Biology subjects

Qerqez, A. N.

Publications and source records attributed to Qerqez, A. N..

5 recordsLinked to original sources

bioRxiv2025

Antibodies blocking PlGF or VEGF interactions with the NRP1 receptormediate anti-proliferative effects

Antibodies blocking the function of vascular endothelial growth factor A (VEGFA) remain a promising therapeutic strategy, especially when combined with check-point inhibitors, but their efficacy is limited by tumor resistance. This can occur via multiple mechanisms, including upregulation of placental growth factor 2 (PlGF-2), an alternative ligand for VEGF receptor 1 (VEGFR1) and neuropilin receptor 1 (NRP1). Activity of both growth factors is mediated by interactions with multiple receptors and extra-cellular matrix components, which complicates efforts to understand their contributions to cancer progression. To complement existing antibodies, we discovered those blocking interactions between PlGF-2 or VEGFA and their shared NRP1 receptor in the presence of heparin. Limiting angiogenesis to promote vascular normalization is one mechanism of anti-VEGF protection; here, anti-VEGFA antibodies blocking interactions with VEGFR1 and NRP1 reduced HUVEC tube formation in a physiological angiogenesis model. By contrast, antibodies binding PlGF-2 or VEGFA to block NRP1 significantly reduced proliferation of Caki-I kidney carcinoma cells in vitro, indicating this receptor mediates additional effects. Interestingly, one antibody exhibited dual-reactive binding to VEGFA and PlGF-2, suggesting a novel therapeutic strategy to prevent PlGF-driven VEGF-resistance. Overall, these antibodies define new mechanisms to disrupt PlGF activity and support a role for NRP1 in cell proliferation. Key ResultsO_LINew antibodies binding VEGFA or PlGF selectively block NRP1-receptor interactions. C_LIO_LIAntibody blockade of VEGFA binding to NRP1 reduced HUVEC angiogenesis. C_LIO_LIBlocking growth factor interactions with NRP1 reduced Caki-I renal carcinoma proliferation. C_LIO_LIIdentified an antibody with dual-reactive binding to VEGFA and PlGF. C_LI

biochemistry↗

bioRxiv2025

A Common PD-Risk GBA1 Variant Disrupts LIMP2 Interaction, Impairs Glucocerebrosidase Function, and Drives Lysosomal and Mitochondrial Dysfunction

Variants in GBA1 cause Gaucher disease (GD), a lysosomal storage disorder, and represent the most common genetic risk factor for Parkinsons disease (PD). While some GBA1 variants are associated with both GD and PD, several coding mutations, including E326K, specifically confer risk for developing PD. It is established that GD-linked variants in {beta}-glucocerebrosidase (GCase), the enzyme encoded by GBA1, are loss-of-function, but it remains unclear whether variants solely associated with PD similarly reduce GCase activity. The mechanisms by which some of these variants impact GCase activity and PD-associated pathways, including lysosomal and mitochondrial function, are also poorly defined. Here, we show that the PD-linked E326K variant significantly reduces lysosomal GCase activity by impairing its delivery to lysosomes via altered interactions with its receptor, LIMP2. Biophysical and structural characterization of this variant, both alone and in complex with LIMP2, reveals a dimeric organization that appears to result from the loss of a key salt bridge between E326 and R329. Restoration of this salt bridge through the introduction of a negatively charged side chain at position 329 promotes monomeric organization and interaction with LIMP2 in cells. GBA1-p.E326K cell models show greater deficits in PD-linked pathways compared to more severe loss of GCase function, including secondary lysosomal lipid storage and mitochondrial dysfunction. We confirm the E326K variant impacts GCase pathway activity in relevant CNS cell types, including iPSC-derived microglia, and in biofluids from heterozygous GBA1-p.E326K variant carriers. Together, our data provide key insights into the nature of GCase dysfunction in GBA1-PD and can inform the development of GCase-targeted therapeutic strategies to treat PD.

cell biology↗

bioRxiv2025

Selective decoupling of IgG1 binding to viral Fc receptorsrestores antibody-mediated NK cell activation against HCMV-infected cells

A key mechanism of antiviral antibodies is to bind cell-surface viral antigens and activate cellular immunity to clear infected cells, yet antibodies targeting human cytomegalovirus (HCMV) have exhibited limited efficacy. This appears due to HCMVs multiple immune evasion mechanisms, including viral receptors (vFc{gamma}Rs) which bind human IgG Fc domains to co-operatively inhibit Fc activation of host Fc{gamma} receptors and impair Fc-mediated effector functions. We biochemically characterized and evaluated the functions of two highly conserved vFc{gamma}Rs, gp34 and gp68, and mapped their binding epitopes on the Fc domain. Based on this information, we then engineered Fc variants that retain binding to CD16A, which is essential for NK activation, and to FcRn but have markedly attenuated binding to gp34 and gp68. IgG1 antibodies targeting the gB fusogen with engineered Fc domains were not internalized by infected cells, mediated enhanced CD16A activation and limited viral spread in HCMV-infected fibroblasts more effectively than wild-type Fc. Together, this work demonstrates a strategy to enhance the efficacy of antibody therapies to clear HCMV infections. HighlightsO_LIHost and HCMV FcR compete for IgG1 binding but engage different residues. C_LIO_LIFc-engineering abrogates viral FcR antagonism while retaining CD16A activation. C_LIO_LIAntibodies that resist vFcR capture promote superior ADCC against infected cells. C_LIO_LIDesigner Fc domains complement Fabs to create enhanced disease-specific therapies. C_LI

immunology↗

bioRxiv2025

Dual targeting of transferrin receptor and CD98hc enhances brain exposure of large molecules

Targeting proteins highly expressed at the blood-brain barrier, including transferrin receptor (TfR) and CD98hc, is a transformative approach enabling more effective brain delivery of biotherapeutics for treatment of neurological diseases. TfR-mediated delivery promotes rapid, high brain uptake, while CD98hc-mediated delivery is slower with more prolonged exposure. Here, we engineer a huIgG Fc domain to bind both TfR and CD98hc to create a dual transport vehicle (TV) platform that drives distinct brain delivery properties. Dual TVs achieve significantly higher brain concentrations than TVs targeting either TfR or CD98hc alone. Modulation of TfR and CD98hc affinities shifts dual TV brain exposure kinetics and biodistribution. Stronger TfR affinity drives faster brain uptake and clearance, while stronger CD98hc affinity yields higher, more sustained concentrations, likely due to CD98hc affinity-dependent reduction in TfR-mediated neuronal internalization. This dual targeting strategy leverages the complementary properties of TfR and CD98hc-mediated brain exposure to increase optionality for brain delivery of biotherapeutics.

neuroscience↗

bioRxiv2021

Identification of a conserved neutralizing epitope present on spike proteins from highly pathogenic coronaviruses

Three pathogenic human coronaviruses have emerged within the last 20 years, with SARS-CoV-2 causing a global pandemic. Although therapeutic antibodies targeting the SARS-CoV-2 spike currently focus on the poorly conserved receptor-binding domain, targeting essential neutralizing epitopes on the more conserved S2 domain may provide broader protection. We report an antibody binding an epitope conserved in the pre-fusion core of MERS-CoV, SARS-CoV and SARS-CoV-2 spike S2 domains. Antibody 3A3 binds a conformational epitope with ~2.5 nM affinity and neutralizes spike from SARS-CoV, SARS-CoV-2 and variants of concern in in vitro pseudovirus assays. Hydrogen-deuterium exchange mass spectrometry identified residues 980-1006 in the flexible hinge region at the S2 apex as the 3A3 epitope, suggesting 3A3 prevents the S2 conformational rearrangements required for conversion to the spike post-fusion state and virus-host cell fusion. This work defines a conserved vulnerable site on the SARS-CoV-2 S2 domain and guides the design of pan-protective spike immunogens.

biochemistry↗