Biology subjects

Dionne, K.

Publications and source records attributed to Dionne, K..

5 recordsLinked to original sources

bioRxiv2024

The asymmetric opening of HIV-1 Env by a potent CD4 mimetic enables anti-coreceptor binding site antibodies to mediate ADCC

HIV-1 envelope glycoproteins (Env) from primary HIV-1 isolates typically adopt a pretriggered "closed" conformation that resists to CD4-induced (CD4i) non-neutralizing antibodies (nnAbs) mediating antibody-dependent cellular cytotoxicity (ADCC). CD4-mimetic compounds (CD4mcs) "open-up" Env allowing binding of CD4i nnAbs, thereby sensitizing HIV-1-infected cells to ADCC. Two families of CD4i nnAbs, the anti-cluster A and anti-coreceptor binding site (CoRBS) Abs, are required to mediate ADCC in combination with the indane CD4mc BNM-III-170. Recently, new indoline CD4mcs with improved potency and breadth have been described. Here, we show that the lead indoline CD4mc, CJF-III-288, sensitizes HIV-1-infected cells to ADCC mediated by anti-CoRBS Abs alone, contributing to improved ADCC activity. Structural and conformational analyses reveal that CJF-III-288, in combination with anti-CoRBS Abs, potently stabilizes an asymmetric "open" State-3 Env conformation, This Env conformation orients the anti-CoRBS Ab to improve ADCC activity and therapeutic potential.

microbiology↗

bioRxiv2024

The combination of three CD4-induced antibodies targeting highly conserved Env regions with a small CD4-mimetic achieves potent ADCC activity

The majority of naturally-elicited antibodies against the HIV-1 envelope glycoproteins (Env) are non-neutralizing (nnAbs), because they are unable to recognize the Env timer in its native "closed" conformation. Nevertheless, it has been shown that nnAbs have the potential to eliminate HIV-1-infected cells by Antibody-Dependent Cellular Cytotoxicity (ADCC) provided that Env is present on the cell surface in its "open" conformation. This is because most nnAbs recognize epitopes that become accessible only after Env interaction with CD4 and the exposure of epitopes that are normally occluded in the closed trimer. HIV-1 limits this vulnerability by downregulating CD4 from the surface of infected cells, thus preventing a premature encounter of Env with CD4. Small CD4-mimetics (CD4mc) sensitize HIV-1-infected cells to ADCC by opening the Env glycoprotein and exposing CD4-induced (CD4i) epitopes. There are two families of CD4i nnAbs, termed anti-cluster A and anti-CoRBS Abs, which are known to mediate ADCC in the presence of CD4mc. Here, we performed Fab competition experiments and found that anti-gp41 cluster I antibodies comprise a major fraction of the plasma ADCC activity in people living with HIV (PLWH). Moreover, addition of gp41 cluster I antibodies to cluster A and CoRBS antibodies greatly enhanced ADCC mediated cell killing in the presence of a potent indoline CD4mc, CJF-III-288. This cocktail outperformed broadly-neutralizing antibodies and even showed activity against HIV-1 infected monocyte-derived macrophages. Thus, combining CD4i antibodies with different specificities achieves maximal ADCC activity, which may be of utility in HIV cure strategies. IMPORTANCEThe elimination of HIV-1-infected cells remains an important medical goal. While current antiretroviral therapy decreases viral loads below detection levels, it does not eliminate latently infected cells which form the viral reservoir. Here, we developed a cocktail of non-neutralizing antibodies targeting highly conserved Env regions and combined it with a potent indoline CD4mc. This combination exhibited very potent ADCC activity against HIV-1-infected primary CD4+ T cells as well as monocyte-derived macrophages, suggesting its potential utility in decreasing the size of the viral reservoir.

microbiology↗

bioRxiv2022

Ethanol Exposure Perturbs Sea Urchin Development and Disrupts Developmental Timing

Ethanol is a known vertebrate teratogen that causes craniofacial defects as a component of fetal alcohol syndrome (FAS). Our results show that sea urchin embryos treated with ethanol similarly show broad skeletal patterning defects, potentially analogous to the defects associated with FAS. The sea urchin larval skeleton is a simple patterning system that involves only two cell types: the primary mesenchymal cells (PMCs) that secrete the calcium carbonate skeleton and the ectodermal cells that provide migratory, positional, and differentiation cues for the PMCs. Perturbations in RA biosynthesis and Hh signaling pathways are thought to be causal for the FAS phenotype in vertebrates. Surprisingly, our results indicate that these pathways are not functionally relevant for the teratogenic effects of ethanol in developing sea urchins. We found that developmental morphology as well as the expression of ectodermal and PMC genes was delayed by ethanol exposure. Temporal transcriptome analysis revealed significant impacts of ethanol on signaling and metabolic gene expression, and a disruption in the timing of GRN gene expression that includes both delayed and precocious gene expression throughout the specification network. We conclude that the skeletal patterning perturbations in ethanol-treated embryos likely arise from a loss of temporal synchrony within and between the instructive and responsive tissues.

developmental biology↗

bioRxiv2021

Structural and functional analysis of lorlatinib analogs reveals roadmap for targeting diverse compound resistance mutations in ALK-positive lung cancer

The treatment approach to advanced, ALK-positive non-small cell lung cancer (NSCLC) utilizing sequential ALK tyrosine kinase inhibitors (TKIs) represents a paradigm of precision oncology. Lorlatinib is currently the most advanced, potent and selective ALK tyrosine kinase inhibitor (TKI) in the clinic. However, tumors invariably acquire resistance to lorlatinib, and after sequential ALK TKIs culminating with lorlatinib, diverse refractory compound ALK mutations can emerge. Here, we determine the spectrum of lorlatinib-resistant compound ALK mutations identified in patients after treatment with lorlatinib, the majority of which involve ALK G1202R or I1171N/S/T. By assessing a panel of lorlatinib analogs against compound ALK mutant in vitro and in vivo models, we identify structurally diverse lorlatinib analogs that harbor differential selective profiles against G1202R- versus I1171N/S/T-based compound ALK mutations. Structural analysis revealed that increased potency against compound mutations was achieved primarily through two different mechanisms of improved targeting of either G1202R- or I1171N/S/T-mutant kinases. Based on these results, we propose a classification of heterogenous ALK compound mutations designed to focus the development of distinct therapeutic strategies for precision targeting of compound resistance mutations following sequential TKIs.

cancer biology↗

bioRxiv2021

APOBEC3A drives acquired resistance to targeted therapies in non-small cell lung cancer

Acquired drug resistance to even the most effective anti-cancer targeted therapies remains an unsolved clinical problem. Although many drivers of acquired drug resistance have been identified1-6, the underlying molecular mechanisms shaping tumor evolution during treatment are incompletely understood. The extent to which therapy actively drives tumor evolution by promoting mutagenic processes7 or simply provides the selective pressure necessary for the outgrowth of drug-resistant clones8 remains an open question. Here, we report that lung cancer targeted therapies commonly used in the clinic induce the expression of cytidine deaminase APOBEC3A (A3A), leading to sustained mutagenesis in drug-tolerant cancer cells persisting during therapy. Induction of A3A facilitated the formation of double-strand DNA breaks (DSBs) in cycling drug-treated cells, and fully resistant clones that evolved from drug-tolerant intermediates exhibited an elevated burden of chromosomal aberrations such as copy number alterations and structural variations. Preventing therapy-induced A3A mutagenesis either by gene deletion or RNAi-mediated suppression delayed the emergence of drug resistance. Finally, we observed accumulation of A3A mutations in lung cancer patients who developed drug resistance after treatment with sequential targeted therapies. These data suggest that induction of A3A mutagenesis in response to targeted therapy treatment may facilitate the development of acquired resistance in non-small-cell lung cancer. Thus, suppressing expression or enzymatic activity of A3A may represent a potential therapeutic strategy to prevent or delay acquired resistance to lung cancer targeted therapy.

cancer biology↗