The CDK4/6-EZH2 pathway is a potential therapeutic target for psoriasis
Anne Müller, … , Klaus Schulze-Osthoff, Daniela Kramer
Anne Müller, … , Klaus Schulze-Osthoff, Daniela Kramer
Published July 23, 2020
Citation Information: J Clin Invest. 2020;130(11):5765-5781. https://doi.org/10.1172/JCI134217.
View: Text | PDF
Research Article Dermatology Article has an altmetric score of 6

The CDK4/6-EZH2 pathway is a potential therapeutic target for psoriasis

Abstract

Psoriasis is a frequent, inflammatory skin disease characterized by keratinocyte hyperproliferation and a disease-related infiltration of immune cells. Here, we identified a novel proinflammatory signaling pathway driven by cyclin-dependent kinase 4 (CDK4) and CDK6 and the methyltransferase EZH2 as a valid target for psoriasis therapy. Delineation of the pathway revealed that CDK4/6 phosphorylated EZH2 in keratinocytes, thereby triggering a methylation-induced activation of STAT3. Subsequently, active STAT3 resulted in the induction of IκBζ, which is a key proinflammatory transcription factor required for cytokine synthesis in psoriasis. Pharmacological or genetic inhibition of CDK4/6 or EZH2 abrogated psoriasis-related proinflammatory gene expression by suppressing IκBζ induction in keratinocytes. Importantly, topical application of CDK4/6 or EZH2 inhibitors on the skin was sufficient to fully prevent the development of psoriasis in various mouse models by suppressing STAT3-mediated IκBζ expression. Moreover, we found a hyperactivation of the CDK4/6-EZH2 pathway in human and mouse psoriatic skin lesions. Thus, this study not only identifies a novel psoriasis-relevant proinflammatory pathway, but also proposes the repurposing of CDK4/6 or EZH2 inhibitors as a new therapeutic option for patients with psoriasis.

Authors

Anne Müller, Antje Dickmanns, Claudia Resch, Knut Schäkel, Stephan Hailfinger, Matthias Dobbelstein, Klaus Schulze-Osthoff, Daniela Kramer

×

Figure 3

CDK4 and CDK6 phosphorylate EZH2 to induce STAT3 activation.

Options: View larger image (or click on image) Download as PowerPoint
CDK4 and CDK6 phosphorylate EZH2 to induce STAT3 activation. (A) STAT3 a...
(A) STAT3 activity was detected by analyzing the phosphorylation state at tyrosine 705 (Y705) and threonine 727 (T727) of STAT3 in primary human keratinocytes. After overnight starvation, cells were stimulated for 1 hour with IL-36α or IL-17A/TNF-α in the presence or absence of abemaciclib (Abe). (B) STAT3 activity in CDK4- and CDK6-depleted keratinocytes. Stimulation as in A. (C) Immunoblot detection of phosphorylated STAT3 (Y705) in IL-36α–stimulated keratinocytes, in which EZH2 function was suppressed by the EZH2 inhibitor EPZ6438 (EPZ, 10 μM) or shRNA-mediated knockdown. Detection of H3K27me3 controlled effective EZH2 inhibition or depletion. (D) Immunoblot detection of phosphorylated EZH2 at threonine 345 (T345) and threonine 487 (T487) in abemaciclib-treated or CDK4/6-depleted keratinocytes following stimulation with IL-36α. (E) Coimmunoprecipitation of EZH2 and STAT3 in HaCaT cells treated for 30 minutes with IL-36α in the presence or absence of abemaciclib. An EZH2-specific antibody or IgG was used for pull down of protein complexes. STAT3 and pEZH2 (T345) were detected by immunoblotting. (F) Luciferase activity assay of the NFKBIZ promoter in HEK293T cells, which transiently overexpress CDK6, WT EZH2 (wt), mutant EZH2 (T345A), or STAT3, alone or in combination. Equal protein expression was detected by immunoblotting. n = 3 ± SD. (G) Gene expression in IL-36α– and abemaciclib-treated, primary keratinocytes following transient expression of a phospho-mimicking EZH2 (T345D) mutant. Input controls (left). mRNA levels of NFKBIZ and its target genes were normalized to RPL37A (right). n = 3 ± SD. (H) Overexpression of IκBζ overrides the inhibitory effects of EPZ6438 (EPZ) on IL-36α–stimulated gene expression in primary keratinocytes. n = 3 ± SD. Significance was calculated using a 1-way ANOVA for multiple groups and a 2-tailed Student’s t test for comparing 2 groups: *P < 0.05; **P < 0.01; ***P < 0.001.