The TAB1-p38α complex aggravates myocardial injury and can be targeted by small molecules
Gian F. De Nicola, … , James Clark, Michael S. Marber
Gian F. De Nicola, … , James Clark, Michael S. Marber
Published August 23, 2018
Citation Information: JCI Insight. 2018;3(16):e121144. https://doi.org/10.1172/jci.insight.121144.
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Research Article Cardiology Therapeutics

The TAB1-p38α complex aggravates myocardial injury and can be targeted by small molecules

Abstract

Inhibiting MAPK14 (p38α) diminishes cardiac damage in myocardial ischemia. During myocardial ischemia, p38α interacts with TAB1, a scaffold protein, which promotes p38α autoactivation; active p38α (pp38α) then transphosphorylates TAB1. Previously, we solved the X-ray structure of the p38α-TAB1 (residues 384–412) complex. Here, we further characterize the interaction by solving the structure of the pp38α-TAB1 (residues 1–438) complex in the active state. Based on this information, we created a global knock-in (KI) mouse with substitution of 4 residues on TAB1 that we show are required for docking onto p38α. Whereas ablating p38α or TAB1 resulted in early embryonal lethality, the TAB1-KI mice were viable and had no appreciable alteration in their lymphocyte repertoire or myocardial transcriptional profile; nonetheless, following in vivo regional myocardial ischemia, infarction volume was significantly reduced and the transphosphorylation of TAB1 was disabled. Unexpectedly, the activation of myocardial p38α during ischemia was only mildly attenuated in TAB1-KI hearts. We also identified a group of fragments able to disrupt the interaction between p38α and TAB1. We conclude that the interaction between the 2 proteins can be targeted with small molecules. The data reveal that it is possible to selectively inhibit signaling downstream of p38α to attenuate ischemic injury.

Authors

Gian F. De Nicola, Rekha Bassi, Charlie Nichols, Mariana Fernandez-Caggiano, Pelin Arabacilar Golforoush, Dibesh Thapa, Rhys Anderson, Eva Denise Martin, Sharwari Verma, Jens Kleinjung, Adam Laing, Jonathan P. Hutchinson, Philip Eaton, James Clark, Michael S. Marber

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Figure 10

TAB1 and 3-amino-1-adamantanol compete for the same hydrophobic pocket on the noncanonical site of p38α.

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TAB1 and 3-amino-1-adamantanol compete for the same hydrophobic pocket o...
(A) 3-Amino-1-adamantanol binding site. The hydrophobic pocket on p38α is shown as a semitransparent surface, the 3-amino-1-adamantanol molecule is shown in magenta. The hydrogen bonds between the 3-amino group and the hydroxyl group of the adamantane and the oxygens of the backbone carbonyl of Leu 222 and Leu 234 are shown as dotted lines. The van der Waals surface of the adamantanol is shown as a mesh in magenta. (B) Zoom-in of the noncanonical site in pp38α-TAB1 complex, the hydrophobic pocket used by the 3-amino-1-adamantanol is shown in identical representation and orientation as in A. TAB1 is shown in ribbon form (cyan) with the side chains of Arg 384, Val 385, and Tyr 386 shown. (C) Representative fluorescence based thermal shift assay of p38α (5 μM) with DMSO baseline control (green) vs. 12.5 mM 3-amino-1-adamantanol (orange) and DMSO + 50μM SB220025 (blue) vs. 12.5 mM 3-amino-1-adamantanol + 50μM SB220025 (red). Inset: Box and whisker representation indicating that 3-amino-1-adamantanol binding is not competitive to the high-affinity ATP competitive inhibitor SB220025. (D) Western blot analysis of pp38α-TAB1 IVKA in the presence and in the absence of 12.5 mM 3-amino-1-adamantanol. It shows that the ligand prevents pp38α phoshorylation of TAB1.