Biology subjects

Enserink, J. M.

Publications and source records attributed to Enserink, J. M..

13 recordsLinked to original sources

bioRxiv2026

The human leukemic fusion protein MLL-AF4 promotes autophagy and cell death in the fat body of Drosophila melanogaster

MLL-rearranged (MLLr) leukemia is an aggressive form of acute leukemia driven by chromosomal translocations fusing MLL with one of more than 100 partner genes, most commonly AF4. We previously showed that expression of the human MLL-AF4 fusion protein in the larval hematopoietic system of Drosophila melanogaster promotes hyperproliferation. Here, we report that the same oncogene elicits a strikingly opposite response in the larval fat body, inducing cell shrinkage, autophagy, and caspase-dependent cell death in a manner dependent on the intact fusion protein. Autophagy induction preceded caspase activation, yet the two programs operated in parallel rather than in series. Mechanistically, MLL-AF4-expressing fat body cells displayed elevated AMPK phosphorylation and reduced mTORC1 activity, and depletion of AMPK abolished caspase activation. Despite producing opposite phenotypes, both tissue-specific responses depended on conserved complex partners, suggesting that MLL-AF4 co-opts a shared mechanism to produce starkly different outcomes depending on cellular context. Uncovering how MLL-AF4 induces apoptosis-like phenotypes in the fat body could potentially be used to rewire leukemic signaling and remove malignant cells.

cancer biology↗

bioRxiv2026

SQSTM1/p62 accumulation is a hallmark of FLCN loss in Birt-Hogg-Dube syndrome-associated kidney cancer

Birt-Hogg-Dube syndrome (BHD) is an autosomal, dominant condition caused by Folliculin (FLCN) mutation and characterized by enhanced risk for kidney tumors. Previous studies have shown constitutive nuclear localization of the transcription factor TFEB and simultaneous hyperactivation of canonical MTORC1 signaling in the absence of FLCN. Here we assess the impact on autophagy under this situation of combined anabolic and catabolic activation. Using an established BHD patient-derived kidney cancer cell line, we confirmed that TFEB was permanently localized in the nucleus combined with an increase in canonical MTORC1 signaling, whereas bulk autophagy flux and LC3 lipidation was unaffected by FLCN status. However, we found that the autophagy receptor SQSTM1/p62 accumulated in enlarged puncta in the absence of FLCN. Finally, we recapitulate these findings in a Norwegian cohort of BHD kidney tumor samples. Our results demonstrate SQSTM1/p62 accumulation as a hallmark of FLCN loss, although SQSTM1/p62 appeared dispensable for anchorage-independent growth.

cancer biology↗

bioRxiv2025

Perturbational fitness analysis of CRISPR screens uncovers information-theoretic relation between gene function and selection

Despite major advances in genetic screening technology, a formal approach for quantifying gene function remains underdeveloped, thereby limiting the utility of these techniques in deciphering the complex behavior of human cells. In this study, we leverage information theory with a perturbational analysis of replicator dynamics to characterize functional drivers of selection in pooled CRISPR screens. Our approach challenges established methods for CRISPR screen analysis, while offering additional insight into selection dynamics through the Kullback-Leibler divergence (DKL) and cumulants of the fitness distribution. By modeling fluctuations in gene-fitness effects as a linear response to environmental perturbations, we derive a geometric measure for genomic information content based on a second-order approximation of the DKL. Our analysis reveals that functional information--encoded (or shared) between genes--can be quantified by analyzing the directions corresponding to maximal conditional selection within the space of decomposed gene-environment interactions. This geometric representation offers several advantages for the functional analysis of the human genome and its network architecture. Moreover, by constraining the space to cell-type-specific fluctuations, we uncover developmental and tissue-specific functional signatures. These findings represent significant progress in the dynamic analysis of gene function and in the functional wiring of the human genome.

systems biology↗

bioRxiv2025

SUMOylation Restricts Adaptive Thermogenesis by Suppressing Beiging Gene Networks

SUMOylation regulates chromatin states and transcriptional programs that preserve cellular identity, yet how transient perturbation of the SUMO pathway impacts adipocyte plasticity remains unclear. Here we show that brief pharmacologic inhibition of SUMO conjugation in human pre-adipocytes using TAK-981 primes stable de novo beige differentiation in the presence of the PPARG agonist rosiglitazone. Transient TAK-981 exposure before adipogenic induction produces long-lasting changes in the transcriptome and metabolism of mature adipocytes, including robust induction of canonical beiging markers like UCP1 and increased mitochondrial respiration. Mechanistically, ATAC-seq and transcription factor footprinting revealed immediate and durable chromatin remodeling and early mobilization of CEBP family members, followed by stable activation of CEBPA and PPARG regulatory networks. ChIP experiments demonstrated loss of H3K27me3 and gain of H3K27ac at PPAR response elements within key thermogenic enhancers, with increased PPARG occupancy across the UCP1 regulatory unit. This mechanism is enforced by enhanced cAMP-PKA-p38 signaling, and stabilization of beiging transcriptional activators. Our data support a model in which transient relief of SUMO-mediated repression unlocks dominant regulatory units, notably the UCP1 enhancer cluster, producing a monomorphic, cell type specific reprogramming toward adaptive thermogenesis. These findings identify SUMOylation as a reversible epigenetic barrier to adipocyte beiging and suggest that temporally controlled SUMO pathway inhibition combined with PPARG activation could be exploited to modulate adipose tissue thermogenic capacity. Graphical abstract O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=85 SRC="FIGDIR/small/642034v3_ufig1.gif" ALT="Figure 1"> View larger version (15K): org.highwire.dtl.DTLVardef@9efd29org.highwire.dtl.DTLVardef@1fecda3org.highwire.dtl.DTLVardef@16eb784org.highwire.dtl.DTLVardef@1d25683_HPS_FORMAT_FIGEXP M_FIG C_FIG SUMOylation restricts de novo differentiation of pre-adipocytes into beige adipocytes by repressing cAMP signaling and preventing epigenetic and transcriptional reprogramming of white adipocytes.

molecular biology↗

bioRxiv2024

Genome-wide profiling of the hierarchical control of autophagy dynamics using deep learning

Recycling of cellular components through autophagy maintains homeostasis in dynamic nutrient environments, and its dysregulation is linked to several human disorders. Although extensive research has characterized the core mechanisms of autophagy, limited insight into its systems-wide dynamic control has hampered predictive modeling and effective in vivo manipulation. In this study, we mapped the genetic network that controls both the dynamic activation and inactivation of autophagy during nitrogen changes, using a combination of time-resolved high-content imaging, deep learning, and latent feature analysis. This approach generated a comprehensive genome-wide profiling repository, termed AutoDRY, categorizing 5919 mutants based on their nutrient response kinetics and differential contributions to autophagosome formation and clearance. Integrating these profiles with functional and genetic network data unveiled a hierarchical and multi-layered control of autophagy, identifying new regulatory aspects of the core machinery and established nutrient-sensing pathways. By leveraging multi-omics resources and explainable machine learning to predict genetic perturbation effects and infer new regulatory mechanisms, we identified the retrograde pathway as a pivotal, time-varying autophagy modulator through transcriptional tuning of core genes. By charting the systems-wide dynamical control of autophagy, we have laid the groundwork for connecting the complexity of genome-wide influences with specific core mechanisms. This represents a significant advancement in studying complex genetic phenotypes, guides functional genomics of dynamic cellular processes in any organism, and provides a powerful starting point for hypothesis-based research on autophagy.

systems biology↗

bioRxiv2022

The human leukemic oncogene MLL-AF4 promotes hyperplastic growth of hematopoietic tissues in Drosophila larvae

MLL-rearranged leukemias are among the leukemic subtypes with poorest survival, and treatment options have barely improved over the last decades. Furthermore, despite increasing molecular understanding of the mechanisms behind these hematopoietic malignancies, this knowledge has had poor translation into the clinic. Identification of novel treatment methods is hampered by the lack of relevant in vivo models that allow for rapid identification of actionable drug targets and small molecule inhibitors. Here, we report a Drosophila melanogaster model system to explore the pathways affected in MLL-rearranged leukemia. We show that expression of the human leukemic oncogene MLL-AF4 in the Drosophila hematopoietic system resulted in increased levels of circulating hemocytes and an enlargement of the larval hematopoietic organ, the lymph gland. Strikingly, depletion of Drosophila orthologs of known interactors of MLL-AF4, such as DOT1L, rescued the leukemic phenotype. In agreement, treatment with small-molecule inhibitors of DOT1L also prevented the MLL-AF4-induced leukemia-like phenotype. Taken together, this model provides an in vivo system to unravel the genetic interactors involved in leukemogenesis and offers a strategy for a prompt identification of potential therapeutic options for treatment of MLL-rearranged leukemia.

cancer biology↗

bioRxiv2022

metascreen: A modular tool for the design and analysis of drug combination screens

There is a rapidly growing interest in high-throughput drug combination screening to identify synergizing drug interactions for treatment of various maladies, such as cancer and infectious disease. This creates the need for pipelines that can be used to design such screens, perform quality control on the data, and generate data files that can be analyzed by synergy-finding bioinformatics applications. metascreen is an open source, end-to-end modular tool available as an R-package for the design and analysis of drug combination screens. The tool allows for a customized build of pipelines through its modularity and provides a flexible approach to quality control and data analysis. metascreen is adaptable to various experimental requirements with an emphasis on precision medicine. It can be coupled to other R packages, such as bayesynergy, to identify synergistic and antagonistic drug interactions in cell lines or patient samples. metascreen is scalable and provides a complete solution for setting up drug sensitivity screens, read raw measurements and consolidate different datasets, perform various types of quality control, and analyze, report and visualize the results of drug sensitivity screens. Availability and implementationThe R-package and technical documentation is available at https://github.com/Enserink-lab; the R source code is publicly available at https://github.com/Enserink-lab/metascreen under GNU General Public License v3.0; bayesynergy is accessible at https://github.com/ocbe-uio/bayesynergy/ Selected modules will be available through Galaxy, an open-source platform for FAIR data analysis, Norway: https://usegalaxy.no

bioinformatics↗

bioRxiv2022

Mitotic chromosome condensation resets chromatin to maintain transcriptional homeostasis

Mitotic entry correlates with the condensation of the chromosomes, remodeling of histone modifications, exclusion of transcription factors from DNA and the broad downregulation of transcription. However, whether mitotic condensation influences transcription in the subsequent interphase is unknown. Here, we show that preventing one chromosome to condense during mitosis causes it to fail resetting transcription. Rather it diverted the transcription machinery and underwent unscheduled initiation of gene expression. This caused the activation of inducible transcriptional programs, such as the GAL genes, even in absence of the relevant stimuli. Strikingly, aberrant gene expression persisted into the next interphase. Thus, our study identifies the maintenance of transcriptional homeostasis as an unexpected and yet unexplored function of mitotic chromosome condensation. One-Sentence SummaryMitotic chromatin condensation resets the transcriptome to protect cells from transcriptional drifting after anaphase.

molecular biology↗

bioRxiv2022

Phenotypic deconvolution in heterogeneous cancer cell populations using drug screening data

Tumor heterogeneity is an important driver of treatment failure in cancer since therapies often select for drug-tolerant or drug-resistant cellular subpopulations that drive tumor growth and recurrence. Profiling the drug-response heterogeneity of tumor samples using traditional genomic deconvolution methods has yielded limited results, due in part to the imperfect mapping between genomic variation and functional characteristics. Here, we leverage mechanistic population modeling to develop a statistical framework for profiling phenotypic heterogeneity from standard drug screen data on bulk tumor samples. This method, called PhenoPop, reliably identifies tumor subpopulations exhibiting differential drug responses, and estimates their drug-sensitivities and frequencies within the bulk. We apply PhenoPop to synthetically-generated cell populations, mixed cell-line experiments, and multiple myeloma patient samples, and demonstrate how it can provide individualized predictions of tumor growth under candidate therapies. This methodology can also be applied to deconvolution problems in a variety of biological settings beyond cancer drug response. MotivationTumors are typically comprised of heterogeneous cell populations exhibiting diverse phenotypes. This heterogeneity, which is correlated with tumor aggressiveness and treatment failure, confounds current drug screening efforts aimed at informing therapy selection. In order to optimally select treatments, understanding the frequency and drug-response profile of individual subpopulations within a tumor is critical. Furthermore, quantitative profiles of tumor drug-response heterogeneity, in combination with predictive mathematical modeling of tumor dynamics, can be used to design effective temporal drug-sequencing strategies for tumor reduction. Here, we present a method that enables the deconvolution of tumor samples into individual sub-components exhibiting differential drug-response. This method relies on standard bulk drug-screen measurements and outputs the frequencies and drug-sensitivities of tumor subpopulations. This framework can also be applied more broadly to deconvolve cellular populations with heterogeneous responses to a variety of external stimuli and environmental factors.

cancer biology↗

bioRxiv2021

Waves of sumoylation support transcription dynamics during adipocyte differentiation

Tight control of gene expression networks required for adipose tissue formation and plasticity is essential for adaptation to energy needs and environmental cues. However, little is known about the mechanisms that orchestrate the dramatic transcriptional changes leading to adipocyte differentiation. We investigated the regulation of nascent transcription by the sumoylation pathway during adipocyte differentiation using SLAMseq and ChIPseq. We discovered that the sumoylation pathway has a dual function in differentiation; it supports the initial downregulation of pre-adipocyte-specific genes, while it promotes the establishment of the mature adipocyte transcriptional program. By characterizing sumoylome dynamics in differentiating adipocytes by mass spectrometry, we found that sumoylation of specific transcription factors like Ppar{gamma}/RXR and their co-factors is associated with the transcription of adipogenic genes. Our data demonstrate that the sumoylation pathway coordinates the rewiring of transcriptional networks required for formation of functional adipocytes. This study also provides an in-depth resource of gene transcription dynamics, SUMO-regulated genes and sumoylation sites during adipogenesis.

genomics↗

bioRxiv2020

Rala and the exocyst control Pvr trafficking and signaling to ensure lymph gland homeostasis in Drosophila melanogaster

The balance between hematopoietic progenitors and differentiated hemocytes is finely tuned during development. In the larval hematopoietic organ of Drosophila, called the lymph gland, the receptor tyrosine kinase Pvr signals from differentiated cells to maintain a pool of undifferentiated progenitors. However, little is known about the processes that support Pvr function. The small GTPase Ral is involved in the regulation of several membrane trafficking events. Drosophila has a single Ral protein, Rala, which has been implicated in the development of various tissues. Here, we investigated the involvement of Rala in the larval fly hematopoietic system. We discovered that the loss of Rala activity phenocopies Pvr loss of function by promoting hemocyte progenitor differentiation. Moreover, using epistasis analysis, we found that the guanine exchange factor RalGPS lies upstream of Rala in this event, whereas the exocyst and Rab11 are acting downstream. Strikingly, the loss of Rala activity leads to a considerable accumulation of Pvr at the plasma membrane, hence suggesting a trafficking defect and reduced Pvr function. Consistent with this hypothesis, Rala loss of function phenotype in the lymph gland is fully suppressed by constitutive STAT activity, which normally mediates Pvr function in the lymph gland. Together, our findings unravel a novel RalGPS-Rala-exocyst-Rab11 axis for the maintenance of lymph gland homeostasis through Pvr.

developmental biology↗

bioRxiv2020

A cell competition-based drug screen identifies a novel compound that induces dual c-Myc degradation and p53 activation

BCR-Abl is a driver oncogene that causes chronic myeloid leukemia and a subset of acute lymphoid leukemias. Although tyrosine kinase inhibitors provide an effective treatment for these diseases, they generally do not kill leukemic stem cells. Leukemic stem cells are cancer-initiating cells that compete with normal hematopoietic stem cells for the bone marrow niche. Using BCR-Abl as a model oncogene, we performed a drug screen based on competition between isogenic untransformed cells and BCR-Abl-transformed cells, and identified several compounds that selectively target BCR-Abl-transformed cells. Systems-level analysis of one of these novel compounds, DJ34, revealed that it induced depletion of c-Myc and activation of p53. c-Myc depletion occurred in a wide range of tumor types, including leukemia, lymphoma, lung, glioblastoma and breast cancer. Further analyses revealed that DJ34 interferes with c-Myc synthesis at the level of transcription, and we provide data showing that DJ34 is a DNA intercalator and topoisomerase II inhibitor. Physiologically, DJ34 induced apoptosis, cell cycle arrest and cell differentiation, and primary leukemic stem cells were particularly sensitive to DJ34. Taken together, we have identified a novel compound that dually targets c-Myc and p53 in a wide variety of cancers, and with particularly strong activity against leukemic stem cells.

cancer biology↗

bioRxiv2018

Increased Adhesion Of CML Cells By ABL1 Tyrosine Kinase Inhibitors Induce Tunneling Nanotubes

Summary statementThis study describes the effects of tyrosine kinase inhibitors on tunneling nanotube formation via increased adhesion through {beta}-integrin in chronic myeloid leukemia cells.\n\nAbstractThe actin-containing cell-to-cell communicator tunneling nanotube (TNT) is involved in regulation of cell death threshold of leukemic cells, while the mechanism of TNT regulation is mostly unknown. We have investigated TNT formation and its response to treatment in chronic myeloid leukemia (CML) cells with the pathognomonic chimeric fusion kinase BCR-ABL1 after treatment with the tyrosine kinase inhibitor nilotinib and interferon-. Bone marrow cells of chronic phase CML patients and the CML cell line Kcl-22 formed few or no TNTs. Nilotinib and interferon- treatment induced TNT formation in Kcl-22 cells and were found to be linked to increased adherence to fibronectin coated surfaces by restoration of {beta}1-integrin function. This suggests modulation of TNT cell-cell communication in CML as a novel mechanism in kinase inhibitor therapy of CML.

cell biology↗