Biomedical subjects

Alexander B Taylor

Publications and source records attributed to Alexander B Taylor.

7 recordsLinked to original sources

PubMed2026

Antibody-Mediated Targeting of Secretory Protein SCUBE3 Suppresses Cancer Progression by Inhibiting Oncogenic Signaling and Inducing Antitumor Immunity.

UNLABELLED: Approaches targeting factors that simultaneously promote tumor growth and progression, induce therapy resistance, and inhibit antitumor immunity offer clear benefits over therapies targeting only one of these tumor-promoting processes. Through comprehensive loss-of-function genomic screening, we identified SCUBE3 as a pivotal factor that supports survival and therapy resistance and also orchestrates an immunosuppressive tumor microenvironment. Secretory SCUBE3 supported oncogenic activity through interactions with key oncogenic cell surface receptor proteins, including EGFR, mutant CALR, and TGFβRI/II. These interactions activated the transcription factors FOXR2 and c-Myc, promoting cancer cell proliferation and therapy resistance by enhancing DNA damage repair. Additionally, the SCUBE3-FOXR2 axis created an immunosuppressive tumor microenvironment by facilitating recruitment of the DNMT1 epigenetic repressor complex to the transcription regulator IRF1, thereby inhibiting the expression of MHC-I and MHC-II genes. A first-in-class neutralizing antibody targeting SCUBE3, which was developed using a sophisticated antibody discovery platform and engineered with specific mutations in the heavy chain for enhanced specificity and efficacy, demonstrated profound therapeutic potential across various cancer types in preclinical models, including patient-derived breast and ovarian cancer xenografts. This discovery marks an advancement toward developing a targeted therapy for cancers characterized by hyperactive SCUBE3-associated signaling pathways. SIGNIFICANCE: Targeting SCUBE3 with a neutralizing antibody inhibits tumor growth and metastasis by blocking oncogenic signaling through FOXR2 and c-Myc and by circumventing immunosuppression, providing a promising pan-cancer treatment approach.

Humans↗

PubMed2003

Structure-function analysis of the auxilin J-domain reveals an extended Hsc70 interaction interface.

J-domains are widespread protein interaction modules involved in recruiting and stimulating the activity of Hsp70 family chaperones. We have determined the crystal structure of the J-domain of auxilin, a protein which is involved in uncoating clathrin-coated vesicles. Comparison to the known structures of J-domains from four other proteins reveals that the auxilin J-domain is the most divergent of all J-domain structures described to date. In addition to the canonical J-domain features described previously, the auxilin J-domain contains an extra N-terminal helix and a long loop inserted between helices I and II. The latter loop extends the positively charged surface which forms the Hsc70 binding site, and is shown by directed mutagenesis and surface plasmon resonance to contain side chains important for binding to Hsc70.

Amino Acid Sequence↗

PubMed2003

An alternative mechanism of bicarbonate-mediated peroxidation by copper-zinc superoxide dismutase: rates enhanced via proposed enzyme-associated peroxycarbonate intermediate.

Hydrogen peroxide can interact with the active site of copper-zinc superoxide dismutase (SOD1) to generate a powerful oxidant. This oxidant can either damage amino acid residues at the active site, inactivating the enzyme (the self-oxidative pathway), or oxidize substrates exogenous to the active site, preventing inactivation (the external oxidative pathway). It is well established that the presence of bicarbonate anion dramatically enhances the rate of oxidation of exogenous substrates. Here, we show that bicarbonate also substantially enhances the rate of self-inactivation of human wild type SOD1. Together, these observations suggest that the strong oxidant formed by hydrogen peroxide and SOD1 in the presence of bicarbonate arises from a pathway mechanistically distinct from that producing the oxidant in its absence. Self-inactivation rates are further enhanced in a mutant SOD1 protein (L38V) linked to the fatal neurodegenerative disorder, familial amyotrophic lateral sclerosis. The 1.4 A resolution crystal structure of pathogenic SOD1 mutant D125H reveals the mode of oxyanion binding in the active site channel and implies that phosphate anion attenuates the bicarbonate effect by competing for binding to this site. The orientation of the enzyme-associated oxyanion suggests that both the self-oxidative and external oxidative pathways can proceed through an enzyme-associated peroxycarbonate intermediate.

Amyotrophic Lateral Sclerosis↗

PubMed2003

Amyloid-like filaments and water-filled nanotubes formed by SOD1 mutant proteins linked to familial ALS.

Mutations in the SOD1 gene cause the autosomal dominant, neurodegenerative disorder familial amyotrophic lateral sclerosis (FALS). In spinal cord neurons of human FALS patients and in transgenic mice expressing these mutant proteins, aggregates containing FALS SOD1 are observed. Accumulation of SOD1 aggregates is believed to interfere with axonal transport, protein degradation and anti-apoptotic functions of the neuronal cellular machinery. Here we show that metal-deficient, pathogenic SOD1 mutant proteins crystallize in three different crystal forms, all of which reveal higher-order assemblies of aligned beta-sheets. Amyloid-like filaments and water-filled nanotubes arise through extensive interactions between loop and beta-barrel elements of neighboring mutant SOD1 molecules. In all cases, non-native conformational changes permit a gain of interaction between dimers that leads to higher-order arrays. Normal beta-sheet-containing proteins avoid such self-association by preventing their edge strands from making intermolecular interactions. Loss of this protection through conformational rearrangement in the metal-deficient enzyme could be a toxic property common to mutants of SOD1 linked to FALS.

Amyloid↗

PubMed2003

Structure of Mycobacterium tuberculosis methionine sulfoxide reductase A in complex with protein-bound methionine.

Peptide methionine sulfoxide reductase (MsrA) repairs oxidative damage to methionine residues arising from reactive oxygen species and reactive nitrogen intermediates. MsrA activity is found in a wide variety of organisms, and it is implicated as one of the primary defenses against oxidative stress. Disruption of the gene encoding MsrA in several pathogenic bacteria responsible for infections in humans results in the loss of their ability to colonize host cells. Here, we present the X-ray crystal structure of MsrA from the pathogenic bacterium Mycobacterium tuberculosis refined to 1.5 A resolution. In contrast to the three catalytic cysteine residues found in previously characterized MsrA structures, M. tuberculosis MsrA represents a class containing only two functional cysteine residues. The structure reveals a methionine residue of one MsrA molecule bound at the active site of a neighboring molecule in the crystal lattice and thus serves as an excellent model for protein-bound methionine sulfoxide recognition and repair.

Amino Acid Motifs↗

PubMed2002

Copper chaperones.

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Amino Acid Sequence↗

PubMed2002

Crystal structure of the human TbetaR2 ectodomain--TGF-beta3 complex.

Transforming growth factor-beta (TGF-beta) is the prototype of a large family of structurally related cytokines that play key roles in maintaining cellular homeostasis by signaling through two classes of functionally distinct Ser/Thr kinase receptors, designated as type I and type II. TGF-beta initiates receptor assembly by binding with high affinity to the type II receptor. Here, we present the 2.15 A crystal structure of the extracellular ligand-binding domain of the human TGF-beta type II receptor (ecTbetaR2) in complex with human TGF-beta3. ecTbetaR2 interacts with homodimeric TGF-beta3 by binding identical finger segments at opposite ends of the growth factor. Relative to the canonical 'closed' conformation previously observed in ligand structures across the superfamily, ecTbetaR2-bound TGF-beta3 shows an altered arrangement of its monomeric subunits, designated the 'open' conformation. The mode of TGF-beta3 binding shown by ecTbetaR2 is compatible with both ligand conformations. This, in addition to the predicted mode for TGF-beta binding to the type I receptor ectodomain (ecTbetaR1), suggests an assembly mechanism in which ecTbetaR1 and ecTbetaR2 bind at adjacent positions on the ligand surface and directly contact each other via protein--protein interactions.

Amino Acid Sequence↗