Biology subjects

Superti-Furga, G.

Publications and source records attributed to Superti-Furga, G..

At least 19 recordsLinked to original sources

bioRxiv2026

The topology of transmembrane protein-protein interaction interfaces is encoded in their physicochemical features

Transmembrane (TM) protein-protein interactions (PPIs) are essential mediators of signal transduction, transport of solutes and communication, yet the biophysical features that characterize their diverse topologies remain poorly understood. To reduce this knowledge gap we use the human solute carrier (SLC) interactome to study whether physicochemical features of PPI interfaces encode information about their TM topology (i.e., their position and arrangement with respect to the membrane). To this end we predicted structures for 2, 055 experimentally validated PPIs using AlphaFold v3.0, performed molecular dynamics simulations and annotated the PPI interfaces by TM coverage. As a result every interface is characterized by 63 physicochemical, structural and energy features. A reproducible machine learning workflow allows us to study the interdependence between these interface properties and interface topology. We found that amino acid composition and secondary structure contributed most to distinguishing soluble from fully membrane-embedded interfaces. Membrane-embedded interfaces contained a larger fraction of hydrophobic residues and -helices, while charged residues were depleted. For partially and full membrane-embedded interfaces, amino acid composition and secondary structure get more similar and differences are increasingly observed in charge and energy related features. As particularly noteworthy we find that PPI interface characteristics vary with the number of annotated TM segments mainly through differences in proportions of secondary structure, charge, and flexibility. We hence conclude that PPI interface characteristics harbor substantial information about TM interface topology and provide a framework for the study and design of membrane protein interaction interfaces.

bioinformatics↗

bioRxiv2026

Targeting an allosteric binding site in the citrate transporter NaCT (SLC13A5)

The Na+-dependent citrate transporter NaCT (SLC13A5) is a key regulator of citrate homeostasis and has emerged as a therapeutic target for metabolic and neurological disease, including the SLC13A5 Epilepsy, a rare disease marked by severe sezures and neurodevelopmental delays. Current NaCT inhibitors are substrate-like molecules that competitively bind the substrate binding site. In this study, we identify previously unknown small molecule inhibitors of NaCT by targeting a putative allosteric site located at the dimer interface. We performed a virtual screen of 3.5 million compounds from the ZINC20 database against this site and selected 54 candidates for experimental testing using a cell-based citrate uptake assay. Through initial experiments, we identified three weak inhibitors, and subsequent evaluation of 26 structurally related analogs yielded six compounds with improved potency (IC50 = 12.78 M and 15.49 M). We then performed further analysis of the putative binding site by integrating structural data with deep mutational scanning evidence and comparisons with homolog structures. This analysis highlighted the importance of key residues (e.g., Phe362) in ligand modulation. These findings reveal a promising allosteric pocket and establish a chemically distinct series of NaCT inhibitors, providing a foundation for rational development of pharmacological modulators of NaCT function.

biophysics↗

bioRxiv2025

Genetic identification of the RAS proteostatic machinery and its failure to regulate oncogenic variants

The regulation of cellular homeostasis, differentiation, and proliferation is safeguarded by proteostatic mechanisms, which are crucial for maintaining cellular function. We used endogenously affinity-tagged KRAS cells in a fluorescence-activated cell sorting (FACS)-based CRISPR knockout screen to map genome-wide genetic requirements for proteostatic KRAS regulation. Three regulatory modules emerged, specifically cullin E3 ligase activity (CUL3, NAE1, UBE2M, CAND1, and UBE2L3), LZTR1 protein function (LZTR1, NUDCD3, and ZRSR2), and RAS GTPase modulation and processing (NRAS, HRAS, FNTB, RCE1, ICMT, and GOLGA7), all critical for regulating KRAS abundance. This expands our knowledge on the machinery controlling ubiquitin-meditated RAS family member regulation. Combining endogenous affinity tagging with genetic variant introduction, we found that the oncogenic KRAS G12D mutant exhibits reduced regulation by CRL3LZTR1, potentially contributing to oncogenic transformation and proliferation. In summary, our study genetically defines the machinery regulating RAS GTPase protein abundance, providing a foundation for a deeper molecular understanding and potential therapeutic exploitation of CRL3LZTR1-RAS GTPase regulation in human disease.

cell biology↗

bioRxiv2025

Leukemia Risk Factor ARID5B Coordinates HDAC-Mediated Transcriptional Repression

Multiple genetic association studies linked variants at ARID5B with predisposition to B-cell derived acute lymphoblastic leukemia (B-ALL) in children. Still, the molecular function of ARID5B remains largely uncharacterized. Here, we employ a combination of proteomics, genomics and transcriptomics to describe the molecular mechanisms of ARID5B. We identify that ARID5B interacts with MIER1, C16ORF87, HDAC1 and HDAC2 forming a chromatin repressor complex. By CUT&RUN, we mapped ARID5B binding in active regions of the genome, tethering HDAC1 and HDAC2 to distal regulatory elements and promoters. Genes actively repressed by the ARID5B repressor complex are involved in B cell proliferation and B cell-specific signaling. Together, we describe how ARID5B assembles into a repressor complex and regulates B cell-specific processes. Understanding its molecular mechanism will help elucidating how non-coding germline variants at ARID5B predispose to B-ALL.

cancer biology↗

bioRxiv2025

Purine nucleobases enhance CD8+ T cell effector function

During antiviral immune responses, activated immune cells remodel metabolic pathways towards uptake and utilization of biosynthetic and bioenergetic metabolites. Concurrently, viral infections alter metabolic environments, impacting metabolite availability for the establishment of an effective immune response. Here, we integrated in vivo metabolomics data from murine and human viral infections with in vitro metabolite screens, identifying purine nucleobases as novel immunometabolites that enhance CD8+ T cell effector function. We found that CD8+ T cells can switch from resource-intensive purine de novo synthesis to purine salvage pathway, to produce nucleotides from purine nucleobases. This strategy of metabolic adaptation allows diversion of biosynthetic and bioenergetic resources towards enhancing effector molecule production. Our findings unveil an adaptation strategy by CD8+ T cells to manage metabolic challenges in dynamic organismal environments and suggest pharmacological targets in purine metabolism as potential targets for immunotherapy. Graphical Abstract O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=144 SRC="FIGDIR/small/669899v1_ufig1.gif" ALT="Figure 1"> View larger version (65K): org.highwire.dtl.DTLVardef@17b4b15org.highwire.dtl.DTLVardef@17e57a3org.highwire.dtl.DTLVardef@1abc36aorg.highwire.dtl.DTLVardef@1aa704a_HPS_FORMAT_FIGEXP M_FIG C_FIG Instead of producing nucleotides via purine de novo synthesis, CD8+ T cells can import and utilize purine nucleobases via the purine salvage pathway to divert bioenergetic and biosynthetic resources towards effector function. By shifting from purine de novo synthesis to the purine salvage pathway, cells save significant resources: 5 moles of the key bioenergetic metabolite ATP, and biosynthetic metabolites including 2 moles of glutamine, 1 mole each of serine or glycine, and 1 mole of aspartate.

immunology↗

bioRxiv2025

Disruption of the SAGA CORE triggers collateral degradation of KAT2A

The SAGA transcriptional co-activator complex regulates gene expression through histone acetylation at promoters, mediated by its histone acetyl transferase, KAT2A. While its structure and function have been extensively investigated, how the stability of individual subunits of SAGA, including KAT2A, is regulated, remains unclear. Here, using a fluorescence-based KAT2A stability reporter, we systematically dissect the molecular dependencies controlling KAT2A protein abundance. We identify the non-enzymatic SAGA CORE module subunits--TADA1, TAF5L, and TAF6L-- as necessary for KAT2A stability, with loss of these subunits disrupting the integrity of SAGA, leading to non-chromatin-bound KAT2A that is degraded by the proteasome, consequently leading to reduced H3K9 acetylation. Proteomic profiling reveals progressive loss of CORE and HAT components upon acute disruption of the SAGA CORE, indicating that an intact CORE is required for the stability of numerous components of SAGA. Finally, a focused CRISPR screen of ubiquitin-proteasome system genes identifies the E3 ligase UBR5, a known regulator of orphan protein degradation, and the deubiquitinase OTUD5, as regulators of KAT2A degradation when the SAGA CORE is perturbed. Together, these findings reveal a dependency of KAT2A protein stability on SAGA CORE integrity and define an orphan quality control mechanism targeting unassembled KAT2A, revealing a potential vulnerability in SAGA-driven malignancies.

molecular biology↗

bioRxiv2024

Data- and knowledge-derived functional landscape of human solute carriers

Research on the understudied solute carrier (SLC) superfamily of membrane transporters would greatly profit from a comprehensive knowledgebase, synthesizing data and knowledge on different aspects of SLC function. We consolidated multi-omics data sets with selected curated information from the public domain, such as structure prediction, substrate annotation, disease association and subcellular localization. This SLC-centric knowledge is made accessible to the scientific community via a web portal, featuring interactive dashboards and a tool for family-wide, tree-based visualization of SLC properties. Making use of the systematically collected and curated data sets, we selected eight feature-dimensions to compute an integrated functional landscape of human SLCs. This landscape represents various functional aspects, harmonizing local and global features of the underlying data sets, as demonstrated by inspecting structural folds and subcellular locations of selected transporters. Based on all available data sets and their integration, we assigned a biochemical/biological function to each SLC, making it one of the largest systematic annotations of human gene function and likely acting as a blueprint for future endeavours.

systems biology↗

bioRxiv2024

The genetic interaction map of the human solute carrier superfamily

Solute carriers (SLCs), the largest superfamily of transporter proteins in humans with about 450 members, control the movement of molecules across membranes. A typical human cell expresses over 200 different SLCs, yet their collective influence on cell phenotypes is not well understood due to overlapping substrate specificities and expression patterns. To address this, we performed systematic pairwise gene double knockouts using CRISPR-Cas12a and -Cas9 in human colon carcinoma cells. A total of 1,088,605 guide combinations were used to interrogate 35,421 SLC-SLC and SLC-enzyme double knockout combinations across multiple growth conditions, uncovering 1,236 genetic interactions with a growth phenotype. Further exploration of an interaction between the mitochondrial citrate/malate exchanger SLC25A1 and the zinc transporter SLC39A1 revealed an unexpected role for SLC39A1 in metabolic reprogramming and anti-apoptotic signaling. This full-scale genetic interaction map of human SLC transporters is the backbone for understanding the intricate functional network of SLCs in cellular systems and generates hypotheses for pharmacological target exploitation in cancer and other diseases. The results are available at www.resolute.eu/dashboards/genomics.

systems biology↗

bioRxiv2024

The solute carrier superfamily interactome

Solute carrier (SLC) transporters form a protein superfamily that enables transmembrane transport of diverse substrates including nutrients, ions and drugs. There are about 450 different SLCs, residing in a variety of subcellular membranes. Loss-of-function of an unusually high proportion of SLC transporters is genetically associated with a plethora of human diseases, making SLCs a rapidly emerging but challenging drug target class. Knowledge of their protein environment may elucidate the molecular basis for their functional integration with metabolic and cellular pathways and help conceive pharmacological interventions based on modulating proteostatic regulation. We aimed at obtaining a global survey of the SLC protein interaction landscape and mapped the protein-protein interactions of 396 SLCs by interaction proteomics. We employed a functional assessment based on RNA interference of interactors in combination with measurement of protein stability and localization. As an example, we detail the role of a SLC16A6 phospho-degron, and the contributions of PDZ-domain proteins LIN7C and MPP1 to the trafficking of SLC43A2. Overall, our work offers a resource for SLC-protein interactions for the scientific community.

systems biology↗

bioRxiv2024

Metabolic mapping of the human solute carrier superfamily

Solute carrier (SLC) transporters govern most of the chemical exchange across cellular membranes and are integral to metabolic regulation, which in turn is linked to cellular function and identity. Despite their key role, individual functions of the members of the SLC superfamily were not evaluated systematically. We determined the metabolic and transcriptional profiles upon SLC overexpression in knock-out or wild-type isogenic cell backgrounds. Targeted metabolomics provided a fingerprint of 189 intracellular metabolites, while transcriptomics offered insights into cellular programs modulated by SLC expression. Beyond the metabolic profiles of 102 SLCs directly related to their known substrates, we also identified putative substrates or metabolic pathway connections for 71 SLCs without previously annotated bona fide substrates, including SLC45A4 as a new polyamine transporter. By comparing the molecular profiles, we identified functionally related SLC groups, including some with distinct impacts on osmolyte balancing and glycosylation. The assessment of functionally related human genes presented here may serve as a blueprint for other systematic studies of human gene function and supports future investigations into the functional roles of SLCs.

systems biology↗

bioRxiv2024

Inhibitor-induced supercharging of kinase turnover via endogenous proteolytic circuits

Targeted protein degradation has emerged as a promising new pharmacological strategy. Traditionally, it relies on small molecules that induce proximity between a target protein and an E3 ubiquitin ligase to prompt target ubiquitination and degradation by the proteasome. Sporadic reports indicated that ligands designed to inhibit a target can also induce its destabilization. Among others, this has repeatedly been observed for kinase inhibitors. However, we lack an understanding of the frequency, generalizability, and mechanistic underpinnings of these phenomena. To address this knowledge gap, we generated dynamic abundance profiles of 98 kinases after cellular perturbations with 1570 kinase inhibitors, revealing 160 selective instances of inhibitor-induced kinase destabilization. Kinases prone to degradation are frequently annotated as HSP90 clients, thus affirming chaperone deprivation as an important route of destabilization. However, detailed investigation of inhibitor-induced degradation of LYN, BLK and RIPK2 revealed a differentiated, common mechanistic logic where inhibitors function by inducing a kinase state that is more efficiently cleared by endogenous degradation mechanisms. Mechanistically, effects can manifest by ligand-induced changes in cellular activity, localization, or multimerization which may be triggered by direct target engagement or network effects. Collectively, our data suggest that inhibitor-induced kinase degradation is a common event and positions supercharging of endogenous degradation circuits as an alternative to classical proximity-inducing degraders.

molecular biology↗

bioRxiv2023

Orpinolide disrupts a leukemic dependency on cholesterol transport by inhibiting the oxysterol-binding protein OSBP

Metabolic alterations in cancer precipitate in associated dependencies that can be therapeutically exploited. To meet this goal, natural product inspired small molecules can provide a resource of invaluable chemotypes. Here, we identify orpinolide, a synthetic withanolide analog with pronounced anti-leukemic properties via orthogonal chemical screening. Through multi-omics profiling and genome-scale CRISPR/Cas9 screens, we identify that orpinolide disrupts Golgi homeostasis via a mechanism that requires active phosphatidylinositol 4-phosphate (PI4P) signaling at the endoplasmic reticulum (ER)-Golgi membrane interface. Thermal proteome profiling and genetic validation studies reveal the oxysterol-binding protein OSBP as the direct and phenotypically relevant target of orpinolide. Collectively, these data reaffirm sterol transport as a therapeutically actionable dependency in leukemia and motivate ensuing translational investigation via the probe-like compound orpinolide.

pharmacology and toxicology↗

bioRxiv2022

A genome-wide CRISPR functional survey of the human phagocytosis molecular machinery

Phagocytosis, the process of engulfing large particles by cells, is a multilayered biological activity driving tissue clearance and host defense. Dysregulation of phagocytosis is connected to autoimmunity, accumulation of toxic disease proteins, and increased risks for infections. Despite its importance and multiple roles, we lack a full understanding of the cellular machinery involved in executing and regulating the process, including the coordination with other cellular events. To create a functional map in human cells, we performed a reporter- and FACS-based genome-wide CRISPR/Cas9 knock-out screen that identified 716 genes. Mapping the gene hits to a comprehensive protein-protein interaction network annotated for functional cellular processes, allowed to highlight those protein complexes identified multiple times, to identify missing components of the cellular phagocytosis network, and to suggest functional partition among complexes. We validate complexes known to be involved, such as the Arp2/3 complex, the vacuolar-ATPase-Rag machinery, and the Wave-2 complex, as well as processes previously not or only poorly associated with phagocytosis. Among the novel, phagocytosis-relevant cellular functions validated are the oligosaccharyltransferase complex (MAGT1/SLC58A1, DDOST, STT3B, and RPN2) as well as the hypusine pathway (eIF5A, DHPS, and DOHH). Overall, our network of phagocytosis regulators and effectors maps elements of cargo uptake, cargo shuffling and cargo biotransformation through the cell, providing a valuable resource for the identification of potential novel drivers for diseases of the endo-lysosomal system. We further propose that our approach of mining and integrating publicly available protein-protein interaction data with datasets derived from reporter-based genome-wide screens offers a broadly applicable way to functionally map biological processes onto the molecular machinery of the cell. Summary blurbThe validation and interpretation of a FACS reporter-based genome-wide CRISPR/Cas9 knock-out screen through protein-protein interaction data yields a comprehensive view of the molecular network regulating and executing phagocytosis in human cells.

genomics↗

bioRxiv2022

Selenocysteine metabolism is a targetable vulnerability in MYCN-amplified cancers

Understanding the operational molecular, and metabolic networks that determine the balance between pro- and anti-ferroptotic regulatory pathways could unravel unique vulnerabilities to be exploited for cancer therapy. Here we identify the selenoprotein P (SELENOP) receptor, LRP8, as a key determinant protecting MYCN-amplified neuroblastoma cells from ferroptosis in vitro and in orthotopic neuroblastoma mouse models. Specifically, the exquisite dependency on LRP8-mediated selenocysteine import is caused by the failure of MYCN-amplified cells to efficiently utilize alternative forms of selenium/selenocysteine based uptake necessary for selenoprotein biosynthesis. Increased activity of one of such transporters, SLC7A11, in MYCN-amplified cells leads to cysteine overload, progressive mitochondrial decline and impaired proliferation. These data reveal in LRP8 a targetable, and specific vulnerability of MYCN-amplified neuroblastoma cells and disclose a yet-unaccounted mechanism for selective ferroptosis induction that has the potential to become an important therapeutic entry point for MYCN-amplified neuroblastoma. Statement of significanceGiven the largely unsuccessful repurposing of adult oncology drugs for the treatment of neuroblastoma, our discoveries pave the way for novel ferroptosis based strategies for this entity. Specifically, targeting of LRP8 may offer novel therapeutic and safer opportunities for a number of pediatric malignancies and MYCN driven cancers.

cancer biology↗

bioRxiv2022

Gain-of-function genetic screens in human cells identify SLC transporters overcoming environmental nutrient restrictions

Solute carrier (SLC) transporters control fluxes of nutrients and metabolites across membranes and thereby represent a critical interface between the microenvironment and cellular and subcellular metabolism. Because of substantial functional overlap, the interplay and relative contributions of members of this family in response to environmental stresses remain poorly elucidated. In order to infer functional relationships between SLCs and metabolites, we developed a strategy to identify human SLCs able to sustain cell viability and proliferation under growth-limiting concentrations of essential nutrients. One-by-one depletion of 13 amino acids required for cell proliferation enabled gain-of-function genetic screens using a SLC-focused CRISPR/Cas9-based transcriptional activation approach to uncover transporters relieving cells from the growth-limiting metabolic bottleneck. We identified the cationic amino acid transporter SLC7A3 as a gene that, when upregulated, overcame low availability of arginine and lysine by increasing their uptake. SLC7A5 (LAT1), on the other hand, was able to sustain cellular fitness upon deprivation of several neutral amino acids. A genome-wide screen identified SLC7A3 as the single main gene product able to rescue cell survival in the limiting arginine conditions tested, demonstrating the potentially decisive role of transporters in overcoming nutrient limitations. Moreover, we identified metabolic compensation mediated by the glutamate/aspartate transporters SLC1A2 and SLC1A3 under glutamine-limiting conditions. Overall, this gain-of-function approach using human cells led to the definition of functional transporter-nutrient relationships and revealed that upregulation of transport activity may be sufficient to overcome environmental metabolic restrictions.

cell biology↗

bioRxiv2022

PCYT2 controls muscle health and muscle aging

Muscle degeneration is the most prevalent cause for frailty and dependency in inherited diseases and ageing, affecting hundreds of millions of people. Elucidation of pathophysiological mechanisms, as well as effective treatments for muscle diseases represents an important goal in improving human health. Here, we show that phosphatidylethanolamine cytidyltransferase (PCYT2/ECT), the critical enzyme of the Kennedy branch of phosphatidylethanolamine (PE) synthesis pathway, has an essential role in muscle health. Human genetic deficiency in PCYT2 causes a severe disease with failure to thrive and progressive muscle weakness. Pcyt2 mutant zebrafish recapitulate the patient phenotypes, indicating that the role of PCYT2/PE in muscle is evolutionary conserved. Muscle specific Pcyt2 knockout mice exhibited failure to thrive, impaired muscle development, progressive muscle weakness, muscle loss, accelerated ageing, and reduced lifespan. Mechanistically, Pcyt2 deficiency affects mitochondrial bioenergetics and physicochemical properties of the myofiber membrane lipid bilayer, in particular under exercise strain. We also show that PCYT2 activity declines in the aging muscles of humans and mice. AAV-based delivery of PCYT2 rescued muscle weakness in Pcyt2 knock-out mice and, importantly, improved muscle strength in old mice, offering a novel therapeutic avenue for rare disease patients and muscle aging. Thus, PCYT2 plays a fundamental, specific, and conserved role in vertebrate muscle health, linking PCYT2 and PCYT2 synthesized PE lipids to severe muscle dystrophy, exercise intolerance and aging.

genetics↗

bioRxiv2021

Convergent use of phosphatidic acid for Hepatitis C virus and SARS-CoV-2 replication organelle formation

Double membrane vesicles (DMVs) are used as replication organelles by phylogenetically and biologically distant pathogenic RNA viruses such as hepatitis C virus (HCV) and severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2). Viral DMVs are morphologically analogous to DMVs formed during autophagy, and although the proteins required for DMV formation are extensively studied, the lipids driving their biogenesis are largely unknown. Here we show that production of the lipid phosphatidic acid (PA) by acylglycerolphosphate acyltransferase (AGPAT) 1 and 2 in the ER is important for DMV biogenesis in viral replication and autophagy. Using DMVs in HCV-replicating cells as model, we found that AGPATs are recruited to and critically contribute to HCV replication and DMV formation. AGPAT1/2 double knockout also impaired SARS-CoV-2 replication and the formation of autophagosome-like structures. By using correlative light and electron microscopy, we observed the relocalization of AGPAT proteins to HCV and SARS-CoV-2 induced DMVs. In addition, an intracellular PA sensor accumulated at viral DMV formation sites, consistent with elevated levels of PA in fractions of purified DMVs analyzed by lipidomics. Apart from AGPATs, PA is generated by alternative pathways via phosphotidylcholine (PC) and diacylglycerol (DAG). Pharmacological inhibition of these synthesis pathways also impaired HCV and SARS-CoV-2 replication as well as formation of autophagosome-like DMVs. These data identify PA as an important lipid used for replication organelle formation by HCV and SARS-CoV-2, two phylogenetically disparate viruses causing very different diseases, i.e. chronic liver disease and COVID-19, respectively. In addition, our data argue that host-targeting therapy aiming at PA synthesis pathways might be suitable to attenuate replication of these viruses. One Sentence SummaryPhosphatidic acid is important for the formation of double membrane vesicles, serving as replication organelles of hepatitis C virus and SARS-CoV-2, and offering a possible host-targeting strategy to treat SARS-CoV-2 infection.

microbiology↗

bioRxiv2020

A systematic genetic interaction map of human solute carriers assigns a role to SLC25A51/MCART1 in mitochondrial NAD uptake

Solute Carriers (SLCs) represent the largest family of human transporter proteins, consisting of more than 400 members1,2. Despite the importance of these proteins in determining metabolic states and adaptation to environmental changes, a large proportion of them is still orphan and lacks associated substrates1,3,4. Here we describe a systematic mapping of genetic interactions among SLCs in human cells. Network-based identification of correlated genetic interaction profile neighborhoods resulted in initial functional assignments to dozens of previously uncharacterized SLCs. Focused validation identified SLC25A51/MCART1 as the SLC enabling mitochondrial import of NAD(H). This functional interaction map of the human transportome offers a route for systematic integration of transporter function with metabolism and provides a blueprint for elucidation of the dark genome by biochemical and functional categories.

cell biology↗