Davda D

References (4)

Title : APT2 Inhibition Restores Scribble Localization and S-Palmitoylation in Snail-Transformed Cells - Hernandez_2017_Cell.Chem.Biol_24_87
Author(s) : Hernandez JL , Davda D , Cheung See Kit M , Majmudar JD , Won SJ , Gang M , Pasupuleti SC , Choi AI , Bartkowiak CM , Martin BR
Ref : Cell Chemical Biology , 24 :87 , 2017
Abstract : The multidomain scaffolding protein Scribble (Scrib) organizes key signaling complexes to specify basolateral cell polarity and suppress aberrant growth. In many human cancers, genetically normal Scrib mislocalizes from cell-cell junctions to the cytosol, correlating with enhanced growth signaling and malignancy. Here we confirm that expression of the epithelial-to-mesenchymal transcription factor (EMT-TF) Snail in benign epithelial cells leads to Scrib displacement from the plasma membrane, mimicking the mislocalization observed in aggressive cancers. Upon further examination, Snail promotes a transcriptional program that targets genes in the palmitoylation cycle, repressing many protein acyl transferases and elevating expression and activity of protein acyl thioesterase 2 (APT2). APT2 isoform-selective inhibition or knockdown rescued Scrib membrane localization and palmitoylation while attenuating MEK activation. Overall, inhibiting APT2 restores balance to the Scrib palmitoylation cycle, promoting membrane re-localization and growth attenuation. These findings emphasize the importance of S-palmitoylation as a post-translational gatekeeper of cell polarity-mediated tumor suppression.
ESTHER : Hernandez_2017_Cell.Chem.Biol_24_87
PubMedSearch : Hernandez_2017_Cell.Chem.Biol_24_87
PubMedID: 28065656

Title : Molecular Mechanism for Isoform-Selective Inhibition of Acyl Protein Thioesterases 1 and 2 (APT1 and APT2) - Won_2016_ACS.Chem.Biol_11_3374
Author(s) : Won SJ , Davda D , Labby KJ , Hwang SY , Pricer R , Majmudar JD , Armacost KA , Rodriguez LA , Rodriguez CL , Chong FS , Torossian KA , Palakurthi J , Hur ES , Meagher JL , Brooks CL, 3rd , Stuckey JA , Martin BR
Ref : ACS Chemical Biology , 11 :3374 , 2016
Abstract : Post-translational S-palmitoylation directs the trafficking and membrane localization of hundreds of cellular proteins, often involving a coordinated palmitoylation cycle that requires both protein acyl transferases (PATs) and acyl protein thioesterases (APTs) to actively redistribute S-palmitoylated proteins toward different cellular membrane compartments. This process is necessary for the trafficking and oncogenic signaling of S-palmitoylated Ras isoforms, and potentially many peripheral membrane proteins. The depalmitoylating enzymes APT1 and APT2 are separately conserved in all vertebrates, suggesting unique functional roles for each enzyme. The recent discovery of the APT isoform-selective inhibitors ML348 and ML349 has opened new possibilities to probe the function of each enzyme, yet it remains unclear how each inhibitor achieves orthogonal inhibition. Herein, we report the high-resolution structure of human APT2 in complex with ML349 (1.64 A), as well as the complementary structure of human APT1 bound to ML348 (1.55 A). Although the overall peptide backbone structures are nearly identical, each inhibitor adopts a distinct conformation within each active site. In APT1, the trifluoromethyl group of ML348 is positioned above the catalytic triad, but in APT2, the sulfonyl group of ML349 forms hydrogen bonds with active site resident waters to indirectly engage the catalytic triad and oxyanion hole. Reciprocal mutagenesis and activity profiling revealed several differing residues surrounding the active site that serve as critical gatekeepers for isoform accessibility and dynamics. Structural and biochemical analysis suggests the inhibitors occupy a putative acyl-binding region, establishing the mechanism for isoform-specific inhibition, hydrolysis of acyl substrates, and structural orthogonality important for future probe development.
ESTHER : Won_2016_ACS.Chem.Biol_11_3374
PubMedSearch : Won_2016_ACS.Chem.Biol_11_3374
PubMedID: 27748579
Gene_locus related to this paper: human-LYPLA1 , human-LYPLA2

Title : Substrate-Competitive Activity-Based Profiling of Ester Prodrug Activating Enzymes - Xu_2015_Mol.Pharm_12_3399
Author(s) : Xu H , Majmudar JD , Davda D , Ghanakota P , Kim KH , Carlson HA , Showalter HD , Martin BR , Amidon GL
Ref : Mol Pharm , 12 :3399 , 2015
Abstract : Understanding the mechanistic basis of prodrug delivery and activation is critical for establishing species-specific prodrug sensitivities necessary for evaluating preclinical animal models and potential drug-drug interactions. Despite significant adoption of prodrug methodologies for enhanced pharmacokinetics, functional annotation of prodrug activating enzymes is laborious and often unaddressed. Activity-based protein profiling (ABPP) describes an emerging chemoproteomic approach to assay active site occupancy within a mechanistically similar enzyme class in native proteomes. The serine hydrolase enzyme family is broadly reactive with reporter-linked fluorophosphonates, which have shown to provide a mechanism-based covalent labeling strategy to assay the activation state and active site occupancy of cellular serine amidases, esterases, and thioesterases. Here we describe a modified ABPP approach using direct substrate competition to identify activating enzymes for an ethyl ester prodrug, the influenza neuraminidase inhibitor oseltamivir. Substrate-competitive ABPP analysis identified carboxylesterase 1 (CES1) as an oseltamivir-activating enzyme in intestinal cell homogenates. Saturating concentrations of oseltamivir lead to a four-fold reduction in the observed rate constant for CES1 inactivation by fluorophosphonates. WWL50, a reported carbamate inhibitor of mouse CES1, blocked oseltamivir hydrolysis activity in human cell homogenates, confirming CES1 is the primary prodrug activating enzyme for oseltamivir in human liver and intestinal cell lines. The related carbamate inhibitor WWL79 inhibited mouse but not human CES1, providing a series of probes for analyzing prodrug activation mechanisms in different preclinical models. Overall, we present a substrate-competitive activity-based profiling approach for broadly surveying candidate prodrug hydrolyzing enzymes and outline the kinetic parameters for activating enzyme discovery, ester prodrug design, and preclinical development of ester prodrugs.
ESTHER : Xu_2015_Mol.Pharm_12_3399
PubMedSearch : Xu_2015_Mol.Pharm_12_3399
PubMedID: 26262434
Gene_locus related to this paper: human-CES1

Title : Acyl protein thioesterase inhibitors as probes of dynamic S-palmitoylation - Davda_2014_Medchemcomm_5_268
Author(s) : Davda D , Martin BR
Ref : Medchemcomm , 5 :268 , 2014
Abstract : Protein palmitoylation describes the hydrophobic post-translational modification of cysteine residues in certain proteins, and is required for the spatial organization and composition of cellular membrane environments. Certain palmitoylated proteins are processed by acyl protein thioesterase (APT) enzymes, which catalyze thioester hydrolysis of palmitoylated cysteine residues. Inhibiting APT enzymes disrupts Ras trafficking and attenuates oncogenic growth signaling, highlighting these enzymes as potential therapeutic targets. As members of the serine hydrolase enzyme family, APT enzymes can be assayed by fluorophosphonate activity-based protein profiling (ABPP) methods, allowing rapid profiling of inhibitor selectivity and potency. In this review, we discuss recent progress in the development of potent and selective inhibitors to APT enzymes, including both competitive and non-competitive chemotypes. These examples highlight how ABPP methods integrate with medicinal chemistry for the discovery and optimization of inhibitors in complex proteomes.
ESTHER : Davda_2014_Medchemcomm_5_268
PubMedSearch : Davda_2014_Medchemcomm_5_268
PubMedID: 25558349
Gene_locus related to this paper: human-LYPLA1