Œ≤-agonists selectively modulate proinflammatory gene expression in skeletal muscle cells via non-canonical nuclear crosstalk mechanisms
Authors: Krzysztof Kolmus
Christophe Ampe
Guy Haegeman
Jan Tavernier
Karlien Van Wesemael
Marleen Van Troys
Sarah Gerlo
Journal: PLoS ONE (2014)
Discipline: Multidisciplinary
Keywords: TNF-Œ±; skeletal muscle; C2C12 cells; Œ≤-agonists; inflammatory program
Affiliations: Department of Medical Protein Research, VIB, Gent, Belgium; Department of Biochemistry, Faculty of Medicine and Health Sciences, Ghent University, Gent, Belgium., Department of Biochemistry, Faculty of Medicine and Health Sciences, Ghent University, Gent, Belgium., Department of Physiology, Faculty of Sciences, Ghent University, Gent, Belgium.

Abstract:  The proinflammatory cytokine Tumour Necrosis Factor (TNF)-Œ± is implicated in a variety of skeletal muscle pathologies. Here, we have investigated how in vitro cotreatment of skeletal muscle C2C12 cells with Œ≤-agonists modulates the TNF-Œ±-induced inflammatory program. We observed that C2C12 myotubes express functional TNF receptor 1 (TNF-R1) and Œ≤2-adrenoreceptors (Œ≤2-ARs). TNF-Œ± activated the canonical Nuclear Factor-Œ∫B (NF-Œ∫B) pathway and Mitogen-Activated Protein Kinases (MAPKs), culminating in potent induction of NF-Œ∫B-dependent proinflammatory genes. Cotreatment with the Œ≤-agonist isoproterenol potentiated the expression of inflammatory mediators, including Interleukin-6 (IL-6) and several chemokines. The enhanced production of chemotactic factors upon TNF-Œ±/isoproterenol cotreatment was also suggested by the results from migrational analysis. Whereas we could not explain our observations by cytoplasmic crosstalk, we found that TNF-R1-and Œ≤2-AR-induced signalling cascades cooperate in the nucleus. Using the IL-6 promoter as a model, we demonstrated that TNF-Œ±/isoproterenol cotreatment provoked phosphorylation of histone H3 at serine 10, concomitant with enhanced promoter accessibility and recruitment of the NF-Œ∫B p65 subunit, cAMP-response element-binding protein (CREB), CREB-binding protein (CBP) and RNA polymerase II. In summary, we show that Œ≤-agonists potentiate TNF-Œ± action, via nuclear crosstalk, that promotes chromatin relaxation at selected gene promoters. Our data warrant further study into the mode of action of Œ≤-agonists and urge for caution in their use as therapeutic agents for muscular disorders. 

Retracted: No

PubPeer comments:
 Concern about Figure 6A. The top 2 left panels (u201cvehu201d and u201cisou201d) look very similar to each other.  , 
 #1 Dear Mr. Parvum, There has indeed been a mixup in the illustrative images in Fig. 6B. We have checked the raw data regarding the quantitative migration analysis (which was performed semi-automatically) and no inconsistencies are present there, so the interpretation of the experiments is correct. Nevertheless, we hope to get the chance to correct the error and are are working on a solution with the journal editors. Best wishes, Sarah Gerlo , 
 This issue has been reported to the journal in 2015, more than four years ago, and the authors promised a correction more than two years ago. However, as of today, no updates yet. I hope the authors can follow up. ,