Protein SUMOylation Promotes cAMP-Independent EPAC1 Activation

Authors

Wenli Yang
Fang C Mei
Wei Lin
Mark A White
Li Li
Yue Li
Sheng Pan
Xiaodong Cheng

Publication Date

7-4-2024

Journal

Cellular and Molecular Life Sciences

Abstract

Protein SUMOylation is a prevalent stress-response posttranslational modification crucial for maintaining cellular homeostasis. Herein, we report that protein SUMOylation modulates cellular signaling mediated by cAMP, an ancient and universal stress-response second messenger. We identify K561 as a primary SUMOylation site in exchange protein directly activated by cAMP (EPAC1) via site-specific mapping of SUMOylation using mass spectrometry. Sequence and site-directed mutagenesis analyses reveal that a functional SUMO-interacting motif in EPAC1 is required for the binding of SUMO-conjugating enzyme UBC9, formation of EPAC1 nuclear condensate, and EPAC1 cellular SUMOylation. Heat shock-induced SUMO modification of EPAC1 promotes Rap1/2 activation in a cAMP-independent manner. Structural modeling and molecular dynamics simulation studies demonstrate that SUMO substituent on K561 of EPAC1 promotes Rap1 interaction by increasing the buried surface area between the SUMOylated receptor and its effector. Our studies identify a functional SUMOylation site in EPAC1 and unveil a novel mechanism in which SUMOylation of EPAC1 leads to its autonomous activation. The findings of SUMOylation-mediated activation of EPAC1 not only provide new insights into our understanding of cellular regulation of EPAC1 but also will open up a new field of experimentation concerning the cross-talk between cAMP/EPAC1 signaling and protein SUMOylation, two major cellular stress response pathways, during cellular homeostasis.

Keywords

Guanine Nucleotide Exchange Factors, Sumoylation, Humans, Cyclic AMP, Ubiquitin-Conjugating Enzymes, rap1 GTP-Binding Proteins, HEK293 Cells, Molecular Dynamics Simulation, Shelterin Complex, Signal Transduction, Telomere-Binding Proteins, rap GTP-Binding Proteins, Heat-Shock Response, Amino Acid Sequence, Protein Binding, SUMO, SUMO-interacting motif, Biomolecular condensate, Heat shock, Molecular dynamics

Comments

Supplementary Materials

Data Availability Statement

PMID: 38963422