Biology subjects

Costanzo, M.

Publications and source records attributed to Costanzo, M..

At least 19 recordsLinked to original sources

bioRxiv2026

Yra2 regulates proteolysis of Cse4 to prevent its mislocalization to non-centromeric regions for chromosomal stability in budding yeast

Restricting the localization of centromere-specific histone H3 variant Cse4 (CENP-A in humans) to centromeric chromatin is essential for chromosome segregation. Mislocalization of overexpressed Cse4/CENP-A to non-centromeric regions contributes to chromosomal instability (CIN) in model organisms and human cells. CIN is an important hallmark of many cancers and hence defining mechanisms that prevent mislocalization of Cse4 is clinically significant. Here we report a role for YRA2 (Yeast RNA Annealing Protein 2) in ubiquitin mediated proteolysis of Cse4 to prevent its mislocalization for chromosomal stability. YRA2 was identified in a genome-wide screen for gene deletions that exhibit synthetic dosage lethality (SDL) upon overexpression of CSE4 (GALCSE4). We determined that yra2{Delta} strains exhibit increased Cse4 stability, enriched Cse4 chromatin association, reduced Cse4 ubiquitination, Cse4 mislocalization, and CIN. Defects in interaction of E3 ubiquitin ligase Psh1 with Cse4 contributes to stability of Cse4 in yra2{Delta} strains. Consistent with these results, overexpression of PSH1 suppresses GALCSE4 SDL in yra2{Delta} strain. We determined that Yra2 mediated proteolysis of Cse4 is independent of its RNA related functions as strain deleted for the C-terminal ChTOP domain of Yra2 with an intact N-terminal RNA binding domain exhibits GALCSE4 SDL and defects in Cse4 proteolysis. Furthermore, poly(A)+ RNA export mutants in YRA1 (yra1-2) and MEX67 (mex67-5), that interact with Yra2, do not exhibit GALCSE4 SDL and defects in RNA export are not observed in yra2{Delta} cells. In summary, we have defined a key role for Yra2 in preventing mislocalization of Cse4 by facilitating its proteolysis to preserve chromosomal stability. Article summaryAccurate segregation of chromosomes during cell division is essential because segregation errors are linked to cancer and developmental disorders. We investigated how cells prevent mislocalization of centromere-specific histone H3 variant Cse4, which is essential for faithful chromosome segregation. We found that the yeast RNA annealing protein Yra2 prevents Cse4 mislocalization by promoting Psh1 mediated ubiquitination and degradation of Cse4. Cells lacking Yra2 showed increased stability of Cse4, enhanced chromatin enrichment with mislocalization to non-centromeric regions and CIN. These defects were suppressed by induction of Psh1. Our findings reveal a novel role for Yra2 in regulating Cse4 levels for chromosomal stability.

genetics↗

bioRxiv2026

The Nematicide Tioxazafen Disrupts Proteasome Function via Cytochrome P450 Bioactivation

Tioxazafen is an effective nematicide whose commercialization was halted because handlers reportedly developed rashes after working with seeds coated with a tioxazafen-laced cocktail. Here, we show that tioxazafen is bioactivated into toxic products by nematode and human cytochrome P450s. Through systematic analyses, we found that bioactivated tioxazafen disrupts proteasome function, leading to the accumulation of the NRF1 transcription factor ortholog SKN-1A in the nematode C. elegans, and a bounce-back transcriptional up-regulation of proteasome components. Genetic upregulation of the C. elegans proteasome supresses tioxazafens lethality, indicating that proteotoxicity is a key contributor to death. A survey of human P450s revealed that skin-expressed CYP1A1 toxifies tioxazafen and may account for the reaction to tioxazafen-coated seeds. We also found that rabbit CYP1A1 fails to bioactivate tioxazafen, which may explain the pre-market failure to detect robust adverse skin reactions. Our work highlights vulnerabilities in pre-market toxicological assays and a provides potential solution to prospectively identifying P450 toxication events. One-Sentence SummaryTioxazafen is bioactivated by cytochrome P450s into a proteasome disruptor.

pharmacology and toxicology↗

bioRxiv2026

Predicted Effector Gene Aggregation, Standards and Unified Schema (PEGASUS): A Community Framework for Effector Gene Reporting

Genome-wide association studies (GWAS) increasingly report predicted effector genes (PEGs) - genes hypothesised to mediate the biological effects of associated variants. These function as key outputs for advancing variant-to-function research, mechanistic understanding, and therapeutic discovery. However, the rapid growth of PEG lists has not been matched by standards for organising, annotating, and reporting these predictions. As shown by recent landscape analyses, PEG lists vary widely in methodology, evidence definition, nomenclature, provenance tracking, and data structure, limiting interoperability, benchmarking, reuse, and adherence to FAIR principles. To address this gap, we convened an international multi-stakeholder community comprising method developers, data generators, resource maintainers, curators, funders, journal editors, and downstream users. Through a 2024 workshop and a 2025 working group series, we developed the Predicted Effector Gene Aggregation, Standards and Unified Schema (PEGASUS) framework. PEGASUS specifies (i) a metadata standard to capture provenance, trait and GWAS descriptors, evidence sources, and integration methods; (ii) a structured evidence matrix reporting all genes and all evidence underpinning prioritisation at each locus; and (iii) a concise PEG list that summarises author-prioritised genes linked transparently to underlying evidence. The framework balances transparency, machine readability, burden on submitters, and alignment with existing community standards. PEGASUS provides the first community-developed schema for reporting predicted effector genes and their supporting evidence. Adoption of this framework by authors will improve the comparability, reproducibility, and reusability of PEG outputs across studies, facilitating more robust biological inference, enabling cross-resource comparison of gene-prioritisation methods to support community benchmarking, and integration into downstream resources and analytical pipelines. PEGASUS-compliant data can be shared via the PEG Data Registry platform (https://kpndataregistry.org/peg), promoting re-use and establishing the basis for future integration with publicly shared GWAS data.

genomics↗

bioRxiv2026

Expanding TheCellMap.org to visualize a genome-scale genetic interaction network for a human cell line

Genetic interaction networks map functional connections between genes and their corresponding pathways and complexes. We previously developed TheCellMap.org as a central repository for storing and analyzing quantitative genetic interaction data produced by genome-scale Synthetic Genetic Array (SGA) analysis in the budding yeast, Saccharomyces cerevisiae. We have expanded TheCellMap.org to include ~89,000 quantitative genetic interactions identified from genome-scale CRISPR-based analysis of ~4 million human gene pairs in the haploid cell line, HAP1. TheCellMap.org enables users to readily access, visualize and explore human HAP1 genetic interactions, as well as to extract and reorganize sub-networks, applying data-driven network layouts in an intuitive and interactive manner.

systems biology↗

bioRxiv2025

A global genetic interaction map of a human cell reveals conserved principles of genetic networks

We generated a genome-scale, genetic interaction network from the analysis of more than 4 million double mutants in the haploid human cell line, HAP1. The network maps [~]90,000 genetic interactions, including thousands of extreme synthetic lethal and genetic suppression interactions. Genetic interaction profiles enabled assembly of a hierarchical model of cell function, including modules corresponding to protein complexes, pathways, biological processes, and cellular compartments. Comparative analyses showed that general principles of genetic networks are conserved from yeast to human cells. A genetic interaction network mapped in a single genetic background complements the DepMap gene co-essentiality network, recapitulating many of the same biological connections and also capturing unique functional information to reveal roles of uncharacterized genes and molecular determinants of specific cancer cell line genetic dependencies.

systems biology↗

bioRxiv2025

Quantitative analysis of genetic interactions in human cells from genome-wide CRISPR-Cas9 screens

Genetic interaction (GI) networks in model organisms have revealed how combinations of genome variants can impact phenotypes. To advance efforts toward a reference human GI network, we developed the quantitative Genetic Interaction (qGI) score, a method for precise GI measurement from genome-wide CRISPR-Cas9 screens in different query mutants constructed in a single human cell line. We found surprising prevalent systematic variation unrelated to GIs in CRISPR screen data, including both genomically linked effects and functionally coherent covariation. Leveraging [~]40 control screens in wild-type cells and half a billion differential fitness effect measurements, we developed a pipeline for CRISPR screen data processing and normalization to correct these artifacts and measure accurate, quantitative GIs. We also comprehensively characterized GI reproducibility by characterizing 4 - 5 biological replicates for [~]125,000 unique gene pairs. The qGI framework enables systematic identification of human GIs and provides broadly applicable strategies for analyzing context-specific CRISPR screen data.

bioinformatics↗

bioRxiv2024

Tbx1 haploinsufficiency causes brain metabolic and behavioral anomalies in adult mice which are corrected by vitamin B12 treatment

IntroductionThe brain-related phenotypes observed in 22q11.2 deletion syndrome (22q11.2DS) are highly variable and their origin is poorly understood. Changes in brain metabolism may cause or contribute to the phenotypes, given that many of the deleted genes (approx. 10%) are implicated in metabolic processes, but this is currently unknown. It is clearly important to address this knowledge gap, but in humans, the primary material required for studying brain metabolism is inaccessible. For this reason, we sought to address the issue using two mouse models of 22q11.2DS. MethodsWe used three independent approaches to investigate brain metabolism in young adult mice, namely, mass spectrometry, nuclear magnetic resonance spectroscopy and transcriptomics. We selected to study primarily Tbx1 single gene mutants because it is the primary candidate disease gene. We then confirmed key findings in the multi-gene deletion mutant Df1/+. ResultsWe found that Tbx1 mutants have alterations of specific brain metabolites, including methylmalonic acid, which is highly brain-toxic, as well as a more general metabolomic imbalance. We provide transcriptomic evidence of an interaction genotype-vB12 treatment, and behavioural evidence of a response to vB12 treatment, which rescued some of the behavioural anomaly observed in Tbx1 mutants. We conclude that Tbx1 haploinsufficiency causes extensive brain metabolic anomalies, which are partially responsive to vB12 treatment. We suggest that alterations of glutamine-glutamate metabolism and fatty acid metabolism are key components of the metabolic phenotype in these mutants.

genetics↗

bioRxiv2023

A scalable platform for efficient CRISPR-Cas9 chemical-genetic screens of DNA damage-inducing compounds

Current approaches to define chemical-genetic interactions (CGIs) in human cell lines are resource-intensive. We designed a scalable chemical-genetic screen platform by generating a DNA damage response (DDR)-focused custom sgRNA library. We performed five proof-of-principle compound screens and found that the compounds known modes-of-action (MoA) were enriched among the compounds CGIs. These scalable screens recapitulated expected CGIs at a comparable signal-to-noise ratio (SNR) relative to genome-wide screens. Furthermore, time-resolved CGIs, captured by sequencing screens at various time points, suggested an unexpected, late time point interstrand-crosslinking (ICL) repair pathway response to camptothecin-induced DNA damage. Our approach can facilitate screening compounds at scale and produce biologically informative CGI profiles.

systems biology↗

bioRxiv2023

K29-linked unanchored polyubiquitin chains disrupt ribosome biogenesis and direct ribosomal proteins to the Intranuclear Quality control compartment (INQ)

Ribosome assembly requires precise coordination between the production and assembly of ribosomal components. Mutations in ribosomal proteins that inhibit the assembly process or ribosome function are often associated with Ribosomopathies, some of which are linked to defects in proteostasis. In this study, we examine the interplay between several yeast proteostasis enzymes, including deubiquitylases (DUBs), Ubp2 and Ubp14, and E3 ligases, Ufd4 and Hul5, and we explore their roles in the regulation of the cellular levels of K29-linked unanchored polyubiquitin (polyUb) chains. Accumulating K29-linked unanchored polyUb chains associate with maturing ribosomes to disrupt their assembly, activate the Ribosome assembly stress response (RASTR), and lead to the sequestration of ribosomal proteins at the Intranuclear Quality control compartment (INQ). These findings reveal the physiological relevance of INQ and provide insights into mechanisms of cellular toxicity associated with Ribosomopathies.

cell biology↗

bioRxiv2023

Leveraging type 1 diabetes human genetic and genomic data in the T1D Knowledge Portal

Translating genetic discoveries for type 1 diabetes (T1D) into mechanistic insight can reveal novel biology and therapeutic targets but remains a major challenge. We developed the T1D Knowledge Portal (T1DKP), a disease-specific resource of genetic and functional annotation data that enables users to develop hypotheses for T1D-based research and target discovery. The T1DKP can be used to query genes and genomic regions for genetic associations, identify epigenomic features, access results of bioinformatic analyses, and obtain expert-curated resources. The T1DKP is available at http://t1d.hugeamp.org.

genetics↗

bioRxiv2022

A stem cell zoo uncovers intracellular scaling of developmental tempo across mammals

Differential speeds in biochemical reactions have been proposed to be responsible for the differences in developmental tempo between mice and humans. However, the underlying mechanism controlling the species-specific kinetics remains to be determined. Using in vitro differentiation of pluripotent stem cells, we recapitulated the segmentation clocks of diverse mammalian species varying in body weight and taxa: marmoset, rabbit, cattle and rhinoceros. Together with the mouse and human, the segmentation clock periods of the six species did not scale with the animal body weight, but were rather grouped according to phylogeny. The biochemical kinetics of the core clock gene HES7 displayed clear scaling with the species-specific segmentation clock period. However, the cellular metabolic rates did not show an evident correlation. Instead, genes involving biochemical reactions showed an expression pattern that scales with the segmentation clock period. Altogether, our stem cell zoo uncovered general scaling laws governing species-specific developmental tempo.*

developmental biology↗

bioRxiv2022

N-terminal acetylation shields proteins from degradation and promotes age-dependent motility and longevity

Most eukaryotic proteins are N-terminally acetylated, but the functional impact on a global scale has remained obscure. Using genome-wide CRISPR knockout screens in human cells, we reveal a strong genetic dependency between a major N-terminal acetyltransferase and specific ubiquitin ligases. Biochemical analyses uncover that both the ubiquitin ligase complex UBR4-KCMF1 and the acetyltransferase NatC recognize proteins bearing an unacetylated N-terminal methionine followed by a hydrophobic residue. NatC KO-induced protein degradation and phenotypes are reversed by UBR knockdown, demonstrating the central cellular role of this interplay. We reveal that loss of Drosophila NatC is associated with male sterility, reduced longevity, and age-dependent loss of motility due to developmental muscle defects. Remarkably, muscle-specific overexpression of UbcE2M, one of the proteins targeted for NatC KO mediated degradation, suppresses defects of NatC deletion. In conclusion, NatC-mediated N-terminal acetylation acts as a protective mechanism against protein degradation, which is relevant for increased longevity and motility. In BriefVarland, Silva et al. define that a major cellular role of N-terminal acetylation is shielding proteins from proteasomal degradation by specific ubiquitin ligases. The human N-terminal acetyltransferase NatC protects the neddylation regulator UBE2M from degradation, while overexpression of Drosophila UBE2M/UbcE2M rescues the longevity and motility defects of NatC deletion. HighlightsO_LIN-terminal acetylation by NatC protects proteins from degradation, including UBE2M C_LIO_LIUBR4-KCMF1 targets unacetylated N-terminal Met followed by a hydrophobic residue C_LIO_LIDrosophila NatC is required for adult longevity and motility in elderly C_LIO_LIOverexpression of UBE2M/UbcE2M suppresses Drosophila NatC deletion phenotypes C_LI

molecular biology↗

bioRxiv2022

Reproducibility metrics for CRISPR screens

CRISPR screens are used extensively to systematically interrogate the phenotype-to-genotype problem. In contrast to early CRISPR screens, which defined core cell fitness genes, most current efforts now aim to identify context-specific phenotypes that differentiate a cell line, genetic background or condition of interest, such as a drug treatment. While CRISPR-related technologies have shown great promise and a fast pace of innovation, a better understanding of standards and methods for quality assessment of CRISPR screen results is crucial to guide technology development and application. Specifically, many commonly used metrics for quantifying screen quality do not accurately measure the reproducibility of context-specific hits. We highlight the importance of reporting reproducibility statistics that directly relate to the purpose of the screen and suggest the use of metrics that are sensitive to context-specific signal.

genomics↗

bioRxiv2021

Genetic, Genomic and Biophysical Case Study: Familial 46, XY Sex Reversal due to a Novel Inherited Mutation in Human Testis-Determining Factor SRY

ObjectiveTo describe the clinical, histopathological and molecular features of a novel inherited SRY allele (p.Met64Val; consensus box position 9) observed within an extensive pedigree: two 46, XY sisters with primary amenorrhea (16 and 14 years of age; probands P1 and P2), their normal father and brother, and an affected paternal XY grandaunt. Design, Setting, Participants and Outcome MeasurementsFollowing DNA sequencing to identify the SRY mutation, hormonal studies of the probands and histopathological examination of their gonads were performed. Functional consequences of p.Met64Val (and other mutations at this site) were also investigated. ResultsBreast development in P1 and P2 was Tanner II and IV, respectively. Mullerian structures and gonads resembling ovaries were found in each sister. Histopathology revealed gonadal dysgenesis, gonadablastoma and dysgerminoma. AMH/MIS, P450 SCC, and P450 aromatase were expressed in gonadoblastoma tissues. Genomic sequencing revealed no candidate mutations in other genes related to sexual differentiation. Variant p.Met64Val impaired Sox9 transcriptional activation associated with attenuated occupancy of the testis-specific enhancers Enh13 and TESCO. Biophysical studies indicated that the mutant HMG box retains specific DNA binding and DNA bending but with accelerated rate of protein-DNA dissociation. ConclusionThe partial biological activity of p.Met64Val SRY, maintained at the threshold of SRY function, rationalizes opposing paternal and proband phenotypes (the "the father-daughter paradox"). Steroidal biosynthesis by gonadoblastoma may delay genetic diagnosis and recognition of gonadal tumors. Quantitative assessment of inherited SRY alleles highlights the tenuous transcriptional threshold of developmental decision-making in the bipotential gonadal ridge.

developmental biology↗

bioRxiv2020

Major functional bias for mitochondrial complexes in genome-wide CRISPR screens

We present FLEX (Functional evaluation of experimental perturbations), a pipeline that leverages several functional annotation resources to establish reference standards for benchmarking human genome-wide CRISPR screen data and methods for analyzing them. We apply FLEX to analyze data from the diverse cell line screens generated by the DepMap project. We identify a dominant mitochondria-associated signal, which our time-resolved CRISPR screens and analysis suggests may reflect screen dynamics and protein stability effects rather than genetic dependencies.

systems biology↗

bioRxiv2020

Reduced Gene Dosage of Histone H4 Prevents CENP-A Mislocalization in Budding Yeast

Mislocalization of the centromeric histone H3 variant (Cse4 in budding yeast, CID in flies, CENP-A in humans) to non-centromeric regions contributes to chromosomal instability (CIN) in yeast, fly, and human cells. Overexpression and mislocalization of CENP-A has been observed in cancers, however, the mechanisms that facilitate the mislocalization of overexpressed CENP-A have not been fully explored. Defects in ubiquitin-mediated proteolysis of overexpressed Cse4 (GALCSE4) leads to its mislocalization and synthetic dosage lethality (SDL) in mutants for E3 ubiquitin ligases (Psh1, Slx5, SCFMet30, SCFCdc4), Doa1, Hir2, and Cdc7. In contrast, defects in sumoylation of GALcse4K215/216/A/R prevent its mislocalization and do not cause SDL in a psh1{Delta} strain. Here, we used a genome-wide screen to identify factors that facilitate the mislocalization of overexpressed Cse4 by characterizing suppressors of the psh1{Delta} GALCSE4 SDL. Deletions of histone H4 alleles (HHF1 or HHF2), which were among the most prominent suppressors, also suppress slx5{Delta}, cdc4-1, doa1{Delta}, hir2{Delta}, and cdc7-4 GALCSE4 SDL. Reduced dosage of H4 contributes to defects in sumoylation and reduced mislocalization of overexpressed Cse4. We determined that the hhf1-20, cse4-102, and cse4-111 mutants, which are defective in the Cse4-H4 interaction, also exhibit reduced sumoylation of Cse4 and do not display psh1{Delta} GALCSE4 SDL. In summary, we have identified genes that contribute to the mislocalization of overexpressed Cse4 and defined a role for the gene dosage of H4 in facilitating Cse4 sumoylation and mislocalization to non-centromeric regions, contributing to SDL when Cse4 is overexpressed in mutant strains.

genetics↗

bioRxiv2019

Systematic mapping of genetic interactions for de novo fatty acid synthesis

The de novo synthesis of fatty acids has emerged as a therapeutic target for various diseases including cancer. While several translational efforts have focused on direct perturbation of de novo fatty acid synthesis, only modest responses have been associated with mono-therapies. Since cancer cells are intrinsically buffered to combat metabolic stress, cells may adapt to loss of de novo fatty acid biosynthesis. To explore cellular response to defects in fatty acid synthesis, we used pooled genome-wide CRISPR screens to systematically map genetic interactions (GIs) in human HAP1 cells carrying a loss-of-function mutation in FASN, which catalyzes the formation of long-chain fatty acids. FASN mutant cells showed a strong dependence on lipid uptake that was reflected by negative GIs with genes involved in the LDL receptor pathway, vesicle trafficking, and protein glycosylation. Further support for these functional relationships was derived from additional GI screens in query cell lines deficient for other genes involved in lipid metabolism, including LDLR, SREBF1, SREBF2, ACACA. Our GI profiles identified a potential role for a previously uncharacterized gene LUR1 (C12orf49) in exogenous lipid uptake regulation. Overall, our data highlights the genetic determinants underlying the cellular adaptation associated with loss of de novo fatty acid synthesis and demonstrate the power of systematic GI mapping for uncovering metabolic buffering mechanisms in human cells.

systems biology↗

bioRxiv2018

Hydraulic control of embryo size, tissue shape and cell fate

Size control is fundamental in tissue development and homeostasis1,2. While the role of cell proliferation in this process has been widely studied3, the mechanisms of organ size control and how it impacts cell fates remain elusive. Here, we use mouse blastocyst development as a model to unravel a key role of fluid-filled lumen in embryonic size control and cell fate specification. We find that during blastocyst expansion, there is a two-fold increase in the pressure of the lumen that translates into a concomitant increase in the cortical tension of trophectoderm (TE) cells lining the lumen. Increased cortical tension leads to vinculin mechanosensing and maturation of the functional tight junctions, thereby establishing a positive feedback loop to accommodate lumenal growth. However, when the cortical tension reaches a critical threshold, cell-cell adhesion cannot be sustained, and mitotic entry leads to a rupture of TE epithelium, fluid leakage and collapse of the blastocyst cavity. A simple theory of hydraulically-gated oscillations that integrates these feedback interactions recapitulates the evolution of cavity size and predicts the scaling of embryonic size with the tissue volume. Our theory further predicts that reduced cortical tension or disrupted tight junctions, and increased tissue stiffness lead to smaller embryonic size. These predictions are verified experimentally by embryological, pharmacological and genetic manipulations of the embryos. Remarkably, these changes to lumenal size, without a change in the tissue volume, lead to alteration of tissue architecture and cell fate. Overall, our study reveals how lumenal pressure and tissue mechanics control embryonic size at the tissue scale, that in turn couples to cell position and fate at the cellular scale.

developmental biology↗