Proc Natl Acad Sci U S A. 2022 Aug 30;119(35):e2204752119.
A Escós, J Martín-Gómez, D González-Romero, E Díaz-Mora, R Francisco-Velilla, C Santiago, JM Cuezva, S Domínguez-Zorita, E Martínez-Salas, N Sonenberg, JJ Sanz-Ezquerro, S Mehdi Jafarnejad, A Cuenda
Abstract
p38γ and p38δ (p38γ/p38δ) regulate inflammation, in part by controlling tumor progression locus 2 (TPL2) expression in myeloid cells. Here, we demonstrate that TPL2 protein levels are dramatically reduced in p38γ/p38δ-deficient (p38γ/δ-/-) cells and tissues without affecting TPL2 messenger ribonucleic acid (mRNA) expression. We show that p38γ/p38δ posttranscriptionally regulates the TPL2 amount at two different levels. p38γ/p38δ interacts with the TPL2/A20 Binding Inhibitor of NF-κB2 (ABIN2)/Nuclear Factor κB1p105 (NF-κB1p105) complex, increasing TPL2 protein stability. Additionally, p38γ/p38δ regulates TPL2 mRNA translation by modulating the repressor function of TPL2 3' Untranslated region (UTR) mediated by its association with aconitase-1 (ACO1). ACO1 overexpression in wild-type cells increases the translational repression induced by TPL2 3'UTR and severely decreases TPL2 protein levels. p38δ binds to ACO1, and p38δ expression in p38γ/δ-/- cells fully restores TPL2 protein to wild-type levels by reducing the translational repression of TPL2 mRNA. This study reveals a unique mechanism of posttranscriptional regulation of TPL2 expression, which given its central role in innate immune response, likely has great relevance in physiopathology.
Keywords: 3′UTR; ACO1; TPL2; mRNA translation; p38γ/p38δ-MAPK.
doi: 10.1073/pnas.2204752119.