ANKRD1 modulates inflammatory responses in C2C12 myoblasts through feedback inhibition of NF-κB signaling activity

• Published in: Biochemical and biophysical research communications 2015-08, Vol.464 (1), p.208-213
• Main Authors: Liu, Xin-Hua, Bauman, William A., Cardozo, Christopher
• Format: Article
• Language: English
• Subjects: 60 APPLIED LIFE SCIENCES; Animals; AnkrD1; ATROPHY; Binding Sites; Cell Differentiation; Cell Line; Cell Survival; CHROMATIN; Chromatin - metabolism; FEEDBACK; Feedback, Physiological; Gene Expression Regulation; IMMUNITY; INFLAMMATION; Inflammation - genetics; Inflammation - metabolism; Inflammation - pathology; INHIBITION; MESSENGER-RNA; Mice; Muscle Proteins - agonists; Muscle Proteins - antagonists & inhibitors; Muscle Proteins - genetics; Muscle Proteins - metabolism; Muscle, Skeletal - metabolism; Muscle, Skeletal - pathology; MYOBLASTS; Myoblasts - drug effects; Myoblasts - metabolism; Myoblasts - pathology; NF-kappa B - genetics; NF-kappa B - metabolism; NF-kB signaling; Nuclear Proteins - agonists; Nuclear Proteins - antagonists & inhibitors; Nuclear Proteins - genetics; Nuclear Proteins - metabolism; PROMOTERS; Protein Binding; Protein Subunits - genetics; Protein Subunits - metabolism; Repressor Proteins - agonists; Repressor Proteins - antagonists & inhibitors; Repressor Proteins - genetics; Repressor Proteins - metabolism; RNA, Messenger - genetics; RNA, Messenger - metabolism; RNA, Small Interfering - genetics; RNA, Small Interfering - metabolism; Signal Transduction; SIGNALS; TRANSCRIPTION FACTORS; Tumor Necrosis Factor-alpha - pharmacology
• ISSN: 0006-291X; 1090-2104
• DOI: 10.1016/j.bbrc.2015.06.118

Transcription factors of the nuclear factor-kappa B (NF-κB) family play a pivotal role in inflammation, immunity and cell survival responses. Recent studies revealed that NF-κB also regulates the processes of muscle atrophy. NF-κB activity is regulated by various factors, including ankyrin repeat domain 2 (AnkrD2), which belongs to the muscle ankyrin repeat protein family. Another member of this family, AnkrD1 is also a transcriptional effector. The expression levels of AnkrD1 are highly upregulated in denervated skeletal muscle, suggesting an involvement of AnkrD1 in NF-κB mediated cellular responses to paralysis. However, the molecular mechanism underlying the interactive role of AnkrD1 in NF-κB mediated cellular responses is not well understood. In the current study, we examined the effect of AnkrD1 on NF-κB activity and determined the interactions between AnkrD1 expression and NF-κB signaling induced by TNFα in differentiating C2C12 myoblasts. TNFα upregulated AnkrD1 mRNA and protein levels. AnkrD1-siRNA significantly increased TNFα-induced transcriptional activation of NF-κB, whereas overexpression of AnkrD1 inhibited TNFα-induced NF-κB activity. Co-immunoprecipitation studies demonstrated that AnkrD1 was able to bind p50 subunit of NF-κB and vice versa. Finally, CHIP assays revealed that AnkrD1 bound chromatin at a NF-κB binding site in the AnrkD2 promoter and required NF-κB to do so. These results provide evidence of signaling integration between AnkrD1 and NF-κB pathways, and suggest a novel anti-inflammatory role of AnkrD1 through feedback inhibition of NF-κB transcriptional activity by which AnkrD1 modulates the balance between physiological and pathological inflammatory responses in skeletal muscle. •AnkrD1 is upregulated by TNFα and represses NF-κB-induced transcriptional activity.•AnkrD1 binds to p50 subunit of NF-κB and is recruited to NF-κB bound to chromatin.•AnkrD1 mediates a feed-back inhibitory loop on NF-κB in response to inflammation.