Biology subjects

Maujean, T.

Publications and source records attributed to Maujean, T..

3 recordsLinked to original sources

bioRxiv2025

MAPK Pathway Inhibition Reshapes Kinase Chemical Probe Reactivity Reflecting Cellular Activation States

Despite the pivotal role of oncogenic kinases in cancer initiation, progression, and therapeutic resistance, functionally profiling their activity and conformational dynamics in live cells remains challenging. Existing methods often fail to capture inhibitor-bound structural states of kinases, particularly in clinically relevant contexts such as treatment response and acquired resistance, where genomic data alone are insufficient. Here, we use activity-based protein profiling (ABPP) to monitor composite amino acid reactivity changes - across cysteine, lysine, and carboxylic acid residues - as a functional readout of kinase conformation and activation state. Using electrophilic probes, we show that treatment of BRAFV600E-mutant melanoma cells with vemurafenib or trametinib decreases overall cysteine and lysine reactivity in BRAFV600E and MEK1/2, likely reflecting composite changes in amino acid accessibility across multiple reactive residues associated with inhibitor binding. Changing the order of probe addition and inhibitor treatment altered labeling outcomes, consistent with competitive engagement and structural stabilization. Comparative analysis of ATP-competitive BRAFV600E inhibitors vemurafenib and dabrafenib revealed distinct impacts on aspartate and glutamate labeling patterns, suggesting that ABPP can distinguish inhibitor-dependent differences in residue accessibility that may reflect distinct inhibitor-bound conformations. In inhibitor-resistant melanoma models, ABPP detected differential residue reactivity relative to parental cells, consistent with BRAF overexpression and the MEK2 Q60P activation mutation, both established mechanisms of MAPK inhibitor resistance. Moreover, global proteome analyses of cysteine and lysine reactivity upon BRAFV600E inhibition, revealed probe-accessible cysteine labeling changes in labeling on KSR2, indicating broader MAPK pathway remodeling. Together, these findings establish ABPP as a powerful chemical biology approach for investigating inhibitor-dependent changes in kinase residue accessibility, providing a framework to explore how conformational dynamics and pathway adaptation shape therapeutic response and resistance in oncogenic signaling networks.

cancer biology↗

bioRxiv2024

A selective S-acyltransferase inhibitor suppresses tumor growth

S-acyltransferases play integral roles in essential physiological processes including regulation of oncogenic signaling pathways. While discovered over 40 years ago the field still lacks specific S-acylation inhibitors thus the potential benefit of pharmacologically targeting S-acyltransferases for human disease is still unknown. Here we report the identification of an orally bioavailable acyltransferase inhibitor SD-066-4 that inhibits the acyltransferase ZDHHC20. We identified a specific alanine residue that accommodates the methyl group of SD-066-4, thus providing isoform selectivity. SD-066-4 stably reduces EGFR S-acylation in Kras mutant cells and blocks the growth of Kras mutant lung tumors extending overall survival. We find that lung cancer patients harboring deletions in ZDHHC20 or ZDHHC14 concurrent with Kras alterations have a significant survival benefit, underscoring the translational importance of these enzymes.

cancer biology↗

bioRxiv2023

Pooled endogenous protein tagging and recruitment for scalable discovery of effectors for induced proximity therapeutics

The field of induced proximity therapeutics is in its ascendancy but is limited by a lack of scalable tools to systematically explore effector-target protein pairs in an unbiased manner. Here, we combined Scalable POoled Targeting with a LIgandable Tag at Endogenous Sites (SPOTLITES) for the high-throughput tagging of endogenous proteins, with generic small molecule-based protein recruitment to screen for novel proximity-based effectors. We apply this methodology in two orthogonal screens for targeted protein degradation: the first using fluorescence to monitor target protein levels directly, and the second using a cellular growth phenotype that depends on the degradation of an essential protein. Our screens revealed a multitude of potential new effector proteins for degradation and converged on members of the CTLH complex which we demonstrate potently induce degradation. Altogether, we introduce a platform for pooled induction of endogenous protein-protein interactions that can be used to expand our toolset of effector proteins for targeted protein degradation and other forms of induced proximity.

cell biology↗