Biology subjects

Aifantis, I.

Publications and source records attributed to Aifantis, I..

At least 19 recordsLinked to original sources

bioRxiv2026

Cell autonomous inflammation in VEXAS is mediated by cGAS-STING

VEXAS (vacuoles, E1 enzyme, X-linked, autoinflammatory, somatic) is a severe adult-onset inflammatory disease caused by somatic mutations that reduce cytoplasmic activity of UBA1, the primary initiating enzyme for ubiquitylation. How this hypomorphic state drives cell-intrinsic immune activation in mature myeloid cells is unknown. Using unbiased multi-omic, biochemical, and cell biological analyses of model systems and patient-derived cells, we show that loss of cytoplasmic UBA1 activity convergently disrupts endoplasmic reticulum- associated degradation (ERAD) and mitochondrial homeostasis. ERAD failure arises from preferential under-charging of ERAD E2 enzymes, explaining hallmark VEXAS features, including ER-derived vacuoles and unfolded protein response activation, and promotes accumulation of the ERAD substrate STING. Simultaneously, mitochondrial dysfunction drives cytosolic leakage of mitochondrial DNA, inducing cGAS-dependent STING signaling and inflammatory cytokine production. STING inhibition or reversal of mitochondrial DNA leakage resolves multi-cytokine inflammation in VEXAS models and patient myeloid cells, establishing the cGAS-STING pathway as a therapeutically actionable vulnerability.

genetics↗

bioRxiv2026

Chromatin architecture and physical constriction cooperate in phenotype switching and cancer cell dissemination

Phenotypic plasticity is a prominent cancer feature that contributes to metastatic potential and resistance to therapy across multiple cancer types. Cancer cell state transitions have been attributed to transcriptional programs, such as the AP1/TEAD-regulated gene network driving the mesenchymal-like (MES) phenotype. In addition, during dissemination, tumor cells are subjected to variable loads of physical mechanical pressure and constriction across transited tissue, which are thought to impact nuclear molecular crowding. How the interplay between mechanical pressure, global 3D nuclear architecture and transcriptional programs contributes to MES identity and metastatic adaptation remains unclear. Using cutaneous melanoma as a model for early dissemination, we integrate in vitro and in vivo epigenomic profiling with nanoscale imaging of cell lines and patient samples to investigate chromatin organization features underlying the MES phenotype. We find that in MES cells, CTCF is relocated from domain boundaries to regulatory regions of EMT-like genes, leading to reduced insulation, extended topological associated domains (TADs) and increased inter-domain contacts, and de novo formation of chromatin hubs. This conformational rewiring, along with loss of heterochromatin, supports nuclear deformability during invasion and dissemination. Conversely, physical constriction of melanocytic cells induces MES-like chromatin features--including CTCF repositioning and heterochromatin loss-- and promotes metastasis in vivo. Similarly, pharmacological inhibition of the heterochromatin mark H3K9me3 triggers MES characteristics and increases invasiveness. These results demonstrate that metastatic competency involves both epigenetic and structural nuclear reprogramming, enabling shifts in gene networks and physical adaptability. Our findings reveal mechanistic links between nuclear architecture and aggressive tumor behavior, identifying potential biomarkers and therapeutic targets to intercept metastatic progression.

cancer biology↗

bioRxiv2025

TASC: A transcriptome-driven machine learning classifier to explore molecular heterogeneity and relapse-associated programs in T-cell Acute Lymphoblastic Leukemia

T-cell acute lymphoblastic leukemia is a biologically heterogeneous malignancy characterized by diverse transcriptional and genomic alterations. Recent studies have defined a set of recurrent molecular subtypes associated with distinct differentiation stages and clinical outcomes. However, no unified framework currently exists for assigning these subtypes in a standardized and accessible manner. Existing approaches often rely on mutation or fusion detection and may overlook broader transcriptional programs. The lack of a comprehensive, transcriptome-based classification tool has hampered the use of subtype-specific insights in both research and clinical settings. Here, we present a machine learning-based classifier trained on transcriptomic data to predict previously defined multi-omic subtypes of T-cell acute lymphoblastic leukemia. The model accurately assigns subtype identity across patient samples and cell lines, and provides a practical tool for standardized molecular stratification, supporting future integration into diagnostic and translational workflows, as demonstrated by its ability to reveal subtype-specific patterns of relapse.

bioinformatics↗

bioRxiv2025

A K27-linked Ubiquitin Checkpoint Controls NOTCH Homeostasis

Cell surface receptors such as NOTCH1 must be tightly regulated to ensure developmental fidelity and prevent pathological activation. Although the proteolytic steps culminating in nuclear NOTCH1 signaling are established, how cells prevent excessive or uncontrolled activation has remained unresolved. Here we identify the autophagy-related protein UVRAG as a negative regulator of NOTCH1. Upon receptor activation, UVRAG, acting independently of autophagy, recruits and activates the E3-ligase ITCH to catalyze K27-linked ubiquitination of membrane-tethered NOTCH1, thereby licensing ESCRT-dependent lysosomal degradation. Disruption of the UVRAG-ITCH-ESCRT axis stabilizes activated NOTCH1 intermediates and amplifies oncogenic signaling. In T-cell leukemia models driven by constitutive NOTCH1 activity, restoring UVRAG expression reinstates receptor turnover, suppresses disease progression, and improves therapeutic response. These findings define a ubiquitin-directed safeguard circuit that enforces NOTCH1 signaling homeostasis and reveals a tunable axis for intervention in NOTCH1-driven cancers.

molecular biology↗

bioRxiv2025

Multiomic characterization, early detection, and therapeutic targeting of myeloid sarcoma

Myeloid sarcoma, an aggressive extramedullary subtype of acute myeloid leukemia (AML), occurs in [~]10% of patients, and has not yet been included in large-scale genomic studies. The critical biological changes that drive tumor evolution are unknown, its detection in asymptomatic patients remains a clinical challenge, and treatment options are limited as patients are often excluded from clinical trials, rendering it a neglected disease entity. Based on comprehensive multi-omic profiling, we demonstrate that myeloid sarcoma evolves from medullary AML with distinct sitespecific clonal evolution patterns. Additionally, we show that circulating tumor DNA sequencing can serve as a non-invasive method for molecular profiling of myeloid sarcoma, offering a novel avenue in molecular diagnostics. We characterize unique transcriptional profiles of myeloid sarcoma, reflecting immune evasion and adaptation to an extramedullary microenvironment. We provide evidence for a key role of RAS pathway activation and demonstrate in murine models of myeloid sarcoma that RAS inhibition effectively reduces tumor burden. Overall, our data highlight key differences between medullary AML and myeloid sarcoma including universal molecular evolution and RAS pathway activation as hallmarks of the disease and nominate RAS inhibition as a promising therapeutic strategy for patients with myeloid sarcoma.

cancer biology↗

bioRxiv2024

RNA Binding of GAPDH Controls Transcript Stability and Protein Translation in Acute Myeloid Leukemia

Dysregulation of RNA binding proteins (RBPs) is a hallmark in cancerous cells. In acute myeloid leukemia (AML) RBPs are key regulators of tumor proliferation. While classical RBPs have defined RNA binding domains, RNA recognition and function in AML by non-canonical RBPs (ncRBPs) remain unclear. Given the inherent complexity of targeting AML broadly, our goal was to uncover potential ncRBP candidates critical for AML survival using a CRISPR/Cas-based screening. We identified the glycolytic enzyme glyceraldehyde-3-phosphate dehydrogenase (GAPDH) as a pro-proliferative factor in AML cells. Based on cross-linking and immunoprecipitation (CLIP), we are defining the global targetome, detecting novel RNA targets mainly located within 5UTRs, including GAPDH, RPL13a, and PKM. The knockdown of GAPDH unveiled genetic pathways related to ribosome biogenesis, translation initiation, and regulation. Moreover, we demonstrated a stabilizing effect through GAPDH binding to target transcripts including its own mRNA. The present findings provide new insights on the RNA functions and characteristics of GAPDH in AML.

cancer biology↗

bioRxiv2024

CRISPR-inhibition screen for lncRNAs linked to melanoma growth and metastasis

Melanoma being one of the most common and deadliest skin cancers, has been rising since the past decade. Patients at advanced stages of the disease have very poor prognoses, as opposed to at the earlier stages. Nowadays the standard-of-care of advanced melanoma is resection followed by immune checkpoint inhibition based immunotherapy. However, a substantial proportion of patients either do not respond or develop resistances. This underscores a need for novel approaches and therapeutic targets as well as a better understanding of the mechanisms of melanoma pathogenesis. Long non-coding RNAs (lncRNAs) comprise a poorly characterized class of functional players and promising targets in promoting malignancy. Certain lncRNAs have been identified to play integral roles in melanoma progression and drug resistances, however systematic screens to uncover novel functional lncRNAs are scarce. Here, we profile differentially expressed lncRNAs in patient derived short-term metastatic cultures and BRAF-MEK-inhibition resistant cells. We conduct a focused growth-related CRISPR-inhibition screen of overexpressed lncRNAs, validate and functionally characterize lncRNA hits with respect to cellular growth, invasive capacities and apoptosis in vitro as well as the transcriptomic impact of our lead candidate the novel lncRNA XLOC_030781. In sum, we extend the current knowledge of ncRNAs and their potential relevance on melanoma. SignificancePreviously considered as transcriptional noise, lncRNAs have emerged as novel players in regulating many cellular aspects in health and disease including melanoma. However, the number and as well as the extent of functional significance of most lncRNAs remains elusive. We provide a comprehensive strategy to identify functionally relevant lncRNAs in melanoma by combining expression profiling with CRISPR-inhibition growths screens lowering the experimental effort. We also provide a larger resource of differentially expressed lncRNAs with potential implications in melanoma growth and invasion. Our results broaden the characterized of lncRNAs as potential targets for future therapeutic applications.

cancer biology↗

bioRxiv2024

circPCMTD1: A protein-coding circular RNA that regulates DNA damage response in BCR/ABL-positive leukemias

Circular RNAs are a novel class of RNA transcripts, which regulate important cellular functions in health and disease. Herein, we report on the functional relevance of the circPCMTD1 transcript in acute leukemias. In screening experiments, we found that circPCMTD1 depletion strongly inhibited the proliferative capacity of leukemic cells with BCR-ABL translocations. Mass cytometry experiments identified the aberrant activation of the DNA damage response as an early downstream event of circPCMTD1 depletion. In in vivo experiments, circPCMTD1 targeting prolonged the survival of mice engrafted with leukemic blasts harboring the Philadelphia chromosome. Mechanistically, we found that circPCMTD1 was enriched in the cytoplasm and associated with the ribosomes of the leukemic cells. We detected a cryptic open reading frame within the circPCMTD1 sequence and found that circPCMTD1 could generate a peptide product. The circPCMTD1-derived peptide interacted with proteins of the BTR complex and enhanced BTR complex formation, thereby increasing tolerance to genotoxic stress.

cancer biology↗

bioRxiv2024

Interferon-sensitized hematopoietic progenitors dynamically alter organismal immunity

Inflammation has enduring impacts on organismal immunity. However, the precise mechanisms by which tissue-restricted inflammation conditions systemic responses are poorly understood. Here, we leveraged a highly compartmentalized model of skin inflammation and identified a surprising type I interferon (IFN)- mediated activation of hematopoietic stem/progenitor cells (HSPCs) that results in profound changes to systemic host responses. Post-inflamed mice were protected from atherosclerosis and had worse outcomes following influenza virus infection. This IFN-mediated HSPC modulation was dependent on IFNAR signaling and could be recapitulated with the administration of recombinant IFN. Importantly, the transfer of post-inflamed HSPCs was sufficient to transmit the immune suppression phenotype. IFN modulation of HSPCs was rooted both in long-term changes in chromatin accessibility and the emergence of an IFN- responsive functional state from multiple progenitor populations. Collectively, our data reveal the profound and enduring effect of transient inflammation and more specifically type I IFN signaling and set the stage for a more nuanced understanding of HSPC functional modulation by peripheral immune signals.

immunology↗

bioRxiv2023

Oncogenic drivers dictate immune control of acute myeloid leukemia.

Acute myeloid leukemia (AML) is a genetically heterogeneous, aggressive hematological malignancy induced by distinct oncogenic driver mutations. The effect of specific AML oncogenes on immune activation or suppression has not been investigated. Here, we examine immune responses in genetically distinct models of AML and demonstrate that specific AML oncogenes dictate immunogenicity, the quality of immune response and immune escape through immunoediting. Specifically, expression of NrasG12D alone is sufficient to drive a potent anti-leukemia response through increased MHC Class II expression that can be overcome with increased expression of Myc. These data have important implications for the design and implementation of personalized immunotherapies for patients with AML. Statement of SignificanceThe endogenous immune response against acute myeloid leukemia (AML) is determined by leukemia-specific oncogenic driver mutations. Mutant Nras drives immunological selection of AML.

cancer biology↗

bioRxiv2022

Germline Transmission of a Circular Human Artificial Chromosome in the Mouse

Although the structure and function of the alphoid-tetO Human Artificial Chromosome (tetO-HAC) has been previously described in cell culture models and somatically in the mouse, in vivo persistence and stability throughout meiosis and across generations were not evaluated. Here we report germline transmission of a circular tetO-HAC across three mouse generations without observable health or reproductive deficiencies. Furthermore, we show that the tetO-HAC is maintained without selection as an episome and can be efficiently transmitted by both ova and sperm.

synthetic biology↗

bioRxiv2022

Cell type-specific prediction of 3D chromatin architecture

The mammalian genome is spatially organized in the nucleus to enable cell type-specific gene expression. Investigating how chromatin organization determines this specificity remains a challenge. Methods for measuring the 3D chromatin organization, such as Hi-C, are costly and bear strong technical limitations, restricting their broad application particularly in high-throughput genetic perturbations. In this study, we present C.Origami, a deep neural network model that performs de novo prediction of cell type-specific chromatin organization. The C.Origami model enables in silico experiments to examine the impact of genetic perturbations on chromatin interactions in cancer genomes and beyond. In addition, we propose an in silico genetic screening framework that enables high-throughput identification of impactful genomic regions on 3D chromatin organization. We demonstrate that cell type-specific in silico genetic perturbation and screening, enabled by C.Origami, can be used to systematically discover novel chromatin regulatory mechanisms in both normal and disease-related biological systems.

genomics↗

bioRxiv2021

Antigen presentation by type 3 innate lymphoid cells instructs the differentiation of gut microbiota-specific regulatory T cells

The mutualistic relationship of gut-resident microbiota and cells of the host immune system promotes homeostasis that ensures maintenance of the microbial community and of a poised, but largely non-aggressive, immune cell compartment1, 2. Consequences of disturbing this balance, by environmental or genetic factors, include proximal inflammatory conditions, like Crohns disease, and systemic illnesses, both metabolic and autoimmune. One of the means by which this equilibrium is achieved is through induction of both effector and suppressor or regulatory arms of the adaptive immune system. In mice, Helicobacter species induce regulatory (iTreg) and follicular helper (Tfh) T cells in the colon-draining mesenteric lymph nodes under homeostatic conditions, but can instead induce inflammatory Th17 cells when iTreg cells are compromised3, 4. How Helicobacter hepaticus and other gut bacteria direct T cells to adopt distinct functions remains poorly understood. Here, we investigated which cells and molecular components are required to convey the microbial instruction for the iTreg differentiation program. We found that antigen presentation by cells expressing ROR{gamma}t, rather than by classical dendritic cells, was both required and sufficient for iTreg induction. These ROR{gamma}t+ cells, likely to be type 3 innate lymphoid cells (ILC3) and/or a recently-described population of Aire+ cells termed Janus cells5, require the MHC class II antigen presentation machinery, the chemokine receptor CCR7, and v integrin, which activates TGF-{beta}, for iTreg cell differentiation. In the absence of any of these, instead of iTreg cells there was expansion of microbiota-specific pathogenic Th17 cells, which were induced by other antigen presenting cells (APCs) that did not require CCR7. Thus, intestinal commensal microbes and their products target multiple APCs with pre-determined features suited to directing appropriate T cell differentiation programs, rather than a common APC that they endow with appropriate functions. Our results illustrate the ability of microbiota to exploit specialized functions of distinct innate immune system cells, targeting them to achieve the desired composition of equipoised T cells, thus maintaining tolerance.

immunology↗

bioRxiv2021

SOX2-phosphorylation toggles a bistable differentiation-switch in squamous cell carcinoma

The fate choice between stem cell self-renewal and differentiation is regulated by bistable transcriptional networks, which are balanced in homeostasis and imbalanced in tumors. Yet, how stem cells switch from self-renewal to differentiation remains a conundrum. Here, we discover a molecular mechanism that allows stem cell-like tumor propagating cells (TPCs) in squamous cell carcinomas (SCCs) to switch from a mutually exclusive SOX2-PITX1-TP63 self-renewal circuit to a KLF4 driven differentiation program, dependent on the relative occupancy of a novel Klf4-regulatory enhancer cluster (Klf4EC944) by SOX2 or KLF4, respectively. We find SOX2 occupies this site in TPCs to inhibit Klf4 transcription, but upon phosphorylation SOX2 becomes evicted from Klf4EC944, allowing residual KLF4 to occupy this site instead, boost the expression of KLF4 and its downstream targets, and differentiate self-renewing TPCs into post-mitotic SCC cells. This mechanism allows SOX2 to promote self-renewal and tumor formation, while preserving the differentiation potential in SCC cells. Our data suggest that stochastic cell fate decisions depend on the effective concentration of enzymatically regulated transcription factors. The surprising specificity by which SOX2-phosphorylation governs the bistable Klf4EC944 network-switch in SCCs reveals a conceptual framework for the identification of similar switches in other stem cell and cancer types and their potential development into cell type specific differentiation therapies for diseases in which tissue homeostasis has gone awry.

cancer biology↗

bioRxiv2020

High titers of multiple antibody isotypes against the SARS-CoV-2 spike receptor-binding domain and nucleoprotein associate with better neutralization.

Understanding antibody responses to SARS-CoV-2 is indispensable for the development of containment measures to overcome the current COVID-19 pandemic. Here, we determine the ability of sera from 101 recovered healthcare workers to neutralize both authentic SARS-CoV-2 and SARS-CoV-2 pseudotyped virus and address their antibody titers against SARS-CoV-2 nucleoprotein and spike receptor-binding domain. Interestingly, the majority of individuals have low neutralization capacity and only 6% of the healthcare workers showed high neutralizing titers against both authentic SARS-CoV-2 virus and the pseudotyped virus. We found the antibody response to SARS-CoV-2 infection generates antigen-specific isotypes as well as a diverse combination of antibody isotypes, with high titers of IgG, IgM and IgA against both antigens correlating with neutralization capacity. Importantly, we found that neutralization correlated with antibody titers as quantified by ELISA. This suggests that an ELISA assay can be used to determine seroneutralization potential. Altogether, our work provides a snapshot of the SARS-CoV-2 neutralizing antibody response in recovered healthcare workers and provides evidence that possessing multiple antibody isotypes may play an important role in SARS-CoV-2 neutralization.

microbiology↗

bioRxiv2019

Dynamic 3D chromosomal landscapes in acute leukemia

Three-dimensional (3D) chromatin architectural changes can alter the integrity of topologically associated domains (TADs) and rewire specific enhancer-promoter interactions impacting gene expression. Recently, such alterations have been implicated in human disease, highlighting the need for a deeper understanding of their role. Here, we investigate the reorganization of chromatin architecture in T cell acute lymphoblastic leukemia (T-ALL) using primary human leukemia specimens and its dynamic responses to pharmacological agents. Systematic integration of matched in situ Hi-C, RNA-Seq and CTCF ChIP-Seq datasets revealed widespread changes in intra-TAD chromatin interactions and TAD boundary insulation in T-ALL. Our studies identify and focus on a TAD \"fusion\" event being associated with loss of CTCF-mediated insulation, enabling direct interactions between the MYC promoter and a distal super-enhancer. Moreover, our data show that small molecule inhibitors targeting either oncogenic signal transduction or epigenetic regulation reduce specific 3D interactions associated with transformation. Overall, our study highlights the impact, complexity and dynamic nature of 3D chromatin architecture in human acute leukemia.\n\nOne Sentence Summary3D chromatin alterations in T cell leukemia are accompanied by changes in insulation and oncogene expression and can be partially restored by targeted drug treatments.

cancer biology↗

bioRxiv2017

Robust Estimation Of Hi-C Contact Matrices Using Fused Lasso Reveals Preferential Insulation Of Super-Enhancers By Strong TAD Boundaries

The metazoan genome is compartmentalized in megabase-scale areas of highly interacting chromatin known as topologically associating domains (TADs), typically identified by computational analyses of Hi-C sequencing data. TADs are demarcated by boundaries that are largely conserved across cell types and even across species, although, increasing evidence suggests that the seemingly invariant TAD boundaries may exhibit plasticity and their insulating strength can vary. However, a genome-wide characterization of TAD boundary strength in mammals is still lacking. A systematic classification and characterization of TAD boundaries may generate new insights into their function. In this study, we first use fused two-dimensional lasso as a machine learning method to improve Hi-C contact matrix reproducibility, and, subsequently, we categorize TAD boundaries based on their insulation score. We demonstrate that higher TAD boundary insulation scores are associated with elevated CTCF levels and that they may differ across cell types. Intriguingly, we observe that super-enhancer elements are preferentially insulated by strong boundaries, i.e. boundaries of higher insulation score. Furthermore, we perform a pan-cancer analysis to demonstrate that strong TAD boundaries and super-enhancer elements are frequently co-duplicated in cancer patients. Taken together, our findings suggest that super-enhancers insulated by strong TAD boundaries may be exploited, as a functional unit, by cancer cells to promote oncogenesis.

bioinformatics↗

bioRxiv2016

lncRNA-screen: an interactive platform for computationally screening long non-coding RNAs in large genomics datasets

Long non-coding RNAs (lncRNAs) have emerged as a class of factors that are important for regulating development and cancer. Computational prediction of lncRNAs from ultra-deep RNA sequencing has been successful in identifying candidate lncRNAs. However, the complexity of handling and integrating different types of genomics data poses significant challenges to experimental laboratories that lack extensive genomics expertise. To address this issue, we have developed lncRNA-screen, a comprehensive pipeline for computationally screening putative lncRNA transcripts over large multimodal datasets. The main objective of this work is to facilitate the computational discovery of lncRNA candidates to be further examined by functional experiments. lncRNA-screen provides a fully automated easy-to-run pipeline which performs data download, RNA-seq alignment, assembly, quality assessment, transcript filtration, novel lncRNA identification, coding potential estimation, expression level quantification, histone mark enrichment profile integration, differential expression analysis, annotation with other type of segmented data (CNVs, SNPs, Hi-C, etc.) and visualization. Importantly, lncRNA-screen generates an interactive report summarizing all interesting lncRNA features including genome browser snapshots and lncRNA-mRNA interactions based on Hi-C data. In summary, our pipeline provides a comprehensive solution for lncRNA discovery and an intuitive interactive report for identifying promising lncRNA candidates. lncRNA-screen is available as free open-source software on GitHub.

bioinformatics↗