Ashouri, A. | bioRxiv Science

bioRxiv2026

Somatic Genome Diversification and Clonal Evolution of Pathogenic B Cells in Systemic Autoimmunity

Systemic autoimmune rheumatic diseases are characterized by persistent immune activation and clinical heterogeneity, yet the molecular processes sustaining and diversifying pathogenic immune states remain incompletely understood. Here, we investigate somatic genome diversification as a potential driver of immune variation and disease progression. Using Systemic Lupus Erythematosus as a model disease, we generated a subset-resolved map of somatic mutations across B-cell subsets from 35 patients. Double-negative (DN) B cells carried the highest mutational burden, which was associated with disease duration and immunosuppressive therapy, rather than with disease activity. Integration with single-cell transcriptomes linked DN mutations to dysregulated signalling and proteostasis. Notably, DN cells harboured mutations in genes recurrently altered in B-cell lymphomas. Together, these findings identify somatic genome diversification as a feature of pathogenic B-cell subsets and provide a resource for understanding how chronic stimulation and therapeutic pressure shape the clonal evolution of autoimmunity. KEY POINTSO_LIDouble-negative B cells in SLE carry the highest somatic mutational burden among circulating B-cell subsets and show evidence of treatment-associated mutational processes. C_LIO_LIPathogenic variants in DN cells are acquired de novo or through selective expansion of pre-existing variant-bearing clones. C_LIO_LIAcquisition of lymphoma-relevant mutations by DN cells is common, supporting a molecular-level linkage between chronic systemic autoimmunity and B-cell malignancies. C_LIO_LIThe high-depth, subset-resolved map provides a foundational resource for the functional prioritization of variants and the development of targeted sequencing strategies for monitoring pathogenic clones. C_LI

genomics↗

bioRxiv2022

Reduced mitochondrial transcription sensitizes acute myeloid leukemia cells to BCL-2 inhibition

Overcoming drug-resistance and the subsequent relapse that often occurs with monotherapy is crucial in the treatment of acute myeloid leukemia. We here demonstrate that therapy-resistant leukemia initiating cells can be targeted using a novel inhibitor of mitochondrial transcription (IMT). The compound inhibits mitochondrial RNA polymerase activity and sensitizes the resistant population to the induction of apoptosis. In vitro studies on acute myeloid leukemia cells demonstrate that IMT prevents cell proliferation, and together with a selective BCL-2 inhibitor, venetoclax, induces apoptosis and suppress oxidative phosphorylation (OXPHOS) synergistically. AML mouse models treated with IMT in combination with venetoclax show prolonged survival in venetoclax-resistant models. Our findings suggest that certain therapy-resistant leukemia cell populations display a unique dependency on mitochondrial transcription and can be targeted with IMT.

cancer biology↗

bioRxiv2020

Genome-wide imaging screen uncovers molecular determinants of arsenite-induced protein aggregation and toxicity and an important role for transcriptional and translational control

Exposure to toxic metals and metalloids such as cadmium and arsenic results in widespread misfolding and aggregation of cellular proteins. How these protein aggregates are formed in vivo, the mechanisms by which they affect cells, and how cells prevent their accumulation during environmental stress is not fully understood. To find components involved in these processes, we performed a genome-wide imaging screen and identified yeast deletion mutants with either enhanced or reduced protein aggregation levels during arsenite exposure. Mutants with reduced aggregation levels were enriched for functions related to protein biosynthesis and transcription, whilst functions related to cellular signalling, metabolism, and protein folding and degradation were overrepresented among mutants with enhanced aggregation levels. On a genome-wide scale, protein aggregation correlated with arsenite resistance and sensitivity, indicating that many of the identified factors are crucial to safeguard protein homeostasis (proteostasis) and to protect against arsenite toxicity. Dedicated follow-up experiments indicated that intracellular arsenic is a direct cause of protein aggregation and that accurate transcriptional and translational control are crucial for proteostasis during arsenite stress. Specifically, we provide evidence that global transcription affects protein aggregation levels, that loss of transcriptional control impacts proteostasis through distinct mechanisms, and that translational repression is central to control protein aggregation and cell viability. Some of the identified factors are associated with pathological conditions suggesting that arsenite-induced protein aggregation may impact disease processes. The broad network of cellular systems that impinge on proteostasis during arsenic stress provides a valuable resource and a framework for further elucidation of the mechanistic details of metalloid toxicity and pathogenesis. AUTHOR SUMMARYHuman exposure to poisonous metals is increasing in many parts of the world and chronic exposure is associated with certain protein folding-associated disorders such as Alzheimers disease and Parkinsons disease. While the toxicity of many metals is undisputed, their molecular modes of action have remained unclear. Recent studies revealed that toxic metals such as arsenic and cadmium profoundly affect the correct folding of proteins, resulting in the accumulation of toxic protein aggregates. In this study, we used high-content microscopy to identify a broad network of cellular systems that impinge on protein homeostasis and cell viability during arsenite stress. Follow-up experiments highlight the importance of accurate transcriptional and translational control for mitigating arsenite-induced protein aggregation and toxicity. Some of the identified factors are associated with pathological conditions suggesting that arsenite-induced protein aggregation may impact disease processes. The broad network of cellular systems that impinge on proteostasis during arsenic stress provides a valuable resource and a framework for further elucidation of the mechanistic details of metal toxicity and pathogenesis.

cell biology↗