SPSB1-mediated inhibition of TGF-ß receptor-II impairs myogenesis in inflammation.

BACKGROUND: Sepsis-induced intensive care unit-acquired weakness (ICUAW) features profound muscle atrophy and attenuated muscle regeneration related to malfunctioning satellite cells. Transforming growth factor beta (TGF-ß) is involved in both processes. We uncovered an increased expression of the TGF-ß receptor II (TßRII)-inhibitor SPRY domain-containing and SOCS-box protein 1 (SPSB1) in skeletal muscle of septic mice. We hypothesized that SPSB1-mediated inhibition of TßRII signalling impairs myogenic differentiation in response to inflammation. METHODS: We performed gene expression analyses in skeletal muscle of cecal ligation and puncture- (CLP) and sham-operated mice, as well as vastus lateralis of critically ill and control patients. Pro-inflammatory cytokines and specific pathway inhibitors were used to quantitate Spsb1 expression in myocytes. Retroviral expression plasmids were used to investigate the effects of SPSB1 on TGF-ß/TßRII signalling and myogenesis in primary and immortalized myoblasts and differentiated myotubes. For mechanistical analyses we used coimmunoprecipitation, ubiquitination, protein half-life, and protein synthesis assays. Differentiation and fusion indices were determined by immunocytochemistry, and differentiation factors were quantified by qRT-PCR and Western blot analyses. RESULTS: SPSB1 expression was increased in skeletal muscle of ICUAW patients and septic mice. Tumour necrosis factor (TNF), interleukin-1ß (IL-1ß), and IL-6 increased the Spsb1 expression in C2C12 myotubes. TNF- and IL-1ß-induced Spsb1 expression was mediated by NF-κB, whereas IL-6 increased the Spsb1 expression via the glycoprotein 130/JAK2/STAT3 pathway. All cytokines reduced myogenic differentiation. SPSB1 avidly interacted with TßRII, resulting in TßRII ubiquitination and destabilization. SPSB1 impaired TßRII-Akt-Myogenin signalling and diminished protein synthesis in myocytes. Overexpression of SPSB1 decreased the expression of early (Myog, Mymk, Mymx) and late (Myh1, 3, 7) differentiation-markers. As a result, myoblast fusion and myogenic differentiation were impaired. These effects were mediated by the SPRY- and SOCS-box domains of SPSB1. Co-expression of SPSB1 with Akt or Myogenin reversed the inhibitory effects of SPSB1 on protein synthesis and myogenic differentiation. Downregulation of Spsb1 by AAV9-mediated shRNA attenuated muscle weight loss and atrophy gene expression in skeletal muscle of septic mice. CONCLUSIONS: Inflammatory cytokines via their respective signalling pathways cause an increase in SPSB1 expression in myocytes and attenuate myogenic differentiation. SPSB1-mediated inhibition of TßRII-Akt-Myogenin signalling and protein synthesis contributes to a disturbed myocyte homeostasis and myogenic differentiation that occurs during inflammation.

Anthocyanins: Multi-Target Agents for Prevention and Therapy of Chronic Diseases.

Anthocyanins, a flavonoid class of polyphenols, are water soluble dark colored natural pigments found in fruits and vegetables. Owing to their wide distribution in plant materials, dietary consumption of anthocyanins is high compared to other flavonoids. Anthocyanins, due to their multifaceted medicinal properties are the active components in many herbal folk medicines. As in vitro and in vivo results, animal models, and clinical trials in various cell lines suggest, anthocyanins possess antioxidant, antidiabetic, antihyperlipidemic, anti-inflammatory, anticarcinogenic, antiulcer, and preventive activities against cardiovascular diseases. Additionally, anthocyanins exhibit chemotherapeutic, cardioprotective, hepatoprotective, and neuroprotective activities. In the diet, anthocyanins are absorbed in the stomach and intestinal cells and rapidly detected in the plasma. These promising properties of anthocyanins may well provide health benefits against chronic diseases.

15-Lipoxygenase metabolites of α-linolenic acid, [13-(S)-HPOTrE and 13-(S)-HOTrE], mediate anti-inflammatory effects by inactivating NLRP3 inflammasome.

The ratio of ω-6 to ω-3 polyunsaturated fatty acids (PUFAs) appears to be critical in the regulation of various pathophysiological processes and to maintain cellular homeostasis. While a high proportion of dietary intake of ω-6 PUFAs is associated with various inflammatory disorders, higher intake of ω-3 PUFAs is known to offer protection. It is now well established that beneficial effects of ω-3 PUFAs are mediated in part by their oxygenated metabolites mainly via the lipoxygenase (LOX) and cyclooxygenase (COX) pathways. However, the down-stream signaling pathways that are involved in these anti-inflammatory effects of ω-3 PUFAs have not been elucidated. The present study evaluates the effects of 15-LOX metabolites of α-linolenic acid (ALA, ω-3 PUFA) on lipopolysaccharide (LPS) induced inflammation in RAW 264.7 cells and peritoneal macrophages. Further, the effect of these metabolites on the survival of BALB/c mice in LPS mediated septic shock and also polymicrobial sepsis in Cecal Ligation and Puncture (CLP) mouse model was studied. These studies reveal the anti-inflammatory effects of 13-(S)-hydroperoxyoctadecatrienoic acid [13-(S)-HPOTrE] and 13-(S)-hydroxyoctadecatrienoic acid [13-(S)-HOTrE] by inactivating NLRP3 inflammasome complex through the PPAR-γ pathway. Additionally, both metabolites also deactivated autophagy and induced apoptosis. In mediating all these effects 13-(S)-HPOTrE was more potent than 13-(S)-HOTrE.

In silico-prediction of downstream MYB interacting partners of MAPK3 in Arabidopsis.

Protein-Protein interactions (PPIs) are vital to most biological processes thus the identification of PPIs is of primary importance. Here, we endeavor to identify the downstream interacting partners of (AtMAPK3P) in Arabidopsis thaliana using the docking approach. Out of 131 members of MYB transcription factors 41 members are showing interactions with AtMAPK3P while the rest are showing non-interaction. Using minimal sequence motif search as well as through docking approach several novel MYB interacting proteins were also reported in the present study which need to be confirmed by in vitro kinase assay. Together, the results obtained essentially enhance our knowledge of the MAPK interacting protein network and provide a valuable research resource for developing a nearly important link between pathogen-activated MAPK signaling pathways and downstream transcriptional programming.

in silico-prediction of downstream WRKY interacting partners of MAPK3 in Brassica.

Protein-Protein interactions (PPIs) are vital to most biological processes thus the identification of PPIs is of primary importance. Here, we endeavor to identify the downstream interacting partners of (BjMPK3P) in Brassica juncea using the docking approach. Out of 63 and 37 members of BrWRKY and BnWRKY transcription factors, 50 and 29 members are showing interactions with BjMPK3P respectively while the rest are showing non-interaction. Twenty two WRKY members are common to both the species. Using minimal sequence motif search as well as through docking approach several novel WRKY interacting proteins were also reported in the present study which need to be confirmed by in vitro kinase assay. Together, the results obtained essentially enhance our knowledge of the MAPK interacting protein network and provide a valuable research resource for developing a nearly important link between pathogen-activated MAPK signaling pathways and downstream transcriptional programming.