Mediator cyclin‐dependent kinases upregulate transcription of inflammatory genes in cooperation with NF‐κB and C/EBPβ on stimulation of Toll‐like receptor 9

Abstract

In eukaryotes, the Mediator complex has important roles in regulation of transcription by RNA polymerase II. Mediator is a large complex with more than 20 subunits that form head, middle, tail and CDK/cyclin modules. Among them, CDK8 and/or CDK19 (CDK8/19), and their counterpart cyclin C, form the CDK/cyclin module together with Mediator subunits MED12 and MED13. Despite evidences of both activation and repression, the precise functional roles of CDK8/19 in transcription are still elusive. Our previous results indicate that CDK8/19 recruits epigenetic regulators to repress immunoresponse genes. Here, this study focused on Toll-like receptors (TLRs), which exert innate immune responses through recognition of pathogen-associated molecular patterns and examined the functional roles of CDK8/19. As a result, CDK8/19 regulated transcription of inflammatory genes on stimulation of TLR9 in myeloma-derived RPMI8226 cells, which led to expression of inflammation-associated genes such as IL8, IL10, PTX3 and CCL2. Mediator subunits CDK8/19 and MED1, inflammation-related transcriptional activator NF-κB and C/EBPβ, and general transcription factors TFIIE and TFIIB colocalized at the promoter regions of these genes under this condition. Our results show that CDK8/19 positively regulates inflammatory gene transcription in cooperation with NF-κB and C/EBPβ on stimulation of TLR9.

Small-molecule studies identify CDK8 as a regulator of IL-10 in myeloid cells

“…9 and Supplementary Data Set 4). Furthermore, similar to results from previous studies of CDK8 function in other contexts including RPMI8226 myeloma cells activated by TLR9 stimulation 26–28 , pretreatment with dCA or BRD6989 suppressed NF-κB activation to a varying degree for all stimuli tested (Fig. 4a and Supplementary Fig.…”

“…We also detected decreased NF-κB activity to varying degrees using different microbial stimuli that appears to be insufficient in magnitude to suppress expression of NF-κB targets on a genome-wide scale. This intermediate suppressive effect may explain why CDK8 inhibition does not block expression of Il10 , itself an NF-κB target gene 28,34 . Our data with dCA and BRD6989 contrasts with the recent identification of an essential role for CDK8 and CDK19 in NF-κB-dependent Il10 expression following stimulation of TLR9 in the B cell–derived myeloma cell line RPMI8226 (ref.…”

“…Our data with dCA and BRD6989 contrasts with the recent identification of an essential role for CDK8 and CDK19 in NF-κB-dependent Il10 expression following stimulation of TLR9 in the B cell–derived myeloma cell line RPMI8226 (ref. 28). Whereas differences in cell type and microbial stimuli may alter the degree to which NF-κB activation depends on CDK8 and CDK19, contrasting effects of depleting CDK8 and CDK19 by RNA interference compared to specifically inhibiting their kinase activity with small molecules may also play a role.…”

CDK8/19 Mediator kinases potentiate induction of transcription by NFκB

“…In the present work, we observed this effect of CDK8/19 inhibition when NFκB was induced by the p21-independent canonical pathway inducers, TNFα and IL1, and noted that the effect of CDK8/19 inhibition on TNFα-induced NFκB-mediated transcription was undiminished by p21 knockout. In addition, a recent study reported that siRNA knockdown of both CDK8 and CDK19 in a myeloma cell line decreased the induction of several NFκB-inducible genes by a Toll-like receptor agonist (30). Thus, CDK8/19 potentiate the transcriptional effects of NFκB induced by different signals.…”

Uterine Fibroids: Bridging Genomic Defects and Chronic Inflammation

“…Yamamoto et al have shown that CDK8/19 recruits epigenetic regulators to repress transcriptional induction of IL8 and TNF genes by phorbol 12-myristate 13-acetate (PMA) treatment of HeLa cells. [58][59][60] It is well known that NF-kB and C/EBPb are the major transcriptional activators of cytokines and chemokines expression. 59 In their recent published work, Yamamoto et al focused on the CDK8, CDK19, NF-kB, and C/EBPb (CCAAT/enhancer-binding protein b) as a transcriptional activator of inflammatory cytokines, challenging their roles inTLR9 stimulation by CpG.…”