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Study explores the linking of stress-responsive 14-3-3–GIGYF2 stabilization to translational repression and antiproliferative activity

This novel study uncovers how a subtle chemical tweak transforms the naturally occurring phytotoxin into a powerful molecular glue, 12-deoxyfusicoccin (12-dFC), that locks 14-3-3 proteins onto the intrinsically disordered translational repressor GIGYF2 in human cells. Through integrated proteomic, biochemical, and functional analyses, the work reveals an AMPK-driven stress pathway that 12-dFC exploits to shut down protein synthesis, rewire metabolism, and halt cell proliferation, pointing to an unexpected and promising strategy for targeting cancer cells.

Protein–protein interactions (PPI) underpin all cellular functions, yet many of these interactions are intrinsically weak, transient, and regulated by reversible chemical modifications such as phosphorylation. These dynamic properties, while essential for cellular flexibility, make PPIs difficult to be targeted therapeutically, especially in cases of cancer. Due to weaker PPI interactions, cancer cells can easily escape from the drug. In recent years, however, molecular glues, small molecules that stabilize pre-existing PPIs, have emerged as a promising strategy to modulate these elusive networks.

In this context, Professor Junko Ohkanda from the Institute of Agriculture, Shinshu University, Japan, along with other researchers from RIKEN, Osaka University, Japan, and Beckman Research Institute, USA, reported that 12-deoxyfusicoccin (12-dFC), a semisynthetic derivative of the phytotoxin fusicoccin A (FC-A), functions as a molecular glue in human cells. Their study, published online in the journal JACS AU on January 20, 2026, demonstrated that 12-dFC selectively stabilizes the interaction between 14-3-3 proteins and the intrinsically disordered translational repressor GRB10-interacting GYF protein 2 (GIGYF2).

The researchers found that the toxin fusicoccin is inactive against cancer cells. However, when the molecule is “chemically edited,” it acts as an antitumor agent. “The intriguing question was how a phytotoxin, which is totally inactive against tumors, can be converted into an antitumor agent that effectively suppresses tumor growth. We wanted to understand what the compound does in cells and why chemical modification is required to add this new activity,” reveals Prof. Ohkanda, as the motivation behind the study. By enhancing this stress-responsive protein complex, 12-dFC suppresses protein synthesis and cellular metabolism under energy-limiting conditions, providing mechanistic insights into its biological activity and revealing a new approach to targeting dynamic protein networks in diseases such as cancer and age-related ailments.

The primary objective of the study was to identify the cellular targets and molecular mechanism underlying the activity of 12-dFC. To achieve this, the researchers developed a tandem-affinity purification (TAP) strategy coupled with quantitative mass spectrometry to isolate ternary complexes composed of 14-3-3 proteins, phosphorylated binding partners, and fusicoccin derivatives. This approach overcame key limitations of conventional co-immunoprecipitation methods, which often fail to capture weak or transient interactions. Using 12-hydroxyfusicoccin (12-hFC) as an inactive control, the team identified GIGYF2 as a previously unrecognized 14-3-3 binding partner that is selectively stabilized by 12-dFC. As Prof. Ohkanda explains, “By using TAP, we were able to capture these fleeting protein interactions that had eluded detection with traditional methods, revealing GIGYF2 as a key player in the mechanism of 12-dFC.”

GIGYF2 is a largely intrinsically disordered scaffold protein that plays a central role in mRNA translational repression. Biochemical and mutational analyses revealed that 12-dFC promotes cooperative binding of 14-3-3 proteins to a mode-1 consensus phosphorylation motif (KGVpS⁵⁴⁶IP) within GIGYF2, enhancing binding affinity by approximately 50-fold. In contrast, 12-hFC failed to stabilize this interaction, likely due to steric hindrance caused by its 12-hydroxy group, highlighting the structural precision required for effective PPI stabilization by molecular glues.

The functional consequences of this interaction were substantial. Using bioorthogonal noncanonical amino acid tagging (BONCAT) assay, the researchers demonstrated that 12-dFC significantly suppresses global protein synthesis, an effect abolished by GIGYF2 knockdown. Proteomic profiling further revealed reduced expression of glycolysis-related proteins by 12-dFC, linking translational repression to metabolic control, thereby highlighting the antiproliferative activity of 12-dFC in cancer cells. Notably, unlike conventional translation inhibitors that directly target ribosomes or elongation factors and often cause toxicity, 12-dFC suppresses protein synthesis indirectly by stabilizing regulatory PPIs, suggesting a potentially safer therapeutic strategy.

Remarkably, for the first time, the researchers discovered the link between energy depletion stress, which activates the energy sensor kinase called the “AMP-activated protein kinase” and translational repression promoted by the identified 14-3-3–GIGYF2 interaction. Together, these results establish 12-dFC as a selective PPI-stabilizing small molecule that reinforces a stress-responsive 14-3-3–GIGYF2 complex, suppressing protein synthesis and metabolism under energy-depleted conditions. This work not only clarifies the molecular basis of 12-dFC’s antiproliferative activity but also illustrates the therapeutic potential of targeting transient interactions involving intrinsically disordered proteins. "These findings have broad implications for pharmaceutical research, not only for developing novel antitumor agents but also potentially for age-related diseases such as Alzheimer’s, Parkinson’s, and cardiovascular disorders," shares Prof. Ohkanda.

Together, these findings establish 12-dFC as a selective molecular glue that stabilizes a stress-responsive 14-3-3–GIGYF2 complex, suppressing protein synthesis and metabolism under energy-limiting conditions. This work not only provides a clear molecular mechanism for the antiproliferative effects of 12-dFC but also illustrates the therapeutic potential of targeting transient, intrinsically disordered protein networks with molecular glues.