Didier Trono

The ongoing emergence of SARS-CoV-2 variants in an increasingly immune-experienced population is largely enabled by the plasticity of the Spike protein, which lies at the frontline of host immune pressure. Here, we investigated how extensive remodeling of the N-terminal domain (NTD) in Spike influences its antigenic properties. Using BA.2.87.1, a variant heavily mutated in this domain, we found that even large deletions do not substantially disrupt overall Spike structure or pseudovirus infectivity. However, our structural and binding analyses revealed that the NTD exhibits increased flexibility and that interaction with a heme–metabolite, known to facilitate the exposure of an immunodominant epitope, is lost. These conformational effects, coupled with 33 NTD mutations, compromised the ability of human convalescent antibodies to engage this domain, contributing to their reduced neutralizing capacity. Consequently, BA.2.87.1-like variants may escape recognition by the preexisting NTD-targeting antibodies, potentially reducing protection. Together, our results highlight the intrinsic adaptability of the Spike beyond the receptor-binding domain, with implications for immune escape during viral evolution.

Analyses routinely conducted in both fundamental research and biomedical studies often report aggregate signals derived from heterogeneous mixtures of cells. These mixtures reflect the intrinsic anatomical and functional complexity of the tissues and organs from which they are derived. Such bulk measurements obscure cell-specific signals, thereby hindering accurate interpretation of the underlying biological processes. Here, we introduce CLIMB and CLIFF, a two-step machine-learning framework that deconvolves bulk RNA-seq into cell-type composition and expression, and then resolves bulk drug sensitivity measurements into cell subtype- and single-cell-specific profiles. We first validate CLIMB using in-vitro mixtures of leukemic cell lines with experimentally known cell-type proportions, then extend this validation to large-scale, cross-dataset pseudo-bulk analyses built from independent scRNA-seq references across two disease contexts and five cancer types — mimicking the reference-to-target mismatches encountered in real applications — and show that CLIMB accurately infers the cellular composition of bulk samples, outperforming state-of-the-art bulk deconvolution methods. We emphasize CLIMB’s effectiveness in acute myeloid leukemia, where it offers highly accurate estimation of leukemic stem cell fractions across three test datasets and three patient cohorts. We then validate CLIFF, our algorithm for estimating cell subtype- and single-cell-specific drug sensitivity, first on the same in-vitro cell line mixtures using experimentally measured drug responses, and then through in-depth, realistic-scale pseudo-bulk simulations. We applied our deconvolution strategy to the beatAML cohort dataset, currently the most extensive database of ex-vivo drug screening data. This analysis generated a cell subtype–resolved drug sensitivity landscape for 121 compounds, revealing multiple compounds putatively active against leukemic stem cells, including midostaurin, A-674563, SNS-032, and foretinib. Collectively, our work introduces a general computational framework for resolving bulk functional measurements at cell-type and single-cell resolution, providing an attractive new computational tool for drug development and precision medicine.

Kruppel associated box zinc finger proteins (KZFPs) form the largest family of transcriptional regulators in mammals, yet most remain uncharacterized. Here we established a scalable framework to probe KZFP function. An arrayed inducible overexpression screen of 366 human KZFPs in K562 cells identified factors that alter cellular proliferation, enabling functional prioritization. Integrative transcriptomic, chromatin and proteomic analyses revealed diverse mechanisms, including transposable element–linked repression (ZNF43), promoter proximal regulation (ZNF257), and SCAN domain dependent transcriptional activation (ZNF498/ZSCAN25 and ZNF18). These results highlight the functional diversity of KZFPs and provide a strategy for their annotation.

The ongoing emergence of SARS-CoV-2 variants in an increasingly immune-experienced population is largely enabled by the plasticity of the Spike protein, which lies at the frontline of host immune pressure. Here, we investigated how extensive remodeling of the N-terminal domain (NTD) in Spike influences its antigenic properties. Using BA.2.87.1, a variant heavily mutated in this domain, we found that even large deletions do not substantially disrupt overall Spike structure or pseudovirus infectivity. However, our structural and binding analyses revealed that the NTD exhibits increased flexibility and that interaction with a heme-metabolite, contributing to assembly of an immunodominant epitope, is lost. These conformational effects, coupled with 33 NTD mutations, compromised the ability of human convalescent antibodies to engage this domain, contributing to their reduced neutralizing capacity. Consequently, BA.2.87.1-like variants may escape recognition by the pre-existing NTD-targeting antibodies, potentially reducing protection. Together, our results highlight the intrinsic adaptability of the Spike beyond the receptor-binding domain, with important implications for immune escape during viral evolution.

Membrane phospholipids are vulnerable to oxidative radicals, and uncontrolled lipid peroxidation affects cell viability. Cells have evolved quality control and defense mechanisms, of which the genetic regulation is not fully understood. Here, we identify what we have coined the Lipid Oxygen Radical Defense (LORD) pathway. It is epigenetically repressed by a complex comprising the KRAB-zinc finger protein ZNF354A, the scaffold protein KAP1/TRIM28, the histone methyltransferase SETDB1, and the transcriptional activator ATF2. Upon lipid peroxide accumulation, p38- and JNK-dependent phosphorylation of ATF2, KAP1/TRIM28, and ZNF354A leads to disassembly of the repressive complex, releasing ZNF354A from specific DNA loci and activating a network of protective genes, including NRF2 targets. The pathway affects the cellular sensitivity to oxidative stress and ferroptosis, revealing a previously uncharacterized layer of epigenetic control in lipid quality control and damage repair. This positions the LORD pathway as a promising therapeutic target for diseases linked to chronic inflammation, neurodegeneration and cancer.

ZNF93 is a primate-restricted Krüppel-associated box zinc finger protein responsible for repressing 20- to 12-My-old L1 transposable elements. Here, we reveal that ZNF93 also regulates the key cancer driver APOBEC3B—a mutagenic enzyme linked to tumorigenesis and cancer progression. ZNF93 depletion impairs DNA synthesis, activates replication and DNA damage checkpoints, and triggers proinflammatory phenotypes. Conversely, its overexpression enhances resistance to exogenous genotoxic stress, mirroring the effects observed with APOBEC3B depletion. ZNF93 expression correlates with cell proliferation rates and is overexpressed in many cancer types. These findings suggest that ZNF93 serves as a critical guardian of genome integrity, co-opted by cancer cells to counterbalance APOBEC3B-induced and L1-derived genomic instability and inflammation.

Membrane phospholipids are vulnerable to oxidative radicals, and uncontrolled lipid peroxidation affects cell viability. Cells have evolved quality control and defense mechanisms, of which the genetic regulation of is not fully understood. Here, we identify the Lipid Oxygen Radical Defense (LORD) pathway. It is epigenetically repressed, by a complex comprising the KRAB-zinc finger protein ZNF354A, the scaffold protein KAP1/TRIM28, the histone methyltransferase SETDB1, and the transcriptional activator ATF2. Upon lipid peroxide accumulation, p38- and JNK-dependent phosphorylation of ATF2, KAP1, and ZNF354A leads to disassembly of the repressive complex, releasing ZNF354A from specific DNA loci and activating a protective gene network, including NRF2 targets. The pathway thus controls cellular sensitivity to oxidative stress and ferroptosis, revealing a novel layer of epigenetic control in lipid quality control and damage defense. This positions the LORD pathway as a promising therapeutic target for diseases linked to chronic inflammation, neurodegeneration and cancer.