Apoptosis signal-regulating kinase 1 (ASK1) is a crucial stress sensor, directing cells toward apoptosis, differentiation, and senescence via the p38 and JNK signaling pathways. ASK1 dysregulation has been associated with cancer and inflammatory, cardiovascular, and neurodegenerative diseases, among others. However, our limited knowledge of the underlying structural mechanism of ASK1 regulation hampers our ability to target this member of the MAP3K protein family towards developing therapeutic interventions for these disorders. Nevertheless, as a multidomain Ser/Thr protein kinase, ASK1 is regulated by a complex mechanism involving dimerization and interactions with several other proteins, including thioredoxin 1 (TRX1). Thus, the present study aims at structurally characterizing ASK1 and its complex with TRX1 using several biophysical techniques. As shown by cryo-EM analysis, in a state close to its active form, ASK1 is a compact and asymmetric dimer, which enables extensive interdomain and interchain interactions. These interactions stabilize the active conformation of the ASK1 kinase domain. In turn, TRX1 functions as a negative allosteric effector of ASK1, modifying the structure of the TRX1-binding domain and changing its interaction with the tetratricopeptide repeats domain. Consequently, TRX1 reduces access to the activation segment of the kinase domain. Overall, our findings not only clarify the role of ASK1 dimerization and inter-domain contacts but also provide key mechanistic insights into its regulation, thereby highlighting the potential of ASK1 protein-protein interactions as targets for anti-inflammatory therapy.

• Keywords
• ASK1, MAP3K, MAPK signaling, biochemistry, chemical biology, human, molecular biophysics, protein kinase, structural biology, thioredoxin,
• MeSH
• Apoptosis MeSH
• Biophysics MeSH
• Cryoelectron Microscopy MeSH
• MAP Kinase Kinase Kinase 5 * MeSH
• Thioredoxins * MeSH
• Publication type
• Journal Article MeSH
• Names of Substances
• MAP Kinase Kinase Kinase 5 * MeSH
• Thioredoxins * MeSH

Apoptosis signal-regulating kinase (ASK) 1, a member of the mitogen-activated protein kinase kinase kinase (MAP3K) family, modulates diverse responses to oxidative and endoplasmic reticulum (ER) stress and calcium influx. As a crucial cellular stress sensor, ASK1 activates c-Jun N-terminal kinases (JNKs) and p38 MAPKs. Their excessive and sustained activation leads to cell death, inflammation and fibrosis in various tissues and is implicated in the development of many neurological disorders, such as Alzheimer's, Parkinson's and Huntington disease and amyotrophic lateral sclerosis, in addition to cardiovascular diseases, diabetes and cancer. However, currently available inhibitors of JNK and p38 kinases either lack efficacy or have undesirable side effects. Therefore, targeted inhibition of their upstream activator, ASK1, stands out as a promising therapeutic strategy for treating such severe pathological conditions. This review summarizes recent structural findings on ASK1 regulation and its role in various diseases, highlighting prospects for ASK1 inhibition in the treatment of these pathologies.

• Keywords
• 14-3-3, ASK1, MAP kinase, kinase, phosphorylation, protein–protein interaction,
• MeSH
• Apoptosis physiology   MeSH
• Phosphorylation MeSH
• JNK Mitogen-Activated Protein Kinases metabolism   MeSH
• Humans MeSH
• MAP Kinase Kinase Kinase 5 genetics   metabolism   physiology   ultrastructure   MeSH
• MAP Kinase Signaling System MeSH
• MAP Kinase Kinase Kinases genetics   metabolism   MeSH
• Protein Interaction Maps genetics   physiology   MeSH
• p38 Mitogen-Activated Protein Kinases metabolism   MeSH
• Oxidation-Reduction MeSH
• Oxidative Stress MeSH
• 14-3-3 Proteins metabolism   MeSH
• Apoptosis Regulatory Proteins metabolism   MeSH
• Signal Transduction drug effects   MeSH
• Endoplasmic Reticulum Stress MeSH
• Animals MeSH
• Check Tag
• Humans MeSH
• Animals MeSH
• Publication type
• Journal Article MeSH
• Review MeSH
• Names of Substances
• JNK Mitogen-Activated Protein Kinases MeSH
• MAP Kinase Kinase Kinase 5 MeSH
• MAP Kinase Kinase Kinases MeSH
• MAP3K5 protein, human MeSH Browser
• p38 Mitogen-Activated Protein Kinases MeSH
• 14-3-3 Proteins MeSH
• Apoptosis Regulatory Proteins MeSH

Phosphorylation by kinases governs many key cellular and extracellular processes, such as transcription, cell cycle progression, differentiation, secretion and apoptosis. Unsurprisingly, tight and precise kinase regulation is a prerequisite for normal cell functioning, whereas kinase dysregulation often leads to disease. Moreover, the functions of many kinases are regulated through protein-protein interactions, which in turn are mediated by phosphorylated motifs and often involve associations with the scaffolding and chaperon protein 14-3-3. Therefore, the aim of this review article is to provide an overview of the state of the art on 14-3-3-mediated kinase regulation, focusing on the most recent mechanistic insights into these important protein-protein interactions and discussing in detail both their structural aspects and functional consequences.

• Keywords
• 14-3-3, ASK1, CaMKK2, LRRK2, PI4KB, PKC, RAF kinase, kinase, phosphorylation,
• MeSH
• Allosteric Regulation genetics   MeSH
• Apoptosis genetics   MeSH
• Phosphorylation genetics   MeSH
• Humans MeSH
• p38 Mitogen-Activated Protein Kinases genetics   MeSH
• Protein Kinases genetics   MeSH
• 14-3-3 Proteins genetics   MeSH
• Signal Transduction genetics   MeSH
• Check Tag
• Humans MeSH
• Publication type
• Journal Article MeSH
• Review MeSH
• Names of Substances
• p38 Mitogen-Activated Protein Kinases MeSH
• Protein Kinases MeSH
• 14-3-3 Proteins MeSH