Transcription modulation by CDK9 regulates inflammatory genes and RIPK3-MLKL-mediated necroptosis in periodontitis progression

Jiao Li,Lang Lei,Yunhe Zhao,Yue Pan,Houxuan Li,Jiahong Shi,Fuhua Yan

doi:10.1038/s41598-019-53910-y

Jiao Li, Lang Lei + Show 5 more

Open Access

https://doi.org/10.1038/s41598-019-53910-y

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Journal: Scientific Reports	Publication Date: Nov 22, 2019
Citations: 16	License type: open-access

Affiliation: Nanjing University

Abstract

Cyclin-dependent kinase 9 (CDK9), one crucial molecule in promoting the transition from transcription pausing to elongation, is a critical modulator of cell survival and death. However, the pathological function of CDK9 in bacterial inflammatory diseases has never been explored. CDK9 inhibition or knock-down attenuated Porphyromonas gingivalis-triggered inflammatory gene expression. Gene-expression microarray analysis of monocytes revealed that knock-down of CDK9 not only affected inflammatory responses, but also impacted cell death network, especially the receptor-interacting protein kinase 3 (RIPK3)-mixed lineage kinase domain-like (MLKL)-mediated necroptosis after P. gingivalis infection. Inhibition of CDK9 significantly decreased necroptosis with downregulation of both MLKL and phosphorylated MLKL. By regulating caspase-8 and cellular FLICE inhibitory protein (cFLIP), key molecules in regulating cell survival and death, CDK9 affected not only the classic RIPK1-RIPK3-mediated necroptosis, but also the alternate TIR-domain-containing adapter-inducing interferon-β-RIPK3-mediated necroptosis. CDK9 inhibition dampened pro-inflammatory gene production in the acute infection process in the subcutaneous chamber model in vivo. Moreover, CDK9 inhibition contributed to the decreased periodontal bone loss and inflammatory response induced by P. gingivalis in the periodontal micro-environment. In conclusion, by modulating the RIPK3-MLKL-mediated necroptosis, CDK9 inhibition provided a novel mechanism to impact the progress of bacterial infection in the periodontal milieu.

Highlights

Periodontitis is a kind of bacteria-inflicted inflammation in the periodontal tissue
Minor protein expression of TOP1, Bromodomain-containing protein (Brd)[4] and cyclin-dependent kinase 9 (CDK9) can be found in the healthy gingiva, while significant higher protein expression can be detected in the diseased periodontal tissues by Western blot, indicating robust gene transcriptions of inflammatory genes in the periodontal biopsies (Fig. 1B)
To gain insights into the pathologic role of CDK9 in the periodontitis, we first investigated the expression of CDK9, Brd[4] and RNA Polymerase II, which coordinate in modulating gene transcription

Summary

Introduction

Periodontitis is a kind of bacteria-inflicted inflammation in the periodontal tissue. Ligation of PRRs with PAMPs will initiate a cascade of downstream signaling pathway to address the disrupted cellular microenvironment, leading to changes in the PAMP response genes[3]. Such inflammatory response leads to the generation of multiple chemokines to recruit more sentinel cells to sites of inflammation to combat the invasion of bacteria; in addition, production of pro-inflammatory mediators, such as tumor necrosis factor α (TNF-α) and transforming growth factor-β (TGF-β) may facilitate survival of host cells to sustain the infection[4]. Our research demonstrated that CDK9 activation regulated the inflammatory gene transcription and RIPK3-mixed lineage kinase domain-like (MLKL)-mediated necroptosis following P. gingivalis invasion and further influenced the progress of periodontitis

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