ERK2 stimulates MYC transcription by anchoring CDK9 to the MYC promoter in a kinase activity–independent manner

Abstract

The transcription factor MYC regulates cell proliferation, transformation, and survival in response to growth factor signaling that is mediated in part by the kinase activity of ERK2. Because ERK2 can also bind to DNA to modify gene expression, we investigated whether it more directly regulates MYC transcription. We identified ERK2 binding sites in the MYC promoter and detected ERK2 at the promoter in various serum-stimulated cell types. Expression of nuclear-localized ERK2 constructs in serum-starved cells revealed that ERK2 in the nucleus—regardless of its kinase activity—increased MYC mRNA expression and MYC protein abundance. ERK2 bound to the promoter through its amino-terminal insert domain and to the cyclin-dependent kinase CDK9 (which activates RNA polymerase II) through its carboxyl-terminal conserved docking domain. Both interactions were essential for ERK2-induced MYC expression, and depleting ERK impaired CDK9 occupancy and RNA polymerase II progression at the MYC promoter. Artificially tethering CDK9 to the MYC promoter by fusing it to the ERK2 insert domain was sufficient to stimulate MYC expression in serum-starved cells. Our findings demonstrate a role for ERK2 at the MYC promoter acting as a kinase-independent anchor for the recruitment of CDK9 to promote MYC expression.

Conformation selection by ATP-competitive inhibitors and allosteric communication in ERK2

“…Indeed, remote conformational changes induced by conformation selective inhibitors have been shown to alter noncatalytic scaffolding functions of protein kinases via interactions with regulatory enzymes ( Agudo-Ibáñez et al, 2023 ; Leroux and Biondi, 2020 ; Fang et al, 2020 ; Sonti et al, 2018 ; Joseph et al, 2022 ). In fact, an intriguing recent study demonstrates that ubiquitination and degradation of 2P-ERK2 can be enhanced by BVD523, suggesting that conformation selective inhibitors may act as ‘kinase degraders’ that preferentially target the activated kinase ( Balmanno et al, 2023 ).…”

Targeted Degradation of CDK9 Potently Disrupts the MYC Transcriptional Network

“…The filtrate was concentrated to give a crude material, which was purified by silica gel column chromatography (hexane:ethyl acetate = 90:10 to 60:40) to yield the title compound as a white solid (997 mg, quant). 1 H NMR (500 MHz, CDCl 3 ) δ 8.05 (d, J = 8.5 Hz, 2H), 7.62 (dd, J = 8.3, 6.6 Hz, 4H), 7.46 (d, J = 8.0 Hz, 2H), 4.76 (s, 2H), 1.62 (s, 9H). 13 C NMR (126 MHz, CDCl 3 ) δ 165.82, 144.87, 140.89, 139.68, 130.96, 130.09, 127.65, 127.58, 126.95, 81.21, 65.13, 28.37.…”

“…The title compound was obtained as a gray solid (3.32 g, quant). 1 H NMR (500 MHz, DMSO) δ 11.17 (s, 1H), 8.35 (d, J = 8.0 Hz, 1H), 8.24 (d, J = 7.6 Hz, 1H), 8.12 (t, J = 7.8 Hz, 1H), 5.20 (dd, J = 12.9, 5.3 Hz, 1H), 2.89 (ddd, J = 17.2, 13.9, 5.4 Hz, 1H), 2.66 – 2.57 (m, 1H), 2.56 – 2.45 (m, 1H), 2.12 – 2.03 (m, 1H). 13 C NMR (126 MHz, DMSO) δ 172.74, 169.52, 165.19, 162.54, 144.44, 136.84, 133.02, 128.89, 127.32, 122.57, 49.44, 30.88, 21.74.…”

“…MYC gene expression is an important hallmark of stimulated signaling pathways that promote cell proliferation 1,2 . Dysregulation of MYC expression resulting from genomic amplification or increased gene copy number of the gene, among a variety of other genomic alterations, is a key driver in cancer development and progression 3 .…”

“…CDK9 is the catalytic subunit of the positive transcription elongation factor b (P-TEFb), and is crucial for the upstream and downstream regulation of MYC. MYC gene expression depends highly on CDK9 which is tethered to the MYC promoter through the scaffolding activity of the ERK protein 1 . Moreover, CDK9’‘s influence on MYC dynamics extends to the protein level as well.…”