDs). In this review, we will discuss the role of IL-22 in several CTDs, such as system lupus erythematosus, rheumatoid arthritis, Sjögren’s syndrome, systemic sclerosis and dermatomyositis, suggesting that IL-22 may be a potential therapeutic target in CTDs.

Tofacitinib and Baricitinib Are Taken up by Different Uptake Mechanisms Determining the Efficacy of Both Drugs in RA

Background: Rheumatoid arthritis (RA) is a systemic autoimmune disease in which synovial fibroblasts (SF) play a key role. Baricitinib and Tofacitinib both act intracellularly, blocking the ATP-binding side of JAK proteins and thereby the downstream signalling pathway via STAT-3. Therefore, we investigated the role of organic cation transporters (OCTs) in Baricitinib and Tofacitinib cellular transport. Methods: OCT expression was analysed in SF isolated from RA and osteoarthritis (OA) patients, as well as peripheral blood mononuclear cells. The interaction of Baricitinib and Tofacitinib with OCTs was investigated using quenching experiments. The intracellular accumulation of both drugs was quantified using LC/MS. Target inhibition for both drugs was tested using Western blot for phosphorylated JAK1 and STAT3 upon stimulation with IL-6. Results: MATE-1 expression increased in OASF compared to RASF. The other OCTs were not differentially expressed. The transport of Baricitinib was not OCT dependent. Tofacitinib; however, was exported from RASF in a MATE-1 dependent way. Tofacitinib and Baricitinib showed comparable inhibition of downstream signalling pathways. Conclusion: We observed different cellular uptake strategies for Baricitinib and Tofacitinib. Tofacitinib was exported out of healthy cells due to the increased expression of MATE1. This might make Tofacitinib the favourable drug.

RNF114 suppresses tumour metastasis through the regulation of PARP10

Background ADP-ribosylation is a multifunctional post-translational modification catalysed by intracellular ADP-ribosyltransferases. Previously, we demonstrated that the mono-ADP-ribosyltransferase PARP10 suppresses tumour metastasis through the negative regulation of Aurora A kinase activity. However, the mechanisms of PARP10 regulation and modification were unclear. Methods Interaction of RNF114 and PARP10 was identified by exogenous and endogenous reciprocal immunoprecipitation (IP) assays and pull-down assays. Ubiquitination of PARP10 by RNF114 was analysed by in vivo ubiquitination assays. Potential effects of ubiquitination on PARP10’s activity was detected by western blots and pull-down assays. Potential role of RNF114 in tumour metastasis were determined by migration and invasion assays and in vivo metastasis assay. Results That E3 ubiquitin ligase RNF114 is a partner of PARP10 was identified by IP assays. The auto-mono-ADP-ribosylation of PARP10 is required for the interaction of RNF114 and PARP10. RNF114 ubiquitinates PARP10 through K27-linked polyubiquitination, which enhances PARP10 enzymatic activity. Moreover, RNF114 deficiency promotes tumour cell migration and tumour metastasis through the regulation of PARP10 and its downstream signalling pathway. Conclusions Our findings identify RNF114 as a novel functional regulator of PARP10 and provide evidence of crosstalk between the components of K27-linked polyubiquitination and mono-ADP ribosylation.

Homeostatic regulation of STING by Golgi-to-ER membrane traffic

Coat protein complex I (COP-I) mediates the retrograde transport from the Golgi to the ER1,2. Mutation of the COPA gene, encoding one of the COP-I subunits (α-COP), causes an immune dysregulatory disease (COPA syndrome)3. The molecular mechanism by which the impaired retrograde transport results in autoinflammation is not understood. Here we report that STING4, an innate immunity protein, is a cargo of the Golgi-to-ER membrane transport. In the presence of the disease-causative α-COP variants, STING cannot be retrieved back to the ER from the Golgi. The forced Golgi residency of STING results in the cGAS-independent and palmitoylation-dependent activation of the STING downstream signalling pathway. Surf45, a protein that circulates between the ER and the Golgi, binds STING and α-COP, and mediates retrograde transport of STING to the ER. STING/Surf4/α-COP complex is disrupted in the presence of the disease-causative α-COP variant. Intriguingly, the STING ligand cGAMP also impairs the formation of STING/Surf4/α-COP complex. Our results suggest a homeostatic regulation of STING at the resting state by the Golgi-to-ER membrane traffic and provide insights into the pathogenesis of COPA syndrome.

Interstitial macrophage-derived thrombospondin-1 contributes to hypoxia-induced pulmonary hypertension

Aims Transforming growth factor-β (TGF-β) signalling is required for chronic hypoxia-induced pulmonary hypertension (PH). The activation of TGF-β by thrombospondin-1 (TSP-1) contributes to the pathogenesis of hypoxia-induced PH. However, neither the cellular source of pathologic TSP-1 nor the downstream signalling pathway that link activated TGF-β to PH have been determined. In this study, we hypothesized that circulating monocytes, which are recruited to become interstitial macrophages (IMs), are the major source of TSP-1 in hypoxia-exposed mice, and TSP-1 activates TGF-β with increased Rho-kinase signalling, causing vasoconstriction. Methods and results Flow cytometry revealed that a specific subset of IMs is the major source of pathologic TSP-1 in hypoxia. Intravenous depletion and parabiosis experiments demonstrated that these cells are circulating prior to recruitment into the interstitium. Rho-kinase-mediated vasoconstriction was a major downstream target of active TGF-β. Thbs1 deficient bone marrow (BM) protected against hypoxic-PH by blocking TGF-β activation and Rho-kinase-mediated vasoconstriction. Conclusion In hypoxia-challenged mice, BM derived and circulating monocytes are recruited to become IMs which express TSP-1, resulting in TGF-β activation and Rho-kinase-mediated vasoconstriction.